Perfil fenotípico de cepas típicas e recombinantes de Toxoplasma gondii (Nicolle & Manceaux, 1909) isoladas de animais de produção : infectividade, cistogênese e relação com a virulência molecular

• Autor(a) principal: ANDRADE, Müller Ribeiro
• Data de Publicação: 2019
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFRPE
• Texto Completo: http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/8143
• topic: Toxoplasmose; Toxoplasma gondii; Caracterização fenotípica; CIENCIAS AGRARIAS::MEDICINA VETERINARIA

Toxoplasma gondii is an obligate intracellular protozoan parasite that presents a lytic cycle consisted of stages of recognition, penetration, multiplication, and can leave the host cell or evade the immune response from a mechanism of encystation, remaining in the intracellular space. These stages influence the infection capacity of the parasite, relating to its infectivity and, consequently, its virulence. This work’s purpose is to characterize phenotypically isolated T. gondii from tissues of animals from Alagoas, Brazil, under the aspect of infectivity (invasion and proliferation) and latency induced in the in vitro model. The in vitro biological behavior characterization tests chosen were: tachyzoite/bradyzoite conversion capacity, invasion rate and proliferation test. The first test evaluated the efficiency of tachyzoites in altering the metabolism to a stage of bradyzoites and was conducted through exogenous stress induction (medium with alkaline pH). The invasion test evaluated the penetration capacity of the isolates in three times 2h, 6h and 48h. And, finally, the proliferation test that consisted in verifying the multiplication capacity of the isolates in cell culture measured by real-time PCR. In the first article, isolates of T. gondii associated with abortion in small ruminants and classified as genotype II (TgGtBrAL01, TgGtBrAL02, TgShSp1 and ME49) were submitted to all the evaluations previously described. The TgShSp1 isolate had a higher rate of encystation and lower rates of invasion and proliferation was considered low infectivity. The isolates TgGtBrAL01 and TgGtBrAL02, coming from the same abortion outbreak in goats, differed only in the formation of cysts and showed the similar phenotypic profile in the other tests. In the second article the tachyzoite-bradyzoite conversion capacity of the recombinant genotypes TgCkBrAL01 (#277) and TgCkBrAL03 (#114) from chicken tissues were evaluated; TgPigBrAL01, TgPigBrAL02 and TgPigBrAL03 (all #114), isolated from pigs and strains of clonal RH (type I) and ME49 (type II). Differences in cyst formation responses of recombinant genotype isolates were observed in comparison to typical genotypes, resulting in an increase in vacuoles formation and decrease in lysis plaques. It was further revealed that isolates of the same genotype (#114) show different conversion rates. In the third article, the five recombinant genotype isolates described above, are characterized phenotypically in the parasite invasion and intracellular proliferation assays. In addition, the ROP18 and ROP5 gene profiles of two isolates of different genotypes, TgPigBrAL01 (# 114) and TgCkBrAL01 (# 277), were determined. Recombinant genotype isolates had a low rate of invasion and proliferation in relation to the RH and ME49 strains but did not show any differences between them. The infectivity characteristics of two recombinant isolates corroborate with the profile ROP5/ROP18 (1/3) gene, considered to be avirulent or non-lethal in mouse. The use of in vitro characterization has shown to be able to reveal characteristics of the infectivity that are directly related to virulence of T. gondii.