Action of β-glucan in pigs experimentally infected with Toxoplasma gondii tachyzoites

The present study tested the action of Beta-glucan in swine experimentally infected with tachyzoites of Toxoplasma gondii. The experiment design used 8 mixed breed pigs (21 days) divided into three groups: G1 (Beta-glucan treated and infected, n = 3), G2 (untreated and infected, n = 3), and G3 (untreated uninfected, n = 2). The G1 animals were treated with 1g of Beta-glucan by intramuscularly route at days 0, 14, and 28 before experimental infection, while the other groups (G2 and G3) received only saline. The G1 and G2 were infected with viable tachyzoites (107) of the RH strain at day 35 of experiment. The parasitemy was determined by mouse bioassay and PCR from whole blood of each swine, obtained at days 3, 7, 14, 21, 31, 39, 47 e 69 post infections. The antibody levels of serum, aqueous and vitreous humor were measured by indirect immunofluorescence assay (IFA); a title >/= 64 was considered as positive. There were differences in the hematocrit, hemoglobin, plasmatic proteins, and eosinophils values between groups (P< 0.05). The swine of G1 and G2 serum converted 7 days post infection, and the highest title observed was 1024 in two pigs. Samples of aqueous and vitreous humor did not show antibodies against T. gondii. Parasite was detected of whole blood on days 3, 14, 31, 39, and 47 in two animals from G1, and three animals from G2. There were no differences between PCR and mouse bioassay. Animals from G3 remained without parasitemy by both PCR and bioassay throughout the experiment. The use of Beta-glucan, as was used here, was not protective for pigs against T. gondii tachyzoites acute infection. Additionally, the lineage of RH strain showed nonpersistent for pigs (muscles and retina) 69 days after infection.