Epitope mapping of a common 57 kDa antigen of Leishmania species by monoclonal antibodies

BALB/c mice were immunized with freeze-thawed promastigote of Leishmania infantum. Five monoclonal antibodies (mAb) were selected, four IgM (designated as P1A9, P2G8, P5E3 and P6B3) and one IgG1 (P3D2). ELISA and Western blot analysis suggested that all monoclonal antibodies are specific to a band of 57 kDa antigen of L. infantum as well as other three Leishmania species (L. tropica, L. major and L. donovani). ELISA additivity tests revealed four epitopes on 57 kDa antigen as defined by four IgM monoclonal antibodies. Three distinct epitopes were recognized by P1A9, P2G8, and P6B3 antibodies and one epitope recognized by P5E3 antibody that shared with P2G8, and P6B3 epitopes. The 57 kDa protein was purified with affinity column and was shown to possess proteolytic activity. It seems that 57 kDa protein is the major surface Leishmania antigen (gp63) that has been used as subunit vaccine with appropriate adjuvant and induced protection against L. major infection in BALB/c mice.