Phenotypic and genetic characterization of emerging trematodiasis: fascioliasis and schistosomiasis
- Autores: Marta Reguera Gómez
- Directores de la Tesis: Santiago Mas Coma (dir. tes.), María Dolores Bargues (codir. tes.), María Adela Valero (codir. tes.)
- Lectura: En la Universitat de València ( España ) en 2021
- Idioma: español
- Tribunal Calificador de la Tesis: Manuel Fresno Escudero (presid.), María Manuela Morales Suárez-Varela (secret.), RAQUEL da SILVA PACHECO (voc.)
- Programa de doctorado: Programa de Doctorado en Parasitología Humana y Animal por la Universitat de València (Estudi General)
- Materias:
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- Resumen
Fascioliasis and Schistosomiasis are two major (re)emerging trematodiasis with large impact on human health. Given the necessity to characterize the Trematode populations involved, the aims of the present research are, first, analyze the impact of Fasciola hepatica experimental reinfection on immunological, clinical and biological phenotypes by means of an experimental design which reproduced the usual reinfection/chronicity conditions in human Fascioliasis endemic areas. Second, the morphological phenotypic characterization of parasite eggs from Schistosomiasis haematobium infected sub-Saharan migrants in Spain and introduction of a new study methodology. The specific results have been grouped into four parts. A. Impact of Fascioliasis reinfection on host immune response: relationship with the clinical phenotypes of anemia. The profile of the Th1/Th2/Th17/Treg expression levels is analyzed after reinfection, correlating them with their corresponding hematological biomarkers of morbidity. Reinfection in the chronic phase is able to activate a mixed immune response (Th1/Th2/Th17/Treg). The systemic immune response is different in each group, suggesting that suppression is mediated by different mechanisms in each case. Multivariate mathematical models were built to describe the Th1/Th2/Th17/Treg expression levels and the clinical phenotype. B. Impact of Fascioliasis reinfection on F. hepatica egg shedding: relationship with the immune-regulatory response. Serical IgG1 levels and eggs per gram of feces (epg) were analyzed after reinfection, correlating them with their corresponding profile of the Th1/Th2/Th17/Treg expression levels. A transiently higher averages of epg and epg/worm in reinfected groups vs primoinfected group (PI) were detected at least in the weeks following reinfection. The kinetics of IgG1 levels shows that reinfected groups followed a pattern similar to the one in the PI group, but transiently higher averages of IgG1 levels in reinfected groups vs the PI group were detected in the weeks following reinfection. Epg correlated with IgG1 levels and also with systemic Il10 and thymic Ifng and Il10 expression levels. These results suggest that epg depends on the Th1 and Treg phenotype and that the determination of the fluke burden by epg is likely to be an overestimation in cases of recent reinfection in low burden situations. A strategy to facilitate the implementation of epg count techniques and the subsequent decision on the appropriate treatment dose for each patient to prevent colic risk is required. C. Phenotypic analysis of Schistosoma species eggs: proposal for a standardized study methodology. The present study focuses on eggs, considered genetically pure S. haematobium by genetic characterization (intergenic ITS region of the rDNA and cox 1 mtDNA by RD-PCR). A phenotypic characterization of S. haematobium eggs was made by morphometric comparison with experimental populations of S. bovis and S. mansoni. Analyses were made by Computer Image Analysis System (CIAS) applied on new standardized measurements and geometric morphometric tools. The principal component analysis (PCA), including seventeen non-redundant measurements, showed three phenotypic patterns in eggs of S. haematobium, S. bovis and S. mansoni. Mahalanobis distances between each pair of groups were calculated for each discriminant analysis performed. In general, S. mansoni and S. bovis present larger distances between them than with S. haematobium, i.e. they present the greatest differences. Regarding the spine, S. haematobium and S. mansoni are the most distant species. Results show the usefulness of this methodology for the phenotypic differentiation between eggs from these Schistosoma species, capable of discerning morphologically close eggs, as is the case of the haematobium group. Schistosoma egg phenotyping approaches may be applied to assess not only hybrid forms but also potential influences of a variety of other factors. D. Phenotypic characterization of S. haematobium-like and genetically pure eggs: description of morphotypes and analysis of the influence of the geographical origin on egg phenotypes. The above-described methodology allowed us to classify the eggs from Schistosomiasis haematobium infecting sub-Saharan migrants in Spain into three morphotypes: round, elongated and spindle. The results show an uneven distribution of these morphotypes among countries. In addition, an egg sample was both geno- and phenotyped (intergenic ITS region of the rDNA and cox 1 mtDNA by RD-PCR), allowing us to compare only genetically pure eggs and eliminate the variability hybrid eggs might entail. Regarding the influence of the geographical origin, great intraspecific variation was found among countries. Further studies will confirm these results and the utility of this tool for comparative studies of hybrid Schistosoma egg morphology.
Key words: Fasciola hepatica, Schistosoma haematobium, Schistosoma mansoni, Schistosoma bovis, reinfection, Th1/Th2/Th17/Treg expression levels, anemia, epg, IgG1, egg shedding, egg morphology, ITS region of the rDNA, cox 1 mtDNA, CIAS, PCA, sub-Saharan migrants, Spain.
