To characterize the immune response induced by SAG1 encoding plasmid combined with IL 2 gene adjuvant in mice and to assess the protective effect of this vaccination against toxoplasmosis Methods Mice were co inje...To characterize the immune response induced by SAG1 encoding plasmid combined with IL 2 gene adjuvant in mice and to assess the protective effect of this vaccination against toxoplasmosis Methods Mice were co injected intramuscularly with plasmid encoding Toxoplasma gondii SAG1 plus murine IL 2 expression vector at a dose of 100 μg Booster immunizations were employed 2 more times at 3 week interval As controls, mice were inoculated with PBS or empty plasmid pcDNA3 Humoral and cellular responses were assayed using ELISA for the determination of Ab, Ab isotype and IFN γ, as well as IL 4 To detect the integration and dissemination of DNA in the injected mice, PCR and in situ hybridization were performed All mice were then infected with highly virulent RH tachyzoites of Toxoplasma gondii intraperitoneally Results Significant increases in specific IgG levels were observed in mice after immunization three times with SAG1 expression plasmid With respect to the IgG isotype, co inoculation of IL 2 expression plasmid enhanced the level of IgG2a and the production of IFN γ Challenging mice by vaccinating with combined plasmids with RH tachyzoites resulted in prolonged survival Conclusion Humoral and cytokine responses elicited by SAG1 DNA immunization can be modulated by co inoculation with IL 2 expression plasmid The use of DNA vaccine in combination with an appropriate cytokine gene to prevent T gondii infection warrants further investigation展开更多
Salicylic acid(SA)is an important plant hormone that regulates defense responses and leaf senescence.It is imperative to understand upstream factors that regulate genes of SA biosynthesis.SAG202/SARD1 is a key regulat...Salicylic acid(SA)is an important plant hormone that regulates defense responses and leaf senescence.It is imperative to understand upstream factors that regulate genes of SA biosynthesis.SAG202/SARD1 is a key regulator for isochorismate synthase 1(ICS1)induction and SA biosynthesis in defense responses.The regulatory mechanism of SA biosynthesis during leaf senescence is not well understood.Here we show that AtNAP,a senescence-specific NAC family transcription factor,directly regulates a senescence-associated gene named SAG202 as revealed in yeast one-hybrid and in planta assays.Inducible overexpreesion of AtNAP and SAG202 lead to high levels of SA and precocious senescence in leaves.Individual knockout mutants of sag202 and ics1 have markedly reduced SA levels and display a significantly delayed leaf senescence phenotype.Furthermore,SA positively feedback regulates AtNAP and SAG202.Our research has uncovered a unique positive feedback regulatory loop,SA-AtNAP-SAG202-ICS1-SA,that operates to control SA biosynthesis associated with leaf senescence but not defense response.展开更多
文摘To characterize the immune response induced by SAG1 encoding plasmid combined with IL 2 gene adjuvant in mice and to assess the protective effect of this vaccination against toxoplasmosis Methods Mice were co injected intramuscularly with plasmid encoding Toxoplasma gondii SAG1 plus murine IL 2 expression vector at a dose of 100 μg Booster immunizations were employed 2 more times at 3 week interval As controls, mice were inoculated with PBS or empty plasmid pcDNA3 Humoral and cellular responses were assayed using ELISA for the determination of Ab, Ab isotype and IFN γ, as well as IL 4 To detect the integration and dissemination of DNA in the injected mice, PCR and in situ hybridization were performed All mice were then infected with highly virulent RH tachyzoites of Toxoplasma gondii intraperitoneally Results Significant increases in specific IgG levels were observed in mice after immunization three times with SAG1 expression plasmid With respect to the IgG isotype, co inoculation of IL 2 expression plasmid enhanced the level of IgG2a and the production of IFN γ Challenging mice by vaccinating with combined plasmids with RH tachyzoites resulted in prolonged survival Conclusion Humoral and cytokine responses elicited by SAG1 DNA immunization can be modulated by co inoculation with IL 2 expression plasmid The use of DNA vaccine in combination with an appropriate cytokine gene to prevent T gondii infection warrants further investigation
基金This research was supported by National Science Foundation(NSF)Grant MCB-0445596,Department of Energy(DOE)Grant DE-FG02-02ER15341 and Cornell University(to S.G.).Both B.L.and Y.H.were funded by scholarships from China Scholars Council.
文摘Salicylic acid(SA)is an important plant hormone that regulates defense responses and leaf senescence.It is imperative to understand upstream factors that regulate genes of SA biosynthesis.SAG202/SARD1 is a key regulator for isochorismate synthase 1(ICS1)induction and SA biosynthesis in defense responses.The regulatory mechanism of SA biosynthesis during leaf senescence is not well understood.Here we show that AtNAP,a senescence-specific NAC family transcription factor,directly regulates a senescence-associated gene named SAG202 as revealed in yeast one-hybrid and in planta assays.Inducible overexpreesion of AtNAP and SAG202 lead to high levels of SA and precocious senescence in leaves.Individual knockout mutants of sag202 and ics1 have markedly reduced SA levels and display a significantly delayed leaf senescence phenotype.Furthermore,SA positively feedback regulates AtNAP and SAG202.Our research has uncovered a unique positive feedback regulatory loop,SA-AtNAP-SAG202-ICS1-SA,that operates to control SA biosynthesis associated with leaf senescence but not defense response.
