Detection of microtubules of the flagellate Trichomonas vaginalis by monoclonal antibodies specific for beta-tubulin.

Monoclonal antibodies specific for mammalian beta-tubulin recognized the microtubule cytoskeleton of the flagellated protozoon Trichomonas vaginalis. Of seven antibodies, two demonstrated the axostyle, costa, recurrent flagellum, and anterior flagella by indirect immunofluorescence microscopy. The remaining five stained a hazy reticular pattern in the cytoplasm of formaldehydefixed, detergent-extracted organisms. Western immunoblots of whole T. vaginalis extracts treated with protease inhibitors and electrophoresed on polyacrylamide gels containing sodium dodecyl sulfate showed a major band at molecular weight 50,000 when probed with only one of the antibodies which stained the axial cytoskeleton. The antibodies which stained only the cytoplasm showed a different western blot pattern with a major doublet band at MW 58,000-60,000. Another antibody, which stained both the axial cytoskeleton and the reticular cytoplasmic pattern showed major bands at MW 58,000-60,000 and also at MW 40,000-42,000. The recognition of microtubule populations in T. vaginalis by these monoclonal antibodies was different than we found earlier with Leishmania donovani and Toxoplasma gondii, where all seven antibodies recognize cytoskeletal microtubules and produce western blots characteristic of tubulin. Only one of these seven antibodies recognizes tubulin in T. vaginalis by immunoblot. The microtubules of T. vaginalis do not demonstrate all epitopes recognized by monoclonal antibodies specific for mammalian beta-tubulin; one of the antibodies appears to recognize an epitope which is morphologically associated with microtubules but does not have the characteristic MW of tubulin.