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Toxoplasma gondii infection is a serious health problem of economic importance to humans and animals worldwide.T.gondii eukaryotic initiation factor:2 a (TgIF2 a) plays a crucial role in parasite viability and is an important virulence factor ofT.gondii.To evaluate the vaccine potential of TgIF2 α,we constructed a novel eukaryotic plasmid pVAX:IF2 α expressing TgIF2 α from the RH strain and validated expression and immunogenicity in vitro in the Marc 145 cells expression system by indirect immunofluorescence (IFA).Administration ofpVAX:IF2 α intramuscularly induced specific humoral immune responses including high levels of specific TgIF2 α IgG antibody and a mixed IgG1/IgG2a response with predominance of IgG2aproduction.The cellular immune response was elicited,showing significant production ofIFN: γ and IL:2 associated with Th 1 type response,and thus strong cell:mediated cytotoxic activity with increased frequencies of IFN: γ parameters analyzed in both CD4+ and CD8+T cell compartments (CD4+ IFN: γ + T cells and CD8+ IFN: γ + T cells).Immunization resulted in partial protection against acute and chronic toxoplamosis in Kunming mice,demonstrated by a significantly prolonged survival time (15.9 ± 4.6 days) after challenge with the virulent RH strain and significant reduction in brain cyst (44.1%) against chronic infection with PRU cyst in contrast to control mice.Our data suggested that pVAX:IF2 α could be used as a DNA vaccine candidate against both acute and chronic T.gondii infection by the activation ofeffective humoral and cellular immune responses.