Host and tissue specificity of Trichomonas vaginalis is not mediated by its known adhesion proteins

Abstract

Adhesion of Trichomonas vaginalis is believed to be dependent on four adhesion proteins, which are thought to bind to vaginal epithelial cells in a specific manner with a ligand-receptor type of interaction. However, the specific receptors on the host cell have not yet been identified. In this work, the ability of the T. vaginalis adhesins to bind to cells of different histologic derivations and from different species has been studied. HeLa, CHO, and Vero cell lines; erythrocytes from different species; and a prokaryote without a cell wall, Mycoplasma hominis, were employed in order to investigate the cell specificity of the T. vaginalis adhesins. We observed that the T. vaginalis adhesins are able to bind to the different cell types to the same extent, suggesting that the host and tissue specificity of T. vaginalis adhesion should not be due to specificity of the parasite adhesins. Our results suggest that the data published to date on the subject are probably artifactual and that the experiments reported in the literature are not appropriate for identification of protozoan adhesins.

FIG. 1

(A) Representative ligand assays of T. vaginalis proteins obtained with fixed HeLa (lane 1), CHO (lane 2), and Vero (lane 3) cells. (B) Representative ligand assay of T. vaginalis proteins obtained with fixed M. hominis cells. Cells were detached by trypsinization or collected by centrifugation, washed, fixed with glutaraldehyde, and incubated with total T. vaginalis proteins. The adhered trichomonad proteins were detached by boiling fixed cells in Laemmli buffer, subjected to electrophoresis on 10% polyacrylamide gels, and revealed with Coomassie blue. Molecular mass markers (kilodaltons) are indicated on the left.

FIG. 2

Representative immunoblot showing the T. vaginalis proteins that bind to trypsinized human group 0 erythrocytes. The same proteins could be observed with trypsinized and nontrypsinized human and rabbit erythrocytes. Washed erythroctes were incubated with total T. vaginalis proteins, and membranes were collected, washed, subjected to electrophoresis, and transferred to nitrocellulose. Bound parasite proteins were then revealed by using total anti-T. vaginalis antibodies. Molecular mass markers (kilodaltons) are indicated on the left.