H7N9 is Rapidly Mutating: Pandemic Potential Increased Due to ‘Viral Fitness’
Thursday, December 12, 2013
It’s common knowledge that influenza viruses mutate. They change and adapt quickly. One of these mutations, the one that enables them to become drug resistant, comes at a high price to the virus. It weakens it.
Almost universally, flu viruses become less virulent when they become drug resistant. In becoming drug resistant, their ability to replicate and its effectiveness is usually considerably reduced.
This is not the case with H7N9. Patients suffering with H7N9 have been treated with Oseltamivir (Tamiflu) and the virus has shown it is resistant in several patients. Normally this would improve the prognosis for the patient, but it hasn’t. Patients have still suffered a long duration of illness and poor clinical outcomes generally, with some patients still dying from the disease.
Nicole Bouvier M.D., Assistant Professor of Medicine, Infectious Diseases at the Icahn School of Medicine at Mount Sinai said:
In this outbreak, we saw some differences in the behavior of H7N9 and other avian influenza strains that can infect humans, beginning with the rapid development of antiviral resistance in some people who were treated with oseltamivir and the persistence of high viral loads in those patients.”
But surprisingly, transmission of the drug-resistant virus was no less efficient than that of the drug-sensitive version. Many of the people infected with H7N9 during the outbreak in China were elderly or had other conditions that predisposed them to severe influenza illness,” observed Dr. Bouvier. “Nevertheless, our study suggests that flu viruses can indeed develop drug-resistant mutations without suffering a penalty in terms of their own fitness. (source)