Typhoid Vaccine Studies VII: Typhoid-Paratyphoid Vaccine

Abstract

The special problems involved in the selection of desirable vaccine strains of organisms comprising T.A.B. vaccine and on the production of circulating protective substances by vaccination with T.A.B. vaccine are presented, and the apparent relationship of typhoid-paratyphoid immunization to the morbidity of all diarrheal diseases in the U. S. Army is briefly discussed. Vaccine strains of organisms were chosen on the basis of their virulence for mice on the one hand, and for their immuno-genic potency as demonstrated by active immunization of mice, on the other. Initial vaccination of young adult [male][male] with T.A.B. vaccine produced significant amts. of protective substances in the blood serum active against Eberthella typhosa, Salmonella paratyphi, S. schottmuelleri, the Java strain of paratyphoid B, S. enteritidis, S. typhimurium, and against 2 coliform organisms containing Salmonella O-anti-gens I and II, and IV and V, respectively. Such vaccination failed to produce, by the method used for detection, demonstrable protective substances active against S. cholerae suis, S. oranienburg, and Proteus morganii. Replacement of the originally selected strain of S. paratyphi as the Para A component of T.A.B. vaccine with a relatively more virulent strain of this organism was followed by a general improvement in the potency of the combined product, as evidenced by significantly higher protective titers for E. typhosa, S. paratyphi, and S. schottmuelleri. Coliform organisms containing Salmonella antigens offer an interesting group of possible etiological agents for study, particularly in view of the antigenic and immunogenic relationship between these and the T.A.B. vaccine organisms. It is probable that, if coliform organisms suspected of causing or inciting enteric infections were typed with diagnostic Salmonella sera, many more of such antigenic relationships would be revealed.