Description:
The influenza virus hemagglutinin (HA) mediates viral entry into target cells. HA is synthesized as an inactive precursor and depends on proteolytic processing by host cell proteases to become active. TMPRSS2, a member of the type II transmembrane serine protease (TTSP) family, can cleave and activate HA in cell culture and was recently shown to be essential for spread and pathogenesis of influenza viruses of the H1N1 subtype in mice. In contrast, an H3N2 influenza virus was less dependent on TMPRSS2, implying that this virus may hijack other TTSPs for its activation. Moreover, studies with...