[The effect of immunostimulants on the resistance of white mice to the causative agent of typhoid fever].

The influence of prodigiosan, salmosan, polyribonate and levamisole on the body nonspecific and specific resistance to S. typhi strain 4446 has been studied. Prodigiosan and salmosan have proved to be the most effective. The injection of these compounds simultaneously with typhoid vaccine (both chemical adsorbed vaccine and alcohol-treated vaccine, enriched with Vi-antigen) significantly increases the survival rate of immunized animals (by 35-45%), elevates the resistance index (1.5- to 2.3-fold) and the effectiveness index of the vaccine (17- to 32-fold) in comparison with the controls. Besides, prodigiosan and salmosan alone are capable of increasing nonspecific resistance to S. typhi strain 4446, which is manifested by an increase of the survival rate of stimulated animals by 61.87%. Proceeding from the results thus obtained, the possibility of good prospects for prodigiosan and salmosan in the prophylaxis of typhoid fever in humans may be inferred.