Observations on the Relationship Between Hemagglutinin and Neuraminidase of Influenza Viruses.

A number of mucoids of varying NANA content were found to differ widely in their capacity to inhibit the hemagglutinin of several strains of myxovirus when assayed under standardized conditions. This pattern of inhibition bore no quantitative relationship to the content of NANA of individual mucoids, each of which was found to be susceptible to the neuraminidase of 2 or more strains of active virus. Receptor substance from human and guinea pig erythrocytes inhibited hemagglutination and was susceptible to viral neuraminidase. Stroma and sialic acid-containing receptor-like substances from sheep erythrocytes were neither capable of inhibiting hemagglutination nor susceptible to viral neuraminidase. The implications of these findings are discussed with respect to the separate identities of myxovirus hemagglutinin and enzyme.