Not all bee venom is made equal, a new study explains. According to the findings, ‘angry’ bees produce a more potent mixture. Bee venom is known for its benefits against degenerative and infectious diseases such as Parkinson’s and osteoarthritis.
This study is the first to analyze the protein diversity in samples of venom retrieved from western honeybees (Apis mellifera ligustica) in southern-western Australia. Surprisingly, they explain, bees that react with more intensity to stimuli from the researchers — in essence, more aggressive bees — produced a more protein-diverse venom.
Sting like a bee
“We found there are 99 bee venom proteins of which about one third had been formerly identified. The more proteins found in the venom, the higher the potential quality and effect,” said lead researcher Dr. Daniela Scaccabarozzi from the Curtin University School of Molecular and Life Sciences. “To understand the protein diversity of bee venom and find out what drivers impacted this, the multidisciplinary research team looked at a range of factors including the behavioral patterns of the bees.
The team worked with samples from 25 hives spread across a 200 km-latitudinal range in Southwestern Australia. The venom was analyzed using a mass spectrometer, which allowed the researchers to accurately measure levels of individual proteins. They then looked at how levels of these proteins varied with environmental and behavioral factors.
As far as behavioral factors are concerned, protein diversity levels seen in venom was associated with how active or docile individual bees were, the team reports. Bees that reacted more intensely to stimuli during the trials secreted “a richer, more protein-dense bee venom”, they add.
“The overall quantity of venom released by bees relies on the alarm pheromone secretion that induces other bees to aggressively react by stinging. This may be a result of changes in genetics that can provoke aggression in bees,” Dr. Scaccabarozzi explains.
Beyond genetic factors, temperature also seems to have an effect on the protein makeup of bee venom. High temperatures are especially detrimental to bee activity both inside and outside of the hive, according to the authors. Out of the 25 hives that they tested, the team found that those at sites with higher overall temperatures showed the lowest amounts of venom production.
“This met our expectation that seasonal factors do cause a change in the protein profile of bee venom. The optimal range for high protein diversity varies from 33 to 36 degrees Celsius,” Dr. Scaccabarozzi said.
Geographical location and the flowering stage of local flowers when harvested by the bees further impacted the composition of venom in each hive.
While research like this might seem inconsequential to most of us, it does actually have practical applications. Beekeeping is big business, and bee venom is quite the hot commodity — one gram of it can command up to US$300. Furthermore, the medicinal applications of bee venom are dependent on its quality. Knowing what factors influence this will allow us better quality and more reliable use of venom.
That being said, Dr. Scaccabarozzi says we need more research to help beekeepers ensure a constant quality of venom from their hives. This is especially important for clinical and therapeutic uses. Designing cost-effective harvesting strategies that maintain the quality of the venom would also go a long way towards establishing it for medical uses, the team adds.
The paper “Factors driving the compositional diversity of Apis mellifera bee venom from a Corymbia calophylla (marri) ecosystem, Southwestern Australia” has been published in the journal PLOS ONE.
Researchers have investigated the origins of one of the most highly specialized straits in the animal kingdom: oral venom. Unexpectedly, the researchers found that the basic genetic machinery is present in both mammals and reptiles. Specifically, there’s a molecular link between a venomous snake’s venom glands and a mammal’s salivary glands. In theory, if there’s pressure from natural selection, mice could potentially become venomous as well.
“This represents an ancient molecular framework that was likely already established in the ancestors of snakes and mammals. Mammals took a less complicated route and developed simple salivary glands while snakes diversified this system extensively to form the oral venom system. This allowed us to propose a unified model of venom evolution, namely that venoms across lizards and snakes evolved by taking advantage of existing genes in the salivary glands of their ancestors,” Agneesh Barua, a Ph.D. student at the Okinawa Institute of Science and Technology Graduate University (OIST) and lead author of the new study, told ZME Science.
Venom can be defined as a mixture of toxic molecules (“toxins”, which are mostly proteins) that one organism delivers to another (e.g. by a bite or a sting) for the purpose of defending itself, securing a meal, or deterring a competitor. Many different types of creatures — jellyfish, spiders, scorpions, snakes, and even some mammals — seem to have independently evolved venom. This had some scientists wondering whether venom actually evolved from non-venomous but related biological components inherited from a common ancestor. This couldn’t be proved — until now.
Researchers at the Okinawa Institute of Science and Technology Graduate University (OIST) in Japan and the Australian National University carefully assessed thousands of genes related to venom. Previously, scientists had focused on genes that express the toxic proteins found in venom. But Barua and colleagues took it a step further and cast a wider net so they could identify genes that were likely present before the venom system evolved.
To this aim, they used venom glands harvested from the Taiwan habu snake (Protobothrops mucrosquamatus), a pit viper that’s indigenous to Okinawa.
“We have been trying to understand how non-venomous animals evolved venom for a long time. But, this was difficult to do because venoms evolve rapidly and the ancestral state gets difficult to reconstruct with great accuracy. We worked around that by focusing not on the toxins themselves, but on the machinery that makes them, which turned out to be highly conserved,” the researcher said.
More than 3,000 “cooperating” genes were identified that interact in some way or form with venom genes. Some protected the host cells from stress caused by producing lots of toxic proteins, while others regulated protein modification and folding. This is actually extremely important because misfolded proteins can accumulate and damage cells.
“This makes perfect sense because venoms are a cocktail of toxin proteins. It is vital that the protein structure of these toxins is maintained, otherwise, the venom won’t work, and the animal would not be able to catch its prey,” Barua said.
The surprising part was when the researchers looked at the genomes of other animals, including those you’d never think to connect with a venomous creature, such as dogs, chimpanzees, or humans, and found that they contained their own versions of these genes. When they realized that venom genes were actually co-expressed together and with a relatively small number of other genes, this was a “striking moment” for the researchers.
“This suggests that there is a common molecular framework between venom glands in snakes and salivary tissue in non-venomous mammals. This represents an ancient molecular framework that was likely already established in the ancestors of snakes and mammals. Mammals took a less complicated route and developed simple salivary glands while snakes diversified this system extensively to form the oral venom system. This allowed us to propose a unified model of venom evolution, namely that venoms across lizards and snakes evolved by taking advantage of existing genes in the salivary glands of their ancestors,” Barua added.
The study suggests that salivary gland tissues within mammals were expressed by genes that had a similar pattern of activity to that seen in venomous snakes, so genes for salivary glands and venom glands must share an ancient functional core. After the two lineages split hundreds of millions of years ago, the venomous species evolved biological systems that produced toxins, the authors note.
Bearing all of this in mind, it’s not all that surprising that over a dozen species of mammals are actually venomous. These include Eulipotyphla (solenodons and some shrews), Monotremata (platypus), Chiroptera (vampire bats), and Primates (slow and pygmy slow lorises).
Theoretically, this means that virtually any species of mammal could potentially become venomous with enough prodding from natural selection.
“Humans will never develop venom. But there is a distinct possibility in other mammals. For example, suppose there is a genetic mutation in a few individuals of some species of wild mice that allows them to catch more insects. These individuals will be able to procure more food and thus have ‘higher fitness’. This could lead them to out-compete their peers in terms of mating (or just general well-being) and thereby produce more offsprings that will carry the beneficial mutation. Now imagine this happening for several generations. There will come a time when populations of these newly formed venomous mice could drive the non-venomous ones extinct, thereby firmly establishing the venom character in the gene pool,” Barua wrote in an e-mail.
“We would like to try evolving venomous mice in the laboratory. It would be a practical test of the mechanisms we hypothesise in the paper, and potentially provide clues about why venom doesn’t evolve more often.”
In the future, the team of researchers plans on further exploring the genetic regulatory network that underlies venom gland evolution.
“One question is — how does venom evolution modify this network? We’re planning a couple of different studies on this front. One is to look across species that have evolved venom, including other reptiles and mammals. Are there commonalities in these two lineages?”
“One of the main scepticisms regarding the idea of evolution is that of ‘intelligent design.’ Proponents of this idea validate it by citing examples where scientists have not been able to completely decipher the origin of highly specialised traits. Scientists have quite a good idea of how traits originate, but direct mechanistic explanations are rare owing to the incredible genetic complexity of traits. We provide a mechanistic explanation of one of the most specialised traits in nature, oral venoms. Our study, therefore, provides a firm argument for evolution and can provide people will the proof they need to denounce pseudoscientific claims like intelligent design,” Barua said.
Twenty-year-old Mamadou is lying on a metal cot, eyes half-closed, breathing fast. At his bedside sits his boss, fanning him.
Mamadou is a herder. He guides cattle through large open fields for days on end. A few days ago, having slept outdoors with the cows, he was getting ready to complete his usual route, when a sudden pain in his foot caught him off guard. He had been bitten by a snake.
And not by just any snake: Echis ocellatus, the West African carpet viper. It’s responsible for thousands of venomous bites each year, and is thought to kill more people in Africa than any other species.
