Recombinant Mouse Prolactin Confers Partial Protection Against Toxoplasma gondii Infection in a Pre-treated Experimental Murine Model

Introduction Toxoplasmosis is one of the most important health-threatening diseases with worldwide distribution and global impact. It is caused by Toxoplasma gondii ( T. gondii ), an intracellular apicomplexan parasite that can evade the host immune responses and establish a chronic infection. The available treatments are not efficient against this stage and have many adverse effects. There are no available effective vaccines, apart from Toxovax ® , which is used in sheep to prevent abortion. Studies documented that prolactin (PRL) had in vivo and in vitro anti- Toxoplasma effects. Detailed research was recommended about the mechanisms of such inhibitory effects. Aim This study was designed to assess the possible protective role of the recombinant prolactin (rPRL) against T. gondii . Materials and Methods Sixty experimentally infected mice with T. gondii were used. The treated mice received rPRL for five days before infection. Serum prolactin levels were measured; survival rate was monitored; number, size, and DNA of T. gondii cysts in the brain were measured; and histopathological and immunological studies were done. Results There was a significant increase in the survival rate of the rPRL-treated mice, a significant decrease in the number, size, and DNA amount of T. gondii cysts in the brain with a noticeable improvement of histopathological lesions in the brain and liver tissues when compared to the infected untreated group. These effects seem to be achieved through stimulating humoral and cell-mediated immune responses that were evident by the significant rise in serum levels of anti- Toxoplasma IgM, IFN-γ, and TNF-α. Conclusion The rPRL elicited robust immune responses, which provided efficient protection against murine T. gondii infection.