Distribution of hemagglutinin and neuraminidase on influenza virions as revealed by immunoelectron microscopy.

Monoclonal antibodies specific for the hemagglutinin (HA) or the neuraminidase (NA) of influenza viruses were used in immunoelectron microscopic studies to determine the distribution of the two surface spikes on the virion. Indirect immunogold staining revealed that the HA is uniformly distributed on the virion while the NA occurs in discrete areas. Crosslinking and low temperature studies argue against redistribution of the HA and NA after antibody attachment and indicate that the NA on influenza virus occurs in patches.