Antigenic Relationship of 1961–1962 Type B Influenza Viruses to Earlier Type B Strains

Abstract

Summary

Evidence is presented that there has been considerable antigenic change in type B influenza viruses. This evidence is obtained on the basis of results in the hemagglutination inhibition test using sera prepared in animals, and in sera collected from patients recovering from current cases of influenza virus infection. That the viruses constitute an homogenous subgroup is shown by demonstrating that viruses isolated in different geographic areas behave similarly in serologic tests. Consideration should be given to separation of type B influenza viruses into subgroups in an officially adopted system of nomenclature.