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

Abstract

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.

Intra-strain clonal phenotypic variation of Tritrichomonas foetus is related to the cytotoxicity exerted by the parasite to cultured cells

“…The ability of the parasite to destroy cultured epithelial cells has been reported (Silva-Filho and de Souza 1988; Burgess et al 1990; Burgess and McDonald 1992;Singh et al 1999). The cytotoxicity exerted by T. foetus on cultured cells seems to be greatly dependent on the expression of both specific parasite surface molecules and proteases (SilvaFilho and de Souza 1988;Lo´pez et al 2000). Thus, it has been proposed that the cytotoxicity exerted by T. foetus is a cell contact-dependent phenomenon (Singh et al 1999).…”

The binding of Tritrichomonas foetus to immobilized laminin-1 and its role in the cytotoxicity exerted by the parasite

“…In contrast, among cows the effects of the disease range from asymptomatic to severe clinical manifestations including vaginitis, cervicitis, endometritis and pyometra, resulting in transient infertility or fetal loss. Such clinical characteristics indicate the ability of T. foetus to invade host tissues (Parsonson et al, 1976;Ló pez et al, 2000). Trichomonads possess a diversity of surface glycoconjugates including adhesins (Corbeil et al, 1989;Singh et al, 1999;Alderete & Garza, 1988) and extracellular matrix (ECM)-binding molecules (Silva-Filho et al, 1988), which play important roles during the interaction of the parasites with their hosts.…”

“…foetus is an extracellular parasite usually found associated with the epithelium lining the urogenital cavities. Under certain conditions the parasite may invade host tissue (Parsonson et al, 1976;Ló pez et al, 2000). T. foetus, as well as other cavity parasites, appears to attach tightly to host tissue to overcome removal by physical forces.…”

Tritrichomonas foetus: a scanning electron microscopy study of erythrocyte adhesion associated with hemolytic activity

“…Among infected calves, the occurrence of endometritis, accompanied by uterine, cervical, and vaginal catarrh, is frequent. Since endometritis and uterine catarrh may prevent fertilisation affecting the regularity of the estrous cycle, some of the infected calves may remain permanently sterile [2,22].…”

“…The interaction of T. foetus with the epithelium lining of the urogenital cavities is the initial and crucial step for the establishment of bovine trichomoniasis [22]. Although extensively studied, the mechanisms of the pathogenicity of T. foetus have not yet been well defined.…”