Cohen Liza Miriam, Bossé Janine T, Stegger Marc, Li Yanwen, Langford Paul R, Kielland Camilla, Klem Thea Blystad, Gulliksen Stine Margrethe, Ranheim Birgit, Grøntvedt Carl Andreas, Angen Øystein
Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Oslo, Norway.
Section of Paediatric Infectious Disease, Department of Infectious Disease, Imperial College London, London, United Kingdom.
Front Microbiol. 2021 Sep 10;12:729637. doi: 10.3389/fmicb.2021.729637. eCollection 2021.
is the etiological agent of porcine pleuropneumonia, a disease of major impact on pig health, welfare, and productivity globally. Serovar 8 (APP) is the predominant clinical serovar in Norway and the United Kingdom (UK), and has been isolated from clinical cases in Denmark. The primary objective of this study was to characterize the genetic variability of isolates of APP8 in the Norwegian population. The secondary objectives were to determine the within-host variability of APP8; to compare the APP8 bacterial populations in Norway, Denmark, and the UK, including antimicrobial resistance (AMR) gene profiles and to assess the effect of national differences in antimicrobial drug use and restricted animal movement on the occurrence of resistance. Isolates of APP8 from the UK (=67), Denmark (=22), and Norway (=123) collected between 1983 and 2020 were compared using whole genome sequencing. To investigate genetic variability within individual hosts, an additional 104 APP8 isolates from the lungs of six Norwegian pigs were compared. Very low within-host variation was observed (≤ 2 single nucleotide polymorphisms). The phylogeny of 123 Norwegian APP8 isolates from 76 herds revealed some within-herd genetic variation, but substantial geographical clustering. When inferring the relatedness of the three international APP8 collections, the topology highlighted the existence of two distinct monophyletic branches characterized by the Norwegian and UK isolates, respectively. Three Danish isolates were scattered across the UK branch, whereas the remaining 19 Danish isolates clustered in two monophyletic groups nested in the Norwegian branch. Coalescence analysis, performed to estimate the divergences from a common ancestor, indicated a last common ancestor several centuries ago. The phylogenetic analyses also revealed striking differences in occurrence of AMR genes, as these were 23-times more prevalent among the UK isolates than among the Norwegian isolates. An increased understanding of the effects of population strategies is helpful in surveillance and control of infectious diseases.
是猪胸膜肺炎的病原体，猪胸膜肺炎是一种对全球猪的健康、福利和生产力有重大影响的疾病。血清型8（APP）是挪威和英国的主要临床血清型，并且已从丹麦的临床病例中分离出来。本研究的主要目的是描述挪威猪群中APP8分离株的遗传变异性。次要目的是确定APP8在宿主体内的变异性；比较挪威、丹麦和英国的APP8细菌群体，包括抗菌药物耐药性（AMR）基因谱，并评估各国在抗菌药物使用和限制动物移动方面的差异对耐药性发生的影响。使用全基因组测序比较了1983年至2020年期间从英国（=67株）、丹麦（=22株）和挪威（=123株）收集的APP8分离株。为了研究个体宿主体内的遗传变异性，还比较了从六头挪威猪的肺中分离出的另外104株APP8分离株。观察到宿主体内变异非常低（≤2个单核苷酸多态性）。来自76个猪群的123株挪威APP8分离株的系统发育显示出一些猪群内的遗传变异，但有明显的地理聚类。在推断三个国际APP8菌株集合的亲缘关系时，拓扑结构突出显示存在两个不同的单系分支，分别以挪威和英国的分离株为特征。三株丹麦分离株分散在英国分支中，而其余19株丹麦分离株聚集在嵌套在挪威分支中的两个单系群中。进行合并分析以估计与共同祖先的分歧，结果表明最后一个共同祖先存在于几个世纪前。系统发育分析还揭示了AMR基因出现情况的显著差异，因为这些基因在英国分离株中的流行率比挪威分离株高23倍。更好地理解群体策略的影响有助于传染病的监测和控制。
