Antigenic analysis of human and bovine parainfluenza virus type 3 strains with monoclonal antibodies.

The antigenic characteristics of eight human strains and two bovine strains, one of which is represented by two plaque variants, of parainfluenza virus type 3 were analysed. The strains and variants were compared using 52 monoclonal antibodies against five, two, six and six epitopes of the haemagglutinin-neuraminidase (HN), fusion, nucleocapsid and matrix viral proteins respectively, employing radioimmuno-precipitation and immunofluorescence assays. The human strains, seven of which were isolated over 6 years at different geographical locations and the eighth one representing an older prototype strain, showed very little antigenic variation. Extensive differences were detected in all four proteins examined between the human strains and the two strains of bovine origin. Two bovine variants were less effectively neutralized than the prototype human strain with a series of monoclonal antibodies against the HN protein.