Abstract
Toxoplasma gondii (T. gondii) is the most common zoonotic protozoa and has infected about one-third of the population worldwide. Recombinant epitopes encapsulated in nanospheres have advantages over traditional T. gondii vaccines. For an efficient delivery system, poly (DL-lactide-co-glycolide) (PLGA) and chitosan are the most frequently used biodegradable polymeric nanospheres with strong safety profiles. In the present study, we first expressed and purified histone H2A1 of T. gondii using the prokaryotic expression system. The effects of recombinant TgH2A1 on the functions of murine macrophages were then studied. Purified recombinant TgH2A1 was then encapsulated in nanospheres with PLGA and chitosan. After subcutaneous vaccination in mice, the immune response was evaluated by double antibody sandwich ELISA kits. The results from this study showed that PLGA and chitosan loaded with rTgH2A1 could trigger a stronger Th1 oriented immune response and prolong the survival time of mice effectively. In conclusion, PLGA and chitosan nanospheres loaded with histone H2A1 are an effective method for the development of vaccines against T. gondii. Further studies should focus on evaluating the regulatory mechanism of TgH2A1, vaccine potency, and cellular response in chronic T. gondii infections.
Highlights
Toxoplasma gondii (T. gondii) is an obligate intracellular protozoan parasite that causes infections in approximately 30% of the population [1,2]
After the expression purification and endotoxin removal of recombinant protein, the endotoxin level of the purified recombinant TgH2A1 (rTgH2A1) was decreased to 0.1 EU/mL, and rTgH2A1 was subjected to SDS-PAGE analysis yielding a band of approximately 37 kDa visualized through Coomassie blue staining (Figure 1a)
Western bolt results showed that recombinant T. gondii H2A1 (TgH2A1) reacted with sera separated from rats challenged with T. gondii (Figure 1b), while native TgH2A1 from T. gondii lysates could be identified by anti-rTgH2A1 polyclonal antibodies (Figure 1c) at the position of 19.5 kDa
Summary
Toxoplasma gondii (T. gondii) is an obligate intracellular protozoan parasite that causes infections in approximately 30% of the population [1,2]. It is generally asymptomatic in adults, but most infections result in severe symptoms in immunocompromised individuals [3]. Human infections occur mainly through ingestion of uncooked raw meat, vegetables, and water contaminated with the oocysts of T. gondii [6,7,8]. Drug treatments such as sulfonamides and folic acid derivatives have been unable to control this disease completely and show significant side effects [9], because the bradyzoites of T. gondii have a strong resistance to the environment [10].
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