乙肝DNA疫苗pVAX-PS对树(鼠句)的免疫保护作用

目的:以树(鼠句)为实验对象研究乙肝DNA疫苗接种后所产生的免疫应答及对乙肝病毒攻击的保护作用.方法:以PCR法从adr亚型乙肝患者血清的病毒基因组中扩增含乙肝病毒的PreS2+S基因,插入pVAX1载体构建乙肝DNA疫苗pVAX-PS,并以此为候选疫苗,从股四头肌接种免疫树(鼠句).免疫接种方式为肌注2次,间隔2周.用ELISA法分析DNA免疫诱导的抗体水平及阳转率.DNA免疫后部分树(鼠句)用乙肝患者(HBsA+,HBeAg+,HBcAb+)血清进行病毒攻击实验,通过检测乙肝感染的各种血清学指标及肝组织病理的变化来评价DNA疫苗的免疫保护作用.结果:DNA疫苗免疫2周后开始检出HBsAb,6周后达到峰值,8周后所有免疫接种树(鼠句)抗体阳转;与阴性对照组相比,DNA疫苗免疫使乙肝病毒攻击所致的各项血清学指标阳转率明显降低,肝脏病理性损伤明显减轻.结论:乙肝DNA疫苗pVAX-PS免疫树(鼠句)后诱发明显的体液免疫应答,并对乙肝病毒感染提供有效的保护作用.

Immunological protection effects of HBV DNA vaccine pVAX-PS on tree shrews

Objective:To assess the immune responses and the protective efficacy of pVAX-PS, a DNA vaccine for hepatitis B virus (HBV), in tree shrews. Methods: Tree shrews (Tupaia belangeri chinenesis) were experimentally infected with human HBV by inoculation with human serum positive of HBV. pVAX-PS was constructed by inserting the gene encoding the middle (Pre-S2 plus S) envelope protein of HBV into the plasmid vector pVAX. Tree shrews were intramuscularly injected with pVAX-PS twice at 2 weeks interval. DNA vaccination-induced seroconversion and levels of antibody to HBV surface antigen (HBsAb) were analyzed by ELISA. Protective effects of pVAX-PS vaccination against subsequent HBV challenge were evaluated by detection of the HBV seromarkers change and observation of liver injury in HBV-infected tree shrews. Results : Serum anti-HBs were detectable 2 weeks after pVAX-PS vaccination and peaked on 6 weeks. The antibody of model tree shrews had positive conversion. Immunization with pVAX-PS decreased the positive conversion rate of all HBV seromarkers and relieved liver injury in tree shrews challenged with HBV. Conclusion: pVAX-PS immunization can induce remarkable humoral immune response and prevent the experimental infection of HBV in model tree shrews.