RESUMO
Toxoplasma gondii is commonly transmitted among animals and humans by ingestion of infected animal tissues or by consumption of food and water contaminated with environmentally-resistant oocysts excreted by cats. Tissue cysts and oocysts have different walls, whose structures and compositions are poorly known. Herein, we describe an immunomagnetic separation (IMS) method that was successfully used for purification of T. gondii tissue cysts generated in cell culture. We used an IgG monoclonal antibody (mAb) that reacts against antigens in tissue cyst walls. Many in vitro produced cysts were obtained by this IMS; >2,000 T. gondii cysts were isolated from a single culture flask of 25 cm2. Tissue cysts from two Hammondia spp., H. hammondi, and H. heydorni, produced in cell culture were also separated using this method. As a reference, purification of tissue cysts by Percoll gradients was used. Percoll was able to separate T. gondii tissue cysts produced in mice but was not suitable for purifying T. gondii tissue cysts produced in vitro. The IMS described here should favor proteomic studies involving tissue cysts of T. gondii.
RESUMO
Toxoplasma gondii (T. gondii) crosses the intestinal barrier in oral infections and can lead to changes in different cell types, including the neurons located there. In the gastrointestinal system, the autonomous nervous system component that regulate blood flow and mucous secretion is the submucosal plexus. The aim of this study was to examine the effects of T. gondii infection on intraepithelial lymphocytes (IELs), goblet cells and submucosal neurons that are immunoreactive to vasoactive intestinal peptide (VIP-IR) of rat jejunum. Twenty male rats distributed as a control group (CG) and an infected group (IG), which received a suspension with 500 parasite oocysts (strain ME-49, genotype II) orally, were assessed. Routine histological sections were used to quantify IELs and to detect mucins secreted by goblet cells. Whole mounts including the submucosal layer were examined using immunofluorescence to detect the VIP neurotransmitter. Quantitative alterations in IELs were not observed. However, the reduction (P < 0.05) in the number of goblet cells that produce neutral mucins (PAS+) and sulphomucins (AB pH 1.0) and the maintenance of sialomucin-secreting cells (AB pH 2.5) resulting in a more fluid mucous were observed. Concerning the VIP-IR submucosal neurons, an increase in fluorescence on IG animals was observed. There was a reduction (P < 0.05) in the number of VIP-IR submucosal neurons and atrophy of their cell bodies in IG rats. Infection with T. gondii caused alterations in the chemical composition of the intestinal mucous and reduction in the neuron number and atrophy of the remaining neurons in this cell subpopulation.