Identification and characterization of protein antigens of Leishmania tropica isolates.

Promastigotes of 4 Leishmania tropica isolates were biosynthetically labeled with 35S-methionine or surface radioiodinated, and the detergent lysates were analyzed by 2 dimensional gel electrophoresis. The protein patterns of cytoplasmic and membrane proteins detected in two independent isolates from simple cutaneous leishmaniasis cases were similar to each other, but were different from 2 isolates taken over a 20-yr interval from a case of leishmaniasis recidiva. The analysis of radioiodinated membrane proteins of L. tropica promastigotes revealed a simple pattern of 6 to 7 labeled major proteins and some minor ones. Unlike cytoplasmic proteins, membrane proteins were highly resistant to digestion by proteases. Partial cleavage of radioiodinated surface proteins by staphylococcal V-8 protease in the presence of 4.5 M urea and peptide mapping confirmed the presence of shared and isolate-specific proteins. The significance of these findings for the classification of Leishmania spp. and the pathogenesis of the different disease states that they cause are discussed.