Iron enhancement of experimental infection of mice by Tritrichomonas foetus

Abstract

The ability of a microbial invader to acquire iron from its vertebrate host has been recognized as an important virulence mechanism in some pathogenic bacteria. We examined the involvement of similar mechanisms in an experimental infection of mice by a protozoan pathogen of cattle, Tritrichomonas foetus. In a series of experiments, outbred ICR mice were inoculated intraperitoneally with two strains of T. foetus, the moderately virulent KV-1 (approximately 5% mortality rate) and the highly virulent LUB-1MIP (approximately 80% mortality rate). Treatment of mice with ferric ammonium citrate (FeAC) (100 mg/kg per day intraperitoneally) increased the mortality rate caused by the KV-1 infection up to the level determined for the highly virulent strain. The treatment effect was dose dependent and required early administration of FeAC after inoculation of parasites and its continued supply for at least 3 subsequent days. Daily sampling of peritoneal exudate showed that the infection-enhancing effect of iron overload was associated with a stimulation of parasite multiplication, which in the case of KV-1 infection was strongly suppressed in untreated mice. Consistent with these findings, the strain of lower virulence (KV-1) showed considerably lower efficiency accumulating radiolabeled iron from transferrin and a low-molecular source [Fe(III)nitrilotriacetic acid] in vitro. The results indicate an involvement of iron uptake mechanisms by the parasite as a virulence factor in T. foetus infection.

Transferrin Binding Proteins as a Means to Obtain Iron in Parasitic Protozoa

“…When examined in vitro, the KV-1 strain showed significantly lower iron acquisition from holo-TF and low molecular mass complexes than the highly virulent strain. These data indicate a correlation between strain virulence and iron acquisition from holo-TF [Kulda et al, 1999]. Growth of parasites using holoTF as a sole iron source has been reported in vitro [Tachezy et al, 1996].…”

“…Administration of ferric ammonium citrate to infected mice increased the mortality rate to the level associated with the highly virulent LUB-1MIP strain (~80% mortality rate) [Kulda et al, 1999]. When examined in vitro, the KV-1 strain showed significantly lower iron acquisition from holo-TF and low molecular mass complexes than the highly virulent strain.…”

Construction and bootstrap analysis of DNA fingerprinting-based phylogenetic trees with the freeware program FreeTree: application to trichomonad parasites.

“…The methods of molecular taxonomy can be divided into two groups : single-locus methods and multilocus methods. The result of any single-locus method, such as DNA sequencing, microsatellite analysis or singlestranded conformational polymorphism (SSCP) analysis, is the so-called ' gene tree ', the topology of (1986) ; 'Forsgren & Forssman (1979) ; (Meingassner & Thurner (1979) ; ) Kulda et al (1999) ; * Kulda & Honigberg (1969) ; "! Culberson et al (1986) ; "" Kulda et al (1974).…”

The Effects of Iron Supplementation on the Growth Rate and Antioxidant Activity of Trichomonas vaginalis

“…Leishmania chagasi also expresses a NADPHdependent iron reductase capable of converting oxidized Fe 3+ into the more soluble Fe 2+ form [20]. In addition, the ability of Tritrichomonas foetus for the uptake of iron from the host environment may be a critical factor for its pathogenicity and virulence [21]. The parasite grows in the bovine vagina where lactoferrin is available and also invades the bovine uterus, where abundant transferrin exists [22].…”