Heterogeneity of influenza B viruses

Antigenic analysis of influenza B strains isolated in 1981-82 from England, Japan, and the USA, using a panel of monoclonal antibodies to the haemagglutinin of B/Oregon/5/80, showed considerable heterogeneity among the isolates, the majority of which had distinct reactivity patterns. Antigenically similar viruses were isolated from England, Japan, and the USA, and heterogeneity was detected among isolates from each country. Further studies are needed to determine whether this marked heterogeneity reflects different cocirculating strains or antigenic drift during an epidemic. The monoclonal antibodies failed to detect any difference between influenza B isolates from patients with Reye's syndrome and those circulating in the community.The monoclonal antibodies, each recognizing different determinants on the haemagglutinin of B/Oregon/5/80, were pooled and compared with ferret antisera to determine if the pool could be used as a reference reagent. The monoclonal antibody pool discriminated between isolates, contained no non-specific inhibitors of haemagglutination, and avoided the problems associated with differences between ferret antisera. In general, viruses that were shown to be antigenically different by ferret antisera were also different with the pooled monoclonal antibodies, but further studies are required to determine the optimal mixture of antibodies that will detect epidemiologically significant differences between strains.