The Antigenic Variation of Influenza B Viruses. Demonstration of an Antigenic Spectrum by Use of Titer Ratios

Abstract

Abstract Soon after the identification of influenza B virus in 1940 (1, 2), B strains of different antigenic composition were described (3–5). When epidemic influenza B recurred in 1945–46, other antigenically different strains were isolated (6–9). Most of the new strains were but distantly related to the original Lee strain and the possibility existed that mouse passage had altered the antigenic pattern of the Lee virus (8). In general, strains recovered from the same epidemic (6, 7), or during the same year (8) showed similar antigenic behavior. But at least two antigenically distinct strains have been isolated from the same epidemic, one strain, passed only through eggs, being closely related to Lee (9). The isolation of a number of new B strains in 1949–51 (10, 11) and the growing realization of the biologic significance of antigenic and other variations among influenza viruses (12, 13) prompted several studies of the antigenic relationships between various strains recovered since the first influenza B virus was described (14–17).