Identification and properties of Trichomonas vaginalis proteins involved in cytadherence

Abstract

Trichomonas vaginalis NYH286 surface proteins which are candidates for mediating parasite cytadherence (adhesins) were identified. At least four trichomonad protein ligands ranging in relative molecular mass from 65 to less than or equal to 21 kilodaltons were found to selectively bind to chemically stabilized HeLa cells. The proteins were present on the surfaces of 10 different isolates of T. vaginalis examined; however, the nonpathogenic trichomonad T. tenax did not possess similar HeLa cell-binding proteins under identical experimental conditions, suggesting that these proteins are unique to the pathogenic human trichomonads. The surface nature of the candidate adhesins was confirmed by the ability of the proteins on intact, live organisms to be radioiodinated and to be removed with trypsin treatment. Rabbit antiserum (immunoglobulin G fraction) generated against adhesin proteins electroeluted from acrylamide preparations inhibited cytadherence compared with control immunoglobulin G. An adherence-negative subpopulation of T. vaginalis NYH286 organisms was also isolated. These nonadherent trichomonads did not synthesize the adhesin proteins. Interestingly, absence of adhesins from these parasites paralleled expression of a major immunogen known to undergo phenotypic variation. Revertant organisms derived from the adherence-minus subpopulation synthesized the adhesins and attached to HeLa cells. The emergence of revertant adherent T. vaginalis organisms also corresponded with the appearance of parasites which were without the major immunogen on their surface. Finally, it was determined that only those parasites lacking the major surface immunogen were capable of adherence and toxicity to HeLa cells.

Iron regulates growth of Trichomonas vaginalis and the expression of immunogenic trichomonad proteins

“…Lactoferrin binding was measured as described in the Experimental procedures. Protein synthesis of cycloheximide-treated organisms was inhibited as has been described (Aiderete and Garza, 1988). The inset demonstrates the return to baseline levels of lactoferrin binding after addition of iron {O) but not trace metal solution (•) (Linstead, 1981) of parasites grown under stringent iron-limitation.…”

A Trichomonas vaginalis 120 kDa protein with identity to hydrogenosome pyruvate:ferredoxin oxidoreductase is a surface adhesin induced by iron

“…Despite that four-trichomonad surface adhesins: AP65, AP51, AP33 and AP23, have been identified and characterized previously (Alderete and Garza, 1988;Arroyo et al, 1992), no putative receptors on the human urogenital cells have been identified for any of them yet. Nevertheless, in this work, we showed the identification of a putative receptor to the AP120 adhesin in HeLa cells, a 130 kDa surface protein.…”

Investigation of the Secretory Pathway in Trichomonas vaginalis Argues against a Moonlighting Function of Hydrogenosomal Enzymes

“…The inability of APs to enter the secretory pathway that was demonstrated in this study is in direct contradiction to previous investigations. Polyclonal rabbit antisera against AP65 and AP51 ( Alderete and Garza 1988;Arroyo et al 1992) have been used as Golgi markers for the investigation of Golgi structure and division within the T. vaginalis cell cycle . AP65 antiserum strongly labeled Golgi ribbons and a few vesicles in the cytoplasm.…”

“…The last group of proteins includes the enzymes pyruvate ferredoxin oxidoreductase (PFO), malic enzyme, and the aand b-subunits of succinyl-CoA synthetase (SCS), which mediate key steps of energy metabolism in hydrogenosomes (Brugerolle et al 2000;Drmota et al 1996;Hrd y and M€ uller 1995;Lahti et al 1992Lahti et al , 1994. Curiously, the same proteins have been reported to function as the surface adhesins AP120 (PFO), AP65 (malic enzyme), AP33 (a-SCS), and AP51 (b-SCS) (Alderete and Garza 1988;Alderete et al 1995a,b;Arroyo et al 1992;Moreno-Brito et al 2004). As adhesin proteins (APs), they are proposed to mediate the cytoadherence of T. vaginalis to vaginal epithelial cells (VECs; Alderete and Garza 1988;Alderete et al , 1995a.…”

“…Curiously, the same proteins have been reported to function as the surface adhesins AP120 (PFO), AP65 (malic enzyme), AP33 (a-SCS), and AP51 (b-SCS) (Alderete and Garza 1988;Alderete et al 1995a,b;Arroyo et al 1992;Moreno-Brito et al 2004). As adhesin proteins (APs), they are proposed to mediate the cytoadherence of T. vaginalis to vaginal epithelial cells (VECs; Alderete and Garza 1988;Alderete et al , 1995a. The expression of APs is induced by contact of T. vaginalis with host cells and upregulated under high-iron conditions (Alderete et al , 2004Garcia et al 2003;Lehker et al 1991).…”