Garofolo Giuliano, Di Giannatale Elisabetta, Platone Ilenia, Zilli Katiuscia, Sacchini Lorena, Abass Anna, Ancora Massimo, Cammà Cesare, Di Donato Guido, De Massis Fabrizio, Calistri Paolo, Drees Kevin P, Foster Jeffrey T
National and OIE Reference Laboratory for Brucellosis, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale", Teramo, Italy.
Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, USA.
BMC Microbiol. 2017 Feb 2;17(1):28. doi: 10.1186/s12866-017-0939-0.
Brucellosis is a common and chronic disease of cattle and other bovids that often causes reproductive disorders. Natural infection in cattle is caused by Brucella abortus and transmission typically occurs during abortions, calving, or nursing. Brucellosis is also a major zoonotic disease due to contamination of dairy products or contact with the tissues of infected animals. Brucellosis has been eradicated from most of the developed world in the last 40 years but persists in many regions-the disease remains prevalent in portions of Africa, the Middle East, Asia, and Central and South America, as well as in the Mediterranean basin. In Italy, B. abortus has persisted in southern regions in both cattle and water buffalo. Previous attempts at analyzing the phylogenetics of B. abortus in Italy have been challenging due to limited genetic variability and unresolved global population genetic structure of this pathogen.
We conducted genome-wide phylogenetic analyses on 11 representative strains of B. abortus from Italy, and compared these sequences to a worldwide collection of publically available genomes. Italian isolates belong to three clades that are basal to the main and global B. abortus lineage. Using six SNP-based assays designed to identify substructure within the Italian clades, we surveyed a collection of 261 isolates and found that one clade predominates throughout endemic districts in the country, while the other two clades are more geographically restricted to portions of southern Italy.
Although related strains exist worldwide, B. abortus isolates from Italy are substantially different than those found in much of the rest of Europe and North America, and are more closely related to strains from the Middle East and Asia. Our assays targeting genetic substructure within Italy allowed us to identify the major lineages quickly and inexpensively, without having to generate whole genome sequences for a large isolate collection. These findings highlight the importance of genetic studies to assess the status and the history of pathogens.
布鲁氏菌病是牛和其他牛科动物常见的慢性疾病，常导致生殖障碍。牛的自然感染由流产布鲁氏菌引起，传播通常发生在流产、产犊或哺乳期间。由于乳制品污染或与感染动物组织接触，布鲁氏菌病也是一种主要的人畜共患病。在过去40年里，布鲁氏菌病已在大多数发达国家被根除，但在许多地区仍然存在——该疾病在非洲、中东、亚洲、中美洲和南美洲部分地区以及地中海盆地仍然普遍流行。在意大利，流产布鲁氏菌在南部地区的牛和水牛中持续存在。由于这种病原体的遗传变异性有限以及全球种群遗传结构尚未解决，之前在意大利分析流产布鲁氏菌系统发育的尝试一直具有挑战性。
我们对来自意大利的11株代表性流产布鲁氏菌菌株进行了全基因组系统发育分析，并将这些序列与全球公开可用基因组的集合进行了比较。意大利分离株属于三个进化枝，它们位于主要的全球流产布鲁氏菌谱系的基部。使用六种基于单核苷酸多态性（SNP）的检测方法来识别意大利进化枝内的亚结构，我们对261株分离株进行了调查，发现一个进化枝在该国的流行地区占主导地位，而其他两个进化枝在地理上更局限于意大利南部的部分地区。
尽管世界各地存在相关菌株，但来自意大利的流产布鲁氏菌分离株与欧洲其他大部分地区和北美的分离株有很大不同，并且与中东和亚洲的菌株关系更密切。我们针对意大利境内遗传亚结构的检测方法使我们能够快速且低成本地识别主要谱系，而无需为大量分离株生成全基因组序列。这些发现凸显了遗传研究对于评估病原体状况和历史的重要性。
