Protective effect of a prime-boost strategy with plasmid DNA followed by recombinant adenovirus expressing TgAMAl as vaccines against Toxoplasma gondii infection in mice

摘要

A heterologous prime-boost strategy with priming plasmid DNA followed by recombinant virus expressing relevant antigens is known to stimulate protective immunity against intracellular parasites. In this study, we have evaluated a heterologous prime-boost strategy for immunizing mice against Toxoplasma gondii infection. Our results revealed that the prime-boost strategy using both plasmid DNA and adenoviral vector encoding TgAMAl may stimulate both humoral and Thl/Th2 cellular immune responses specific for TgAMAl. Moreover, C57BL/6 mice immunized with the pAMAl/Ad5Null, pNull/Ad5AMAl, and pAMAl /Ad5AMAl constructs showed survival rates of 12.5%, 37.5%, and 50%, respectively. In contrast, all the pNull/Ad5Null immunized mice died after infection withthe PLK-GFP strain of T. gondii. Brain cyst burden was reduced by 23% in mice immunized with pAMAl /Ad5AMAl compared with the pNull/Ad5AMAl immunized mice. These results demonstrate that the heterologous DNA priming and recombinant adenovirus boost strategy may provide protective immunity against T. gondii infection.