A Molecular and Epidemiological Description of a Severe Porcine Reproductive and Respiratory Syndrome Outbreak in a Commercial Swine Production System in Russia.

Karyn A Havas,Sergei Shapovalov,Dennis N Makau,Kim Vanderwaal,Ekaterina Tolkova,Scott A Dee,Tymofii Tkachyk,Brad Heron,Gordon D Spronk,Andres Perez

doi:10.3390/v14020375

Abstract

Porcine reproductive and respiratory syndrome (PRRS) is an economically devastating disease of swine in many parts of the world. Porcine reproductive and respiratory syndrome virus (PRRSV) type 1 is endemic in Europe, and prevalence of the subtypes differ spatially. In this study, we investigated a severe PRRS outbreak reported in 30 farms located in eastern Russia that belong to a large swine production company in the region that was also experiencing a pseudorabies outbreak in the system. Data included 28 ORF5 sequences from samples across 18 of the 25 infected sites, reverse transcriptase real-time polymerase chain reaction (RT-qPCR) results from diagnostic testing, reports of clinical signs, and animal movement records. We observed that the outbreak was due to two distinct variants of wildtype PRRSV type 1 subtype 1 with an average genetic distance of 15%. Results suggest that the wildtype PRRSV variants were introduced into the region around 2019, before affecting this production system (i.e., sow farms, nurseries, and finisher farms). Clinical signs did not differ between the variants, but they did differ by stage of pig production. Biosecurity lapses, including movement of animals from infected farms contributed to disease spread.

Highlights

25 separate Porcine reproductive and respiratory syndrome virus (PRRSV) diagnosis were made across 20 sites with complete information regarding clinical presentation based on positive RT-qPCR results
Two sites had two wildtype PRRSV variants detected, and two sites had a wildtype and vaccine variant detected during the same period
The 28 PRRSV sequences obtained from the PRRSV RT-qPCR positive samples collected from sites involved in the outbreak were clustered into three distinct viral variants defined by clades (Figure 1)

Summary

Introduction

Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, Genomics and Molecular Biology Laboratory, Research and Testing Center, Cherkizovo LLC, Pork Division, Cherkizovo Group Limited Liability Corporation, 399870 Lipetsk, Russia; Abstract: Porcine reproductive and respiratory syndrome (PRRS) is an economically devastating disease of swine in many parts of the world. Porcine reproductive and respiratory syndrome virus (PRRSV) type 1 is endemic in Europe, and prevalence of the subtypes differ spatially. In this study, we investigated a severe PRRS outbreak reported in 30 farms located in eastern Russia that belong to a large swine production company in the region that was also experiencing a pseudorabies outbreak in the system. Data included 28 ORF5 sequences from samples across 18 of the 25 infected sites, reverse transcriptase real-time polymerase chain reaction (RT-qPCR) results from diagnostic testing, reports of clinical signs, and animal movement records. We observed that the outbreak was due to two distinct variants of wildtype PRRSV type 1 subtype 1 with an average genetic distance of

Methods

Results

Discussion

Conclusion