AIM:To develop a tumor DNA vaccine encoding a fusionprotein of murine AFP and CTLA4,and to study its ability toinduce specific CTL response and its protective effect againstAFP-producing tumor.METHODS:Murine a-fetoprotein (mAFP) gene was clonedfrom total RNA of Hepa1-6 cells by RT-PCR.A DNA vaccinewas constructed by fusion murine α-fetoprotein gene andextramembrane domain of murine CTLA4 gene.The DNAvaccine was identified by restriction enzyme analysis,sequencing and expression.EL-4 (mAFP) was developedby stable transfection of EL-4 cells with pmAFR Thefrequency of cells producing IFN-γ in splenocytes harvestedfrom the immunized mice was measured by ELISPOT.Miceimmunized with DNA vaccine were inoculated with EL-4(mAFP) cells in back to observe the protective effect ofimmunization on tumor.On the other hand,blood sampleswere collected from the immunized mice to check thefunctions of liver and kidney.RESULTS:1.8 kb mAFP cDNA was cloned from total RNAof Hepa1-6 cells by RT-PCR.The DNA vaccine encoding afusion protein of mAFP-CTLA4 was constructed andconfirmed by restriction enzyme analysis,sequencing andexpression.The expression of mAFP mRNA in EL-4 (mAFP)was confirmed by RT-PCR.The ELISPOT results showedthat the number of IFN-γ-producing cells in pmAFP-CTLA4group was significantly higher than that in pmAFP,pcDNA3.1and PBS group.The tumor volume in pmAFP-CTLA4 groupwas significantly smaller than that in pmAFP,pcDNA3.1 andPBS group,respectively.The hepatic and kidney functionsin each group were not altered.CONCLUSION:AFP-CTLA4 DNA vaccine can stimulatepotent specific CTL responses and has distinctive antitumoreffect on AFP-producing tumor.The vaccine has no impacton the function of mouse liver and kidney. AIM: To develop a tumor DNA vaccine encoding a fusion protein of murine AFP and CTLA4, and to study its ability toinduce specific CTL response and its protective effect against AFP-producing tumor. METHODS: Murine a-fetoprotein (mAFP) gene was cloned from total RNA of Hepa 1-6 cells by RT-PCR. A DNA vaccine constructed constructed by fusion murine alpha-fetoprotein gene andextramembrane domain of murine CTLA4 gene. The DNAvaccine was identified by restriction enzyme analysis, sequencing and expression. EL-4 (mAFP) was developed by stable transfection of EL-4 cells with pmAFR The frequency of cells producing IFN-γ in splenocytes harvestedfrom the immunized mice was measured by ELISPOT. Micimimized with DNA vaccine were inoculated with EL-4 (mAFP) cells in back to observe the protective effect of immunization on tumor. On the other hand, blood samples were collected from the immunized mice to check the activities of liver and kidney .RESULTS: 1.8 kb mAFP cDNA was cloned from total RNA of Hepa 1-6 cells by RT-PCR.The DNA v accine encoding afusion protein of mAFP-CTLA4 was constructed and confirmed by restriction enzyme analysis, sequencing andexpression. The expression of mAFP mRNA in EL-4 (mAFP) was confirmed by RT-PCR.The ELISPOT results showed that the number of IFN- γ-producing cells in pmAFP-CTLA4group was significantly higher than that in pmAFP, pcDNA3.1 and PBS group.The tumor volume in pmAFP-CTLA4 group was significantly smaller than that in pmAFP, pcDNA3.1 and PBS groups, respectively.The hepatic and kidney functionsin each group were not altered. CONCLUSION: AFP-CTLA4 DNA vaccine can stimulate potent specific CTL responses and has distinctive antitumoreffect on AFP-producing tumor. vaccine has no impact on the function of mouse liver and kidney.