Department of Veterinary Pathobiology, Veterinary Academy, Lithuanian University of Health Sciences, Tilzes str. 18, Kaunas LT-47181, Lithuania.
Division of Veterinary Epidemiology and Economics, Institute of Veterinary Medicine, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159c, Warsaw 02-776, Poland.
Prev Vet Med. 2024 Dec;233:106363. doi: 10.1016/j.prevetmed.2024.106363. Epub 2024 Oct 23.
Caprine arthritis-encephalitis (CAE) is a progressive disease of goats caused by small ruminant lentivirus (SRLV) and is considered as one of the most important threats for goat farming in developed countries. The disease prevalence has never been investigated in the Lithuanian goat population. Therefore, a descriptive cross-sectional study was carried out in 2021-2022 to determine if SRLV infection was present in the Lithuanian goat population and, in the case of a positive result, to estimate the true herd-level prevalence of SRLV infection and specify genotypes and subtypes of SRLV responsible for the infection. Thirty goat herds counting >5 adult goats were randomly selected and, in each herd, a representative sample of adult goats was blood-sampled and tested serologically for SRLV infection using a commercial ELISA. The herd was considered infected if at least one goat tested positive and the true herd-level prevalence of SRLV infection was estimated using the Bayesian approach. Seropositive animals were found in 17 / 30 herds (57 %; 95 % confidence interval: 39 %, 73 %). The true herd-level prevalence was 56 % (95 % credible interval: 36 %, 76 %). In 10 / 17 seropositive herds whose owners consented for resampling of seropositive goats, 1-5 seropositive goats were tested using the nested real-time PCR (nRT-PCR). Goats from 9 seropositive herds tested positive in the nRT-PCR: in 4 herds for genotype A, in 4 herds for genotype B, and in 1 herd - 2 goats for genotype B and 1 goat for genotype A. From each of 9 nRT-PCR-positive herds, 1 PCR product of each genotype was sequenced using Sanger method and the phylogenic tree was constructed using the neighbor-joining method in the Molecular Evolutionary Genetics Analysis software. Four herds turned out to be infected with B1 subtype (91 % identity with the prototypic strain), 3 herds with A2 subtype (90 %-92 % identity), and a herd with mixed infection was infected with B1 (91 % identity) and A2 subtype (90 % identity). In one herd, the only seropositive goat was found to be infected with the strain most closely related to the A1 subtype (80 % identity). This study shows for the first time that SRLV infection is present and widespread in the Lithuanian goat population and both classical SRLV genotypes, represented by quite typical subtypes A2 and B1, appear to be responsible for the infection.
绵羊关节炎-脑炎（CAE）是一种由小反刍兽瘟病毒（SRLV）引起的山羊进行性疾病，被认为是发达国家山羊养殖最重要的威胁之一。立陶宛山羊群体中从未调查过该病的流行情况。因此，在 2021-2022 年进行了一项描述性横断面研究，以确定 SRLV 感染是否存在于立陶宛山羊群体中，如果结果为阳性，则估计 SRLV 感染的真实群体流行率，并确定导致感染的 SRLV 基因型和亚型。随机选择了 30 个存栏数>5 只成年山羊的羊群，在每个羊群中，采集成年山羊的代表性样本进行血清学检测，使用商业 ELISA 检测 SRLV 感染。如果至少有一只山羊检测呈阳性，则认为该羊群受到感染，使用贝叶斯方法估计 SRLV 感染的真实群体流行率。在 30 个羊群中，有 17/30 个羊群（57%；95%置信区间：39%，73%）发现了血清阳性动物。真实的羊群流行率为 56%（95%可信区间：36%，76%）。在 17 个血清阳性羊群中，有 10 个（占血清阳性羊群的 59%）的羊群所有者同意对血清阳性山羊进行再次采样，使用巢式实时 PCR（nRT-PCR）对 1-5 只血清阳性山羊进行了检测。在 9 个血清阳性羊群中，有 9 个羊群的山羊 nRT-PCR 检测呈阳性：4 个羊群为基因型 A，4 个羊群为基因型 B，1 个羊群为基因型 B 和 1 个基因型 A。从每个 nRT-PCR 阳性的羊群中，使用 Sanger 法对每个基因型的 1 个 PCR 产物进行测序，并在 Molecular Evolutionary Genetics Analysis 软件中使用邻接法构建系统发育树。结果显示，4 个羊群感染了 B1 亚型（与原型株的同源性为 91%），3 个羊群感染了 A2 亚型（同源性为 90%-92%），1 个混合感染的羊群感染了 B1（同源性为 91%）和 A2 亚型（同源性为 90%）。在一个羊群中，唯一的血清阳性山羊被发现感染了与 A1 亚型最密切相关的毒株（同源性为 80%）。本研究首次表明，SRLV 感染在立陶宛山羊群体中存在且广泛流行，两种经典的 SRLV 基因型，代表相当典型的 A2 和 B1 亚型，似乎都与感染有关。
