Preparations of Type B influenza virus, propagated in the embryonated egg and obtained in the form of allantoic fluid, were found after heating at 56°C. for 30 minutes to retain the capacity to agglutinate erythrocytes but no longer measured specific antibody when used as antigen in titrations of serum antibody.

The dissociation of the two activities suggests the presence in such virus preparations of a complex virus antigen comprising, (1) a heat-stable component which agglutinates erythrocytes and reacts primarily with specific antibody; (2) a heat-labile component reacting with a factor of normal serum which ordinarily tends to inhibit the hemagglutinating activity of influenza virus.

The relation of the reagents to other known serological activities of influenza virus is being studied.

This content is only available as a PDF.