Binding of influenza A virus NS1 protein to dsRNA in vitro.

The non-structural protein NS1 of influenza A virus exhibits two modes of RNA-binding activity. One is sequence-specific binding to minus-sense virus RNA with either a 5'- or 3'-terminal common sequence as reported previously. The other was identified as binding to dsRNA and this activity did not show sequence specificity. The affinity of binding to dsRNA was much higher than that to ssRNA. A short miniature virion RNA forming a panhandle structure by pairing between the 5'- and 3'-terminal common sequences bound NS1 with higher affinity and stability than did a dsRNA of similar sequence and length.