猪囊虫DNA疫苗pEP1的生物安全性研究

STUDIES ON THE BIOSECURITY OF TAENIA SOLIUM DNA VACCINE PEP1

猪囊虫核酸疫苗pEP1能在猪体内产生较高滴度的保护性抗体，具有较高的免疫保护率，本研究就核酸疫苗pEP1的生物安全性问题进行了深入探讨。首先，将核酸疫苗pEPl以肌注方式免疫仔猪，分别于接种后1天、7天、4周、8周分离各组织，提取组织总DNA，利用PCR技术分析质粒DNA在各组织的分布。研究发现，在疫苗接种后第1天几乎所有组织都能检测到质粒DNA，随着时间的延续，仅在注射部位检测到质粒的存在，说明肌注DNA疫苗在注射部位以外组织中很快被清除。其次，对残存质粒的注射部位组织进行细胞基因组整合可能性分析，并未发现质粒DNA整合入宿主细胞基因组中。同时采集猪舍周围样品，PCR法分析DNA疫苗上的CMV启动子基因、抗性基因和抗原表位基因在环境中发生转移和扩散的可能性，结果显示疫苗质粒并没有转化整合环境细菌。因而我们认为该猪囊虫核酸疫苗对猪体和环境都是安全的，具有很好的应用前景。

Taenia solium DNA vaccine pEP1 can induce high titer of protective antibody in pigs, therefore has a high protective ability. The biosecurity of Taenia solium DNA vaccine was studied from two main aspects with pEP1 DNA vaccine as the target. First, the plasmid was intramuscularly injected into pigs, and then the total DNA of different tissues was extracted at 1 d, 7 d, 4 w and 8w after the injection. The distribution of plasmids in different tissues and the possibility of integrating these plasmids into the porcine genome were analyzed by PCR. It was found that the plasmid can be detected in almost all the tissues one day after, the last immunization. As time goes by, the plasmid could be detected only in injected sites, implying that the plasmid had been cleared in short time from tissues except the injected sites. Furthermore, the possibility of integrating the plasmid into the porcine genome was analyzed, while no such an integration was found. Meanwhile, field samples were collected, and the metastasis and extension of CMV promoter gene, resistance gene and antigen gene were studied by PCR. The results revealed that no integration occurred of pEP1 into the environmental bacteria Therefore, the DNA vaccine pEP1 is of good safety for both pigs and the environment