犬传染性肝炎DNA疫苗安全性评价

目的研究犬传染性肝炎核酸疫苗pVAX1-CpG-Loop的安全性。方法 BALB/c小鼠随机分为4组,高剂量组(肌内注射每只200μg)、低剂量组(肌内注射每只100μg)、联合免疫组(肌内注射每只100μg,皮下注射50μg,滴鼻每只50μg)和PBS组,每两周免疫1次,共免疫3次。末次免疫后4周、6个月检测血常规和血液生化及对F1代的影响,用PCR和RT-PCR的方法检测DNA疫苗的生物学分布和存留时间,末次免疫后4周和6个月取脏器观察病理损伤。结果各剂量组的主要血液学检测指标、对F1代的影响差异无显著性。末次免疫后4周各剂量组AST明显高于对照组。DNA疫苗在注射部位可存留8周,其中高剂量组和低剂量组在肝、脾、肾和注射部位有分布,联合免疫组在肺组织也有分布。末次免疫后4周小鼠肝肾有淋巴细胞浸润,6个月后慢性炎症明显好转。结论由犬传染性肝炎病毒DNA疫苗引起的肝肾损伤是一过性的,并且pVAX1-CpG-Loop没有整合到宿主基因组,也没有传递给F1代。

Safety Evaluation of DNA Vaccine pVAX1-CpG-Loop against Infectious Canine Hepatitis Virus

Objective To evaluate the safety of a DNA vaccine against infectious canine hepatitis virus. Methods Mice were divided into high dose group （ DNA vaccine 200 μg /mouse,i. m）,low dose group （ DNA vaccine 100 μg each,i. m）,multiple-site immunization group （ intramuscular injection 100 μg,hypodermic injection s. c 50 μg,nasal instillation 50 μg） as well as control group （PBS 200 μl each,i. m）. Treatment groups were vaccinated （or injected with PBS） every two weeks for 3 times. The hematology and the influence to generation F1 of mice were examined at 4 weeks after the last vaccination. Biochemistry of blood including AST and ALT was observed at 4 weeks and half year after the last immunization,respectively. PCR and RT-PCR were carried out to determine the biodistribution and persistence of the tested vaccine,respectively. Pathological observation was performed to evaluate if there were pathological alterations in the organs of mice. Results No significant differences were observed between the vaccination and control groups by hematological examination,and the influence to generation F1 was not observed either. Compared with the control,there were conspicuous differences in AST among all the tested mice after 4 weeks,but it recovered half year later. The DNA vaccine can persist in the muscle tissue for 12 weeks,which was much longer than that in other tissues such as liver, spleen,kidney as well as lung. Leukomonocytes were observed in liver and spleen tissues of the immunized mice. The chronic inflammation was recovered after half a year. Conclusion The results of this study show that the alterations in the liver and kidney caused by the DNA vaccine against infectious canine hepatitis virus are temporal and that the pVAX1-CpG-Loop plasmid is not integrated into host tissues indefinitely nor transmissible to F1 progeny.