Lethal H5N1 influenza viruses escape host anti-viral cytokine responses.
The H5N1 influenza viruses transmitted to humans in 1997 were highly virulent, but the mechanism of their virulence in humans is largely unknown. Here we show that lethal H5N1 influenza viruses, unlike other human, avian and swine influenza viruses, are resistant to the antiviral effects of interferons and tumor necrosis factor alpha. The nonstructural (NS) gene of H5N1 viruses is associated with this resistance. Pigs infected with recombinant human H1N1 influenza virus that carried the H5N1 NS gene experienced significantly greater and more prolonged viremia, fever and weight loss than did pigs infected with wild-type human H1N1 influenza virus. These effects required the presence of glutamic acid at position 92 of the NS1 molecule. These findings may explain the mechanism of the high virulence of H5N1 influenza viruses in humans.
Division of Virology, Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
Sang Heui
SH
Seo
Erich
E
Hoffmann
Robert G
RG
Webster
D000818:Animals; D002478:Cells, Cultured; D016207:Cytokines / Q000276:immunology*; D024921:Drug Resistance, Multiple, Viral / Q000235:genetics / Q000276:immunology*; D004847:Epithelial Cells / Q000187:drug effects / Q000821:virology; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype; D009980:Influenza A virus / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity*; D007251:Influenza, Human / Q000276:immunology* / Q000635:transmission / Q000821:virology*; D016898:Interferon-alpha / Q000276:immunology / Q000494:pharmacology; D007371:Interferon-gamma / Q000276:immunology / Q000494:pharmacology; D017354:Point Mutation; D013552:Swine; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology / Q000494:pharmacology; D017361:Viral Nonstructural Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D014774:Virulence / Q000235:genetics
D016207:Cytokines; C085820:INS1 protein, influenza virus; D016898:Interferon-alpha; D014409:Tumor Necrosis Factor-alpha; D017361:Viral Nonstructural Proteins; D007371:Interferon-gamma