Zhao Lixiang, Chen Xiang, Xu Xiaojing, Song Gao, Liu Xiufan
Animal Infectious Disease Laboratory, Yangzhou University, Yangzhou, Jiangsu 225009, PR China.
Vet J. 2009 Apr;180(1):124-9. doi: 10.1016/j.tvjl.2007.10.021. Epub 2008 Feb 20.
Three hundred and twenty-four strains of Escherichia coli isolated from weaned pigs with diarrhoea or oedema disease in Eastern China were screened by multiplex PCR for the presence of the gene encoding adhesin involved in diffuse adhesion I (AIDA-I). Two AIDA-I positive strains were subjected to analysis of the nucleotide sequence of the complete orfA and orfB of the AIDA gene. The AIDA-I positive E. coli isolates were also assessed for five fimbriae (F4, F5, F6, F18 and F41) by monoclonal antibodies and for toxin genes (STa, STb, LT, EAST1, Stx2e) by PCR. Twenty-one (6.5%) of the isolates possessed AIDA-I genes. Of these isolates, two carried AIDA-I genes as the only demonstrated virulence factors, and the remaining isolates carried other virulence factor genes. Comparing the AIDA-I sequence from porcine and human sources, a high homology of orfA both in porcine E. coli and human E. coli was observed. However, each orfB of the two porcine E. coli isolates was 3864 nucleotides long compared with 3861 for the E. coli 2787 orfB, and showed 96.5% homology to E. coli 2787. The data indicated (1) that AIDA-I may be an occasional virulence factor in post-weaning diarrhoea and oedema disease in pigs, (2) that it has the potential to transfer between porcine and human E. coli, and (3) that there is a genetic diversity in orfB between human and porcine E. coli.
利用多重聚合酶链反应（multiplex PCR）对从中国东部患腹泻或水肿病的断奶仔猪中分离出的324株大肠杆菌进行筛选，以检测是否存在编码参与弥漫性粘附I（AIDA-I）的粘附素的基因。对两株AIDA-I阳性菌株进行AIDA基因完整orfA和orfB核苷酸序列分析。还通过单克隆抗体对AIDA-I阳性大肠杆菌分离株的五种菌毛（F4、F5、F6、F18和F41）进行评估，并通过聚合酶链反应对毒素基因（STa、STb、LT、EAST1、Stx2e）进行评估。21株（6.5%）分离株携带AIDA-I基因。在这些分离株中，两株携带AIDA-I基因作为唯一已证实的毒力因子，其余分离株携带其他毒力因子基因。比较猪源和人源的AIDA-I序列，观察到猪大肠杆菌和人大肠杆菌中的orfA具有高度同源性。然而，两株猪大肠杆菌分离株的每个orfB长3864个核苷酸，而大肠杆菌2787的orfB为3861个核苷酸，与大肠杆菌2787的同源性为96.5%。数据表明：（1）AIDA-I可能是猪断奶后腹泻和水肿病中的偶发毒力因子；（2）它有可能在猪大肠杆菌和人大肠杆菌之间转移；（3）人和猪大肠杆菌的orfB存在遗传多样性。
