Parco Tecnologico Padano - CERSA, Via Einstein, Lodi 26900, Italy.
BMC Vet Res. 2013 Mar 27;9:58. doi: 10.1186/1746-6148-9-58.
The porcine reproductive and respiratory syndrome (PRRS) is a devastating disease for the pig industry. In this study, we analysed the genetic variability of PRRS virus (PRRSV) as well as the relationship between the genetic variability, the geographical and temporal distribution of the PRRSV strains. Moreover, we investigated the association between the glycosylation patterns in PRRSV sequences and pigs growth.
The data highlight that PRRSV strains evolve rapidly on individual farms, and temporal evolution of PRRSV is an important factor of genetic variability. Analysis of glycosylation sites in the glycoprotein 5 (GP5) ectodomain revealed that PRRSV isolates had seven combinations of putative N-linked glycosylation sites of which the N37/46/53 sites was found in 79% of the sequences. No significant relationship was found between the genetic variation of the PRRSV strains and the geographic distance. A significant relationship was found between the genetic variation and time of sampling when farm was considered as a factor in the analysis. Furthermore, the commercial semen from artificial insemination centres was not a source of PRRS transmission.The PRRSV having the glycosylation site at position N46 (N46+) were observed to have higher burden on pigs and accordingly the corresponding infected pigs had lower average daily gain (ADG) compared with those infected with PRRSV lacking the glycosylation at N46 (N46-) position site. This study showed that the number of piglets by litter infected by PRRSV was lower for the Landrace breed than for the other studied breeds (Large White, Duroc and Pietrain).
The PRRSV genetic variability which is determined by a local and temporal evolution at the farm level could be considered in a perspective of prevention. Moreover, the association between the PRRSV glycosylation patterns and its virulence could be of interest for vaccine development. The differences of resistance to PRRSV infections among pig breeds might open new horizons for the genetic selection of robustness against PRRSV infection.
猪繁殖与呼吸综合征（PRRS）是养猪业的毁灭性疾病。本研究分析了猪繁殖与呼吸综合征病毒（PRRSV）的遗传变异性，以及遗传变异性与 PRRSV 株的地理和时间分布之间的关系。此外，我们还研究了 PRRSV 序列中的糖基化模式与猪生长之间的关系。
数据突出表明，PRRSV 株在单个农场迅速进化，PRRSV 的时间进化是遗传变异性的一个重要因素。对糖蛋白 5（GP5）外域中糖基化位点的分析表明，PRRSV 分离株有 7 种可能的 N 连接糖基化位点组合，其中 N37/46/53 位点在 79%的序列中发现。PRRSV 株的遗传变异与地理距离之间没有显著关系。当考虑农场作为分析因素时，在采样时间与遗传变异之间发现了显著关系。此外，来自人工授精中心的商业精液不是 PRRS 传播的来源。在位置 N46 处具有糖基化位点的 PRRSV（N46+）被观察到对猪的负担更高，因此与缺乏 N46 位置糖基化的 PRRSV（N46-）感染的猪相比，感染的猪平均日增重（ADG）更低。本研究表明，与其他研究品种（长白猪、杜洛克猪和皮特兰猪）相比，兰德瑞斯猪的猪仔感染 PRRSV 的比例较低。
由农场层面的本地和时间进化决定的 PRRSV 遗传变异性可以在预防的角度进行考虑。此外，PRRSV 糖基化模式与其毒力之间的关系可能对疫苗开发有意义。猪品种对 PRRSV 感染的抗性差异可能为针对 PRRSV 感染的遗传选择提供新的思路。
