Institute of Virology, Department of Infectious Diseases, University of Veterinary Medicine Hannover, Buenteweg 17, 30559 Hannover, Germany.
Vet Microbiol. 2010 Jul 14;143(2-4):213-23. doi: 10.1016/j.vetmic.2009.12.006. Epub 2009 Dec 11.
The Porcine reproductive and respiratory syndrome virus (PRRSV) can persist for several weeks in infected pigs, and readily spreads from viraemic pigs to other pigs as well as to other herds. In regions with dense pig populations such as the North-Western part of Germany the virus is endemic. The aim of this study was to analyse the genetic diversity of PRRSV found in 18 herds in this region, which had pigs with respiratory or reproductive failures, and where PRRSV had been demonstrated by RT-PCR. Phylogenetic trees were calculated using the complete nucleotide sequences of the ORF5. Of the 65 samples sequenced, five PRRSV from four herds were of the North American (NA; Type 2) genotype, and 60 of the European (EU; Type 1) genotype. To ascertain if the field PRRSV varied with time and to monitor the health condition of the herds they were revisited 2 years later. Although only two herds still reported clinical signs, PRRSV was found by RT-PCR in 10 of the 18 herds. Phylogenetic analysis showed that of the 23 PRRSV sequenced, 15 were of the European (EU) genotype. The EU genotype isolates from both samplings could be assigned to one of 12 clusters. There was no indication for the existence of herd specific clusters. ORF5 sequence identities between PRRSV from one herd in one cluster were either 100%, or had single base exchanges. These data indicate that the mutation rates for the European field isolates are similar to that found for the NA genotype vaccine strain used in Germany.
猪繁殖与呼吸综合征病毒 (PRRSV) 可在感染猪体内持续存在数周，并可轻易地从带毒猪传播至其他猪，以及传播至其他畜群。在德国西北部等猪群密度较高的地区，该病毒呈地方性流行。本研究旨在分析在该地区 18 个出现呼吸或繁殖失败且经 RT-PCR 证实存在 PRRSV 的猪群中发现的 PRRSV 的遗传多样性。通过 ORF5 的完整核苷酸序列计算了系统发育树。在测序的 65 个样本中，来自 4 个畜群的 5 个 PRRSV 为北美（NA；基因型 2）基因型，而 60 个为欧洲（EU；基因型 1）基因型。为了确定田间 PRRSV 是否随时间而变化，并监测畜群的健康状况，两年后对其进行了回访。尽管只有两个畜群仍报告有临床症状，但在 18 个畜群中的 10 个中通过 RT-PCR 发现了 PRRSV。系统发育分析显示，在测序的 23 个 PRRSV 中，有 15 个为欧洲（EU）基因型。两次采样的 EU 基因型分离株可归入 12 个聚类之一。没有迹象表明存在畜群特异性聚类。一个聚类中一个畜群的 PRRSV 之间的 ORF5 序列同一性要么为 100%，要么只有单个碱基交换。这些数据表明，欧洲田间分离株的突变率与在德国使用的 NA 基因型疫苗株相似。
