Characterization of the equine influenza virus H3 with monoclonal antibodies.

Mouse monoclonal antibodies specific for the hemagglutinin of the prototype equine-2 virus, A/equine/Miami/1/63 (H3, N8) demonstrated two related antigenic sites on the H3. One of the sites was detected on 14 H3 viruses isolated over a 22 year period (1963-1985). Variant viruses were selected with these antibodies at frequencies similar to those described for H3 hemagglutinins from human isolates.