Characterization of oropharyngeal trichomonads in wild birds. Description of new variants, virulence assays and differential proteomic analysis using clonal cultures

Resumen

This Doctoral Thesis analyzed the diversity of oropharyngeal trichomonads in wild birds sampled at their habitat or admitted in wildlife recovery centers. Twenty three of 53 species were positive to the infection with the parasite, with genetic sequences reported from 16 new hosts. Seven genotypes of the ITS1/5.8S/ITS2 region were identified, with two of them isolated from birds with lesions and widely distributed among birds of prey, passeriformes and columbiformes. The overall prevalence rate was 20.3%. Five genotypes, three of them new reports, were related to particular hosts: three in European turtle doves, one in goshawks and one in Egyptian vultures. The likelihood of presenting gross lesions was influenced by the genotype of the parasite, the age of the host and the diet. Genotype Trichomonas gallinae-1, nestlings and non-strict ornithophagous species were risk factors for the presence of macroscopic lesions. Mixed infections and specific strains different from T. gallinae were selected for further characterization by MLST of clonal cultures and morphometric comparison. Two potentially new species of oropharyngeal trichomonads with higher similarity to Trichomonas tenax and Trichomonas canistomae were identified in a racing pigeon and European turtle doves. Moreover, European turtle doves revealed further potentially novel species more similar to Trichomonas tenax and Trichomonas sp. Additionally, a system for the classification of macroscopical lesions compatible with avian trichomonosis is proposed in order to standardize patient evaluation and prognosis among recovery centers. To clarify the pathogenicity of the parasite, clones of the most frequent genotypes (genotypes T. gallinae-1 and T. gallinae-2) were evaluated using in vitro infections on LMH cells. Differences were detected on day one and two post-infection, with clones of genotype T. gallinae-1 showing higher virulence. Finally, a comparative quantification of membrane and organelle membrane proteins of clones with genotype T. gallinae-1 and T. gallinae-2 was completed. Several proteins recognized as virulence factors in Trichomonas vaginalis and T. gallinae were found differentially expressed in both clones. The T. gallinae-1 clone had a higher amount of proteins associated with virulence or the chronicity of infections in other protozoa, in comparison with the T. gallinae-2 clone.