Whether this expansion of IgA immunity is simply a marker of a mucosal immune response, a frontline antimicrobial host defense effector, or a collaborator in the IgG response to infection remains unclear but highlights the importance of future analyses of mucosal responses to gain mechanistic insights into local protective immune functions against Shigella. Furthermore, the expansion of OPS-specific immunity following challenge, regardless of disease severity, argues for a critical role for both IpaB- and OPS-specific immune mechanisms in the resolution of infection. This evidence concerns the gene CD79A and infection.