Department of Animal Medicine, Production and Health (MAPS), University of Padua, Viale dell'Università 16, Legnaro 35020, PD, Italy.
Dipartimento di Prevenzione, AULSS 8 Berica, Via Giovanni Giuseppe Cappellari 6, Vicenza 36100, Italy.
Prev Vet Med. 2023 Jul;216:105943. doi: 10.1016/j.prevetmed.2023.105943. Epub 2023 May 18.
Porcine circovirus type 2 (PCV-2) is among the most burdensome viruses of the swine industry globally. Several genotypes have been periodically emerging, but just three of them (PCV-2a, PCV-2b, and PCV-2d) seem to circulate worldwide and be associated with the disease. Conversely, the spatial-temporal distribution of minor genotypes appears limited and their clinical relevance is still unclear. Recently PCV-2e was incidentally detected for the first time in Europe in a breeding farm in Northeastern Italy, while no connection could be established with countries where this genotype had been previously detected. To investigate circulating genotypes in the neglected rural context and provide a comparison with the most explored industrial context, a molecular survey was performed on samples collected in rural (n = 72) and industrial farms (n = 110) located in the same geographic area. Phylogenetic analysis surprisingly evidenced PCV-2e circulation only in pigs reared in backyard farms (n = 5), while major genotypes (PCV-2a, -2b, -2d) circulate in both rearing contexts. However, the close genetic similarity between the herein detected PCV-2e strains and the previously reported one testify that, although unusual, such rural-to-industrial strains exchange affected also PCV-2e. The greater genetic and phenotypic diversity of PCV-2e genotype compared to other ones might threaten the protection granted by current vaccines. The present study suggests the rural context as an ecological niche for the circulation of PCV-2e, and even of other minor genotypes. PCV-2e detection in pigs with outdoor access further stresses the epidemiological role of backyard farms as interfaces for pathogen introduction, potentially ascribable to the different rearing approaches, lower managerial and biosecurity capabilities, and easier contacts with wildlife.
猪圆环病毒 2 型（PCV-2）是全球养猪业中最具负担的病毒之一。几种基因型定期出现，但只有三种（PCV-2a、PCV-2b 和 PCV-2d）似乎在全球传播，并与该疾病相关。相反，次要基因型的空间和时间分布似乎有限，其临床相关性仍不清楚。最近，PCV-2e 首次在意大利东北部的一个养殖场中偶然在欧洲被检测到，而与之前检测到该基因型的国家没有联系。为了调查在被忽视的农村环境中循环的基因型，并与最具探索性的工业环境进行比较，对在同一地理区域内收集的农村（n=72）和工业农场（n=110）的样本进行了分子调查。令人惊讶的是，系统发育分析表明，PCV-2e 仅在后院农场饲养的猪中传播（n=5），而主要基因型（PCV-2a、-2b、-2d）在两种饲养环境中传播。然而，在此处检测到的 PCV-2e 株与之前报道的株之间的密切遗传相似性证明，尽管不常见，但这种农村到工业的菌株交换也影响了 PCV-2e。与其他基因型相比，PCV-2e 基因型的遗传和表型多样性更大，可能会威胁到当前疫苗提供的保护。本研究表明，农村环境是 PCV-2e 甚至其他次要基因型循环的生态位。具有户外通道的猪中 PCV-2e 的检测进一步强调了后院农场作为病原体引入接口的流行病学作用，这可能归因于不同的饲养方式、较低的管理和生物安全能力以及与野生动物更容易接触。
