Institute of Veterinary Bacteriology, Vetsuisse-Faculty, University of Bern, Postfach, Länggassstrasse 122, CH-3001 Bern, Switzerland; Clinic for Ruminants, Department of Clinical Veterinary Medicine, Vetsuisse-Faculty, University of Bern, Postfach, Bremgartenstrasse 109a, CH-3001 Bern, Switzerland.
Clinic for Ruminants, Department of Clinical Veterinary Medicine, Vetsuisse-Faculty, University of Bern, Postfach, Bremgartenstrasse 109a, CH-3001 Bern, Switzerland.
Vet Microbiol. 2014 Jan 10;168(1):177-84. doi: 10.1016/j.vetmic.2013.11.013. Epub 2013 Nov 21.
Dichelobacter nodosus, the etiological agent of ovine footrot, exists both as virulent and as benign strains, which differ in virulence mainly due to subtle differences in the three subtilisin-like proteases AprV2, AprV5 and BprV found in virulent, and AprB2, AprB5 and BprB in benign strains of D. nodosus. Our objective was a molecular genetic epidemiological analysis of the genes of these proteases by direct sequence analysis from clinical material of sheep from herds with and without history of footrot from 4 different European countries. The data reveal the two proteases known as virulent AprV2 and benign AprB2 to correlate fully to the clinical status of the individuals or the footrot history of the herd. In samples taken from affected herds, the aprV2 gene was found as a single allele whereas in samples from unaffected herds several alleles with minor modifications of the aprB2 gene were detected. The different alleles of aprB2 were related to the herds. The aprV5 and aprB5 genes were found in the form of several alleles scattered without distinction between affected and non-affected herds. However, all different alleles of aprV5 and aprB5 encode the same amino acid sequences, indicating the existence of a single protease isoenzyme 5 in both benign and virulent strains. The genes of the basic proteases BprV and BprB also exist as various alleles. However, differences found in samples from affected versus non-affected herds do not reflect the currently known epitopes that are attributed to differences in biochemical activity. The data of the study confirm the prominent role of AprV2 in the virulence of D. nodosus and shed a new light on the presence of the other protease genes and their allelic variants in clinical samples.
化脓隐秘杆菌是绵羊腐蹄病的病原体，存在毒力和非毒力两种菌株，毒力的差异主要归因于毒力菌株中三种枯草溶菌素样蛋白酶 AprV2、AprV5 和 BprV 以及非毒力菌株中 AprB2、AprB5 和 BprB 之间的细微差异。我们的目的是通过直接从来自 4 个不同欧洲国家无腐蹄病和有腐蹄病史的羊群的临床样本中对这些蛋白酶基因进行分子遗传流行病学分析。数据显示，两种已知的毒力 AprV2 和非毒力 AprB2 蛋白酶与个体的临床状况或畜群的腐蹄病病史完全相关。在来自受影响畜群的样本中，发现 aprV2 基因是单个等位基因，而在来自未受影响畜群的样本中，检测到 aprB2 基因的几个等位基因，这些等位基因存在微小的修饰。不同的 aprB2 等位基因与畜群有关。 aprV5 和 aprB5 基因以几种等位基因的形式存在，没有明显区分受影响和未受影响的畜群。然而， aprV5 和 aprB5 的所有不同等位基因都编码相同的氨基酸序列，表明在毒力和非毒力菌株中都存在单一的蛋白酶同工酶 5。碱性蛋白酶 BprV 和 BprB 的基因也存在多种等位基因。然而，在来自受影响和未受影响的畜群的样本中发现的差异并不反映目前归因于生化活性差异的已知表位。该研究的数据证实了 AprV2 在化脓隐秘杆菌毒力中的突出作用，并为其他蛋白酶基因及其在临床样本中的等位基因变异提供了新的认识。
