Antigenic relationships between the neuraminidases of influenza B virus

Antigenic relationships between neuraminidases of influenza B viruses isolated from 1940 to 1968 were studied by neuraminidase-inhibition tests using hyperimmune rabbit antisera. The cross-reactions between the enzymes of influenza B viruses showed that some antigenic drift had occurred but that they are all related. From these results it is concluded that the differences between the neuraminidases of influenza B viruses are not sufficiently clear-cut to allow the viruses to be separated into subgroups.