Wang Xiaolan, Ding Chan, Wang Shaohui, Han Xiangan, Yu Shengqing
Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, People's Republic of China.
Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, People's Republic of China
Appl Environ Microbiol. 2015 Aug;81(15):5093-102. doi: 10.1128/AEM.00828-15. Epub 2015 May 22.
Riemerella anatipestifer is a well-described pathogen of waterfowl and other avian species that can cause septicemic and exudative diseases. In this study, we sequenced the complete genome of R. anatipestifer strain Yb2 and analyzed it against the published genomic sequences of R. anatipestifer strains DSM15868, RA-GD, RA-CH-1, and RA-CH-2. The Yb2 genome contains one circular chromosome of 2,184,066 bp with a 35.73% GC content and no plasmid. The genome has 2,021 open reading frames that occupy 90.88% of the genome. A comparative genomic analysis revealed that genome organization is highly conserved among R. anatipestifer strains, except for four inversions of a sequence segment in Yb2. A phylogenetic analysis found that the closest neighbor of Yb2 is RA-GD. Furthermore, we constructed a library of 3,175 mutants by random transposon mutagenesis, and 100 mutants exhibiting more than 100-fold-attenuated virulence were obtained by animal screening experiments. Southern blot analysis and genetic characterization of the mutants led to the identification of 49 virulence genes. Of these, 25 encode cytoplasmic proteins, 6 encode cytoplasmic membrane proteins, 4 encode outer membrane proteins, and the subcellular localization of the remaining 14 gene products is unknown. The functional classification of orthologous-group clusters revealed that 16 genes are associated with metabolism, 6 are associated with cellular processing and signaling, and 4 are associated with information storage and processing. The functions of the other 23 genes are poorly characterized or unknown. This genome-wide study identified genes important to the virulence of R. anatipestifer.
鸭疫里默氏菌是一种已被充分描述的水禽和其他禽类病原体,可引起败血性和渗出性疾病。在本研究中,我们对鸭疫里默氏菌Yb2菌株的全基因组进行了测序,并将其与已发表的鸭疫里默氏菌DSM15868、RA-GD、RA-CH-1和RA-CH-2菌株的基因组序列进行了分析。Yb2基因组包含一条2,184,066 bp的环状染色体,GC含量为35.73%,无质粒。该基因组有2,021个开放阅读框,占基因组的90.88%。比较基因组分析表明,除Yb2中一个序列片段的四处倒位外,鸭疫里默氏菌菌株间的基因组结构高度保守。系统发育分析发现,Yb2最接近的亲缘菌株是RA-GD。此外,我们通过随机转座子诱变构建了一个包含3,175个突变体的文库,并通过动物筛选实验获得了100个毒力降低100倍以上的突变体。对这些突变体进行Southern印迹分析和遗传特征鉴定,确定了49个毒力基因。其中,25个编码细胞质蛋白,6个编码细胞质膜蛋白,4个编码外膜蛋白,其余14个基因产物的亚细胞定位未知。直系同源簇的功能分类显示,16个基因与代谢相关,6个与细胞加工和信号传导相关,4个与信息存储和加工相关。其他23个基因的功能特征不明确或未知。这项全基因组研究确定了对鸭疫里默氏菌毒力重要的基因。