The receptor-destroying enzyme of influenza C virus is required for entry into target cells.
The hemagglutinin-esterase (HE) protein of influenza C viruses possesses an acetylesterase activity, which appears essential for replication, as determined by reduced infectivity after inhibition of the viral enzyme [Vlasak et al., J. Virol. 63, 2056-2062 (1989)]. Analysis revealed the absence of virus-specific RNA and protein synthesis in infected cells after inhibition of the receptor-destroying enzyme. In addition, hemolytic activity was reduced after incubation of influenza C/JJ/50 virus with diisopropyl-fluorophosphate or 3,4-dichloro-isocoumarin. Further analysis revealed that inhibition of hemolysis depends on virus and erythrocyte concentrations. It is suggested that an active receptor-destroying enzyme is required for entry of influenza C virus into target cells at a step prior to fusion of the viral and cellular membrane. Our data indicate that cleavage of receptors bound to the HE protein is a prerequisite for the low pH-triggered conformational change required for fusion.
Strobl
B
B
Institute of Molecular Biology, Austrian Academy of Sciences, Salzburg.
Vlasak
R
R
D000115:Acetylesterase / Q000378:metabolism*; D000818:Animals; D015152:Blotting, Northern; D002460:Cell Line; D003374:Coumarins / Q000494:pharmacology; D004285:Dogs; D006389:Hemagglutinins, Viral / Q000378:metabolism*; D006461:Hemolysis; D006801:Humans; D009980:Influenza A virus / Q000502:physiology; D009982:Gammainfluenzavirus / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D049934:Isocoumarins; D007531:Isoflurophate / Q000494:pharmacology; D007668:Kidney; D007700:Kinetics; D012367:RNA, Viral / Q000096:biosynthesis; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D014760:Viral Fusion Proteins; D014764:Viral Proteins / Q000378:metabolism*
D003374:Coumarins; D006389:Hemagglutinins, Viral; D049934:Isocoumarins; D012367:RNA, Viral; D015842:Serine Proteinase Inhibitors; D014760:Viral Fusion Proteins; D014764:Viral Proteins; C060814:hemagglutinin esterase; D007531:Isoflurophate; C046235:3,4-dichloroisocoumarin; D000115:Acetylesterase