Immunoelectron microscopy of influenza A virus neuraminidase glycoprotein topography.

Using immunoelectron microscopy, the distribution of influenza A virus neuraminidase (NA) glycoproteins was examined, after performing immunoreactions to virions on the grid. With polyclonal antibody, the immunolabels of the glycoproteins were found to be homogeneously distributed, whereas with monoclonal antibody they were found to be distributed in clusters. After destruction of haemagglutinin (HA) but not of NA activity with a high concentration of trypsin, the remaining visible spikes were evenly distributed. This finding was consistent with the absence of immunolabelling with anti-HA antibody, and the homogeneous pattern of immunolabels with anti-NA polyclonal antibody, but not with the clustered labelling with the anti-NA monoclonal antibody. Thus, the immunolabelling image with anti-NA polyclonal antibody was considered to reflect the true one.