PRRSV GP5和M蛋白重组腺病毒对猪的安全性和免疫效力

将猪繁殖与呼吸综合征病毒(PRRSV) GP5 重组腺病毒(recombinant Adenovirus-GP5,rAd-GP5)和M蛋白重组腺病毒(rAd‐M)分别接种4只30日龄PRRSV阴性断奶健康仔猪，结果为仔猪接种后2周内体温和食欲正常，猪血液、鼻塞、粪便和猪舍环境中重组腺病毒及其野生型腺病毒检测均为阴性。同时，将rAd‐GP5、rAd-M、rAd-GP5+M (rAd-GP5和rAd-M,V/V=1)和PRRSV-Resp弱毒株分别接种4只30日龄PRRSV阴性仔猪，不同时间检测PRRSV抗体，结果为免疫后14和45 d可检出PRRSV ELISA抗体和中和抗体；免疫后60～90 d，rAd-GP5和rAd-M免疫组ELISA抗体滴度均达1∶2400以上，与PRRSV‐Resp弱毒免疫组相似，而中和抗体滴度达1∶6以上，低于PRRSV-Resp弱毒免疫组；rAd-M免疫组ELISA抗体和中和抗体滴度则低于rAd‐GP5免疫组。rAd-GP5和rAd-M混合免疫组ELISA抗体达1∶4800,其中和抗体滴度与其单独免疫组相似。15只仔猪免疫后28 d进行攻毒保护试验，结果为重组腺病毒免疫猪攻毒后3 d平均体温为39.5℃,病毒血症和排毒时间仅为2周，与PRRSV-Resp弱毒免疫组相似，而空白对照组病毒血症和排毒时间至少60 d。攻毒后7～14 d，rAd-GP5和rAd‐M免疫组ELISA抗体和中和抗体水平明显升高。研究表明rAd-GP5和rAd-M重组腺病毒具有较好的安全性，均可诱导猪体产生较好的免疫反应，两者具有明显的协同免疫作用。

Safety and Immunogenicity of the Recombinant Adenovirus Expressing the GP5 and M Protein of PRRSV in Piglets

In order to study the safety and immunogenicity of recombinant Adenoviruses expressing GP5(rAd-GP5) and M protein(rAd-M) of Porcine reproductive and respiratory syndrome virus (PRRSV), Forty-seven 30-day-old post-weaning PRRSV-negative piglets were vaccinated with the viruses and bred respectively for clinical observation, virus shedding test and immune examination. The results were as following: (1) The piglets vaccinated with rAd-GP5 and rAd-M showed no significant clinical syndrome, and blood, nasal scraping, faecal samples and pen environment were all negative against PRRSV and parental Adenovirus by RT-PCR. (2) The PRRSV specific antibody titers in piglets, which vaccinated with rAd-GP5, rAd-M, rAd-GP5+M (rAd-GP5/rAd-M, V/V=1), PRRSV-Resp strain, and no inoculation, respectively, were examined at different time post immunization. The results indicated that PRRSV specific antibody could be detected by ELISA and neutralization assay 14 and 45 days post vaccination. In groups of rAd-GP5 and rAd-M, the titer of ELISA antibody were more than 1∶2400 at day 60 and 90 post vaccination, which were similar to that of piglets inoculated with PRRSV-Resp vaccine. However, the neutralizing antibody titers in the two groups of rAd-GP5 and rAd-M were less than 1∶6, which were lower than that of PRRS-Resp group, from 60 to 90 days post vaccination. Furthermore the level of ELISA antibody to PRRSV in piglets vaccinated with both rAd-GP5 and rAd-M were more than that of piglets vaccinated with singlerAd-GP5 or rAd-M. (3) Following challenge with virulent strain of PRRSV-S1 at 28 days post vaccination, no significantly temperature variation of the immunized pigs was observed. The time of viremia and virus shedding in piglets vaccinated with recombinant Adenoviruses were only 2 weeks, which were shorter than that of control piglets with no vaccine. And the titers of PRRSV specific ELISA antibody and neutralizing antibody were enhanced in piglets vaccinated with rAd-GP5 or rAd-M post challenge. The results suggest that rAd-GP5 and rAd-M are safe to piglets and can elicit good protective immune responses corporately.