Construction Of DNA Vaccine For Chlamydia Trachomatis E Serotype And Studies On Its Immunological Effects

Infection of human urogenital tract caused by Chlamydia trachomatis (C.t) is more and more these years. Asymptomatic and chronic C.t infection may result in severe complications such as prostatitis, infertility, ectopic pregnancy and chronic pelvic inflammatory disease etc. C.t is remarked for its state of protraction, refractoriness, easy relapse, and striking consumption. Study on C.t infection has been one of the popular topics of the world. It's urgent to improve the prevention and control measures for C.t prevalence. Research on C.t vaccine is the key point of prevention measures. Among all the C.t vaccines studied, DNA vaccine is predominant. Nevertheless, it's a pity that no successful C.t vaccine is born by now.Objective: to construct the DNA vaccine of C.t E serotype and evaluate the immune response and protective effect of the DNA vaccine solo or combining with mIL-2 gene adjuvant in mice.Methods: C.t E serotype was cultured in McCoy cells. The chromosome DNA was extracted out to be the template. Complete omp1 gene was amplified by PCR and then cloned directionally into eukaryotic vector of pcDNA3.1(+) to form the DNA vaccine. After identifying, the recombinant was transfected into HeLa cells by lipofection. Mice were divided into four groups. They were blank plasmid negative control group, solo DNA vaccine group, DNA vaccine plus mIL-2 gene adjuvant group, and inactivated C.t positive control group. Intramuscular inoculation was adopted. The immune effects of C.t DNA vaccine and the gene adjuvant wereevaluated by detecting of antibodies, lymphokines, counteract ability of serum specific antibodies, and observing of DTH response, proliferation assay of spleen lymphocytes, clearance ability for C.t challenge from genital tract, and local histomorphology.Results: 1. DNA vaccine of C.t E serotype was constructed successfully and well expressed in HeLa cell. 2. Inoculating solo DNA vaccine could induce C.t specific cell mediated immunity (CMI) and humoral immunity to some extend. The CMI was more predominant and Thl biased. It could protect mice from C.t vagina challenge. 3.mIL-2 gene adjuvant could dramatically enhance the CMI induced by C.t DNA vaccine. Thl bias was more obvious. Combined inoculation could protect mice from C.t vagina challenge also.Conclusion: 1. DNA vaccine of C.t E serotype was constructed successfully, which could be used in further animal experiments. 2. Antibodies against major outer membrane protein encoded by ompl gene were protective. 3. The DNA vaccine of C.t E serotype exhibited some immunoprotection effect in mice. 4. mIL-2 eukaryotic expression plasmid was an effective immune adjuvant for C.t DNA vaccine. The adjuvant could produce satisfied immunopotentiation effect and be a good choice for further study on C.t vaccine.