Viral Persistence – June 10, 2020
We’ve all heard of the term persistence. But what does it mean in the context of a virus? With acute viral infections (think norovirus), people develop symptoms quickly and then fully recover within days. Other viruses (like chickenpox) can cause initial infection and then remain dormant for the rest of a person’s life (though sometimes manifesting as shingles in this case). Finally, viruses like poliovirus are acute in most people, but persistent in a few who have trouble clearing the virus from their bodies. Where does the novel coronavirus fit in?
Research is currently being conducted to learn all we can about the SARS-CoV-2 virus that causes the disease, COVID-19. We still don’t know how coronavirus persistence might vary person-to-person or even by organ, but we do know that the virus has a genome of RNA rather than DNA. Other families of RNA viruses can lead to chronic illness and even cancer, decades after the original infection. Long-term persistence = long-term consequences, so this is important to quantify. In addition, working out the true windows of viral persistence can help with determining whether people are being re-infected with COVID-19, whether they develop lasting immunity, and how long sick people need to stay isolated.
When people recover from acute infections, typically their immune response kills the cells affected to eliminate the virus. But when viruses infect long-lived cells in the body, such as neurons, the immune system cannot afford to destroy them so the virus goes dormant in the body for long periods of time. This persistence may actually be key to long-term immunity. But with people currently exhibiting all different levels of viral persistence and immunity already in regards to SARS-CoV-2, it makes the development of a vaccine for COVID-19 that much more challenging.
Stay healthy, stay safe, stay informed!
image: CDC public domain