Laboratory of Immunophysiology of Reproduction, Department of Histology and Embryology, Federal University of Uberlândia , Uberlândia, Brazil.
Laboratory of Immunopathology, Institute of Biomedical Sciences, Federal University of Uberlândia , Uberlândia, Brazil.
Front Microbiol. 2015 Mar 10;6:181. doi: 10.3389/fmicb.2015.00181. eCollection 2015.
Considering that Toxoplasma gondii has shown high genetic diversity in Brazil, the aim of this study was to determine whether Calomys callosus chronically infected by the ME-49 strain might be susceptible to reinfection by these Brazilian strains, including vertical transmission of the parasite. Survival curves were analyzed in non-pregnant females chronically infected with ME-49 and reinfected with the TgChBrUD1 or TgChBrUD2 strain, and vertical transmission was analyzed after reinfection of pregnant females with these same strains. On the 19th day of pregnancy (dop), placentas, uteri, fetuses, liver, spleen, and lung were processed for detection of the parasite. Blood samples were collected for humoral and cellular immune response analyses. All non-pregnant females survived after reinfection and no changes were observed in body weight and morbidity scores. In pregnant females, parasites were detected in the placentas of ME-49 chronically infected females and reinfected females, but were only detected in the fetuses of reinfected females. TgChBrUD2 reinfected females showed more impaired pregnancy outcomes, presenting higher numbers of animals with fetal loss and a higher resorption rate, in parallel with higher levels of pro-inflammatory cytokines and IgG2a subclass antibodies. Vertical transmission resulting from chronic infection of immunocompetent C. callosus is considered a rare event, being attributed instead to either reactivation or reinfection. That is, the pregnancy may be responsible for reactivation of the latent infection or the reinfection may promote T. gondii vertical transmission. Our results clearly demonstrate that, during pregnancy, protection against T. gondii can be breached after reinfection with parasites belonging to different genotypes, particularly when non-clonal strains are involved in this process and in this case the reinfection promoted vertical transmission of both type II and Brazilian T. gondii strains.
考虑到刚地弓形虫在巴西表现出很高的遗传多样性，本研究旨在确定慢性感染 ME-49 株的 Calomys callosus 是否易受这些巴西株的再感染，包括寄生虫的垂直传播。分析了慢性感染 ME-49 并再感染 TgChBrUD1 或 TgChBrUD2 株的非妊娠雌性和再感染这些相同株的妊娠雌性的生存曲线，并分析了垂直传播。在妊娠第 19 天（dop），处理胎盘、子宫、胎儿、肝、脾和肺以检测寄生虫。采集血液样本进行体液和细胞免疫反应分析。所有非妊娠雌性在再感染后均存活，体重和发病率评分无变化。在妊娠雌性中，ME-49 慢性感染雌性和再感染雌性的胎盘检测到寄生虫，但仅在再感染雌性的胎儿中检测到寄生虫。TgChBrUD2 再感染雌性表现出更多受损的妊娠结局，具有更高比例的胎儿丢失和更高的吸收率，同时具有更高水平的促炎细胞因子和 IgG2a 亚类抗体。免疫功能正常的 C. callosus 慢性感染的垂直传播被认为是一种罕见事件，归因于再激活或再感染。也就是说，妊娠可能导致潜伏感染的再激活，或者再感染可能促进刚地弓形虫的垂直传播。我们的结果清楚地表明，在怀孕期间，再次感染来自不同基因型的寄生虫会破坏对 T. gondii 的保护，特别是当涉及非克隆株时，在这种情况下，再感染促进了 II 型和巴西刚地弓形虫株的垂直传播。
