ETIDIOH - NEW

  Editor’s summary Birds operate at body temperatures several degrees higher than those of mammals, and, like mammals, birds are infected by influenza viruses. Influenza viruses can move between animal hosts, often reassorting their gene segments as they transition. Knowing that the body temperature of humans often elevates when sick, Turnbull et al. investigated whether virus gene segments originating from hot-blooded birds may give the virus an advantage in feverish mammals. They found that a viral polymerase containing an avian origin PB1 subunit indeed allowed the virus to replicate at higher temperatures in vitro and in a hyperthermic mouse model. —Caroline Ash Structured Abstract INTRODUCTION Influenza A viruses circulate in diverse species of birds and periodically spill over to cause severe or fatal infections in humans . Avian influenza A viruses are adapted to replicate in the gastrointestinal tract of birds at ~40° to 42°C . By contrast, human-adapted seasonal influenza ...

  Abstract Influenza viruses cause hundreds of thousands of infections globally every year. In the past century, seasonal influenza viruses have included H1N1, H2N2 or H3N2 strains . H2N2 influenza viruses circulated in the human population between 1957-1968 . Previously, our group demonstrated a lack of H2N2 influenza virus immunity in individuals born after 1968 , as well as the effectiveness of hemagglutinin (HA) based vaccines for multiple influenza virus subtypes. In this study, H2 antigenic maps and radial graphs were generated using previously published data from H2 HA vaccinations of ferrets and seasonal influenza vaccinations of humans . The antigenic maps revealed a stark difference in clustering of HA antigens between the ferrets and humans, and the radial graphs showed specific antigen recognition varies greatly between different influenza preimmune ferrets . These maps also revealed the significant impact that different pre-existing immunities have on antigenic recogni...

  Abstract H5N1 highly pathogenic avian influenza viruses have spread globally and pose a risk for a human pandemic . Prior studies suggest that early life exposures to group 1 influenza viruses (H1N1 and H2N2) prime antibodies that cross-react to the hemagglutinin of H5N1 , which is also a group 1 virus. Less is known about how immune history affects antibody responses against the neuraminidase (NA) of H5N1 viruses. Here, we measured NA inhibition antibodies against multiple H5N1 viruses using sera from 155 individuals born between 1927 and 2016 . We found that individuals primed in childhood with H1N1 viruses were more likely to possess higher levels of antibodies that cross-react with the NA of H5N1 viruses compared to individuals primed in childhood with H2N2 or H3N2 viruses. While young children rarely possessed cross-reactive NA antibodies, we found that childhood infections with contemporary H1N1 , but not H3N2, viruses can elicit them. These data suggest that immune history...