Serological Properties of γG and γM Antibodies to the Somatic Antigen of Vibrio cholerae During the Course of Immunization of Rabbits

Abstract

Direct- and passive-agglutinating, complement-fixing, and bactericidal properties of γG and γM antibodies produced in rabbits inoculated with live Vibrio cholerae were determined at intervals over a period of 345 days. Although γM antibody titers increased more rapidly than γG during the initial stages of antibody production, the titers of γG and γM declined proportionally during a 3-month rest period and increased proportionally after a booster injection. The relative titers of γM as determined in the four serological procedures remained fairly constant throughout the period of observation. In contrast, early γG was less effective than late γG in vibriocidal, complement-fixing, and passive-hemagglutinating activity. At no stage of immunization was the agglutinating ability of γG affected by 2-mercaptoethanol, but its complement-dependent activity was markedly reduced, more so in early serum than in late. The heat lability of early γG approached that of γM, but γG became more resistant to heat in later stages of immunization.