Distribution of lipophosphoglycan-associated epitopes in differentLeishmania species and in African trypanosomes

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Abstract
Monoclonal antibody (mAb) CA7AE binds specifically to the phosphorylated Gal-β1,4-Man disaccharide repeat epitope ofLeishmania donovani lipophosphoglycan (LPG). This mAb detected the repeat epitope in most but not all of a wide variety ofLeishmania species and strains examined. MAb CA7AE also bound to both glycoprotein and carbohydrate antigens in medium fromL. donovani promastigote cultures. Specifically, mAb CA7AE bound the delipidated form of LPG, the phosphoglycan, and a glycoprotein both of which are released into the medium by the parasite indicating that both share a specific phosphorylated carbohydrate epitope. The epitope was detected in sera fromL. donovani-infected (kala-azar positive) patients when mAb CA7AE was used in an antigen-capture enzyme-linked immunosorbent assay (ELISA). MAb L157 is specific for a protein that is found associated withL. donovani LPG, the lipophosphoglycan-associated protein (LPGAP). This mAb bound to molecules in all 19 strains (representing 9 species) ofLeishmania promastigotes and to molecules in 2 species ofTrypanosoma procyclic culture forms. This wide distribution of the LPGAP epitope implies that it may have a conserved function, for example, in the biochemistry or arrangement of parasite surface molecules. In addition, since the LPGAP is involved in the stimulation of T lymphocyte proliferation, its wide distribution amongst differentLeishmania species suggests that it may be an ideal molecule for testing as a vaccine for leishmaniasis.