Mamadou was first taken to a local health centre, but it couldn’t give him the care he needed. So he was then brought to the regional hospital in Sokodé, Togo’s second-largest city. He’s had to travel over 100 km to get here. He was bitten five days ago.
Mamadou’s story is not uncommon, and he is not the only snakebite victim on the ward. Four others have been hospitalised this week in Sokodé, and the hospital is just one of several healthcare centres in the region that deal with snakebite.
Each year an estimated 2.7 million people around the world are bitten by venomous snakes, and about 100,000 die. Most victims, like Mamadou, live in poor, rural and politically marginalised communities. Data from Africa is fragmented, but the latest figures suggest that snakebite kills up to 20,000 people each year in sub-Saharan Africa alone.
In 2017, the World Health Organization (WHO) finally recognised the problem by classifying venomous snakebite as a neglected tropical disease. This led to renewed discussions about the only specific treatment currently available – antivenom.
When adequately manufactured, distributed and administered, antivenom saves lives. But right now, the world produces less than half of what it needs. Antivenom is made using a technique that’s over a century old, and there aren’t any common standards to measure its safety or effectiveness, leading to a high risk of adverse reactions. And for over 40 per cent of the world’s snake species, there’s no antivenom whatsoever.
Even when antivenom does exist, it often doesn’t reach the people that need it. Unstable markets have driven up costs, allowing cheaper, substandard treatments to appear. With their patchy efficacy and dangerous side-effects, these are deterring people in low-income countries from seeking treatment at all. Falling demand then makes antivenom even more expensive.
The antivenom field is, in short, a disaster. Snakebite should be a treatable condition. Instead it remains, in the words of former UN Secretary-General Kofi Annan, “the biggest public health crisis you’ve never heard of”.
It’s warm where the snakes live. The air in the herpetarium is humid, and on the walls, faded posters sum up the history of antivenom production. The morning is coming to an end, and in transparent boxes, neatly piled up, 163 snakes – spanning 49 different species – are waiting to be fed.
These reptiles, housed here at the Centre for Snakebite Research & Interventions at the Liverpool School of Tropical Medicine, make up the largest and most diverse collection of venomous snakes in the UK. It’s their job is to provide venom for antivenom manufacturers and to help find new ways to treat snakebite.
Today, it’s the turn of the black mamba to be ‘milked’ – that is, to have its venom extracted.
Paul Rowley is the team’s lead herpetologist, an expert in snake handling and husbandry. Slowly, he opens the box to let the mamba out. From behind a large glass window, I follow his careful, deliberate movements as he handles the snake. It’s impressive, a couple of metres long. It’s hard to say if it’s more brown or grey, but it is definitely not black. The snake actually gets its name from the colour of the inside of its mouth.
Despite its length, the black mamba moves surprisingly quickly. Rowley and his assistant have to work together to restrain it, pinning the animal down on the table. Holding its head tightly, they then massage its venom glands to extract the venom as the snake bites on a small container topped with clingfilm. The whole process takes less than five minutes.
“Most snakes will instinctively bite as soon as they are presented with something,” says Nick Casewell, a research fellow at the centre. “As soon as you move the head of the snake towards a Petri dish, usually they will immediately bite, and you will get venom, too. But it is variable how much venom you get on a particular day.”
Milking a snake is the first step in creating antivenom. The process is over 120 years old, and has changed very little in that time. You inject small, non-toxic doses of venom into an animal – usually a horse or a sheep – to stimulate an immune response. The animal then starts producing antibodies against the venom’s toxins, and you draw some of its blood. Finally, you isolate and purify these antibodies, and make them into a stable solution that can be given to patients as an injection.
This may sound simple, but it isn’t. Because antivenom is made up of animal antibodies and foreign proteins, it can cause adverse reactions in the human body – especially if you don’t purify it well enough. Side-effects range from rashes, nausea and headaches to anaphylactic shock in rare cases.
Venoms are also complicated substances to treat. They’re made up of hundreds of different toxins, whose properties and interactions are still not entirely understood. The combinations of toxins and their effects vary widely from species to species.
Broadly speaking, there are two main families of venomous snakes: vipers (such as the West African carpet viper) and elapid snakes (such as the black mamba). Depending on the type of snake, the toxins contained in the venom can cause different problems, such as damage to the nervous system (more commonly associated with elapid snakes) and bleeding (more common with vipers), as well as swelling and tissue destruction at the site of the bite. Within one venom, distinct toxins can create different kinds of problems.
This diversity means that developing effective antivenom is difficult. An antivenom made using venoms extracted from snakes in one place will have no use in another – and yet many find their way into the wrong markets. Indian antivenom made using local species is commonly found throughout Africa, for example, despite having no effect there.
And even if the right antivenom is available, matching it to a particular snakebite is difficult.
“In at least half of cases, the snake is not seen by the patient,” says Achille Massougbodji, president of the African Society of Venomology. “Even if we have the snake, the skills to identify it are extremely low in regions where bites occur.”
Antivenom can however be manufactured to work against more than one type of snake – by immunising horses or sheep with the venom of multiple species from a region. But this ‘polyspecific’ antivenom comes with its own limitations.
In all antivenom, relatively few of the antibodies produced by the sheep or horse are actually specific to the venom’s toxins – studies suggest somewhere between 5 and 36 per cent. In polyspecific antivenom, this figure becomes even lower. “You get a mixture of antibodies that are directed towards different venoms and toxins, and you are only ever bitten by one snake,” says Casewell. “This means only a small proportion of the antibodies in that product are actually against the snake you were bitten by.”
The effect, he says, is that doctors administering a polyspecific antivenom have to use higher doses. This increases the cost of treatment. It also makes it less safe for the patient by raising the risk of side-effects.
In small rural hospitals, concerns over side-effects can leave doctors wary of administering more than one vial of antivenom. In Mamadou’s case, he was referred to Sokodé after being given antivenom so that he could get better follow-up care for the potential side-effects, as well as better treatment for the complications from his bite.
For doctors, finding the balance can be difficult without proper training. Give too much antivenom and you risk side-effects. Give too little, or too late, and it’s not going to work.
In Dankpen prefecture in northern Togo, not far from the border with Burkina Faso, green fields of yams stretch for miles. The rainy season is fast approaching, and dozens of young men are already hard at work picking up tubers from the brown earth. At the side of the road, women are selling cheeses and mangoes, piled up high in their baskets.
In this area, most people work in agriculture, and they are among the most exposed to snakebite. They’re also some of the least able to afford treatment. In Togo, like many countries in sub-Saharan Africa, people have to pay for healthcare out of their own pocket. For many rural workers, the cost is just too great. Around half the country’s households live below the poverty line, particularly in rural areas.
When it comes to snakebite, the country at least fares better than some – the government has recently subsidised antivenom. The Spanish company Inosan Biopharma has also donated 8,000 vials of antivenom, which people will be able to get for free over the next year. However, patients still have to pay for their hospital stay and for other medicines they might need in the course of treatment. And in smaller health centres, antivenom – free or otherwise – isn’t always available.
On a Saturday evening in Dankpen hospital, nurse Amandine Nassimarty is the only person on duty. She is looking after 25-year-old Michel, who was bitten by a carpet viper five days ago while harvesting yams. Curled up on his bed, his arms and legs are covered by thin crusts of dried mud – a treatment he received from the local traditional healer.
Michel has stopped bleeding, but he is still weak. Yet his relatives are asking the hospital to let him go. When they brought him in, unable to speak or swallow due to swelling and bleeding from the mouth, days after the bite, there was no antivenom left to give him. They had to travel by motorbike to the nearest town to buy two doses, costing 37,000 francs each (US$62). The legal minimum wage in the country is 35,000 francs a month.
“We have given him two doses of antivenom, but after that, the family didn’t have the means to do more,” Nassimarty says. “His parents are now asking to leave. Patients understand they should stay, but they can’t pay, and often the next day I arrive and they are gone from the bed.”
Togo isn’t the only country where this happens. The price of antivenom may vary depending on the product, but it’s usually too high for families in low-income countries. In India, it’s been reported that treating a snakebite can cost up to 350,000 rupees, when on average a farmer earned just over 8,000 rupees a month in 2015/16. When someone gets bitten, family members often have to sell some of their most precious possessions – including cattle and tools – to fund the long journey to hospital and the treatment.
And the cost doesn’t always end there. Snakebite survivors – who are often the main providers for their families – may not be able to work afterwards. A family that pays for antivenom can end up facing economic ruin, and so may avoid treatments in the future.
“Having a rural cattle herder or farmer lose a foot, they might survive, but they become a burden to their families,” says Nick Brown, medical director of MicroPharm, a British antivenom manufacturer. “It’s an unseen toll that people are just not aware of.”
It’s a vicious cycle.
People find that they cannot get effective snakebite treatment – because cost or distribution problems make antivenom unavailable, or because they’ve been given a less effective antivenom, or because their treatment has been given to them the wrong way or too long after they’ve been bitten.
