Register Karen B, Ivanov Yury V, Harvill Eric T, Davison Nick, Foster Geoffrey
USDA, Agricultural Research Service, National Animal Disease Center, Ruminant Diseases and Immunology Research Unit, 1920 Dayton Avenue, Ames, IA 50010, USA
The Pennsylvania State University, Department of Veterinary and Biomedical Sciences, W-213 Millennium Science Complex, University Park, PA 16802, USA.
Microbiology (Reading). 2015 Mar;161(Pt 3):580-92. doi: 10.1099/mic.0.000035. Epub 2015 Jan 27.
During a succession of phocine morbillivirus outbreaks spanning the past 25 years, Bordetella bronchiseptica was identified as a frequent secondary invader and cause of death. The goal of this study was to evaluate genetic diversity and the molecular basis for host specificity among seal isolates from these outbreaks. MLST and PvuII ribotyping of 54 isolates from Scottish, English or Danish coasts of the Atlantic or North Sea revealed a single, host-restricted genotype. A single, novel genotype, unique from that of the Atlantic and North Sea isolates, was found in isolates from an outbreak in the Caspian Sea. Phylogenetic analysis based either on MLST sequence, ribotype patterns or genome-wide SNPs consistently placed both seal-specific genotypes within the same major clade but indicates a distinct evolutionary history for each. An additional isolate from the intestinal tract of a seal on the south-west coast of England has a genotype otherwise found in rabbit, guinea pig and pig isolates. To investigate the molecular basis for host specificity, DNA and predicted protein sequences of virulence genes that mediate host interactions were used in comparisons between a North Sea isolate, a Caspian Sea isolate and each of their closest relatives as inferred from genome-wide SNP analysis. Despite their phylogenetic divergence, fewer nucleotide and amino acid substitutions were found in comparisons of the two seal isolates than in comparisons with closely related strains. These data indicate isolates of B. bronchiseptica associated with respiratory disease in seals comprise unique, host-adapted and highly clonal populations.
在过去25年里，海豹瘟病毒爆发期间，支气管败血波氏杆菌被鉴定为常见的继发入侵者和死亡原因。本研究的目的是评估这些疫情中海豹分离株的遗传多样性和宿主特异性的分子基础。对来自大西洋或北海苏格兰、英格兰或丹麦海岸的54株分离株进行多位点序列分型（MLST）和PvuII核糖体分型，发现了单一的、宿主受限的基因型。在里海一次疫情的分离株中发现了一种单一的、与大西洋和北海分离株不同的新基因型。基于MLST序列、核糖体分型模式或全基因组单核苷酸多态性（SNP）的系统发育分析一致地将两种海豹特异性基因型置于同一主要进化枝内，但表明每种基因型都有独特的进化历史。从英格兰西南海岸一只海豹的肠道中分离出的另一株菌株，其基因型在兔、豚鼠和猪的分离株中也有发现。为了研究宿主特异性的分子基础，在全基因组SNP分析推断出的北海分离株、里海分离株及其各自最亲近的亲属之间的比较中，使用了介导宿主相互作用的毒力基因的DNA和预测蛋白质序列。尽管它们在系统发育上存在差异，但在两种海豹分离株的比较中发现的核苷酸和氨基酸替换比与密切相关菌株的比较中更少。这些数据表明，与海豹呼吸道疾病相关的支气管败血波氏杆菌分离株包括独特的、宿主适应的和高度克隆的群体。
