A broadly immunogenic polyvalent Shigella multiepitope fusion antigen protein protects against Shigella sonnei and Shigella flexneri lethal pulmonary challenges in mice.

There are no licensed vaccines for , a leading cause of children's diarrhea and a common etiology of travelers' diarrhea. To develop a cross-protective vaccine, in this study, we constructed a polyvalent protein immunogen to present conserved immunodominant epitopes of invasion plasmid antigens B (IpaB) and D (IpaD), VirG, GuaB, and Shiga toxins on backbone protein IpaD, by applying an epitope- and structure-based multiepitope-fusion-antigen (MEFA) vaccinology platform, examined protein ( MEFA) broad immunogenicity, and evaluated antibody function against invasion and Shiga toxin cytotoxicity but also protection against lethal challenge. Mice intramuscularly immunized with MEFA protein developed IgG responses to IpaB, IpaD, VirG, GuaB, and Shiga toxins 1 and 2; mouse sera significantly reduced invasion of , serotype 2a, 3a, or 6, and type 1 and neutralized cytotoxicity of Shiga toxins of and Shiga toxin-producing . Moreover, mice intranasally immunized with MEFA protein (adjuvanted with dmLT) developed antigen-specific serum IgG, lung IgG and IgA, and fecal IgA antibodies, and survived from lethal pulmonary challenge with or serotype 2a, 3a, or 6. In contrast, the control mice died, became unresponsive, or lost 20% of body weight in 48 h. These results indicated that this MEFA protein is broadly immunogenic, induces broadly functional antibodies, and cross-protects against lethal pulmonary challenges with or serotypes, suggesting a potential application of this polyvalent MEFA protein in vaccine development.