Protein-specific immune response elicited by the 1790GAHB GMMA-based candidate vaccine in adults with varying exposure to .

is a leading cause of diarrheal morbidity and mortality in young children from low- and middle-income countries. Here, we aimed to verify the ability of the generalized modules for membrane antigens (GMMA)-based candidate vaccine 1790GAHB to elicit an anti-protein antibody response. Serum samples from previous clinical trials in adults (a dose-escalation study and its extension in France, a vaccine efficacy study after human challenge in the United States, and a study in Kenya) were investigated using pan-proteome microarrays consisting of 3,150 full-length or fragmented proteins. Pre-/post-vaccination comparisons identified subsets of proteins that were highly immunoreactive and largely overlapped across all trials; the T3SS lipochaperone family protein (expressed on GMMA) was the most reactive in all studies. Responses to several microarray antigens correlated well with LPS serum IgG antibody levels. Overall, we confirmed the ability of GMMA to elicit an anti-protein IgG/IgA response; however, no association with protection against shigellosis was identified. In the challenge study, IgG response to seven antigens (IpaC, IpaB, IpaA, IpaD, IpaH, IpgC, and MxiD; not expressed on GMMA) was associated with a decreased risk of shigellosis. These antigens were observed to also have high IgG responses at baseline in individuals naturally exposed to and could constitute targets for future vaccine development.IMPORTANCE remains a major cause of diarrheal disease, especially in children aged under 5 years from low-to-middle-income countries. No vaccine against shigellosis is yet widely available despite the high public health need. An ideal vaccine would provide protection against the most prevalent species, and ; therefore, it could be relevant to identify common antigens. We developed a microarray containing 3,150 full-length or fragmented proteins selected across species. Sera collected in four clinical trials conducted in three countries of varying endemicity to evaluate a GMMA-based candidate vaccine were tested against these proteins. We identified several proteins (IpaC, IpaB, IpaA, IpaD, IpaH, IpgC, MxiD) that induced robust antibody response following experimental challenge or natural infection. These proteins correlated with a reduced risk of shigellosis after the challenge. We found no apparent role for anti-GMMA proteins' IgG or IgA response in protection against shigellosis.