The dense granule protein 4 （GRA4） is a granular protein from Toxoplasma gondii, and is a candidate for vaccination against this parasite. In this study, the plasmid pcDNA3, 1-GRA4 （pGRA4）, encoding for the GRA4 a...The dense granule protein 4 （GRA4） is a granular protein from Toxoplasma gondii, and is a candidate for vaccination against this parasite. In this study, the plasmid pcDNA3, 1-GRA4 （pGRA4）, encoding for the GRA4 antigen, was incorporated by the dehydration-rehydration method into liposomes composed of 16 mmol/L egg phosphatidylcholine （PC）, 8 mmol/L dioleoyl phosphatidylethanolamine （DOPE）, and 4 mmol/L 1,2-diodeoyl-3-（trimethylammonium） propane （DOTAP）. C57BL/6 mice and BALB/c mice were immunized intramuscularly three times with liposome-encapsulated pGRA4 to determine whether DNA immunization could elicit a protective immune response to T. gondii. Enzyme-linked immunosorbent assay （ELISA） of sera from immunized mice showed that liposome-encapsulated pGRA4 generated high levels of IgG antibodies to GRA4. Production of primary interferon （IFN）-7 and interleukin （IL）-2 in GRA4-stimulated splenocytes from vaccinated mice suggested a modulated Th 1-type response. 72.7% of C57BL/6 mice immunized with liposome-encapsulated pGRA4 survived the challenge with 80 tissue cysts of ME49 strain, whereas C57BL/6 mice immunized with pGRA4 had only a survival rate of 54.5%. When immunized BALB/c mice were intraperitoneally challenged with 103 tachyzoites of the highly virulent RH strain, the survival time of mice immunized with liposome-encapsulated pGRA4 was markedly longer than that of other groups. Our observations show that liposome-encapsulated pGRA4 enhanced the protective effect against infection of T. gondii.展开更多
基金supported by the Science Foundation of the Health Bureau of Zhejiang Province, China (Nos. 2003QN003 and 2005A001)the Science Foundation of the Science and Technology Department of Zhejiang Province, China (No. 2006C13022)
文摘The dense granule protein 4 （GRA4） is a granular protein from Toxoplasma gondii, and is a candidate for vaccination against this parasite. In this study, the plasmid pcDNA3, 1-GRA4 （pGRA4）, encoding for the GRA4 antigen, was incorporated by the dehydration-rehydration method into liposomes composed of 16 mmol/L egg phosphatidylcholine （PC）, 8 mmol/L dioleoyl phosphatidylethanolamine （DOPE）, and 4 mmol/L 1,2-diodeoyl-3-（trimethylammonium） propane （DOTAP）. C57BL/6 mice and BALB/c mice were immunized intramuscularly three times with liposome-encapsulated pGRA4 to determine whether DNA immunization could elicit a protective immune response to T. gondii. Enzyme-linked immunosorbent assay （ELISA） of sera from immunized mice showed that liposome-encapsulated pGRA4 generated high levels of IgG antibodies to GRA4. Production of primary interferon （IFN）-7 and interleukin （IL）-2 in GRA4-stimulated splenocytes from vaccinated mice suggested a modulated Th 1-type response. 72.7% of C57BL/6 mice immunized with liposome-encapsulated pGRA4 survived the challenge with 80 tissue cysts of ME49 strain, whereas C57BL/6 mice immunized with pGRA4 had only a survival rate of 54.5%. When immunized BALB/c mice were intraperitoneally challenged with 103 tachyzoites of the highly virulent RH strain, the survival time of mice immunized with liposome-encapsulated pGRA4 was markedly longer than that of other groups. Our observations show that liposome-encapsulated pGRA4 enhanced the protective effect against infection of T. gondii.
