THE GENE B PROTEIN LOCALIZES TO THE SURFACE OF LEISHMANIA-MAJOR PARASITES IN THE ABSENCE OF METACYCLIC STAGE LIPOPHOSPHOGLYCAN

The stage specific Gene B protein (GBP) of Leishmania major localises to the surface of infective metacyclic parasites, where it associates with the developmentally regulated surface glycoconjugate, lipophospho glycan (LPG). This association has been proposed to aid maintenance of GBP on the parasite surface. In this paper, we show that the abundanc e of GBP on the extracellular metacyclic cell surface is in the order of 100,000 copies per cell. This level of expression is comparable to that seen in the intracellular amastigote stage, in which GBP is also localised to the surface, despite the lack of metacyclic stage specifi c LPG. Furthermore GBP expressed from an episome in avirulent parasite s, which are unable to synthesise metacyclic LPG or endogenous GBP, al so localises to the parasite surface. These data demonstrate that GBP can maintain a surface localisation in the absence of metacyclic LPG, suggesting that it is able to associate with other glycoconjugates on the surface of infective parasites.