Strategies by which some pathogenic trichomonads integrate diverse signals in the decision-marking process

The interaction between each one of Trichomonas vaginalis and Tritrichomonas foetus with their hosts is a complex process in which components associated to the cell surfaces of both parasites and host epithelial cells, and also to soluble components found in vaginal/urethral secretions, are involved. Either cytoadhesion or the cytotoxicity exerted by parasites to host cells can be dictated by virulence factors such as adhesins, cysteine proteinases, laminin-binding proteins, integrins, integrin-like molecules, a cell detachment factor, a pore-forming protein, and glycosidases among others. How trichomonads manipulate informations from the extracellular medium, transduce such informations, and respond to them by stimulating the activities of some surface molecules and/or releasing enzymes are the aspects concerning trichomonal virulence which are here briefly reviewed and discussed.

Proteins of Entamoeba histolytica trophozoites involved in the adhesion to target cells

To identify the molecules involved in the adhesion of Entamoeba histolytica trophozoites to target cell we used monoclonal antibodies (MAbs) and adhesion-deficient mutants. Human red blood cell (RBcs) were also used as especific carriers to identify the ameba molecules with affinity to the target cell receptors. MAbs adh-1 and Adh-2 inhibited adhesion of RBCs to the trophozoites and recognized a 112-kDa surface protein that was present in the wild type strain, but was absent or modified in adhesion-deficient mutants. In other experiments, live trophozoites were incubated with fixed-RBCs and after lysis of the trophozoites, proteins attached to the RBCs surface were separated by PAGE, electrotransferred to nitrocellulose membranes and detected by polyclonal antibodies. The 112 kDa protein was found attached to the RBCs. Other molecules identified as proteins involved in the target cell-parasite contact were the 210, 160, 90, 70, 50 and 24 kDa proteins. The 112, 90 and 24kDa polypeptides were functionally altered in adhesion-deficient mutants