This leads people to stop seeking out treatment, and governments to stop their funding for it, reducing demand and forcing manufacturers to raise their prices. This in turn leads to cheaper, less safe, less effective products flooding the market, which the manufacturers of good-quality treatments then have to compete with – or get out of the market altogether.
This happened infamously with Fav-Afrique, one of Africa’s best polyspecific antivenoms. Its manufacturer, Sanofi Pasteur, decided to stop making it because it couldn’t compete with the cost of rival products. Sanofi released its last batch in 2014, which was usable up until its expiry date in June 2016; from that point on, a new manufacturer would be needed. Only in January 2018, 18 months after that final batch had expired, did MicroPharm announce it was taking over production.
At the root of this lies the biggest – and arguably hardest – problem that needs solving: the overall lack of trust in antivenom therapy.
“When nurses and health centres don’t have the right antivenom – or any at all – each time a snakebite happens, it stigmatises a little more this incompetence. People end up considering that the doctors can’t do anything,” says Achille Massougbodji. “There is a lack of trust, which translates into people massively delaying going to consult health services.”
Many patients reluctantly arrive at hospital days after a bite, when they are too sick to be treated properly. When doctors are then unable to help them, this reinforces the idea that they should seek traditional healers first. But the longer people wait to get antivenom, the less benefit they get from it.
However, cutting out traditional healers from a patient’s therapeutic journey may not be the solution.
In the city of Atakpamé, in south-central Togo, a traditional healer sits by the side of the road, minutes away from the local hospital. On a large white sheet tied around two wooden poles, little painted icons show the different ailments he offers to cure. An eye-catching green snake sits in the top left-hand corner.
Sitting on a bench hidden behind the sheet, the old man refuses to give his name. But he is keen to show the plants and the dried-up snake heads and skins that he keeps in boxes, which are part of his therapeutic tools. Gradually, a little crowd forms around him, eager to hear him speak.
The relationship between traditional healers and their communities is deeply based on trust, and this is crucial in the context of snakebite. In many African cultures, being bitten by a snake is seen as something not entirely natural. People sometimes believe it’s a curse.
“There is this whole perception around snakes that means people tend to first go see the person who will not only treat the physical symptoms, but also address the spiritual aspects linked to snakebite,” Massougbodji explains.
So it’s unlikely that people would suddenly bypass their traditional healer to go straight to hospital. Massougbodji believes that working with healers is key – at least by training them to avoid doing things that could make the bite worse, and by getting them to redirect patients to health centres earlier.
However, rebuilding trust between patients and doctors, and getting people to seek antivenom in hospital, will only be possible if health professionals themselves have the right ideas on antivenom.
Jean-Philippe Chippaux, a research director at the Institute of Research for Development in France, knows this all too well. He has been working for decades in Africa on snakebite. He’s come to the northern Togolese city of Kara to speak to health professionals about his experiences, and to share his recommendations on how best to treat snakebite.
Much of Togo is rural, and many of the attendees see snakebite victims on a regular basis, but they never know quite how to react.
Charles Salou*, a paediatric doctor from the south of the country, is one of them. He is quite shaken up by the death of a 15-year-old boy under his watch the week before.
The boy was brought in by a nun, who paid for his treatment. Fearful of possible side-effects, Salou did as he had been taught, giving only one unit of antivenom, even when the boy’s symptoms persisted. It wasn’t enough to have an effect. The boy’s condition worsened, and he died.
Chippaux encounters misperceptions about antivenom’s safety a lot among health professionals. “They either believe it is a dangerous product that is difficult to administer, or that it’s a miracle product that can solve everything,” he says. “But that’s not the case. Antivenom is here to eliminate the venom out of the organism – not to treat the complications that arise.”
Not only do snakebite victims have to receive adequate antivenom, but they may also need to be given other medicines to help with any persisting symptoms. The problem is that little is known about the long-term complications of snakebite envenoming. Internal bleeding, for example, can still occur days after antivenom has been given.
But even if some outcomes can’t be predicted, or even treated, basic training like Chippaux’s is crucial.
“Had I received this training before the arrival of this patient, I could have saved him,” says Salou. “It pains me when I tell myself that.”
Back in Sokodé, Mamadou is getting weaker by the minute. He is suffering from severe anaemia, but the hospital doesn’t have any of the blood products that he needs. A week after his bite, it’s unlikely that more antivenom will help. Doctors are not even sure whether he is still bleeding internally, or if other problems could suddenly appear, making his condition worse.
In Liverpool, Nick Casewell and his team are working to design safer, more efficient types of antivenom – products that are more specific to the venoms that doctors in Togo and elsewhere in Africa are encountering.
The team have broken down the venoms of 22 medically important species from sub-Saharan Africa, to study the specific toxins they contain. They’re trying to understand why venom protein composition is so diverse, and how and why it differs between related species.
At the Technical University of Denmark, associate professor Andreas Hougaard Laustsen and his colleagues are also looking at toxin-specific approaches. Along with the Liverpool group, they are one of the few teams investigating a new type of antivenom made up of mixtures of human monoclonal antibodies that have been grown in a lab.
Generating cocktails of human antibodies is an idea that’s currently attracting a lot of interest. The antibodies used will be carefully selected so that they’re highly specific to important toxins, clearing them out of the body more efficiently than traditional antivenom. They should also be safer to use than animal antibodies.
In 2018, the Danish team were the first to describe the successful use of human monoclonal antibodies against snake venom toxins, in a study published in Nature Communications. The scientists used black mamba venom for their research, which they then broke down into different components, isolating and analysing the toxins.
They then used an in vitro technique called phage display to identify which types of monoclonal antibody worked best against the venom’s toxins. They ended up with a cocktail of three human monoclonal antibodies. When they tested it against the black mamba’s whole venom in mice, the cocktail stopped the venom’s effects.
Elsewhere, Matt Lewin and his team at Ophirex, a Californian pharma start-up, are investigating a small molecule called varespladib. It works by attaching itself to a set of enzymes that are a major common component of snake venom, stopping them from working, and preventing the paralysis, bleeding and muscle destruction they usually cause. Because varespladib molecules are so small, they can work against venom in bodily tissues that antivenom can’t get to.
The team are testing varespladib alone and together with antivenom to see if they can find the best way to use it. They think it might work as a solo treatment in the field, which could be given to patients right after a bite to give them more time to get to hospital. They’ve had some success using the drug to reverse snakebite symptoms in certain animals, such as mice and pigs. They’re now planning clinical trials.
All this innovative research, though promising, will take time to move outside the lab and into the hands of those that need it. “Innovations are very important, but I think it’s very important to balance it with the fact that people are dying right here and now today,” says David Williams, head of the Australian Venom Research Unit at the University of Melbourne and chair of the WHO’s Snakebite Envenoming Working Group.
The antivenom that we already have, if purified and produced following good manufacturing practices, can be absolutely life-saving, Williams says. “It can make all the difference in the world to bringing a person back to living a normal healthy life, as quickly and easily as possible, at the least cost.”
So the priorities over the coming years will be to improve the treatments we already have – including how they’re made – and to make it easier for people to get products that already have a proven track record.
To help, the WHO is currently testing antivenom quality worldwide as part of a ‘prequalification’ scheme. It’s long used this system to assess and maintain the quality of other drugs.
“I think that prequalification exercise will be a game-changer when it comes,” says Ian Cameron, MicroPharm’s CEO. “It will give African governments confidence that they are buying products with a minimum standard, which will drive the other products which are part of the problem out of the market.”
A few days after my visit to Sokodé, Mamadou died, probably from internal bleeding caused by the venom.
His case is a stark reminder that antivenom alone won’t be enough to solve the problem of snakebite. The time it took for Mamadou to receive care, and the complications he suffered despite receiving antivenom, make it clear that more research and better training and health systems are needed too.
The WHO’s envenoming strategy, published in May 2019, acknowledges this. It promotes safe, effective and affordable treatments, but underlines that treatments will only have their best effect if health systems are improved and communities engage with them. Only when patients seek care straightaway, with the right knowledge and treatments then being applied, can snakebite be most successfully treated.
But this is possible.
Amavi had been coming back from the market near her home in north-western Togo when she had her encounter with a carpet viper. It was already dark, and as she hurried home with her packages, she suddenly felt the intense pain of a bite. Thinking it was a scorpion sting – painful but rarely deadly – she decided to get some sleep and wait for the next day before seeking help.
But in the night she deteriorated. She started bleeding from the mouth and from a wound on her leg that she’d had beforehand. Her family realised it must be a snakebite. They rushed her to the local health centre in the morning, but they didn’t have any antivenom. So, wasting no more time, she perched on the back of her father-in-law’s motorcycle and travelled to the hospital in Kanté, 50 km away. It took them two hours.
“Two hours is long, but it was relatively soon after the bite,” says Chippaux. “Had they waited more, it would have been much worse.”
The hospital they travelled to is small, and its staff have few resources to work with. But when Amavi arrived, the doctors there reacted quickly. Their reaction, combined with good-quality antivenom donated by Inosan, saved Amavi’s life.
* Some names have been changed.
