Increased Severity of Murine Infection with Toxioplasma Gondii Following Vitaman E and Selenium Supplementatoin
Abstract
At present, toxoplasmosis is one of the most common opportunistic infections in immunocompromised patients. The need for a reliable experimental model is crucial not only for achieving a better understanding of the pathophysiology of this infection but also for developing a better method to evaluate new therapeutic regimens. This study was organized to determine if the antioxidants vitamin E and selenium would provide a beneficial effect in mice chronically infected with Toxoplasma gondii. In the first phase of the study, 35 female Swiss Webster mice were infected with oocysts of the Me49 strain of Toxoplasma gondii while receiving diets supplemented with vitamin E alone or in combination with selenium, or a diet deficient in both nutrients. In the second phase of the study, 25 C57BL/6J mice were infected intraperitoneally (i.p) using the ME49 strain. Two different strains of mice were used for this experiment because each vary in their susceptibility to T. gondii infection, with the C57BL/6J mice being a more susceptible model with the development of toxoplasmic encephalitis. In the third phase of the study, because the natural route of infection is the oral route, 25 C57BL/6J mice were infected orally with the ME49 strain of Toxoplasma. The results of all three experiments demonstrate that vitamin E and Se supplementation does not provide a protective effect during murine Toxoplasma gondii infection. Mice fed diets supplemented with vitamin E and Se had more tissue cysts present in their brains, exhibited greater tissue pathology, and suffered the highest percent weight loss. In contrast, the unsupplemented groups (absence of vitamin E and Se from the diet) showed the lowest tissue cyst numbers, minor histopathology, and very little weight loss during experimental infection.