Abstract
Toxoplasma gondii (T. gondii) is an intracellular parasitic protozoan that can cause serious public health problems. However, there is no effectively preventive or therapeutic strategy available for human and animals. In the present study, we developed a DNA vaccine encoding T. gondii oxidoreductase from short-chain dehydrogenase/reductase family (TgSDRO-pVAX1) and then entrapped in chitosan and poly lactic-co-glycolic acid (PLGA) to improve the efficacy. When encapsulated in chitosan (TgSDRO-pVAX1/CS nanospheres) and PLGA (TgSDRO-pVAX1/PLGA nanospheres), adequate plasmids were loaded and released stably. Before animal immunizations, the DNA vaccine was transfected into HEK 293-T cells and examined by western blotting and laser confocal microscopy. Th1/Th2 cellular and humoral immunity was induced in immunized mice, accompanied by modulated secretion of antibodies and cytokines, promoted the maturation and MHC expression of dendritic cells, and enhanced the percentages of CD4+ and CD8+ T lymphocytes. Immunization with TgSDRO-pVAX1/CS and TgSDRO-pVAX1/PLGA nanospheres conferred significant immunity with lower parasite burden in the mice model of acute toxoplasmosis. Furthermore, our results also lent credit to the idea that TgSDRO-pVAX1/CS and TgSDRO-pVAX1/PLGA nanospheres are substitutes for each other. In general, the current study proposed that TgSDRO-pVAX1 with chitosan or PLGA as the delivery vehicle is a promising vaccine candidate against acute toxoplasmosis.
Highlights
As an obligate intracellular parasite, Toxoplasma gondii (T. gondii) can infect almost all warm-blooded vertebrates and are widespread in humans [1, 2]
Cells transfected with TgSDRO-pVAX1 showed specific red fluorescence, whereas cells transfected with pVAX1 did not display red fluorescence (Figure 1B)
Together with the results of antibodies, these results demonstrated that TgSDRO-pVAX1/CS and TgSDRO-pVAX1/ poly lactic-co-glycolic acid (PLGA) nanospheres could elicit both Th1 and Th2 immune responses and mainly skewed to a Th1 biased immunity, which played a critical role in cell-mediated immunity and T. gondii resistance [83, 84]
Summary
As an obligate intracellular parasite, Toxoplasma gondii (T. gondii) can infect almost all warm-blooded vertebrates and are widespread in humans [1, 2]. Based on the published paper, toxoplasmosis may occur by ingestion of contaminated meat, water, or even vegetables [4,5,6]. Such high disease burden makes T. gondii one of the most important food-borne microorganisms and emphasizes the necessity to intervene [7]. The Food Standards Agency questioned its protective immunity in tissue cyst formation [13]. It is an urgent and valued requirement to develop an effective vaccine against T. gondii infection
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