College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
Vaccine. 2011 Sep 16;29(40):7027-34. doi: 10.1016/j.vaccine.2011.07.074. Epub 2011 Jul 30.
To develop a safer, more immunogenic and efficacious vaccine against Streptococcus equi ssp. zooepidemicus (SEZ) infections, the gene of M-like protein (SzP) was placed under the strong vaccinia virus promoter P28 and then inserted into swinepox virus (SPV) genome. The recombinant swinepox virus (rSPV-szp) was isolated in a non-selective medium by the co-expression of Escherichia coli LacZ gene and verified by PCR, western blotting and immunofluorescence assays. To evaluate the immunogenicity of this rSPV-szp, ICR mice were immunized with the rSPV-szp, inactivated SEZ vaccine (positive control), wild type SPV (negative control), or PBS (challenge control). All mice were intraperitoneally challenged with 5 LD(50) of homogenous ATCC 35246 strain 14 days post-vaccination. The results showed that at least 70% mice in rSPV-szp-vaccinated group were protected against homogenous ATCC 35246 challenge, the survival rate was significantly higher compared with mice in the negative control group and the challenge control group (P<0.001). The antibody titers of the rSPV-szp-vaccinated group were significantly higher (P<0.05) than the other three groups. Passive immune protection assays showed that the hyperimmune sera against M-like protein could provide mice with complete protection against challenge of ATCC 35246. Semi-quantitative RT-PCR analysis showed a marked increased in levels of IL-4 and IFN-γ mRNA in immunized mice. The results suggested that the recombinant rSPV-szp provided mice with significant protection from the SEZ infections. It is a promising candidate for the vaccine development against SEZ infections.
为了开发一种更安全、更具免疫原性和疗效的马链球菌兽疫亚种（SEZ）感染疫苗，将 M 样蛋白（SzP）基因置于强痘苗病毒启动子 P28 下，然后插入猪痘病毒（SPV）基因组。通过共表达大肠杆菌 LacZ 基因，在非选择性培养基中分离出重组猪痘病毒（rSPV-szp），并通过 PCR、western blot 和免疫荧光试验进行验证。为了评估该 rSPV-szp 的免疫原性，用 rSPV-szp、灭活 SEZ 疫苗（阳性对照）、野生型 SPV（阴性对照）或 PBS（攻毒对照）免疫 ICR 小鼠。所有小鼠在接种后 14 天经腹腔内用同源 ATCC 35246 株 5LD（50）攻毒。结果表明，rSPV-szp 疫苗接种组至少有 70%的小鼠能抵抗同源 ATCC 35246 攻毒，与阴性对照组和攻毒对照组相比，存活率显著提高（P<0.001）。rSPV-szp 疫苗接种组的抗体滴度明显高于其他三组（P<0.05）。被动免疫保护试验表明，针对 M 样蛋白的高免血清能为小鼠提供针对 ATCC 35246 攻毒的完全保护。半定量 RT-PCR 分析显示，免疫小鼠的 IL-4 和 IFN-γ mRNA 水平显著升高。结果表明，重组 rSPV-szp 能显著保护小鼠免受 SEZ 感染。它是一种有前途的 SEZ 感染疫苗候选物。
