A monoclonal antibody directed to terminal residue of beta-galactofuranose of a glycolipid antigen isolated from Paracoccidioides brasiliensis: cross-reactivity with Leishmania major and Trypanosoma cruzi.

A mouse monoclonal antibody, MEST-1, was produced against Band 1 glycolipid antigen of Paracoccidioides brasiliensis. The glycan structure of Band 1 antigen was recently elucidated and the monosaccharides sequence was defined as: Galf beta 1-->6(Manp alpha 1-->3)Manp beta 1-->2Ins. The reactivity of MEST-1 MAb was determined by solid-phase radioimmunoassay and high performance thin layer chromatography immunostaining. Selective oxidation of galactofuranose residues and inhibition assays with different methyl-glycosides, revealed that MAb MEST-1 is directed against the terminal residue of beta-D-galactofuranose of Band 1, a phosphoglyceroglycolipid antigen of P. brasiliensis. By indirect immunofluorescence, it was observed that the epitope recognized by MEST-1 is accessible to the antibody in yeast forms of this fungus. Reactivity of MEST-1 with parasites known to express galactofuranose containing glycoconjugates was also analyzed by indirect immunofluorescence. A positive fluorescence was observed with promastigotes of Leishmania major and epimastigotes of Trypanosoma cruzi. GIPL-1 was identified as the antigen recognized by MEST-1 in Leishmania major, indicating that the MAb MEST-1 recognizes terminal galactofuranose residue in either beta 1-->6 or beta 1-->3 linkage to the mannose.