 Then, the bacteria is phagocytosized by the host cell and enveloped by a phagosome.Studies have suggested that rOmpB is involved in this process of adhesion and invasion.Both rOmpA and rOmpB are members of a family of surface cell antigens (Sca) which are autotransporter proteins; they act as ligands for the Omp proteins and are found throughout the "rickettsiae".