Abstract
Caused by Toxoplasma gondii, toxoplasmosis has aroused great threats to public health around the world. So far, no effective vaccine or drug is commercially available, and the demands for a safe and effective therapeutic strategy have become more and more urgent. In the current study, we constructed a DNA vaccine encoding T. gondii ribosomal P2 protein (TgP2) and denoted as TgP2-pVAX1 plasmid. To improve the immunoprotection, nanomaterial poly-lactic-co-glycolic acid (PLGA) and chitosan were used as the delivery vehicle to construct TgP2-pVAX1/PLGA and TgP2-pVAX1/CS nanospheres. Before vaccinations in BALB/c mice, TgP2-pVAX1 plasmids were transiently transfected into Human Embryonic Kidney (HEK) 293-T cells, and the expression of the eukaryotic plasmids was detected by laser confocal microscopy and Western blotting. Then the immunoprotection of naked DNA plasmids and their two nano-encapsulations were evaluated in the laboratory animal model. According to the investigations of antibody, cytokine, dendritic cell (DC) maturation, molecule expression, splenocyte proliferation, and T lymphocyte proportion, TgP2-pVAX1 plasmid delivered by two types of nanospheres could elicit a mixed Th1/Th2 immune response and Th1 immunity as the dominant. In addition, TgP2-pVAX1/PLGA and TgP2-pVAX1/CS nanospheres have great advantages in enhancing immunity against a lethal dose of T. gondii RH strain challenge. All these results suggested that TgP2-pVAX1 plasmids delivered by PLGA or chitosan nanomaterial could be promising vaccines in resisting toxoplasmosis and deserve further investigations and applications.
Highlights
Distributed around the world, Toxoplasma gondii is an obligate intracellular parasite that can infect almost all mammals including human beings [1, 2]
The results suggested that T. gondii ribosomal P2 protein (TgP2)-pVAX1/poly-lactic-co-glycolic acid (PLGA) and TgP2-pVAX1/CS nanospheres with satisfactory release curves were spherical in shape and nontoxic to animals
PLGA nanospheres have an advantage as a DNA vaccine carrier, as they could protect the plasmids from undesirable degradation, and they could be efficiently absorbed by host cells for transcription [50, 51]
Summary
Distributed around the world, Toxoplasma gondii is an obligate intracellular parasite that can infect almost all mammals including human beings [1, 2]. Nano Vaccines for T. gondii economic losses, especially in sheep and pigs [1]. Ovilis Toxovax® (Intervet Inc., Angers, France) so far has been the only T. gondii vaccine commercially available for abortion prevention in goats and sheep [9], but the immunoprotection of tissue cyst formation has been questioned by Food Standards Agency [10]. Considering drug residues in animal products and the drug resistance in parasites [11], the development of effective vaccines against toxoplasmosis is a valued and urgent priority
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