Development of an 8-valent Salmonella and Shigella MAPS vaccine.

INTRODUCTION

Salmonella and Shigella infections are two of the leading causes of global diarrheal deaths in children younger than 5 years. Licensed vaccines against Salmonella Typhi have been shown to be effective, and other Salmonella and Shigella vaccine candidates are being evaluated in clinical trials.

METHODS

We have previously described two 4-valent vaccines against Salmonella and Shigella strains separately. Here, we tested the combination of Salmonella and Shigella vaccines in animal models. ELISA was used to determine antibody titers against antigens, and bactericidal and opsonophagocytic assays were used to determine the function of these antibodies.

RESULTS AND DISCUSSION: We found that the 8-valent Salmonella/Shigella vaccine induced immune responses similar to those of the two 4-valent counterparts. The immunological benefits of the addition of the adjuvant aluminum phosphate (alum), R848/Alum, or AddaS03 were evaluated in rabbits. The results demonstrated that alum augments antibody production against vaccine protein components, and the addition of R848/Alum or AddaS03 significantly enhanced antibody production and bactericidal activity for some serotypes.