SAG and infection: Addressing these issues will require testing the effect of multiple SAgs on human PBMC in vitro, ideally combined with humanized animal models to permit an in-depth examination of issues such as the impact of isolates expressing multiple potent SAgs on the TCR Vβ repertoire, whether exposure to Sag-producing bacteria directly affects MAIT cell responses, and if prior exposure to a highly mitogenic isolate results in enhanced susceptibility to future infections.