Tag Archives: bird flu

H7N9 Avian Influenza (Bird Flu) Vaccine Trials Begin

Avian influenza (or bird flu) is a ‘zoonotic infection’ (meaning it is transmitted to humans via animals) caused by viruses that have adapted to affect birds. It primarily affects poultry, such as chicken and ducks. Human infection predominantly occurs via direct contact with infected birds or poultry – their droppings or their contaminated environment – or by handling live or dead birds. The avian influenza virus strains are distinct from human seasonal influenza, and humans have little immune protection as this type of viral infection is relatively uncommon. Clinical presentation of avian influenza in humans includes eye infections (conjunctivitis), flu-like symptoms (e.g., fever, sore throat, cough, muscle aches), or severe respiratory illness (e.g., chest infection).

In the past, the H5N1 strain of influenza virus has been responsible for most human illnesses that have been caused by avian influenza. However, H7N9 now rivals H5N1 as a potential cause of a human pandemic. H7N9 had not been seen in humans until infections were reported in March, 2013, in China. It had previously been isolated to outbreaks in birds in Japan, the Netherlands, and the U.S. Since then, six waves of H7N9 infection have occurred in China, resulting in more than 1,500 cumulative human infections, according to the World Health Organization (WHO). Most cases of human infection with the avian H7N9 virus reported they had had recent exposure to live poultry or potentially contaminated environments, especially markets where live birds were being sold.

Current evidence suggests this virus has not acquired the ability to regularly transmit from human to human, except for small clusters of reported cases which predominantly involved healthcare workers. While a small proportion of human H7N9 illnesses have been mild, most patients have become seriously ill, developing severe respiratory symptoms that required hospitalization and intensive care, and 32 percent diedH7N9 can infect poultry without causing clinical symptoms, which makes monitoring its spread difficult. Health officials reckon the situation is under control, but this could change quickly given avian influenza’s ability to change rapidly. Experts fear that further genomic mutations will lead to the virus binding to human cells, ultimately leading to increased human-to-human transmission.

There is, currently, no vaccine to protect against H7N9. However, two new clinical trials testing an experimental vaccine to prevent H7N9 infection are now enrolling volunteers across the United States. The studies, sponsored by the National Institute of Allergy and Infectious Diseases (NIAID), will test different dosages of the inactivated influenza vaccine candidate (called 2017 H7N9 IIV), as well as different vaccination schedules. The studies also will evaluate whether an adjuvant would be helpful in boosting the immune responses of people receiving the vaccine. The vaccine has been developed by Sanofi Pasteur with support from the Biomedical Advanced Research and Development Authority, part of the US Department of Health and Human Services. Dr. Anthony Fauci, NIAID director, said in a statement:

“As we experience one of the worst seasonal influenza epidemics in recent years, here in the United States, we also must maintain a scientific focus on novel influenza viruses, such as H7N9, that have the potential to cause a pandemic.”

One clinical trial, led by principal investigator, Dr. Lisa A. Jackson, of the Kaiser Permanente Washington Health Research Institute in Seattle, will test the vaccine candidate in various dosages, both with and without the AS03 adjuvant. The second clinical trial will be led by Dr. Kathleen M. Neuzil of the University of Maryland School of Medicine. This trial will test the H7N9 vaccine candidate with AS03 adjuvant in conjunction with a quadrivalent seasonal influenza vaccine. For more information about the two clinical studies, please check out the Questions and Answers.

Adelie penguins going about their way. Photo :Peter & J. Clement/

New bird flu infects Antarctic penguins

Adelie penguins going about their way. Photo :Peter & J. Clement/

Adelie penguins going about their way. Photo :Peter & J. Clement/

It’s so cold even penguins get the flu in the Antarctic. Seriously, researchers report in a paper published in the journal mBio how they identified a new strain of influenza that infects Adelie penguins which breed in huge colonies on the rocky Antarctic Peninsula. The virus itself seems to be dormant as the penguins don’t exhibit any visible flu symptoms, yet the findings do raise important questions like how influenza spreads over the world in extremely isolated regions such as the Antarctic.

Bird flu strikes penguins

Researchers at a World Health Organization flu lab in Australia, led by Aeron Hurt, trekked down to the Antarctic Peninsula a year ago and collected oral samples from two distinct colonies. Using a laboratory technique called real-time reverse transcription-PCR, the researchers found avian influenza virus (AIV) genetic material in 3 percent of the samples.

[NOW READ] Climate change causes penguin colonies to decline by a third

The researchers managed to culture four viruses, demonstrating that live infectious virus was present. All of these were H11N2 influenza viruses that were highly similar to each other, yet when their genomes were compared with those from a database spanning all known animal and human influenzas there was nothing quite alike on the planet. Apparently, this penguin influenza is unique.

This suggests that it has been isolated for many decades — presumably hiding out in the penguins’ digestive and respiratory tracts, or possibly frozen in Antarctic ice. So where did they come from and in Antarctica of all places?

