猪胸膜肺炎放线杆菌山东分离株的血清型与Apx毒素型研究

 从山东省不同地区采集的85份具有严重呼吸道症状病死猪的肺脏、气管和扁桃体进行胸膜肺炎放线杆菌（APP）的分离鉴定，采用凝集试验和PCR方法对分离菌株进行血清型和APX毒素型的检测。结果从山东省不同地区分离到20株分属5个血清型的APP，其中，血清7型6株、血清5型5株、血清3型4株、血清4型3株、血清8型2株，血清7型、5型为优势血清型。不同地区分离的APP血清型不同，同一地区也存在不同的血清型。PCR检测结果表明，不同血清型的 APP共含有4种溶血毒素(Apx)，其中，血清3、4、8型APP含ApxⅡ、ApxⅢ和ApxⅣ，血清5型含ApxⅠ、ApxⅡ和ApxⅣ，血清7型含ApxⅡ和ApxⅣ，20株APP分离株均含有ApxⅡ和ApxⅣ两种毒素，表明野毒株的血清型与毒素基因的种类有一定的相关性。毒素序列分析结果表明，相同毒素型APP，其毒素基因序列的同源性在99.5％~100％之间，与血清型无关。致病性试验结果表明，所含毒素类型不同的APP对小白鼠的致病性不同，其中含ApxⅠ和ApxⅡ的血清5型APP毒力最强。该研究为猪传染性胸膜肺炎的免疫预防、亚单位疫苗的研制及基于ApxⅣ的PCR检测奠定了基础。

Study on Serotype and Apx Toxins Type of Actinobacillus pleuropneumoniae Strains Isolated from Shandong Province

Twenty field strains of Actinobacillus pleuropneumoniae (APP) were isolated from lung, tonsils and trachea in 85 pigs with sever pleuropneumonia in different districts of Shandong Province. Slide agglutination test and PCR were used to determine their serotype and Apx toxins type, respectively. The results of slideagglutination test indicated that there were 5 serotypes among the 20 field strains, serotype 7(6/20) and serotype 5 (5/20) were the dominant, the other serotypes were serotype 3(4/20), serotype 4(3/20) and serotype 8(2/20). The PCR results indicated that there were four kinds of Apx toxins in the 20 field strains，among them，serotype 3, 4, 8 contain ApxⅡ, ApxⅢ and ApxⅣ，serotype 5 contains ApxⅠ, ApxⅡand ApxⅣ, serotype 7 contains ApxⅡ and ApxⅣ, ApxⅡ and ApxⅣ existed in all the 20 field strains. The results of Apx sequence analysis indicated that the homogeneity of Apx gene was 99.5%－100% in different serotype APP if they had the same type of Apx. The pathogenicity was different when mice inoculated with APP which contain different Apx, serotype 5 APP was very virulent, for it contains ApxI and ApxⅡ. This study has established the foundation for control Porcine infectious pleuropneumonia in immune prevention, subunit vaccine and PCR diagnosis based on ApxⅣ gene.