Genomic characterization of Moraxella bovis and Moraxella bovoculi Uruguayan strains isolated from calves with infectious bovine keratoconjunctivitis.

Infectious bovine keratoconjunctivitis (IBK) is an ocular disease that affects bovines and has significant economic and health effects worldwide. Gram negative bacteria Moraxella bovis and Moraxella bovoculi are its main etiological agents. Antimicrobial therapy against IBK is often difficult in beef and dairy herds and, although vaccines are commercially available, their efficacy is variable and dependent on local strains. The aim of this study was to analyze for the first time the genomes of Uruguayan clinical isolates of M. bovis and M. bovoculi. The genomes were de novo assembled and annotated; the genetic basis of fimbrial synthesis was analyzed and virulence factors were identified. A 94% coverage in the reference genomes of both species, and more than 80% similarity to the reference genomes were observed. The mechanism of fimbrial phase variation in M. bovis was detected, and the tfpQ orientation of these genes confirmed, in an inversion region of approximately 2.18kb. No phase variation was determined in the fimbrial gene of M. bovoculi. When virulence factors were compared between strains, it was observed that fimbrial genes have 36.2% sequence similarity. In contrast, the TonB-dependent lactoferrin/transferrin receptor exhibited the highest percentage of amino acid similarity (97.7%) between strains, followed by cytotoxins MbxA/MbvA and the ferric uptake regulator. The role of these virulence factors in the pathogenesis of IBK and their potential as vaccine components should be explored.

Effect of a new anti-T. cruzi metallic compound based on palladium.

Chagas disease is a neglected tropical disease caused by the protozoan parasite Trypanosoma cruzi. It is estimated that 6 million people are infected in Latin America. Current treatment is not effective due to the severe side effects and the limited efficacy towards the chronic phase of the disease. Considering the growing need for specific anti-Trypanosoma cruzi drugs, organometallic Pt and Pd based compounds were previously synthesized. Although the Pt-based compound effects on T. cruzi death have been reported, no mechanism of action has been proposed for the Pd-based analogous compound. In this work, we determined excellent to very good values of IC50 and SI. To analyze the compound mode of action, we measured Pd uptake and its association to the macromolecules of the parasite by electrothermal atomic absorption spectrometry. We found a poor uptake, which reaches only 16% after 24 h of incubation using 10× IC50, being the scarce incorporated metal preferentially associated to DNA. However, this compound has a trypanocidal effect, leading to morphological changes such as shortening of the parasite cell body and inducing necrosis after 24 h of treatment. Furthermore, this compound impairs the parasite development in the host both at the trypomastigote infection process and the intracellular amastigotes replication. In conclusion, our findings support that Pd-dppf-mpo compound constitutes a promising anti-T. cruzi compound effective against the chronic phase of the disease.

Trypanosoma cruzi biochemical changes and cell death induced by an organometallic platinum-based compound.

Chagas disease is an endemic illness in Latin America caused by the parasite Trypanosoma cruzi. Current chemotherapies are old and inadequate, and the emergence of drug-resistant strains underscores the need of new drugs. Platinum-based complexes have been shown to be a promising approach against parasitic diseases. In this work, the effect of 1,1'-bis(diphenylphosphino)ferrocene pyridine-2-thiolate-1-oxide Pt(II) hexafluorophosphate, Pt-dppf-mpo, was studied on T. cruzi. A promising antitrypanosomal activity was determined for the CL Brener strain with a low cytotoxicity determined using in vitro-cultured mammal cells. The compound uptake in parasites treated with concentrations of 1× and 10× the IC50 value reached ~75% and 19%, respectively. Pt-dppf-mpo induced necrosis after 24 hr of parasite incubation. This event was preceded by depolarization of mitochondrial membrane potential. Cell vitality assays showed high esterase activity in treated parasites. However, despite this increase in metabolic activity, treated epimastigotes showed rounded morphology and loss of flagellum with a reduction in mobility as compound concentration and/or time of incubation was increased. At last, we demonstrate that Pt-dppf-mpo incubation also affects the trypomastigote infection process as well as the infection persistence evaluated as the number of amastigotes per cell in a dose-dependent manner.