Wellcome, the publisher of Mosaic, is funding work to transform how snakebite treatments are researched and delivered as one of its priorities.
Nick Casewell currently receives funding from Wellcome.
This article first appeared on Mosaic and is republished here under a Creative Commons licence.
The compounds can kill unwanted bacteria but are completely harmless to humans.
Finally, a use for wasps.
Few creatures are as hated as wasps. Although they do provide some environmental services, they’re often parasitic species, they’re nasty, and their sting can pack quite a punch. Unlike bees, their stingers don’t get lodged in the unfortunate victim, but even so, a wasp’s venom can cause great pain and irritation to humans.
Naturally, it’s also excellent at killing bacteria — the problem is that it also kills healthy, clean cells. Now, A team of MIT researchers managed to tweak the wasp venom so that it only kills bacteria, and leaves good cells alone.
“We’ve repurposed a toxic molecule into one that is a viable molecule to treat infections,” says Cesar de la Fuente-Nunez, an MIT postdoc. “By systematically analyzing the structure and function of these peptides, we’ve been able to tune their properties and activity.”
The key lies in a group of compounds called peptides. These are essentially a group of amino acids linked together to form a chain. They carry out important physiological functions, and in many ways, are similar to proteins. However, peptides are much smaller than proteins. They also tend to be less well defined in structure and scope than proteins.
Peptides in the wasps’ venom kill microbes by destroying their cell membranes — this happens because the peptides have a helix-type structure, with a right-hand spiral spin (which is known to strongly interact with cell membranes). The researchers isolated a venom peptide from a wasp called Polybia paulista, whose habitat ranges over several South American countries.
The peptide is small, containing only 12 amino acids, which allows researchers to experiment with it more easily.
“It’s a small enough peptide that you can try to mutate as many amino acid residues as possible to try to figure out how each building block is contributing to antimicrobial activity and toxicity,” de la Fuente-Nunez says.
A typical alpha-helical structure.
They tweaked a few dozen versions, measuring how each alteration affected the peptide’s properties, and then tested them against seven strains of bacteria and two of fungus, further correlating their structure and physiochemical properties (such as hydrophobicity and helicity) with their antimicrobial potency. After these observations, they designed several other versions, identifying the optimal percentages and structures of different amino acids so that they harm bacteria while leaving healthy tissue intact. Then, to test if the resulting peptides really were harmless, they tested their toxicity on human embryonic kidney cells grown in a lab dish.
The cells were infected with Pseudomonas aeruginosa — a common source of respiratory and urinary tract infections. They found that one peptide could completely clear the infection, eliminating it after only a few days.
“After four days, that compound can completely clear the infection, and that was quite surprising and exciting because we don’t typically see that with other experimental antimicrobials or other antibiotics that we’ve tested in the past with this particular mouse model,” de la Fuente-Nunez says.
In addition, researchers say a similar technique could be used in a wide array of situations.
“I do think some of the principles that we’ve learned here can be applicable to other similar peptides that are derived from nature,” he says. “Things like helicity and hydrophobicity are very important for a lot of these molecules, and some of the rules that we’ve learned here can definitely be extrapolated.”
This is not the first time peptides have been used to kill pathogens. The technique is particularly promising considering the worrying emergence of drug-resistant bacteria. Not only could this technology work as a new class of antibiotics, but it could also render pathogens incapable to adapt to it since adaptation processes usually take place at the cellular walls, and these peptides actually destroy the wall.
Researchers have found a way to take advantage of one of venom’s most dangerous properties: its ability to reach the brain.
Image via Wikipedia.
The brain is the most complex human organ, and like any complex mechanism, it’s vulnerable to external interference. That’s why it’s hidden in our sturdy skulls, surrounded by cerebrospinal fluid, and locked tight by the blood-brain barrier (BBB). The blood-brain barrier is a highly selective semipermeable border that ensures no unwanted pathogens reach the brain.
However, all this protection comes at a cost: it’s really hard to for doctors to deliver necessary drugs to the brain, and sometimes, a drug has to be administered directly into the cerebrospinal fluid.
“About 98% of drugs that could have therapeutic applications cannot be used because they cannot cross this barrier,” explains Ernest Giralt one of the authors of the new study, and lab leader at the Institute for Research in Biomedicine Barcelona.
Giralt and colleagues may have found a workaround that issue, employing the usage of an unexpected substance: venom.
The venom of the Giant Yellow Israeli scorpion (Leiurus quinquestriatus), a species native to desert habitats ranging from North Africa through to the Middle East, could hold the key. The venom holds a small protein (a peptide) derived from chlorotoxin that has the ability to penetrate the blood-brain barrier.
“Our goal is to enable drugs to enter the brain and to do this we bind them to peptides specifically designed to cross the BBB. The conjugation of these drugs to the shuttles would improve their efficacy,” says Meritxell Teixidó, co-leader of the research.
Essentially, the venom could serve as a shuttle for drugs — which is not entirely a new idea. In previous studies, scientists took inspiration from a peptide found in bee venom (named apamin), making a few minor chemical modifications to ensure that it can pass the BBB. However, chlorotoxin, which is found in the venom of the scorpion, already has this ability — it’s one of the reasons why the scorpion’s venom is so dangerous. In other words, they took one of the threats of venom and found a way to use it as an advantage.
“Thousands of venoms that hold millions of peptides with the shuttle potential have been described. We chose chlorotoxin because it has already been reported that it acts like a toxin in the brain,” explains Teixidó.
So far, preliminary results are highly encouraging. Although this still needs to be investigated and thoroughly confirmed, it’s quite promising.
“Our results reveal animal venoms as an outstanding source of new families of BBB-shuttles,” researchers conclude.
The study “From venoms to BBB-shuttles. MiniCTX3: a molecular vector derived from scorpion venom” has been published in Chemical Communications.
Venomous creatures are generally regarded as threatening and dangerous — and quite often, they really are. But in a new study, researchers explain how understanding their venom and how it works could lead to new treatments for things like diabetes, autoimmune diseases, chronic pain, and other conditions.
In 326 BCE, Alexander the Great encountered lethal arrowheads in India that, based on the symptoms of dying soldiers, were most likely laced with venom from the deadly Russell’s viper.”
That’s how the new study begins its foray into how venom has been used. But it hasn’t been all bad — venom (or rather, specific components isolated from venom) can be used for treatment.
“By contrast, snake venom has been used in Ayurvedic medicine since the 7th century BCE to prolong life and treat arthritis and gastrointestinal ailments, while tarantulas are used in the traditional medicine of indigenous populations of Mexico and Central and South America,” the study continues.
So then, why haven’t we explored this more?
Venomous species account for about 15% of the planet’s biodiversity and inhabit virtually all of the Earth’s ecosystem. However, venom remains a critically understudied substance, especially because it’s generally produced in quantities that are too small to study, and the extraction process is extremely tedious. But technical innovations have allowed for better and better analysis using smaller and smaller quantities.
Nowadays, technology has reached a level where researchers are able to uncover important characteristics of venom even with realistic, small amounts. This, researchers say, raises new opportunities to study how compounds from venom could enable us to treat illnesses.
“Knowing more about the evolutionary history of venomous species can help us make more targeted decisions about the potential use of venom compounds in treating illnesses,” said lead author Mandë Holford, an associate professor of chemistry and biochemistry at The Graduate Center of The City University of New York (GC/CUNY) and Hunter College. “New environments, the development of venom resistance in its prey, and other factors can cause a species to evolve in order to survive. These changes can produce novel compounds — some of which may prove extremely useful in drug development.”
While the main focus is deriving new treatments, this isn’t the only research avenue scientists are pursuing.
For instance, peptides derived from venomous sea anemones could help treat autoimmune diseases, while neurotoxins derived from sea snails provide a non-addictive treatment for chronic pain. Scorpion venom might also be useful — chlorotoxin from the deathstalker scorpion could be the basis for a surgical tumor-imaging technique — while spider toxins could help devise eco-friendly insecticides.
To date, only 6 venom-based drugs have been approved by the FDA, but recent work is revealing many more promising therapy candidates.
There’s certainly a lot to learn from venom, and the time has never been better.
Centipedes are famous for being creepy: each segment of their body has its own pair of legs, with some species having up to 300 legs. To make matters even worse, their mouths have large, threatening claws. Nasty, right? Something about these cylinder-shaped insects just makes me shiver. Alongside the nightmare appearance, nature blessed this myriapod with another spooky feature: venom.
Scolopendra subspinipes mutilans, the star of the study. Source: Wikipedia
Although predators generally hunt smaller prey, our rock-star insect can hunt prey 15 times (or even more) larger than them. Giant centipedes from Venezuela have been witnessed crawling up cave walls and killing large bats.
Scolopendra subspinipes mutilans, our protagonist, commonly known as the Chinese red-headed centipede, which lives in Asia and Hawaii, weighs only three grams. Researchers recorded how the Chinese red-head killed a 45 g mouse and found that the mouse died due to a toxin found in the centipede’s venom. Although curiosity made me watch the video, I do not recommend viewing it unless you’re prepared for some serious gore.
