猪传染性胸膜肺炎重组亚单位疫苗诱导小鼠免疫保护效果的观察

Protective Efficacy of Recombinant Subunit Vaccines against Actinobacillus pleuropneumoniae in Mice

重组表达猪传染性胸膜肺炎放线杆菌6种主要毒力因子基因:apxⅠ、apxⅡ、apxⅢ、apxⅣ、apfa和omp,以重组蛋白rApxⅠ、rApxⅡ、rApxⅢ和rOMP组合免疫小鼠作为试验I组,重组蛋白rApxⅠ、rApxⅡ、rApxⅢr、OMPr、ApxⅣ和rApfa组合免疫小鼠作为试验Ⅱ组,PBS为对照组,分3次免疫小鼠,采用背部皮下多点注射,每次间隔2周,免疫剂量为0.2 mL/只,3免后1周分别以APP1型菌Shope 4074株(5×109cfu)和APP2型菌S1536株(5×1010cfu)进行攻毒试验。通过小鼠保护率与抗体效价的相关性研究、肺部病理变化及肺脏细菌的分布情况等指标进行综合评价。结果显示,试验Ⅰ组4种重组蛋白特异性抗体水平显著高于其他两组(P<0.05),对APP1型菌攻毒的保护率(9/10)明显高于试验Ⅱ组(5/10)和对照组(0/8),小鼠的免疫保护率与抗体效价之间存在显著正相关;且该组对APP2型菌攻毒的保护作用(无肺脏损伤)也明显优于其它两组(典型肺部损伤)。间接免疫荧光试验表明试验Ⅰ组对肺脏细菌的清除效果也明显优于其他两组。本试验揭示试验Ⅰ组对不同血清型APP攻击能够提供很好的交叉保护作用,从而为猪传染性胸膜肺炎新型疫苗的研制提供参考。

The study was focused on the comparison of protective efficacy between two recombinant subunit vaccines against serotype 1 and serotype 2 of Actinobacillus pleuropneumoniae in mice, with one containing recombinant Apx Ⅰ , Apx Ⅱ , ApxⅢ and OMP（named Trial group Ⅰ ） and the other containing recombinant Apx Ⅰ , Apx Ⅱ , ApxⅢ , ApxⅣ, OMP and Apfa （named Trial group Ⅱ ）. The BALB/c mice were vaccinated at days 0 , 14 and 28 subcutaneously, and then challenged with serotype 1 strain Shope 4074 and serotype 2 strain 1536 intranasally at day 35. The protective efficacy was evaluated in terms of mortality, lung lesions, bacterial distribution of lung, then the relationship was evaluated between antibody level and protective efficacy. The results suggested that Trial group Ⅰ had a significantly higher antibody level against ApxⅠ, ApxⅡ , ApxⅢ and OMP than that of other two groups （P〈0.05）. The protective efficacy against serotype 1 of Trial group Ⅰ （9/10） was obviously higher than that of Trial group Ⅱ （5/10）and Control group （0/8）, and the protective efficacy against serotype 2 of that （no lung lesion） was obviously better than others（ typical lung lesion）. The bacterial clearance of lung in Trial group Ⅰ was efficacious than the other two groups. Ⅰt was demonstrated that antibody level had a positive correlation to protective efficacy. So,Trial group Ⅰ could provide better crossing protection, which will provide a reference for the development of new vaccine.