Characterization of the neuraminidase of the H1N1/09 pandemic influenza virus.

In this study, we compared properties of the neuraminidase (NA) of the H1N1/2009 pandemic virus (H1N1pdm) and N1 NAs of other influenza viruses. The H1N1pdm NA was more active than NAs of seasonal H1N1 viruses, hydrolyzed Neu5Acα2-3Gal linkage as efficiently as did avian viruses and cleaved Neu5Acα2-6Gal linkage as efficiently as classical swine viruses. To assess the functional balance between heterologous NAs and pandemic virus HA, we generated four recombinant viruses that shared seven genes of A/Hamburg/5/09 and contained the NA gene from representative avian, swine and human viruses. The viruses harboring NA from avian, Eurasian avian-like swine and seasonal human viruses eluted more slowly from red blood cells, were more sensitive to neutralization by human airway mucins, and replicated less efficiently in differentiated human tracheo-bronchial epithelial cultures as compared with the viruses containing the NA of H1N1pdm and the NA of the North American classical swine virus lineage. Our data suggest that functional properties of the NA of H1N1pdm could be closer to those of classical swine viruses than to those of avian, avian-like swine and seasonal human viruses.