The SsTx peptide toxin — nicknamed “Spooky Toxin” by the researchers — is responsible for blocking potassium channels throughout the mouse’s body. These channels are found in the cellular membrane of various cells, one of their roles is in muscular contraction. Inhibiting such molecular gateways can have critical effects on the mammal body: the cardiovascular, respiratory, muscular and nervous systems shut down all at once, death occurring in 30 seconds.
“This molecular strategy has not been found in other venomous animals.” said author Shilong Yang, a toxicologist at the Kunming Institute of Zoology in China.
This can also have real medical significance. Centipede bites accounted for approximately 1 in 10 emergency room visits due to natural causes in Hawaii. The bite has been described as very painful, with a swarm of other symptoms including swelling, redness, skin necrosis, swollen lymph nodes, headache, nausea, vomiting, palpitations, anxiety and local itching and burning sensations. Death due to centipede envenomation is extremely rare, occurring if the victim is a child, an elderly person, a cardiac patient or a pet.
Even though the discovery is frightening, there is some good news. Scientists, having identified the lethal toxin, discovered a possible antidote: Retigabine, an anticonvulsant used to treat epilepsy. This drug reopens potassium channels, thus neutralizing the toxin.
Unlike other venomous fish, a fang blenny (tribe Meiacanthus) bite won’t kill you or have you writhe in agony — it will probably make you dizzy and might even mellow you out. Their venom could form the basis of a new class of powerful painkillers.
Striped poison fang blenny. Image credits Brian Gratwicke.
It’s a tough life being a 1.5-to-3 inch (four-seven centimeter) fish in a big ocean/aquarium, as the fang blennies have found over the ages. So they armed themselves with a set of very big fangs (relatively to their body size) — two canine teeth that jut out menacingly from their lower jaw. And just to make double sure everyone got the message, they also filled these fangs with venom.
But it’s not your typical fish venom, as an international team of researchers found. Its chemical make-up most likely disorients or otherwise impairs predators’ ability to give chase by lacing them in opioids.
The good venom
Getting hold of the venom wasn’t easy. Fang blennies only inject a tiny drop of venom with each bite, much too little for a workable sample. The team worked around this issue by taking the fish out of their tanks and dangling cotton swabs in front of them until they bit to get the venom. The fish were then returned to the tanks and the swabs were suspended in a solution to draw out the venom.
Protein analysis performed on it found three components go into the mix — a neuropeptide also seen in cone snail venom, a lipase similar to the one used by certain species of scorpions, and an opioid peptide. When injected into lab mice, this venom didn’t seem to cause the animals any pain, which was surprising to say the least.
“For the fang blenny venom to be painless in mice was quite a surprise,” says Bryan Fry from the University of Queensland, co-author of the paper.
“Fish with venomous dorsal spines produce immediate and blinding pain. The most pain I’ve ever been in other than the time I broke my back was from a stingray envenomation. ‘Sting’ray sounds so benign. They don’t sting. They are pure hell.”
Stepping away from the traditional take on chemical defense, fang blennies turned to venom whose neuropeptide and opioid components seem to cause a sudden drop in blood pressure, leaving a would-be predator dazed and unable to pursue the fish. It can also be used in case the benny was already caught and eaten. One bite of the predator’s gums or tongue and the venom will make it shake, quiver, and open its jaws and gills really wide — giving the blenny a clean escape.
“The fish injects other fish with opioid peptides that act like heroin or morphine, inhibiting pain rather than causing it,” Fry explains.
“While the feeling of pain is not produced, opioids can produce sensations of extremely unpleasant nausea and dizziness. The venom causes the bitten fish to become slower in movement and dizzy by acting on their opioid receptors.”
The team can’t be sure-sure this painlessness holds true in the wild, however, since the venom has only been tested on mice — who are notorious for their limited vocabulary. There’s also the possibility that this chemical cocktail could interact differently with mammals than it does with fish.
Still, even a non-lethal effect is enough to allow blennies to escape their predators. And the venom’s effect on mammals suggests that it might be used to develop a very powerful class of painkillers.
“To put [the venom’s effects] into human terms, opioid peptides would be the last thing an elite Olympic swimmer would use as performance-enhancing substances. They would be more likely to drown than win gold.”
Bite first, venom later
The skull of Meiacanthus grammistes, showing the specie’s impressive fangs. Image credits Anthony Romilio.
Another surprising find was that the ‘fang’ part of fanged blennies likely evolved before the venom. It’s a very unusual evolutionary line. Most venomous animals, take snakes for example, developed venomous glands first, which then required a delivery system, creating the evolutionary need for fangs. But these tiny fish seem to have grown the canines first and the venom then evolved to make them even more useful.
“These unassuming little fish have a really quite advanced venom system, and that venom system has a major impact on fishes and other animals in its community,” says study co-author Nicholas Casewell of the Liverpool School of Tropical Medicine.
Some other species have found a way to cash in on the venom without going to the trouble of actually evolving to incorporate it — by mimicking the color patterns of venomous fang blenny species, nonvenomous blennies and other small fish can ruse predators into backing down.
“Predatory fish will not eat those fishes because they think they are venomous and going to cause them harm, but this protection provided also allows some of these mimics to get very close to unsuspecting fish to feed on them, by picking on their scales as a micropredator,” Casewell adds.
“All of this mimicry, all of these interactions at the community level, ultimately are stimulated by the venom system that some of these fish have.”
Fry said the fanged blenny was an “excellent example” of why nature and unique habitats must be protected, particularly the Great Barrier Reef.
“If we lose the Great Barrier Reef, we will lose animals like the fang blenny and its unique venom that could be the source of the next blockbuster painkilling drug.”
The team started their study with “no grand hypothesis, just basic wonderment” says Fry, but given the results, they plan to continue the study by analyzing the composition of venoms from different blenny species.
The paper “The Evolution of Fangs, Venom, and Mimicry Systems in Blenny Fishes” has been published in the journal Current Biology.
Cobras are some of the most dangerous snakes in the world, causing crippling losses in Africa and Asia. Even for survivors, amputation is often necessary due to the snake’s flesh-eating venom. But why, and how did they evolve this venom?
The cobra’s dramatic hood and its coloring is a defensive signal that indicates the extreme potency of its venom. Image credits: N. Panagides et al., 2017/Toxins
Associate Professor Bryan Fry of UQ’s School of Biological Sciences wanted to get to the bottom of this extremely dangerous mystery, so they analyzed 29 cobra species and related snakes, finding that the flesh-destroying venom evolved side by side the distinctive broad hoods that make the cobras extra terrifying.
“While we knew the results of their venom, how the cobra’s unique defensive venom evolved remained a mystery until now,” he said. “Our study discovered the evolutionary factors shaping not only cobra venom, but also the ornate markings on their hoods, and the extremely bright warning colourings present in some species.”
Overall, there are over 270 cobra species spread throughout Africa and Asia, and they exact a terrible toll on both human and animal victims. Their venom — which by the way isn’t only delivered by biting, but also by spitting — causes extreme pain, blindness, respiratory failure, possible amputation of limbs, and can very easily kill you. Scientists are very well aware of the flesh eating properties, but did it evolve as an offensive or as a defensive mechanism?
Fry found that as the cobras developed this type of venom, their hoods started to change — warning off potential predators with hood markings, body banding, red colouring and spitting. So they developed an extra-dangerous venom, and they did their best to make sure everyone knows. The more ornate the cobra, the more dangerous the venom.
“Their spectacular hoods and eye-catching patterns evolved to warn off potential predators because unlike other snakes, which use their venom purely for predation, cobras also use it in defence,” he said. “For the longest time it was thought that only spitting cobras had these defensive toxins in high amounts in their venoms, however we’ve shown that they are widespread in cobras. These results show the fundamental importance of studying basic evolution and how it relates to human health.”
Associate Professor Bryan Fry in the Sindh desert of Pakistan with a cobra. Credit: Courtesy Associate Professor Fry
So the potency of the venom developed as a defensive mechanism, but even more interestingly, it developed twice, independently. The first time, in “true” cobras, and then secondly, in king cobras — despite the world ‘cobra’ in their name and despite being the largest venomous snake in the world, king cobras are not real cobras, but they evolved the same mechanism, both for the venom and for the hood.
Now, the next step for researchers is to perform tests on antivenom, to better understand how it can be improved. Because most snakebites occur in developing parts of the world, producers have been reluctant to enter the market, or have left it altogether. Antivenom production in general is underdeveloped.
“Globally, snakebite is the most neglected of all tropical diseases and antivenom manufacturers are leaving the market in favour of products that are cheaper to produce and have a bigger market,” he said. “Antivenom is expensive to make, has a short shelf life and a small market located in developing countries. Therefore, we need to do further research to see how well those remaining antivenoms neutralise not only the toxins that kill a person, but also those that would cause a severe injury.”
Also encouraging is the fact that this type of antivenom could be used in treating some cancers. Because the venom only attacks some tissues and leaves others unharmed, it might be “trained” to only attack cancerous cells. In the end, the devastating venom of the cobra could hold a much-needed cure.
