Trichomonads secrete large amounts of enzymes into liquid growth medium and also have many intracellular proteases. These proteases have been analyzed by gelatin-copolymerized with acrylamide gels showing about 10 bands among 20 and 200 kDa on acidic pH, depending on the isolates. The proteinases belong to cysteine-proteinase classes according to inhibition when leupeptin was used as inhibitor in presence of DTT. Some serine-proteinases could also be found and there was inhibition of the activity of the extracts, since PMSF was used. The extracts were passed through an immunoaffinity-column coupled with anti-T. vaginalis IgG isolated from immune sera and the protease activity seemed to be concentrated in the void. This is the first time that proteinases of Brazilian different isolates are studied and characterized. These data together support the hypothesis that the trichomonad proteases could have an important role in cytoadherence and cytotoxicity which participate on pathogenicity.

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The class A macrophage scavenger receptor (SR) binds an extraordinary wide range of ligands including bacterial pathogens and mediates macrophage adhesion. In the present study, SR knock-out mice were infected with Babesia microti to clarify its role in host defense mechanisms against protozoan infection. Several aspects of the immunological responses of mice during infection were studied. In B. microti infection, the packed cell volumes of SR-/- mice at 16-30 days after infection were significantly higher than those of SR+/+ mice, although the course of parasitemia was not different between these mice. Increase in spleen weights after infection were less obvious in SR-/- mice than in SR+/+ mice at 20 days after infection. Flow cytometric studies revealed that the decreases in the percentages of Thy1.2⁺ as well as CD4⁺ T cells in spleen after B. microti infection were higher in SR+/+ mice than that in SR-/- mice, whereas there were no difference in the rates of B220⁺ cells between SR-/- and SR+/+ mice. The peritoneal macrophages from SR+/+ mice exhibited higher phagocytic activity than those from SR-/- mice. These results indicate that scavenger receptor enhances immune responses and phagocytosis of parasitized erythrocytes, although it does not directly play an important role of protection against B. microti infection.

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Tritrichomonas foetus is the causative agent of bovine tritrichomonosis, a primarily sexually transmitted disease leading to infertility and abortion in cattle. To date, detection of bovine T foetus infection in routine diagnostics is performed by parasitological methods involving microscopial examination of samples directly or after in vitro cultivation in a suitable culture medium like Diamond’s medium or the commercially available InPouch^TMTF test. These methods may be hampered by contamination of the samples with intestinal or coprophilic microorganisms, furthermore they exhibit limited technical sensitivity. Recently, two different molecular diagnostic tests based upon the polymerase chain reaction (PCR) have been developped. In the present study, the performance characteristics of these two tests were determined using diagnostic and clinical samples, and were comparatively assessed with in vitro cultivation methods. The high suitability of a PCR test based upon ribosomal RNA gene unit sequences for routine diagnostic application was thus confirmed.

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