Virulence factor that is important for the establishment of infection in the host. EsxB is required for EsxA synthesis as well as secretion (By similarity). 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). Belongs to the WXG100 family.