Infecção experimental de Calomys callosus pelas cepas brasileiras TgChBrUD1 ou TgChBrUD2 de Toxoplasma gondii e avaliação da toxoplasmose congênita em fêmeas cronicamente infectadas com a cepa ME-49

Abstract

There is a significant genetic diversity of Toxoplasma gondii in Brazil. Two parasite strains were recently isolated from chicken in Uberlândia city, Minas Gerais state, which were named TgChBrUD1 and TgChBrUD2. Congenital toxoplasmosis results mainly from primary maternal infection during pregnancy, but can be occasionally caused by reinfection. Calomys callosus is a suitable experimental model to study different features of T. gondii infection. The present study aimed to evaluate the C. callosus susceptibility when infected with Brazilian T. gondii strains, determine whether females chronically infected with ME-49 strain is susceptible to reinfection with Brazilian strain and if reinfection may cause vertical transmission of the parasite. Male and female were intraperitoneally infected with TgChBrUD1 or TgChBrUD2 tachyzoites and monitored to evaluate the survival. Immunohistochemical assay and qPCR were performed to determine the parasitism in liver, spleen and brain. Males and females are susceptible to infection, but the females were more susceptible to TgChBrUD1 strain and the males to TgChBrUD2 strain. Non-pregnant females were chronically infected with ME-49 and reinfected with TgChBrUD1 or TgChBrUD2 strain and monitored to evaluate the survival. All non-pregnant females survived after reinfection. The vertical transmission was analyzed by reinfection with TgChBrUD1 or TgChBrUD2 strain in the first day of pregnancy in chronically infected females with ME-49. At 19th day of pregnancy, placentas, uterus and fetuses, were processed for detection of the parasite and fetal resorption. Blood samples were collected for antibodies and cytokines analyses. In pregnant females, parasites were detected in placenta and fetuses after reinfection with both Brazilian strains. TgChBrUD2 reinfected females showed more impaired pregnancy outcomes presenting higher number of animals with aborted fetuses and resorption rate. In addition, they presented higher pro-inflammatory cytokines and IgG2a antibody. In conclusion, our results showed that C. callosus are susceptible to both T. gondii Brazilian strains. Therefore, the reinfection reactived the ME-49 latent infection and the protection against T.gondii can be breached after reinfection with parasites belonging to different genotypes and promote the congenital toxoplasmosis.