Detection of Multiple Lineages of PRRSV in Breeding and Growing Swine Farms

Abstract

The detection and co-circulation of multiple variants of porcine reproductive and respiratory syndrome virus (PRRSV) have been observed and reported in swine. However, the potential long-term impact of multiple prevailing PRRSV variants on pig-performance is not yet fully understood. The primary objective of this study was to describe the genetic variation of PRRSV in processing fluid (PF), oral fluid (OF), and tonsil scraping (TS) specimens from five swine farms with different production types and PRRS status over a period of time (~1 year). Furthermore, the association between PRRSV prevalence and production parameters was investigated. Results showed that PRRSV was detected by RT-qPCR in 21–25% of all types of specimens. In breeding farms, PRRSV detection in PF and/or TS samples was correlated with stillborn and mummified fetuses, and pre-weaning mortality throughout the study period. Although ORF5 sequences were obtained in <16% of all sample types, simultaneous detection of PRRSV variants including field and vaccine strains within a single sampling event was identified in both breeding and growing pig farms. Phylogenetic analyses based on the ORF5 sequence classified the detected field PRRSV into L1A and L1H, two sub-lineages of lineage 1 (L1). Our study demonstrated the presence of multiple PRRSV lineages, sub-lineages, and variants in swine herds and its potential association with swine reproductive performance under field conditions.

Epidemiology and Genetic Characteristics of Porcine Reproductive and Respiratory Syndrome Virus in the Hunan and Hebei Provinces of China

“…These results suggested that the PRRSV lineages prevalent in different regions were diverse. Similar to previous investigations [ 17 , 26 ], multiple PRRSV lineages prevalent in one pig farm were also observed, which might contribute to the occurrence of recombination events in the PRRSV genome. In addition, some of the newly identified HP-PRRSV strains in the present study were genetically close to JXA1 and JXA1-P120 strains, which strongly suggests that biosecurity improvement rather than the application of attenuated vaccines should be the priority for PRRS control [ 3 ].…”

“…More recently, the emergence of NADC34-like strains has attracted widespread attention in China [ 15 , 16 ]. Furthermore, the co-circulation of multiple lineages of PRRSV in one pig farm has been observed [ 17 ].…”

A descriptive study on spatial and temporal distributions of genetic clusters of porcine reproductive and respiratory syndrome virus infecting pig sites in Quebec, Canada, between 2010 and 2019

“…Unlike other studies which focused on a single or on few clusters [ 13 ] or subgroups or lineages [ 14 , 22 , 34 ] or limited to a few farms [ 8 ] our study covered all wild-type clusters found over a 10 year-period at the provincial level. Furthermore, each cluster was described based on its detection in at least one of pig site within a year instead of the number of detections, in order to prevent the influence of repeated sampling of the same strain within a herd during the same year.…”

Prevalence and genetic evolution of porcine reproductive and respiratory syndrome virus in commercial fattening pig farms in China

“…Long-term monitoring of PRRSV will be helpful for more comprehensively elucidating the infection situation at commercial fattening pig farms, providing insights of great significance for the prevention and control of PRRSV. The coexistence of multiple PRRSV subtypes has always been a problem faced by the global pig industry [ 29 – 31 ]. Previous studies have demonstrated that PRRSV-2 has long been considered the predominant species in China, cocirculating with PRRSV-1 [ 11 ].…”