Raw blot and gel images.

<div><p><i>Trichomonas vaginalis</i> is the causative agent of the common sexually transmitted disease, trichomoniasis, which affects more than a hundred million people worldwide. Metronidazole and tinidazole, agents belonging to the 5-nitroheterocyclic class of antimicrobials, are most often used to treat infection, but increased resistance has been reported and adverse effects of these drugs can be significant. Consequently, an urgent need exists for the development of novel drug entities against trichomoniasis. Critical for antimicrobial drug development is the demonstration of <i>in vivo</i> efficacy. Murine models of vaginal <i>T</i>. <i>vaginalis</i> infection are unreliable for unknown reasons. Meanwhile, murine infections with the related bovine pathogen, <i>Tritrichomonas foetus</i>, tend to be more robust, although susceptibility to different antimicrobials might differ from <i>T</i>. <i>vaginalis</i>. Here, we explored the utility of <i>T</i>. <i>foetus</i> infection as a surrogate model for drug development against <i>T</i>. <i>vaginalis</i>. Four different <i>T</i>. <i>foetus</i> strains caused robust vaginal infection in young mice, while none of four diverse <i>T</i>. <i>vaginalis</i> strains did. Comparison of drug susceptibility profiles revealed that <i>T</i>. <i>foetus</i> and <i>T</i>. <i>vaginalis</i> were similarly susceptible to a range of 5-nitroheterocyclic and gold(I) compounds. By comparison, proteasome inhibitors were 10- to 15-fold less active against <i>T</i>. <i>foetus</i> than <i>T</i>. <i>vaginalis</i>, although one of the proteasome inhibitors, bortezomib, had low micromolar activity or better against multiple strains of both trichomonads. Different strains of <i>T</i>. <i>foetus</i> were used to demonstrate the utility of the murine vaginal infection models for <i>in vivo</i> efficacy testing, including for bortezomib and a gold(I) compound. The differences in susceptibility to proteasome inhibitors may be partially explained by differences in the proteasome subunit sequences between the two trichomonads, although the functional relevance of the proteasome was similar in both organisms. These findings indicate that <i>T</i>. <i>foetus</i> can serve as a reliable surrogate model for <i>T</i>. <i>vaginalis in vitro</i> and in murine infections <i>in vivo</i>, but caution must be exercised for specific drug classes with targets, such as the proteasome, that may display genetic divergence between the trichomonads.</p></div>