New infections cause dormant viruses to reactivate

Herpes viruses are almost impossible to eliminate from your body. While other viruses succumb when they are defeated by the immune system, the herpes virus remains in the body forever, lying in wait, sometimes reactivating years later. A new study has found that new infections may weaken the body just enough to favor the reawakening of herpes.

Herpes virus

Artistic representation of the herpes virus. Via Gofolic.

For quite a while, scientists have been trying to figure out exactly why the virus sometimes reactivates, even after lying dormant for decades. Herpes, which has been associated to cancer, could be combated with more efficiency if researchers understand the underlying mechanisms of the pathogen. Now, a team has found that interactions with other infections later in life are the catalysts for the awakening.

“Probably 95 percent of us have been infected with at least one herpes virus, but many people never have a problem with it,” said study co-author Rolf Renne, a professor of molecular genetics and microbiology in the UF College of Medicine and a member of the UF Genetics Institute and the UF Health Cancer Center. There are eight herpes viruses that infect humans, causing diseases that range from cold sores and chickenpox to mononucleosis and cancer. “The question has been: What happens to reactivate these viruses to cause disease?”

To me, this information was quite shocking. The fact that Renne, one of the leading voices in the field believes that almost all of us have been infected is quite worrying – especially when in the vast majority of the cases the virus is never truly eliminated from the body.

What they found in this research is that a protein called interferon gamma keeps herpes in check, which explains why the virus typically remains dormant in the body. But when the immune system is challenged, especially when fighting an infection,  another protein called interleukin 4 was released, which not only blocked interferon gamma from doing its job but also directly activated virus replication. Again, the big problem here is not the herpes virus in itself – but rather that when the virus reactivates, it infects new cells, and significantly increases the chances of a cancerous tumor developing.

“The fact that the virus can ‘sense’ the immune reaction to a worm and respond by reactivating is a remarkable example of co-evolution,” said senior author Dr. Herbert W. Virgin IV, of Washington University in St. Louis. “We think other interactions between multiple infectious agents and the immune system will be discovered over time that we will view as similarly sophisticated or maybe even devious. Understanding these interactions will help us survive in a complex microbial world.”

Their findings are quite intuitive – it seems rather safe to assume that the weakening of the body favors the reemergence of dormant virus, but intuitive is not science.

Source: University of Florida

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