title: Phenotypic mixing with recombinant haemagglutinin of high cleavability mediates multi-cycle replication of human influenza virus in cell culture.
abstract: When CV-1 cells expressing haemagglutinin (HA) of fowl plague virus A/FPV/34/Rostock(H7) (FPV) from an SV40-based recombinant vector were superinfected with the human influenza virus A/FM/1/47(H1N1)(FM1), phenotypically mixed progeny virus was observed. It contained cleaved FPV HA and uncleaved FM1 HA, was infectious without trypsin treatment and its infectivity was neutralizable by anti-FPV serum. When superinfection of H7 HA-expressing CV-1 cells was performed at a low multiplicity of infection, multi-cycle replication occurred. Control cells preinfected with an SV40-based recombinant not expressing FPV HA did not allow multi-cycle replication. Multi-cycle replication of FM1 virus was also observed when cells were preinfected with a vector expressing a highly cleavable mutant of influenza virus A/Port Chalmers/1/73(H3) HA carrying an insert of four arginine residues at the cleavage site. This was not the case when cells expressing uncleaved wild-type H3 HA were used. The results show that by phenotypic mixing with recombinant HA of high cleavability, a human influenza virus can be obtained in infectious form from cells lacking a suitable protease to activate this virus.
authors.affiliation: Institut für Virologie, Philipps-Universität Marburg, Germany.
authors.forename: N V
authors.initials: NV
authors.lastname: Kaverin
authors.forename: M
authors.initials: M
authors.lastname: Ohuchi
authors.forename: R
authors.initials: R
authors.lastname: Ohuchi
authors.forename: H D
authors.initials: HD
authors.lastname: Klenk
mesh_terms: D000818:Animals; D002460:Cell Line; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D006389:Hemagglutinins, Viral / Q000235:genetics / Q000502:physiology*; D006801:Humans; D009980:Influenza A virus / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D016865:Reassortant Viruses / Q000235:genetics / Q000502:physiology*; D014357:Trypsin; D014779:Virus Replication
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D006389:Hemagglutinins, Viral; D014357:Trypsin