Immunization of Mice with Piasmid DNA Against Malaria and Regulation of Antigen Expression by Tetracycline-controlled Promoter
重组恶性疟原虫DNA质粒免疫小鼠及抗原表达的调控

Sequence of MSP1 31 of Plasmodium falciparum was constructed into eukaryotic expression vector pTRE,which could be repressed by tetracycline (Tc) and resulted in recombinant plasmid pTRE 31.The plasmid was injected into the quadriceps muscle of BALB/c mice with Tc responsive plasmid pTet off to measure specific antibodies.The MSP1 31 prokaryotic expressed protein was used as antigen in ELISA.Result showed that mice orally administered by Tc had a seroconversion rate of 7 1% (1/14) 4 weeks after injection,whereas the contral mice had a seroconversion rate of 100% and the titers of antibody were raised continusly within 12 weeks.The study suggested that the recombinant plasmids pTRE 31/pTet off could efficiently induce humoral response against MSP1 31 of malaria.Moreover this immune response was controlled by Tc and was revesible after withdrawal of Tc dilivery.The induction of antibody by removing Tc at the fourth week after injection indicated that DNA vaccine could remain in mice and capable of expressing antigen for at least 4 weeks.