Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, USA.
Faculty of Public Heath, Health Sciences Center, Kuwait University, Kuwait City, Kuwait.
Sci Rep. 2017 Jun 28;7(1):4343. doi: 10.1038/s41598-017-04628-2.
The US swine industry has been impaired over the last 25 years by the far-reaching financial losses caused by the porcine reproductive and respiratory syndrome (PRRS). Here, we explored the relations between the spatial risk of PRRS outbreaks and its phylodynamic history in the U.S during 1998-2016 using ORF5 sequences collected from swine farms in the Midwest region. We used maximum entropy and Bayesian phylodynamic models to generate risk maps for PRRS outbreaks and reconstructed the evolutionary history of three selected phylogenetic clades (A, B and C). High-risk areas for PRRS were best-predicted by pig density and climate seasonality and included Minnesota, Iowa and South Dakota. Phylodynamic models demonstrated that the geographical spread of the three clades followed a heterogeneous spatial diffusion process. Furthermore, PRRS viruses were characterized by typical seasonality in their population size. However, endemic strains were characterized by a substantially slower population growth and evolutionary rates, as well as smaller spatial dispersal rates when compared to emerging strains. We demonstrated the prospects of combining inferences derived from two unique analytical methods to inform decisions related to risk-based interventions of an important pathogen affecting one of the largest food animal industries in the world.
在过去的 25 年里，美国的养猪业因猪繁殖与呼吸综合征（PRRS）造成的深远经济损失而受到严重影响。在这里，我们使用从中西部地区养猪场收集的 ORF5 序列，探讨了 1998-2016 年间美国 PRRS 暴发的空间风险与其系统发育历史之间的关系。我们使用最大熵和贝叶斯系统发育模型生成了 PRRS 暴发的风险图，并重建了三个选定的系统发育分支（A、B 和 C）的进化历史。高风险地区是通过猪密度和气候季节性最佳预测的，包括明尼苏达州、爱荷华州和南达科他州。系统发育模型表明，三个分支的地理传播遵循一种不均匀的空间扩散过程。此外，PRRS 病毒的种群大小具有典型的季节性。然而，与新兴毒株相比，地方性毒株的种群增长和进化速度以及空间扩散率要慢得多。我们展示了将两种独特分析方法的推论相结合，以告知与影响世界上最大的食品动物产业之一的重要病原体的基于风险的干预相关的决策的前景。
