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The nucleotide and amino acid sequences of 40 influenza virus hemagglutinin genes of the H3 serotype from mammalian and avian species and 9 genes of the H4 serotype were compared, and their evolutionary relationships were evaluated. From these relationships, the differences in the mutational characteristics of the viral hemagglutinin in different hosts were(More)
Recent isolation of a novel swine-origin influenza A H3N2 variant virus [A(H3N2)v] from humans in the United States has raised concern over the pandemic potential of these viruses. Here, we analyzed the virulence, transmissibility, and receptor-binding preference of four A(H3N2)v influenza viruses isolated from humans in 2009, 2010, and 2011. High titers of(More)
When influenza (H3N2) viruses from infected individuals are grown in embryonated chicken eggs, viruses are isolated which differ antigenically and structurally from viruses grown in mammalian Madin-Darby canine kidney (MDCK) cell culture [G.C. Schild, J.S. Oxford, J.C. de Jong, and R.G. Webster, Nature (London) 303:706-709, 1983]. To determine which of(More)
The influence of the host cell on the selection of antigenic variants of influenza A H3N2 viruses and the relevance of host cell selection to the induction of immunity by these viruses have been investigated. Influenza viruses were isolated from human clinical samples during a single epidemic, were passaged in mammalian Madin-Darby Canine Kidney (MDCK)(More)
The role and interdependence of CD8+ and CD4+ alpha beta-T cells in the acute response after respiratory infection with the murine parainfluenza type 1 virus, Sendai virus, has been analyzed for H-2b mice. Enrichment of CD8+ virus-specific CTL effectors in the lungs of immunologically intact C57BL/6 animals coincided with the clearance of the virus from(More)
Influenza virus (H3N2) host cell variants isolated from a single infected individual were compared for their protective efficacies when used as formalin-inactivated purified whole virus vaccines in ferrets. A/Mem/12/85 virus grown in embryonated chicken eggs (egg-grown), which differs from A/Mem/12/85 grown in mammalian Madin-Darby canine kidney cells(More)
Mice are widely used for studying influenza virus pathogenesis and immunology because of their low cost, the wide availability of mouse-specific reagents, and the large number of mouse strains available, including knockout and transgenic strains. However, mice do not fully recapitulate the signs of influenza infection of humans: transmission of influenza(More)
Influenza viruses grown in embryonated chicken eggs frequently possess antigenically distinguishable hemagglutinin (HA) compared to virus from the same source grown in mammalian cell culture. To further investigate the extent of variation among viruses from an individual, viruses were isolated from throat washes collected over a 48-hr period during(More)
Influenza viruses grown in chicken eggs may comprise mixtures of variants, creating problems in establishing international reference strains and in preparing high growth reassortants. We therefore analyzed representative reference strains of H3N2 viruses from 1987 to 1989 by direct sequencing of HA1. Three of seven reference strains had different(More)
Sendai virus infection of C57BL/6 mice elicits a strong CD4+ and CD8+ T-cell response in the respiratory tract. To investigate the specificity of the CD4+ T-cell response, a panel of hybridomas was generated from cells recovered from the respiratory tracts of infected mice. Using vaccinia virus recombinants expressing individual Sendai virus proteins, we(More)