Agentes da Piroplasmose equina: variabilidade gen?tica de Theileria equi e Babesia caballi em equinos naturalmente infectados do estado do Rio de Janeiro e a din?mica da infec??o de Theileria equi em Rhipicephalus (Boophilus) microplus

• Autor(a) principal: Peixoto, Maristela Peckle
• Data de Publicação: 2017
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFRRJ
• Texto Completo: https://tede.ufrrj.br/jspui/handle/jspui/2587
• topic: Diversidade gen?tica; piroplasmose equina; theileriose equina; transmiss?o transestadial; transmiss?o transovariana; Genetic diversity; equine piroplasmosis; equine teileriosis; transestadial transmission; transovarian transmission; Medicina Veterin?ria

This study aimed to perform the molecular characterization of the B. caballi rap-1 gene and to analyze the degree of heterogeneity of the T. equi 18S rDNA gene of naturally infected horses in the state of Rio de Janeiro. Complete sequences of the T. equi 18S rDNA gene (n = 20) were obtained. The PCR products were cloned and sequenced. Phylogenetic analyzes were performed on ARB-Silva basis. For the molecular characterization of a fragment of the B. caballi rap-1 gene, 32 cELISA and qPCR positive equine samples were used. A nested PCR was developed to amplify a fragment of the rap-1 gene and a conventional PCR, aiming the amplification of the complete gene. The products were sequenced. Sequences were submitted to the Maximum-Likelihood reconstruction method with Poisson model and 1000 replicates. In the analysis of T. equi, twelve different isolates were observed in equines from the state of Rio de Janeiro and were grouped into two of the three clades formed (I, II), most of them grouped in clade I (70%, n = 14/20). The sequences of T. equi are grouped within a clade different from other Theilerids. It was possible to amplify a fragment of the B. caballi rap-1 gene from 23 sequences using nested PCR, identified as single sequences. One of the sequences showed twelve mutation points. In cluster analysis, the Brazilian samples belonged to clade A, being analyzed as amino acids (152a) or nucleotides (1244 bp). The aim of the second chapter was to evaluate the dinamic of infection of T. equi in R. (B.) microplus fed in chronically infected horses. The larvae obtained from a hemoparasite-free colony were used in the infestation of an equine chronically infected by T. equi. Ticks and the horse blood were collected every two days. Ticks were dissected and stored in pools according to the pos-infestation day, evolutionary stage and gender. Some of these specimens were stored entire. Salivary gland and ovary samples were stored properly for Transmission Electron Microscopy. Some stages, prior to ecdysis, were stored in B.O.D. to molt. Samples were tested by qPCR. Regarding to entire tick samples, more than 90% of the samples were positive for T. equi. The mean of parasite load in entire ticks and salivary glands presented gradual increasing with the progress of the feeding period. Of the 45 salivary gland samples, 77.78% were positive for T. equi and had a higher infection rate at the end of the experimental period. It was found freshly molted ticks positives for T. equi by qPCR, indicating transestadial transmission. 84,38% of R. (B.) microplus ovary samples were considered positives for T. equi by molecular tools. Males of R. (B.) microplus were found parasiting the equine for 60 days. This fact associated with the high positivity for T. equi indicates males as an epidemiologically important gender. Transmission micrographs revealed morphologic structures compatible with a Piroplasmid in the acini of salivary glands and ovaries. The phylogenetic analysis of the T. equi 18S rDNA gene and of B. caballi rap-1 gene showed that different isolates co-exist in the same area in Rio de Janeiro, Brazil. Experimently, it was possible to observe that R. (B.) microplus could be infected with T. equi and that the forms of development of this parasite are capable of multiply inside salivary glands and, possibly, ovaries.