Intertypic differentiation and detection of intratypic variants among canine and phocid morbillivirus isolates by kinetic neutralization using a novel immunoplaque assay.

Intertypic antigenic differences and the intratypic variability of the closely related canine (CVD) and phocid distemper viruses (PDV) were examined using a molecular (monoclonal antibodies specific for the H- and F-glycoproteins) and a functional (kinetic neutralization, KN) approach. KN studies were carried out using a novel immunoplaque technique which combined conventional plaque assay and antigen-specific enzyme-immunostaining techniques. Morbillivirus isolates of canine and phocid origin clearly formed two separate groups. Minor antigenic differences were also evident within each cluster. A distemper isolate of mustelid origin was distinguishable from both CDV- and PDV-like prototype viruses by kinetic neutralization.