IMMUNOBLOTTING IDENTIFIES AN ANTIGEN RECOGNIZED BY ANTI GP63 IN THE IMMUNE-COMPLEXES OF INDIAN KALA-AZAR PATIENT SERA

In SDS-PAGE the immune complexes (IC) of kala-azar patient sera showed intense bands at 55 kDa and 20 kDa corresponding to heavy and light c hains of immunoglobulins. In immunoblot experiment, kala-azar and norm al IC after treatment with patient sera showed multiple bands of which the band at 55 kDa was most prominent in kala-azar IC. It is known th at in kala-azar sera antihuman IgG is present, so the heavy band at 55 kDa region may be due to higher amount of IgG and/or other antigen(s) present at that region. Immunoblot experiments of kala-azar IC with a nti gp63 also developed a major band at 55 kDa. It suggests that the a ntigen (55 kDa) and gp63 have common antigenic epitope(s). Normal IC d id not react with anti gp63 indicating absence of this antigen in norm al IC. Antigenic similarity between the IC antigen (55 kDa) and gp63 i ndicated that the former antigen may have been processed from gp63. In summary, identification of a parasite antigen (55 kDa) in IC of kala- azar patients sera may be useful in developing a serodiagnostic assay for visceral leishmaniasis.