中文摘要：

ApxIV是胸膜肺炎放线杆菌的一种RTX毒素,为探究其在胸膜肺炎放线杆菌致病过程中的作用,以血清7型APP HB04为亲本菌株,通过接合转移和负向筛选方法,构建了一株apxIV基因缺失突变株。通过PCR、序列分析、Southern blot分析及遗传稳定性分析等证明成功构建了突变株。对突变株生物学特性进行初步研究,发现突变株与亲本菌株相比,体外生长速度未发生明显变化,对小鼠的致病力有所降低。结果表明,毒素ApxⅣ在胸膜肺炎放线杆菌致病过程中发挥一定作用。突变株的成功构建及生物学特性研究为进一步阐明胸膜肺炎放线杆菌的致病性及开发更为安全、高效的基因工程疫苗奠定了坚实基础。

英文摘要：

In order to study pathogenicity of the fourth RTX toxin ApxIV in the infection of Actinobacillus pleuropneumoniae, an Actinobacillus pleuropneumoniae αpxIVA mutant was constructed by transconjugation and counterselection method, using an A. pleuropneumoniae HB04 strain （serotype 7） as parental strain. The αpxIV mutant was confirmed by PCR, sequence analysis, Southern blot and heredity stability assays. The biological characteristics of this mutant strain was further investigated. The mutant possesses the same growth rate as its parental strain, but it was less virulent on mice. These results indicated that αpxIV was an important virulence factor in the pathogenesis of A. pleuropneumoniae infection. This study have a further illumina- tion on the pathogenicity of A. pleuropneumoniae and it will facilitate the development of more reasonable live attenuated vaccines of APP.