Leishmania major: identification of stage-specific antigens and antigens shared by promastigotes and amastigotes.

A battery of antisera to Leishmania major was used to identify stage-specific antigens, or antigens expressed predominantly in amastigotes or promastigotes. At least 30 protein antigens common to amastigotes and promastigotes could be detected in 35S-methionine labelled preparations. They ranged in molecular weight from 25 000 to 165 000. Two amastigote specific antigens and five antigens expressed predominantly in the amastigote were detected in biosynthetically-labelled preparations. Five promastigote specific antigens were also identified. Antibodies from hyperimmunized mice that were resistant to reinfection with L. major recognized mainly antigens shared by the two life-cycle stages of the parasite. Analysis of parasite antigens on 'western blots' provided a different picture from that obtained by immunoprecipitation and gel electrophoresis of 35S-methionine labelled polypeptides. Only 19 antigens were detected and they were all shared by the two parasite forms. However, the abundance and immunogenicity of some of these antigens may be different in the two life-cycle stages of the parasite. Using the various sera, seven shared membrane antigens were identified in radio-iodinated preparations. Antibodies from hyperimmunized resistant mice that recognized shared antigens in 35S-methionine labelled preparations, detected four amastigote membrane antigens not detected by other sera. The function of the stage-specific antigens remains to be established. It is expected that individual antigens produced by recombinant DNA technology will allow these studies to proceed.