Prevention and treatment of bronchopneumonia in mice caused by mouse-adapted variant of avian H5N2 influenza A virus using monoclonal antibody against conserved epitope in the HA stem region.

The effects of monoclonal antibody (MAb) C179 recognizing a conformational epitope in the middle of the hemagglutinine (HA) stem region were examined in a mouse model in the experiments of prevention and treatment of lethal bronchopneumonia caused by influenza A virus of H5 subtype. To model the lethal infection, avian nonpathogenic strain A/mallard duck/Pennsylvania/10218/84 (H5N2) was adapted to mice. This resulted in highly pathogenic pneumovirulent mouse-adapted (MA) variant, which was characterized. Three amino acid changes were found in the HA1 subunit of HA of MA virus. One of these was located inside the region of the conformational epitope recognized by MAb C179. However, this substitution was not significant for the recognition of HA and virus neutralization by MAb C179 in vitro and in vivo. Intraperitoneal administration of two different concentrations of MAb C179 one day before or two days after the virus challenge significantly decreased mortality rate. These results suggest that MAb C179 is efficient not only in the prevention and treatment of H1 and H2 influenza virus bronchopneumonia, as was reported previously, but also of H5-induced bronchopneumonia as well, and demonstrate in vivo the existence of a common neutralizing epitope in the HAs of these three subtypes.