“Any kind of compound that selectively kills cells could be a good thing,” Dr Fry said. “These chemicals may lead to new cancer treatments if we can find ones that are more potent to cancer cells than normal healthy cells. Cobras are a rich resource of novel compounds in this way so there may ultimately be a silver lining to this very dark cloud.”
Journal ref: Nadya Panagides et al. How the Cobra Got Its Flesh-Eating Venom: Cytotoxicity as a Defensive Innovation and Its Co-Evolution with Hooding, Aposematic Marking, and Spitting, Toxins (2017). DOI: 10.3390/toxins9030103
A serious killer. Credit: University of Queensland
Meet the blue coral snake (Calliophis bivirgatus) — a mesmerizing long-gland snake that’s called as the ‘killer of killers’ because it’s known to attack and eat some of the deadliest snakes in the world. King cobras are on the menu, for instance. Now, a team of researchers who studied the snake’s glands say its venom targets brain receptors that are involved in processing pain in humans. The next generation of painkillers which are quicker and stronger than anything before it could come from this slithering assassin.
You often have to look in peculiar (and dangerous) places for innovation
The snake’s venom gland can be as long as a quarter of its body length. When bitten, a prey will spam becoming instantly paralyzed. Credit: University of Queensland
Native to southeast Asia, the blue coral snake has the biggest venom glands in the world, reaching one quarter of its 2-meter long body length. An international team of researchers, among them Dr Bryan Fry from the University of Queensland, sought to investigate the therapeutic potential of this killer’s venom because it acts very fast.
Venomous snakes can kill people, but the venom itself is typically slow-acting. The prey is dead in hours, but if you extract the venom and turn it into a drug, you can get a nice sedative. The blue coral snake’s venom, however, acts lightning fast because it needs to kill dangerous predators as soon as possible so as not to leave room for retaliation. Making drugs out of this kind of venom, which is similar in action to that of some scorpions and cone snails, could make for a nice painkiller. The added benefit is that it would come from a vertebrate, which would make the drugs more compatible to humans from an evolutionary perspective than venom sourced from scorpions, for instance.
“The speciality in my lab is to use evolution as our map, so we seek out the weirdest things we can find,” Dr Fry told News.com.au. “Because we have a very simple premise that if you want to find something new and wonderful for use in human medicine, you’re more likely to find it from a very unusual venom.”
Simply put, “We can’t predict where the next wonder drug is going to come from,” the venomologist said.
“Here out of this enigmatic, extraordinarily rare animal we have made a discovery that could greatly benefit human health.”
Dr Fry and colleagues found out how the blue coral snake causes its victims to instantly spasm. Inside the venom, a number of unusual peptides bind to receptors in the brain and causes all of the victim’s nerves to fire at once. This neural overload causes instant paralysis.
These peptides act on a particular set of sodium channels which are known to be important in treating human health. So, even if the snake’s venom doesn’t get turned into a drug itself, at least we can learn a lot about how pain relief in the brain works, said Fry.
Also, what Fry and colleagues have done is an exercise in creativity and taking cues from nature. In the future, however, such exercises will become increasingly difficult as the threat to biodiversity becomes greater. Nowadays, the blue coral snake is very rare after its habitat has been reduced by 80 percent. Who knows what other wonders of nature hold secrets and keys to human happiness, longevity or wellness. The products of millions of years of evolution stand before our noses — and we’re squandering them.
A new paper from the Vanderbilt University in Nashville found that one virus, named WO, has hijacked venom-coding genes from the black widow spiders. They suspect the virus uses these genes to overcome cellular defenses in their search for bacterial prey.
Hello, I am the stuff your nightmares are made of. And now these viruses are too. Image credits peasap / Flickr.
It’s not unusual for viruses to steal genes from the organisms they infect. What is surprising, however, is finding bacterial virus — a bacteriophage — exhibiting genes from anything other than bacteria, since it doesn’t infect anything else. However, when Sarah and Seth Bordenstein, microbiologists at Vanderbilt University in Nashville, Tennessee, sequenced the genome of the WO virus, they found exactly this.
The duo was studying eukaryotic viruses (which infect larger cells with a nucleus), who often conscript genes from their hosts to help in overcoming their powerful immune systems. WO, while being a bacteriophage, faces a pretty unusual challenge. It targets the Wolbachiabacteria living in the cells of insects, spiders, and some other animals — so it has to be able to deal with these cells’ far more powerful defenses. So the Bordensteins wanted to see if it would also steal genes to help it survive.
They found several genes closely related to some found in eukaryotes, including one which codes latrotoxin, the venom used by black widow spiders. This substance destroys cell membranes, causing their contents to spill out — and, for a virus that needs to get in and out of cells quickly, having a gene that pokes holes in their walls sure comes in handy. The other eukaryote information found in WO’s genome most likely helps it in evading detection by the immune system.
Wolbachia bacteria infected by viruses, enlarged in the bottom left. Image credits Michelle Marshall and Seth Bordenstein.
And the sheer quantity of eukaryote information they found in the virus genome was stunning. This is the first virus we’ve seen stealing genes from more complex cells, and almost half of its genome is made up of stolen genes. WO probably picks up the eukaryote DNA after breaking out of a Wolbachia cell into the animal cell.
“For a phage to devote about half its genome to these eukaryotic-like genes, they must be important to the phage function,” says Sarah Bordenstein.
This find shows the evolutionary adaptability of phages says Ry Young, who is the director of the Center for Phage Technology at Texas A&M University, College Station. When taken together, their rapid life cycle, high mutation rate, and sheer numbers mean that any possible adaptation will occur relatively quickly.
“Phages are the most advanced form of life on Earth,” he says, only partly joking. “They’ve evolved more than we have.”
The full paper “Eukaryotic association module in phage WO genomes from Wolbachia” has been published in the journal Nature Communications.
The first venomous (yes, venomous – not poisonous) frog was discovered in Brazil by mistake. A frog head-butted Carlos Jared in the hand, and after a while he started feeling a strange pain; it took him a while to connect the dots and realize that the frog was responsible for the pain he was feeling and decided to find out what he was dealing with.
A closeup of C. greeningi frog skin that reveals the spikes on its head. Image credits: Carlos Jared.
‘Venomous’ and ‘poisonous’ are sometimes used interchangeably, but they are different terms. Some frogs are poisonous when eaten and even when touched, but they don’t have a delivery mechanism – in other words, they’re not really venomous. Also, frogs have no fangs (like snakes do), so delivering venom would be quite difficult for them. However, two species of frog in Brazil have been found to be capable of injecting poison using horns on their head. They charge on their opponent and headbutt them, injecting the venom through the horns. This was not only surprising, but raised significant questions about animal toxicology. The study that describes the species writes:
“These frogs have well-developed delivery mechanisms, utilising bony spines on the skull that pierce the skin in areas with concentrations of glands,” the study said. “Because even tiny amounts of these secretions introduced into a wound caused by the head spines could be dangerous, these frogs are capable of using their skin toxins as venoms against their would-be predators.”
Edmund Brodie of Utah State University in the United States explains:
“Discovering a truly venomous frog is nothing any of us expected and finding frogs with skin secretions more venomous than those of the deadly pit vipers … was astounding,” Dr Brodie said.
Jared, now at the Butantan Institute in São Paulo, had to investigate the frogs under a microscope to realize how this mechanism works. Basically, bone spikes erupt near the venom glands, and as the frog’s lips curl back, the glands dribble the venom onto the spikes sticking out of the skull. Then, it’s simply a matter of poking the spikes against the foe.
Corythomantis greeningi frogs carry potent venom in their pouts. (Carlos Jared)
“This is very, very cool. Unprecedented would actually be an understatement,” says Bryan Fry, a molecular biologist at the University of Queensland who was not affiliated with the study. But if we already knew frogs could be poisonous, why is this discovery such a big deal? The answer lies in the often-misunderstood difference between poison and venom.
The venomous traits of the two species, Corythomantis greeningi and Aparasphenodon brunoi actually have a very strong venom; pound per pound, it’s almost twice as dangerous to mammals as typical venom of the fearedBothrops pit vipers, scientists explain. Tests have shown that one gram is capable of killing more than 300 000 mice or about 80 people. However, they produce it in much smaller quantities.
“It is unlikely that a frog of this species produces this much toxin and only very small amounts would be transferred by the spines into a wound. Regardless, we have been unwilling to test this by allowing a frog to jab us with its spines,” Dr Brodie said.
Finding this species shows just how much we still have to learn about animal toxins and venom. Venoms have popped up some 30 times in the tree of life, usually from usual enzymes. For example, spider venom originated from a harmless hormone—the spider version of insulin. Over time, evolution favors individual with more potent venoms. But in the case of the frogs, this came as a complete surprise.
“Even the most recent book on Brazilian frogs lists them as nontoxic,” says study co-author Edmund Brodie.
