Interferon induction by influenza virus: significance of neuraminidase.

During interferon induction in mice in vivo with various strains of influenza A virus differences in titer of produced interferon were observed. Correlation between interferon titer and neuraminidase activity of a given influenza virus strain was noted. Similar correlation was demonstrated with virus fraction purified chromatographically and used for interferon induction. The fractions with high neuraminidase activity were good interferon inducers, whereas the fractions with undeterminable neuraminidase activity did not induce interferon in vivo.