副猪嗜血杆菌hhdB基因的鉴定和分析

Identification and Analysis of the hhdB Gene of Haemophilus parasuis

为了明确副猪嗜血杆菌致病菌株的毒力相关因子,从广东省不同地区发病猪场送检病猪中分离到9株细菌（H1~H9）,并对其hhdB基因进行了鉴定和分析。结果显示,所分离的9株细菌经形态观察、生化特性鉴定和PCR鉴定为副猪嗜血杆菌阳性,并具有卫星现象和不溶血特征。用hhdB基因引物从分离菌株中扩增到了特异性片段,序列分析表明,所获得的hhdB基因序列与GenBank中副猪嗜血杆菌SH0165的hhdB基因同源性为99%,分离菌株hh-dB基因之间序列同源性为97.5%~99.8%,推导的氨基酸序列与少数放线杆菌、杜克雷嗜血杆菌的溶血素激活蛋白具有一定的相似性。RT-PCR扩增到了hhdB基因的目的条带,表明该基因在分离菌株中得到了相应的表达。这将为副猪嗜血杆菌致病菌株毒力特征基因的鉴定以及副猪嗜血杆菌致病机理的研究奠定基础。

The research aimed to know the virulence-associated factors in pathogenic strains of Haemophilus parasuis.Nine strains（H1-H9） of bacteria were isolated from unsound swine within the different regions epidemic farms in Guangdong province,and the hhdB genes of the isolated strains were identified and analyzed.The results showed that the isolated strains belonged to Haemophilus parasuis by morphological observation,biochemical characterization and PCR identify,then had satellite phenomena and nonhemolytic characteristics.The nucleotide sequence similarities of hhdB genes between the isolated strains,Haemophilus parasuis SH0165 are 97.5%-99.8% and 99% respectively.The amino acid sequence of isolated strains hhdB gene and the bacterial hemolysin activation protein（Actinobacillus minor NM305 and Haemophilus ducreyi 35000HP）were similar.RT-PCR indicated that the hhdB gene was expressed in all of the isolated strains.This study would be helpful for identification of virulence gene and pathogenic mechanism study of Haemophilus parasuis.