猪圆环病毒2型灭活疫苗的制备与免疫效力研究

Preparation and Immune Efficacy of Inactivated Vaccine against Porcine Circovirus 2

猪圆环病毒2型(PCV2)经0.2%甲醛37℃作用一定时间后接种PK-15细胞,盲传3代,用PCR方法检测灭活效果。将灭活的PCV2加入适量的白油和氢氧化铝胶制成PCV2油佐剂和铝胶佐剂灭活疫苗,免疫小鼠,共免疫2次,时间间隔为3周,分别于一免后第21天和二免后第14天进行ELISA抗体检测。同时为了评价国产油佐剂和进口油佐剂的免疫效果,笔者进行了猪体免疫效力试验。通过ELISA抗体、攻毒后临床表现及体温变化、剖解时的病理变化、平均日增重及病毒血症等指标对疫苗免疫效果进行评价。结果如下:①PCV2能被0.2%甲醛完全灭活,灭活时间为16 h。②PCV2油佐剂和铝胶佐剂灭活疫苗免疫小鼠后均能产生较好的免疫应答,并且油佐剂灭活疫苗免疫效果好于铝胶佐剂灭活疫苗。③猪体免疫效力试验表明,两种油苗均能产生较高水平的ELISA抗体。攻毒后,攻毒对照猪的体温高于免疫猪,空白对照猪体温正常。免疫猪及空白对照猪平均体重均升高,而攻毒对照猪平均体重有所降低,且两个免疫组和空白对照组之间平均日增重差异显著(P<0.05)。病毒血症检测及病毒DNA在组织中的分布检测表明两油苗均能够有效降低猪体的带毒。以上结果表明,PCV2灭活疫苗免疫小鼠和猪体后均能诱导机体产生免疫应答,并能够在一定程度上抵抗PCV2对猪体的感染。

Porcine circovirus 2 was inactivated with 0. 2% formaldehyde under 37℃, then was passaged on PK-15 cell three times and the inactivation effect was estimated by PCR method. The immune efficacies of the oil-adjuvant and the aluminum hydroxide-adjuvant inactivated vaccines against PCV2 were evaluated in mice. Mice were vaccinated subcutaneously twice at a three-week interval. The specific ELISA antibody against PCV2 were detected at the 21st day after the first immunization and at the 14th day after the boost. In order to compare the immune efficacy between the homemade oil-based and imported oil-based vaccines, piglets were immunized with two inactivated PCV2 vaccines and the immune efficay was evaluated by presence or absence of seroconversion, clinical signs （fever）, gross lesions, growth parameters and viremia. The results were as follows： （1） PCV2 was inactivated completely with 0. 2% formaldehyde after incubation for 16 h. （2） The good immune response could be induced by two vaccines in mice and the immune efficacy of the oil-adjuvant inactivated vaccine was higher than that of the aluminum hydroxideadjuvant inactivated vaccine. （3） High ELISA antibody titers of two oil-adjuvant vaccines could be detected in piglets after the boost. After challenge the rectal temperatures of all piglets were recorded. Average temperature of piglets in challenge control group was higher than that of immunized piglets and no pyrexia was observed in mock piglets. The average weight was increased in two immunized groups and mock group, but decreased in challenge control group. Comparison of average daily weight growth （ADWG） of vaccinated pigs with that of mock pigs revealed statistically significant difference between them （P〈0.05）. The fact that two vaccines could reduce the persistence time of PCV2 in piglets was indicated by detection of viremia and PCV2 in different tissues of challenged piglets. It could be concluded that inactivated PCV2 vaccines could induce immune response in mice and piglets and could protect piglets from PCV2 infection.