Thesis (M.A.)--Boston University / Since the discovery of VI antigen by Felix and Pitt in 1934 (The Lancet, 2:186, 1934), investigators have attempted to isolate, purify and characterize this antigen. Antisera against purified VI antigens would prove a valuable tool for studying the effects of purification on the antigenic molecule. Purified Vi antigen, however, has proven to be a hapten in rabbits with one exception. Landy and Webster's Vi preparation was immunogenic for rabbits as well as for mice (J. Immunol., 69:143, 1952) but the preparations of Ashida (Japan. J. Exper. Med., 20:181, 1949), and of Baker, et al (J. Immunol., 83:687, 1959) were non-immunogenic although Baker's preparation immunized mice and man. Landy and Webster, however, observed that more of their preparation than of whole organisms was necessary to immunize rabbits to an equal degree [TRUNCATED]