[ALSO READ] Dutch researchers create super-influenza, with the capacity to kill billions

Four of the gene segments were most closely related to North American avian lineage viruses from the 1960s to 1980s. Two genes showed a distant relationship to a large number of South American AIVs from Chile, Argentina and Brazil. Using a molecular clock to incorporate the evolutionary rate of each AIV gene segment, the researchers estimated that the virus has been evolving for the past 49 to 80 years without anyone knowing about it.

Concerning this South American connection, it may be possible that long distance migratory birds are the root of the virus’ spreading. The yellow-billed pintail duck, for instance, is known to stray from South America and end up on the Antarctic Peninsula. This coupled with penguins’ utter contempt for hygiene, despite their tuxedo, fancy-like appearance, may have helped spread the virus.

“The large amount of penguin feces in colonies during summer, which in some cases is so significant it can be observed on satellite images, presumably facilitates (viral) transmission by the fecal-oral route,” the scientists note.

While the penguin influenza hasn’t caused any illness yet, it’s still interesting to follow. Scientists might gather from this how often, for instance, infectious viruses can reach isolated communities and far away places like Antarctica and what animals are most vulnerable.

h5n1 virus

H5N1 controversial paper shows that bird flu is only a genetic mutation away from mammal flu

h5n1 virusAt the end of last year, controversy sparked among the medical scientific community when an unprecedented event occurred. Two separate and independent studies made by a team of scientists lead by  Yoshihiro Kawaoka of the University of Wisconsin and TIME 100 honoree Ron Fouchier of Erasmus University in the Netherlands, respectively, had their papers’ postponed and censored for publishing. The scientists research was centered on purposely mutating the deadly H5N1 virus, commonly known as bird flu, to become transmissible to mammals, and thus potentially humans too, in order to be a step ahead of the virus were it to naturally mutate and become stable. A committee decided that both papers could translate in a grave threat for humanity, were it to fall in the wrong hands (bioterrorists). Now, the decision has been ruled out and Kawaoka’s research has been published in full, yet revised in the journal Nature, and as expected, its findings are frighting.

Bird flu first surfaced in Asia, and a couple of years ago the first bird flu human cases appeared, engulfing the world in a pre-pandemic panic. Since then, billions of dollars have been spent on vaccines, while other billions of chickens had been killed in efforts to contain the pandemic. Avian influenza has infected so far 600 humans, of which 353 died, translating in a 59% mortality rate – all of the deaths occurred in Eastern Asia and the Middle East.

[Related] Dutch researchers create super influenza with the capacity of killing billions 

Cases have been rare though, since spreading between humans is highly inefficient for the virus. But this could take a turn for the tragic, if the virus becomes stable, by means of a single mutation, as Kawaoka found. Discovering “that HA needs to be stable to be transmissible through the air between mammals” is a key finding, says influenza virologist Wendy Barclay at Imperial College London.

“Our study shows that relatively few amino acid mutations are sufficient for a virus with an avian H5 hemagglutinin to acquire the ability to transmit in mammals,” says researcher Yoshihiro Kawaoka.

Following a review from the National Science Advisory Board for Biosecurity, the agency recommended that much of the information be redacted. However, in light of arguments which have the benefits outweigh the perils, the paper has been publicly published.

“This study has significant public health benefits and contributes to our understanding of this important pathogen. By identifying mutations that facilitate transmission among mammals, those whose job it is to monitor viruses circulating in nature can look for these mutations so measures can be taken to effectively protect human health.”

The team combined the mutated HA gene with seven other genes of the highly transmissible if not highly deadly H1N1 strain, which caused the 2009 flu pandemic. The hybrid virus evolved further after Kawaoka’s team gave it to ferrets — the best animal model for human influenza. After a few days, one of the ferrets acquired tens of thousands of more viruses than the other ferrets, after it had acquired a third HA mutation: from asparagine to aspartic acid. Afterwards, the hybrid virus spread from ferret to ferret relatively easily which had their cages in close proximity. A worrying fact is that the transmission was airborne.

No ferrets were killed, and it is unclear whether the virus could spread between humans as well as it did between ferrets, or whether the four HA mutations would confer the same ability on a purely H5N1 virus. However, and the new virus remained vulnerable both to the antiviral Tamiflu and a prototype vaccine against H5N1.

In the face of various H5N1 strains that might or already have mutated to attack humans, Kawaoka’s research, as well as Fouchier’s equally controversial work which is expected to be published soon in the journal Science, is indispensable to tackling and preventing a major pandemic, which might prove to deadly for the human race, otherwise.

The study provides “the first clues about what properties of the HA protein, other than receptor specificity, might be important for mammalian airborne transmission”, says Vincent Racaniello, a virologist at Columbia University in New York. “It would have been a huge loss not to publish this.”

 

source : Nature