The influenza virus neuraminidase contributes to secondary bacterial pneumonia

摘要

Secondary bacterial pneumonia is a common cause of death during influenza epidemics. We hypothesized that virus-specific factors could contribute to differences in annual excess mortality. A set of recombinant viruses with neuraminidases from representative influenza virus strains from the last 50 years was created and characterized. Their specific neuraminidase activities correlated with their ability to support secondary bacterial infections. Recombinant viruses with the 1957 and 1997 neuraminidases had the highest activities, while a virus with the 1968 neuraminidase had the lowest activity. The high activity of the 1957 neuraminidase, when compared to other neuraminidases, more strongly supported bacterial adherence in vitro and secondary pneumococcal pneumonia in a mouse model. These data lend support to our hypothesis that the neuraminidase of influenza viruses contributes to secondary bacterial infections and subsequent excess mortality.