Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa.
Arch Virol. 2013 Jan;158(1):155-63. doi: 10.1007/s00705-012-1478-5. Epub 2012 Sep 26.
Bovine viral diarrhoea virus (BVDV) has emerged as one of the economically important pathogens in cattle populations, with a worldwide distribution and causing a complex of disease syndromes. Two genotypes, BVDV 1 and 2, exist and are discriminated on the basis of the sequence of the 5' non-coding region (5' NCR) using real-time PCR. Real-time PCR is more sensitive, specific, and less time-consuming than conventional PCR, and it has less risk of cross-contamination of samples. Limited information exists on BVDV genetic subtypes in South Africa. The aim of this study was to determine the genotypes of BVDV currently circulating in South African feedlots. A total of 279 specimens (219 tissue samples, 59 trans-tracheal aspirates and 1 blood sample) were collected from dead and living cattle with lesions or clinical signs compatible with BVDV infection. Pooled homogenates from the same animals were prepared, and total RNA was extracted. A screening test was performed on the pooled samples, and positive pools were investigated individually. A Cador BVDV Type 1/2 RT-PCR Kit (QIAGEN, Hilden, Germany) was used for the real-time PCR assay on a LightCycler(®) V2.0 real-time PCR machine (Roche Diagnostics, Mannheim, Germany). The results were read at 530 and 640 nm for BVDV 1 and 2, respectively. Bovine viral diarrhoea virus was detected in a total of 103 samples that included 91 tissue samples, 1 blood sample and 11 trans-tracheal aspirates. Eighty-five (82.5 %) of the strains were genotype 1 and 18 (17.5 %) were genotype 2. Comparing the sequencing data, genotypes 1 and 2 from the field strains did not cluster with vaccine strains currently used in feedlots in South Africa. The present study revealed the presence of BVDV genotype 2 in cattle in South Africa based on the high sequence similarity between genotype 2 field strains and strain 890 from North America. The presence of genotype 2 viruses that phylogenetically belong to different clusters and coexist in feedlots is consistent with the possibility of multiple virus introductions. These results represent the first documented evidence for the presence of BVDV genotype 2 in African cattle.
牛病毒性腹泻病毒（BVDV）已成为牛群中具有重要经济意义的病原体之一，其分布广泛，可引起多种疾病综合征。目前存在两种基因型，BVDV1 和 BVDV2，可基于实时 PCR 对 5'非编码区（5'NCR）的序列进行区分。与传统 PCR 相比，实时 PCR 更敏感、更特异、耗时更短，且样品交叉污染的风险更小。南非关于 BVDV 遗传亚型的信息有限。本研究旨在确定目前在南非育肥场循环的 BVDV 基因型。从有病变或有 BVDV 感染临床症状的病死牛和活牛中采集了 279 份标本（219 份组织样本、59 份经气管抽吸物和 1 份血液样本）。对来自同一动物的混合匀浆进行了制备，并提取了总 RNA。对混合样本进行了筛选检测，对阳性混合样本进行了单独检测。使用 Cador BVDV Type 1/2 RT-PCR 试剂盒（QIAGEN，德国希尔德斯海姆）在 LightCycler® V2.0 实时 PCR 仪（罗氏诊断，德国曼海姆）上进行实时 PCR 检测。在 530nm 和 640nm 处分别读取 BVDV1 和 BVDV2 的结果。共在 103 个样本中检测到牛病毒性腹泻病毒，包括 91 个组织样本、1 个血液样本和 11 个经气管抽吸物。85（82.5%）株为基因型 1，18（17.5%）株为基因型 2。比较测序数据，田间株与南非育肥场目前使用的疫苗株没有聚类。本研究基于南非育肥场田间株与北美 890 株的高序列相似性，揭示了南非牛中存在 BVDV 基因型 2。在育肥场中存在亲缘关系不同的聚类且共同存在的基因型 2 病毒，符合多种病毒传入的可能性。这些结果代表了非洲牛中存在 BVDV 基因型 2 的首次有文件记录的证据。