Cone snails have one of the most dangerous venom in the animal kingdom. This complex venomous soup is made up of thousands of chemicals used both to hunt prey and ward off predators. The venom is enough to kill a human in a matter of minutes. Now, these lethal chemicals could be used to create a new class of painkiller for chronic pain and cancer patients undergoing chemotherapy, according to University of Queensland researchers. The same team also used a genetic and proteomic to find out how the cone snails developed its venom. Apparently, the animals initially used their chemical weaponry as a defense mechanism and later on adapted it into an attack.
Cone snail snatching a goldfish. Photo: Bionews
Thousands of peptides (mini-proteins) called conotoxins make up the cone snail venom. Different conotoxins can be found in every Conus species.
The cone snails are quite diverse, too. Some hunt slow-moving worms or other snails, while other species attack fast-moving fish. This is quite a difference. Previously, researchers found cone snails produce and use different venoms for attack and defense. The attacking type is made at the end of the venom duct, while defense venom at the other end. So, by studying the toxins of stunned prey, researchers can tell whether the snails attacked or warded off.
Image: Proceedings of the Royal Society B,
Particularly, to catch fish, the fast-prey hunting cone snails use delta-conotoxins. These toxins stop nerve signals in their tracks and cause quick and deadly paralysis. The reasoning was that cone snails that hunt slow-moving prey have no need for d-conotoxins. Using novel genetic techniques, however, the team from University of Queensland and Université Montpellier found d-conotoxin (d-SuVIA) in the venom of the worm-hunting Conus suturatus. They also discovered 11 other novel d-conotoxin-like sequences from other worm-eating cone snails.
Moreover, these toxins were produced in the venom duct for defense purposes. So, what gives? Well, when the researchers injected the toxin into mice, the mice displayed behaviors consistent with intense pain. As we know, pain is a great mood killer for predators. More plainly, these conotoxins – though heavily used by modern species to kill fish – weren’t initially developed to attack, but to stun and scare predators away.
“We propose that defensive d-conotoxins were originally used by ancestral worm-hunting cone snails to protect against threats such as cephalopod and fish predation,” the authors write in Proceedings of the Royal Society B, “and have been repurposed for fish-hunting.”
An evolutionary tree showing the relatedness between the new worm-hunting snail d-conotoxins and the d-conotoxins found in fish-hunting species. Image: Proceedings of the Royal Society B,
The study delved deeper than ever before in the cone snail venom chemical and biological makeup. Professor Paul Alewood, from UQ’s Institute for Molecular Bioscience, said the team used biochemical and bioinformatics says the findings could be used to develop a new framework that might produce new painkillers. There are 25 known frameworks discovered over the past 25 years, many of which have already led to a drug or drug lead for several diseases.
“Cone snail venom is known to contain toxins proven to be valuable drug leads,” he said.
“This study gives the first-ever snapshot of the toxins that exist in the venom of a single cone snail.
“Cone snail venoms are a complex cocktail of many chemicals and most of these toxins have been overlooked in the past.”
“We expect these newly discovered frameworks will also lead to new medications, which can be used to treat pain, cancer and a range of other diseases.”
Every year, roughly 100,000 people around the world die from a venomous snake bite. Depending on the toxicity of the venom and how much venom is injected into the body, a snakebite will cause tingling, muscle weakness, nausea, swallowing difficulties, excess saliva, and potentially fatal breathing problems.
To avoid death, a snakebite victim must immediately go to a hospital for antivenom treatment. If the patient arrives in due time — and if the hospital has the corresponding antivenom in stock — there’s an almost 100% chance of survival. As you might have guessed, the reason why so many people die from venomous snake bites is that even if a hospital is nearby, there often isn’t enough antivenom to spare. In this post, you’ll learn how antivenom is made, the challenges to antivenom production, and why antivenom is so precious.
Photo: P. Mirtschin, Venom Supplies
The first antivenom
It’s amazing to find out that antivenom was first introduced only 100 years ago — until then, people could only rely on their own immune system to survive, which frequently didn’t cut it. Albert Calmette, a protege of the famous Louis Pasteur, made the first antivenom serum in 1896 in present-day Vietnam after a flood forced monocled cobras into a village near Saigon, where they bit at least 40 people and killed 4. A man of science, Calmette wasn’t satisfied with hope alone to save those unfortunate enough to get bitten, so taking inspiration from the then-innovative vaccination wave, he made it his mission to create antivenom. He eventually discovered a process by which horses could be injected with venom to produce antibodies. He then extracted blood from those horses and injected it into the snake-bitten victim. Today, although techniques have improved over the century, the process remains more or less the same.
How to make antivenom
In a typical antivenom institute, various species of snakes are bred, cared for, and constantly monitored to ensure they are in good health. When the time is ripe, professionals introduce the snakes (which can include some of the deadliest, like banded kraits or black mambas) into a milking room. The snake is grabbed with the thumb and index finger at the very back of the head just behind the angle of the jaw where the venom glands reside. This allows the snake milker to press the snake’s glands without allowing the snake to turn and bite — even so, many professional snake handlers are bitten hundreds of times during their career.
The quantity of venom even seasoned professionals can milk is very small, so the snakes have to be milked many, many times to produce a useful amount. For instance, it took a total of three years and 69,000 milkings to produce a single pint of coral snake venom. Once milked, the venom must be cooled to below -20℃ and is then typically freeze-dried for easier storage and transport. This process also concentrates the venom by removing water. Of course, each vial of venom needs to be correctly labeled with the snake’s species, geographical position and so on. Then comes the immunization part.
Traditionally, horses are used to create antibodies because they thrive in many environments worldwide, have a large body mass, get along with each other and are familiar enough with humans that they aren’t easily scared by the injection process. Goats and sheep are also used, as well as donkeys, rabbits, cats, chickens, camels, and rodents. Some institutes even experiment with sharks. The antivenom produced from sharks is quite effective, but they’re rarely used for obvious reasons.
Before injecting the animal, chemists carefully measure the venom and mix it with distilled water or some other buffer solution. Most importantly, an adjuvant is added to the solution so that the horse’s immune system reacts and produces antibodies that bind to and neutralize the venom. A veterinarian supervises the process at all times so that the horse (or another animal of choice) remains in a healthy condition. Antibodies in the horse’s bloodstream usually peak in about 8-10 weeks. At this point, the horse is ready to have its blood harvested — typically 3 to 6 liters of blood is drained from the jugular vein.
Blood vials are centrifuged for purification. Photo: USFWS/Southeast/Flickr
The next step in the antivenom fabrication process is purification. The blood is then centrifuged to filter the plasma — the liquid portion of blood that doesn’t contain blood cells — to allow separation of the antivenom. During this step, producers typically employ their own methods, many of which are kept a trade secret. However, typically, unwanted proteins are discarded through precipitation by either adjusting the plasma’s pH or adding salts to the solution. One of the last steps in antivenom preparation involves using an enzyme to break down the antibodies and isolate the active ingredients. The last step is usually checked by an outside regulatory body like the FDA in the United States. Once approved, the samples are concentrated in powder or liquid form, then frozen and shipped to hospitals where they’re most needed.
As you can see, the process is extremely complicated, expensive, and of little yield. For instance, a typical antivenom vial costs $1,500 to $2,200, but a snakebite requires between 20 and 25 vials to be neutralized. If you add these up, a man bitten in the US by a venomous snake would have to pay $30,000 in pharmacy costs alone. Yet most snake bites occur in developing countries, especially in rural areas of the tropics. Because the costs and energy required to produce antivenom are so large, producers don’t make enough to provide to these areas because it’s not financially feasible, despite high demand for the product. As such, even if these individuals make it to a hospital for treatment, antivenom is in little or no supply.
How to turn yourself into an antivenom
Antivenom isn’t the only way to survive a highly venomous snakebite. An alternate route, which is only feasible for those that are constantly exposed to the risk of being bitten by venomous snakes, is to build tolerance — after all, humans have been intentionally exposing themselves to poisons for millennia. The first account of such practice may be found in the story of king Mithridates, the ruler of Pontus (a region of in Asia Minor). Mithridates was openly opposed to the Romans, and in those times, the weapon of choice for assassinating the upper class was poison. Paranoid about getting killed after every morsel of food, Mithridates eventually became a veritable scientist and poison control expert. The details are sketchy and have been lost in time — some say he poisoned ducks, then drank of those who survived. Nevertheless, we know that he discovered that by gradually exposing himself to a nonlethal dose of poison (say, arsenic) he would eventually build up immunity — up to a point. Ironically, he killed himself by ingesting an immense amount of poison after suffering a decisive defeat at the hands of the Romans. The practice is now commonly known as mithridatism, which also works for snake venom.
Haast handling a nervous cobra. Photo: bilhaast.com
Bill Haast, a famous snake handler who died at age 100, was known for milking up to 100 snakes a day. You can imagine that, at this rate, he would get bitten often. Realizing this, in 1948 he began injecting himself with increasing doses of diluted cobra venom in order to develop his own immune resistance. By the time he died — of natural causes, we should add — Haast had survived 172 bites from many of the world’s deadliest snakes, including a blue krait, a king cobra, and a Pakistani pit viper. He even flew around the world and donated his blood for direct transfusion, thus saving 21 victims.
