Evaluation of Toll-Like Receptor 11 Agonist Adjuvant Activity in Immunization of BALB/c Mice with Total Lysate Antigens of Toxoplasma gondii RH Strain.

BACKGROUND: In this study, the effect of total lysate antigen (TLA) of Toxoplasma gondii on spleen lymphocyte prolifration, secretion of IL5, INF-γ, and mice survival time was evaluated using agonist of toll-like receptor (TLR) 11, as an adjuvant.

METHODS: This study was done in the Department of Parasitology and Mycology of Urmia University of Medical Sciences, Urmia, Iran in 2018. First, different groups of BALB/c mice were immunized with TLA alone and also TLA + TLR11 agonist. Subsequently, factors such as spleen lymphocyte prolifration, IL-5, and INF-γ secretion and mice survival time in different groups were compared.

RESULTS: Mice immunized with TLA + adjuvant showed higher immunization index than the two other groups and combination of TLR11 (as an adjuvant) and TLA significantly elevated the effect of TLA by increasing the production of INF-γ and IL-5 and by the shift of the immune system to Th1. In addition, the combination of TLA and TLR11 adjuvant increased the proliferation of lymphocytes and survival time in mice against T. gondii.

CONCLUSION: Profilin (as an adjuvant) in combination with TLA could be a potent vaccine candidate that evokes a powerful specific immune response and significantly improves the efficacy of TLA vaccine by increasing the induction of INF-γ production and by shifting the immune responses to Th1 profile through increasing the INF-γ/IL-5 ratio. It causes significant protection against T. gondii after i.p. injection.