Induction of protective immunity against toxoplasmosis in mice by DNA immunization with a plasmid encoding Toxoplasma gondii GRA4 gene.
GRA4 is a dense granule protein of Toxoplasma gondii that is a candidate for vaccination against this parasite. We have inserted the entire coding sequence of GRA4 into an eukaryotic expression vector to determine whether DNA immunization can elicit protective immune response to T. gondii. Susceptible C57BL/6 mice were then vaccinated intramuscularly with GRA4 DNA and orally challenged with a lethal dose of 76 K T. gondii strain cysts. Immunization with pGRA4 resulted in a 62% survival of C57BL/6 infected mice. Mice immunized with GRA4 DNA developed high levels of serum anti-GRA4 immunoglobulin G antibodies as well as a cellular immune response, as assessed by splenocyte proliferation, in response to recombinant GRA4 protein restimulation in vitro. The cellular immune response was associated with IFN-gamma and IL-10 synthesis, suggesting a modulated Th1-type response. Splenocyte proliferation was strongly enhanced and protection slightly higher by inoculation with GRA4 DNA combined with a granulocyte-macrophage colony-stimulating factor expressing vector. This is the first report that demonstrates the establishment of a DNA vaccine-induced protective immunity against the acute phase of T. gondii infection.
Desolme
B
B
Equipe Associée INRA d'Immunologie Parasitaire, Faculté des Sciences Pharmaceutiques, 31 Ave. Monge, 37200 Tours, France.
Mévélec
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MN
Buzoni-Gatel
D
D
Bout
D
D
D000818:Animals; D000913:Antibodies, Protozoan / Q000096:biosynthesis / Q000276:immunology; D019556:COS Cells; D002522:Chlorocebus aethiops; D003602:Cytotoxicity, Immunologic; D005260:Female; D017125:Genes, Protozoan; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics; D007371:Interferon-gamma / Q000096:biosynthesis; D016753:Interleukin-10 / Q000096:biosynthesis; D018664:Interleukin-12 / Q000235:genetics / Q000502:physiology; D016131:Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D010957:Plasmids / Q000235:genetics; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology*; D016052:Protozoan Vaccines / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000276:immunology; D013154:Spleen / Q000166:cytology; D018417:Th1 Cells / Q000276:immunology / Q000378:metabolism; D014122:Toxoplasma / Q000235:genetics / Q000276:immunology*; D014124:Toxoplasmosis, Animal / Q000517:prevention & control*; D014162:Transfection; D014611:Vaccination; D019444:Vaccines, DNA / Q000276:immunology*
D000913:Antibodies, Protozoan; C079248:GRA4 protein, Toxoplasma gondii; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; D011993:Recombinant Fusion Proteins; D019444:Vaccines, DNA; D016753:Interleukin-10; D018664:Interleukin-12; D007371:Interferon-gamma; D016178:Granulocyte-Macrophage Colony-Stimulating Factor