Scorpion toxins may soon be useful as anticancer drugs. Credit: Courtesy of Dipanjan Pan
The difference between a poison and a cure is the dosage – and this could be very well said about this approach. Bio-engineers report that peptides in some venoms bind to cancer cells and block tumor growth and spread and could be effectively used to fight cancer – the only problem is they might also harm healthy cells.
Bioengineer Dipanjan Pan and coworkers at the University of Illinois, Urbana-Champaign, are now using polymeric nanoparticles to deliver venom toxin directly to cancer cells. The problem is limiting the effect it has to the cancer cells, and avoiding any damage to healthy cells. The researchers inserted a derivative of TsAP-1, a toxin peptide from scorpion venom, into specific spherical nanoparticles, constructing what they call NanoVenim. When they tested it on cancerous tissue in the lab, NanoVenim was 10 times more effective at killing the cancerous cells and spreading their growth than the toxin alone.
They researched a similar procedure with a nanoparticle-encapsulated version of melittin (a toxin from honeybee venom), and the results were even more promising. The toxin had potency against cancer cells, but on the upside, it didn’t do any damage at all to healthy cells.
“We have known for some time that venom toxins have anticancer potential, if only we could deliver them safely and selectively to tumors,” said David Oupicky, codirector of the Center for Drug Delivery & Nanomedicine at the University of Nebraska Medical Center.
However, the trick here is nanotechnology; even a simple nanotechnological delivery method can work wonders (such as increasing the efficiency 10 times). Pan’s idea with scorpion venom injected through nanotechnology “is new, and the method of incorporation into nanoparticles is fairly new as well,” he added. But it’s perhaps the honeybee venom which shows the most promise:
“[That it] works against cancer cells but appears not to damage erythrocytes is an important step toward practical application. It will be very interesting to see how the particles behave in vivo.”
Now, having successfully tested the idea on lab tissue, the next step is to conduct animal tests. Pan’s team founded a start-up, VitruVian Biotech which will conduct testings on rats and pigs. However, with so promising results, he believes that they could start human clinical trials in three to five years.
I know this sounds much like a joke, how black mamba venom can really ease you of your pain – but it’s not. A painkiller just as effective as black mamba venom but without the unwanted side effects has been found by French researchers in the venom.
The predator, like many other snakes, uses neurotoxins to paralyze and kill small animals, but according to the team’s research, the venom also contains a very potent painkiller, most likely working to calm down unlucky prey. The researchers analyzed 50 different mamba species before ultimately finding the black mamba’s pain-killing proteins – called mambalgins.
“When it was tested in mice, the analgesia was as strong as morphine, but you don’t have most of the side-effects.”
Morphine has been used as a painkiller for a very long time; it acts on the opioid pathway in the brain (like opium), calming the pain, but also causing addiction, headaches, occasional vomiting, and muscle twitching. However, mambalgins tackle pain in a completely different way, which have virtually no side effects. However, the findings have only been studied in mice so far.
“It is the very first stage, of course, and it is difficult to tell if it will be a painkiller in humans or not. A lot more work still needs to be done in animals.”
This is not only about finding a replacement for morphine, we’re talking about an entire new class of analgesia.
“It’s very exciting, it’s a really great example of drugs from venom, we’re talking about an entirely new class of analgesics.” said Dr Nicholas Casewell, an expert in snake venom at the Liverpool School of Tropical Medicine. Dr Lingueglia said it was “really surprising” that black mamba venom would contain such a powerful painkiller.
A remarkable MIT research has found that by coating carbon nano-tubes with bee venom they can create incredibly faithful sensor detectors for explosives, such as TNT, as well as at least two different types of pesticides.
The find came after MIT chemists, lead by Michael Strano, coated one-atom-thick tubes of carbon with protein fragments found in bee venom saw that the compound reacts with explosives. Not only this, the resulting sensors are actually hypersenstive to the explosives, in terms that each sensor can detect explosives on a molecular level. Also the sensor can also detect the chemical molecules of the explosives as they break down, which could provide experts with a foot print for each explosive and a better assesement of an explosion site.
“When it wraps around a small wire, that allows it to recognize ‘nitro-aromatics’,” Strano explains, the chemical class of explosives like TNT. That wire is a carbon nanotube, a mere one atom thick.
Its applications aren’t limited to explosives either, as the researchers found that the coated nanotubes can also detect two pesticides that contain nitro-aromatic compounds. Meaning that the bee venom detector could be applied in fields from military, to airport security, to agriculture.
Strano has filed for a patent on the sensor, while the team is still working out a compression system to ensure that any molecules in the air come into contact with the tubes and are therefore detected – an indispensable system. A commercial product of this bee venom derived sensor could very much prove to be successful, if it holds up to its claims and proves to be flawlessly reliable, as it is needed in explosive detection.
Boy, you just can’t have enough octopus, that’s for sure – they’re really amazing creatures, that often surprise us. Now, a venomous octopus living in the frozen waters of Antarctica is definitely awesome, but how is this useful?
Well, according to Bryan Fry, of the University of Melbourne, it is. He and his team have been studying how evolution changed the way this octopus hunts, as well as the nature of the venom. The way they do things is drill small holes into large, shelled prey and then inject the toxic saliva.
“We found that venom can work at sub-zero temperatures. It was quite remarkable to find how well octopuses have adapted to Antarctic life,” Fry said.
He also noted the remarkable diversity of the species, with specimens varying in size from as little as a few inches to several meters.
“Evolutionary selection pressures slowly changed their venom, which allowed them to spread into colder and colder waters and eventually spread into super-cold waters,” Mr Fry said. We want to see what cool and wonderful new venom components we can find out of these venoms that would be useful in drug development,” he said. Nature has designed a perfect killing weapon … they have such incredibly accurate activity that there has to be a way to harness that. To tweak it or modify it or just use one little chunk.”
If we take a look at hypertension drugs (such as ACE inhibitors) that are modeled after snake venom, and other diabetes drugs (modeled after lizard saliva), it is understandable where the benefits of this study could pop up.
So, microorganisms and other humans aside, what do you think is the deadliest creature in animal kingdom? A snake, perhaps a lion or bear, a scorpion perhaps? Neah, not even close. The deadliest creature in the world is actually called a sea wasp.
Specialists use the term ‘deadliest’ when they refer to venomous creatures, that produce toxins that can be harmful or deadly to other animals or humans. When they make this ‘top’, they take into consideration two things:
– how many people can an ounce of the venom kill; and
– how long does it take to die from that venom.
For both of those things, the undisputed winner and (as far as we know) all time record holder is the sea wasp. Don’t let the name fool you, because the sea wasp is actually a jellyfish (we’ve been having a lot of those lately); on each tentacle, they have about 500.000 nematocytes. Nematocytes are basically needles that inject venom in everybody that happens to tocuh them.
They actively hunt their prey and they’re quite fast swimmers for jellyfish (5 mph), but are not aggressive and they try to avoid humans. What’s interesting is that turtles are not affected by their venom and actually eat these jellyfish (nature sure has its ways).
If (and we hope not) you would get stung by such a jellyfish, a bottle of vinegar and a first aid kit may very well save your life. Here’s how it goes: pour vinegar over the stung areas. The pain is almost unbearable and vinegar won’t help with that, but it will render the nematocysts that haven’t ‘fired’ harmless. If you attempt to remove the tentacles, it’s very possible to activate them and do even more damage. It’s quite safe to say that vinegar has saved dozens of lives, especially on the Australian beaches.
The Komodo dragon is definitely one of the most impressive and dangerous creatures to roam the Earth. Reaching 3 metres and more than 70 kilos and delivering one of the most fatal bites in the reptilian world, it’s no wonder that it inspired so many legends and fears. However, it does not all end here: it seems that this modern dragon is also among the few species of lizards that are venomous.
Until recently scientists had all kinds of assumptions related to the way the dragon kills its prey as it releases it after the bite. Did they let the prey die because of the severe bleeding or did the bacteria in their saliva finish the job?
Komodo dragons feed on large mammals such as wild boars, deers or goats and they spend hours motionless waiting for the prey to show up. The attack is surprising as the huge lizard ambushes it with its jaws open, which must be an image worse than any nightmare.
The mystery of its killing methods remained until magnetic resonance imaging scans revealed the fact that the bite, which is clearly weaker than the one of a crocodile for example, hid a dirty secret: venom glands.
After this discovery, the glands of a terminally-ill dragon from a zoo were removed for further study. It seems that the poison is similar to the one found in Gila monsters or snakes. The effect is sudden and devastating: it causes a sudden drop in blood pressure which sends the prey into shock. Moreover, it stops the blood from clotting, thus making the animal bleed to death.
The discovery suggests that other lizards may as well hide a trick like this; util recently only the Gila monster and the Mexican beaded lizard, both living in southern US states and Mexico were known to possess venomous glands.