A novel mechanism for the acquisition of virulence by a human influenza A virus.
Cleavage of the hemagglutinin (HA) molecule by proteases is a prerequisite for the infectivity of influenza A viruses. Here, we describe a novel mechanism of HA cleavage for a descendant of the 1918 pandemic strain of human influenza virus. We demonstrate that neuraminidase, the second major protein on the virion surface, binds and sequesters plasminogen, leading to higher local concentrations of this ubiquitous protease precursor and thus to increased cleavage of the HA. The structural basis of this unusual function of the neuraminidase molecule appears to be the presence of a carboxyl-terminal lysine and the absence of an oligosaccharide side chain at position 146 (N2 numbering). These findings suggest a means by which influenza A viruses, and perhaps other viruses as well, could become highly pathogenic in humans.
Department of Virology and Molecular Biology, St. Jude Children's Research Hospital, 332 North Lauderdale, P.O. Box 318, Memphis, TN 38101, USA.
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Goto
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Kawaoka
D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002460:Cell Line; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000378:metabolism; D006801:Humans; D009980:Influenza A virus / Q000472:pathogenicity* / Q000502:physiology; D008958:Models, Molecular; D009439:Neuraminidase / Q000737:chemistry / Q000378:metabolism; D010958:Plasminogen / Q000378:metabolism; D011487:Protein Conformation; D014774:Virulence / Q000502:physiology; D014779:Virus Replication
D019267:Hemagglutinin Glycoproteins, Influenza Virus; D010958:Plasminogen; D009439:Neuraminidase