Virulence factor that is important for the establishment of infection in the host. EsxB is required for EsxA synthesis as well as secretion (PubMed:15657139). Mediates together with EsxA the release of S.aureus from the host cell. Inhibits also host cytokine production and thus modulates dendritic cell-mediated immunity (By similarity). Homodimer. When mixed with EsxA does not form heterodimers. Secreted via the ESAT-6 secretion system (Ess) / type VII secretion system (T7SS). Mutant shows a significant reduction in the ability to establish kidney or liver abscesses in infected mice. Belongs to the WXG100 family.