Studies on the Typhoid and Paratyphoid Fever Vaccine

Abstract

The newer the typhoid and paratyphoid fever vaccine, the stronger is their antigenicity. However, when well preserved, they continue to be effective for several years. These vaccines hardly demonstrate any ability of Vi-antibody: production on rabbits, but a rather strong ability on mice. Infection-preveting antibody is highly produced. by a single injection of vaccine containing Vi-antigen. By 3 or 4 injections, however, the difference is gradually diminished as compared with a vaccine with low potency. This fact is also observed in the examination for potency determination. 0 antibody titer is elevated fairly highly by a single injection of typhoid fever vaccine and reaches the highest degree by 2-3 injections. On the contrary, paratyphoid A and B vaccine produce only a minimum amount of 0 agglutinin.