Mutated strain of H7N9 flu virus developed drug resistance

A strain of the emergent avian influenza A(H7N9) virus, which is now circulating in China, has developed some kind of resistance to antiviral drugs without losing its virulence. These are the conclusion exposed in an article just published on Nature Communications by a group of researchers from the Icahn School of Medicine at Mount Sinai.

They found that some H7N9 clinical isolates had an amino acid substitution in the structure of the viral neuraminidase (NA), a membrane-expressed, glycosylated enzyme to which the haemagglutinin (HA) glycoprotein binds. NA is the target of a class of antiviral drugs, known as NA inhibitors. Studies conducted both in the mouse and in primary human tracheobronchial epithelial cell cultures, revealed that the mutation carried by this strain has been proved to confer high resistance to oseltamivir and peramivir, and partial resistance to zanamivir.

What’s more, similar mutations usually result in a loss of viral pathogenicity but in this case, the researchers found that the replication, virulence or transmissibility of the H7N9 virus were not compromised.