Approach to the Involvement of Influenza B Neuraminidase in the Cleavage of HA by Host Cell Protease Using Low pH-Induced Cell Fusion Reaction

ts7, a temperature-sensitive mutant defective in neuraminidase (NA) of influenza B/Kanagawa/73, lacks NA enzymatic activity at the nonpermissive temperature (37.5C). When MDCK cells were infected with the mutant at the permissive temperature (32C) and exposed to pH 5.2 medium, extensive cell fusion...

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Bibliographic Details
Published in:MICROBIOLOGY and IMMUNOLOGY 1994, Vol.38(10), pp.819-822
Main Authors: Yamamoto-Goshima, Fumi, Maeno, Koichiro
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Carbohydrates
Cell Fusion
Cell Line
Dogs
Endopeptidases - metabolism
Fundamental and applied biological sciences. Psychology
Hemagglutinins, Viral - metabolism
Hydrogen-Ion Concentration
Influenza B virus
Influenza B virus - enzymology
Influenza B virus - genetics
Kidney - virology
Microbiology
Mutation
Neuraminidase
Neuraminidase - metabolism
Replicative cycle, interference, host-virus relations, pathogenicity, miscellaneous strains
Temperature
ts mutant
Virology
Virus Cultivation
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Summary:ts7, a temperature-sensitive mutant defective in neuraminidase (NA) of influenza B/Kanagawa/73, lacks NA enzymatic activity at the nonpermissive temperature (37.5C). When MDCK cells were infected with the mutant at the permissive temperature (32C) and exposed to pH 5.2 medium, extensive cell fusion occurred. In contrast, at the nonpermissive temperature cells did not show cell fusion at all unless they were pretreated with trypsin, suggesting that at 37.5C the hemagglutinin (HA) of ts7 is expressed at the cell surface in an uncleaved form. It was also found that the replacement of RNA segment 6 of ts7 with that of wild-type B/Lee resulted in the emergence of low pH-induced fusion activity as well as NA enzymatic activity at the incubation temperature of 37.5C and that the addition of bacterial NA to the cultures infected with ts7 at 37.5C early in infection brought about low pH-induced cell fusion. We suggest that the removal of neuraminic acid from the carbohydrate moiety of HA by NA is essential for the cleavage of HA by cellular protease.
ISSN:0385-5600
1348-0421
DOI:10.1111/j.1348-0421.1994.tb01864.x