Influenza A virus protein revealed as a possible target for antiviral drugs

University of Texas at Austin researchers announced on Thursday that a protein produced by influenza A helps it evade the body's immune system, revealing a potential target for antiviral drugs.

The team found that when the virus infects a human cell, the host cell's machinery is used to replicate the virus. While studying this process, researchers discovered a protein produced by human cells called DDX21 blocks replication. They also found a protein created by the virus called NS1 blocks DDX21.

The study showed viral replication is inhibited when DDX21 binds with viral protein PB1. The process of NS1 binding to DDX21 releases PB1 to begin replicating again.

"If you could figure out how to stop NS1 from binding to DDX21, you could stop the virus cold," Robert Krug, a UT-Austin professor in the College of Natural Sciences, said.

Krug said that if the NS1 function is blocked, other important functions would be blocked as well, which makes it a good target.

The team found the NS1 protein is bound with the host DDX21 in infected human cells. They used gene silencing to inhibit DDX21 and discovered the virus replicated much more quickly.

"That told us that DDX21 is a host restriction factor, that it inhibits replication," Krug said. "That was the key to understanding what was happening. It was an exciting moment."