Antibody-mediated modification of encephalitis induced by hamster neurotropic measles virus

The acute encephalopathy induced by hamster neurotropic (HNT) measles virus in BALB/c mice was abolished, and a subacute encephalitis was induced instead, when antibody to Edmonston (Ed) measles virus was administered three days after inoculation of HNT virus. Ascites fluid from 79XICI, a monoclonal antibody to the hemagglutinin of strain Ed, had similar effects in vivo. However, other monoclonal antibodies to the hemagglutinin of Ed strain - 79XVV17 and 80IIIB2 - were ineffective in vivo at all doses tested. By viral neutralization, immunofluorescence, and radioimmunoprecipitation assays, it was shown that the hemagglutinin of HNT virus reacted with 79XIC1 antibody but lacked the epitopes recognized by 79XVV17 or 80IIIB2 antibody, a finding that explains their different reactivity in vivo. These observations also identified previously unrecognized antigenic differences between the hemagglutinin of Ed and HNT measles viruses.