猪瘟甲病毒复制子载体DNA疫苗与重组腺病毒活载体疫苗联合免疫效果评价

A prime-boost vaccination strategy using a Semliki Forest virus replicon vectored DNA vaccine followed by a recombinant adenovirus protects pigs from classical swine fever

本实验室先前分别将构建的猪瘟病毒E2基因重组腺病毒疫苗(rAdV-E2)和猪瘟甲病毒复制子载体DNA疫苗(pSFV1CS-E2)在猪体上进行了免疫效力评价,结果显示,rAdV-E2免疫组所有猪虽然在加强免疫后产生了比较高的猪瘟特异性中和抗体,但攻毒后个别猪表现短期体温升高和轻微病变;而pSFV1CS-E2免疫组猪只虽然在攻毒后得到了保护,但产生的抗体水平较低。为了增强猪瘟甲病毒复制子载体疫苗和猪瘟重组腺病毒活载体疫苗的免疫效果,本研究应用了复制子载体DNA疫苗初免和重组腺病毒疫苗加强免疫的初免-加强(Prime-boost)免疫策略,并在猪体上进行了评价。结果显示,所有免疫猪均产生了高水平的猪瘟特异性的中和抗体,用猪瘟强毒攻击后,pSFV1CS-E2初免组所有猪(n=5)均没有出现任何猪瘟的临床症状和病理变化,攻毒后在猪血液中也没有检测到猪瘟病毒RNA,而重组腺病毒初免组(n=5)有一头猪出现短期发热和病毒血症及轻微病理变化。这表明初免-加强免疫策略能显著提高重组疫苗的免疫效力。

We have previously evaluated a Semliki Forest virus （SFV） replicon vectored DNA vaccine （pSFV1CS2-E2） and a recombinant adenovirus （rAdV-E2） expressing the E2 glycoprotein of classical swine fever virus （CSFV） in pigs. The results showed that the immunized pigs were protected from virulent challenge, but few pigs showed short-term fever and occasional pathological changes following virulent challenge. To enhance the immunogenecity of the vaccines, we tried a prime-boost vaccination strategy using a combination of prime with pSFV1CS2-E2 followed by boost with rAdV-E2. The results showed that all the immunized pigs developed high-level CSFV-specific antibodies following prime-boost immunization. When challenged with virulent CSFV, the immunized pigs （n=5） from the heterologous boost group showed no clinical symptoms, and CSFV RNA was not detected following challenge, whereas one of five pigs from the homologous boost group developed short-term fever and CSFV RNA was detected. This demonstrates that the heterologous prime-boost vaccination regime has the potential to prevent against virulent challenge.