Genetic surveillance of PEDV shows limited spread between U.S. regionsGenetic surveillance of PEDV shows limited spread between U.S. regions

Continued sequence monitoring is vital for the swine industry to advance toward disease eradication.

University of Minnesota

January 14, 2025

2 Min Read
Silos near a field and road
National Pork Board

By Joao Paulo Herrera da Silva, Nakarin Pamornchainavakul, Mariana Kikuti, Xiaomei Yue, Cesar A. Corzo and Kimberly VanderWaal, University of Minnesota

Porcine epidemic diarrhea virus causes acute enteric disease in pigs, with severe symptoms in piglets, leading to economic losses. While all viruses evolve through time, it is unknown how the PEDV has evolved and genetically changed in the past decade.

Following the introduction of the virus in the U.S. in 2013, a high number of cases were reported during the first two years, but declined in the third year as the virus became endemic in the U.S. Since then, there has been a relatively low number of cases per year, except in 2021, when the incidence of PEDV was higher compared to other years of the endemic period. Genetic surveillance was also more intense during the early epidemic period, and decreased afterward. During the endemic period, approximately one sequence was generated for every 10 infected sow farms participating in the Morrison Swine Health Monitoring Project.   

To assess how the virus has evolved during the endemic period, we analyzed 556 spike protein sequences, focusing on the more virulent non-INDEL strain, which is predominant in the U.S. Although PEDV spike protein sequences exhibit high similarity (average genetic similarity = 99.7%), a strong pattern of genetic differentiation was detected across time. Most sequences sampled after 2017 clustered into two small sub-groups. Circulation of these groups is restricted to specific geographic regions, suggesting compartmentalized circulation within those regions with limited spread between sow farms in different regions. This insight helps determine the risk of re-introduction of PEDV if it were regionally eliminated. No descendants derived from other clades present during the epidemic period were detected, suggesting that these clades are no longer circulating in the U.S. 

Related:Researchers discover molecule that could disable PRRSV

A limitation of this analysis is that PEDV sequence data is not routinely generated, and thus we do not have a full picture of PEDV diversity across the U.S.  Our findings are based on available data only.

Continued sequence surveillance is vital for the swine industry to advance toward disease eradication and is key to:

  • Confirming the extinction of older clades.

  • Mapping the distribution of recent clades.

  • Understanding PEDV's evolutionary diversification.

Taken together, this information can guide the strategies adopted by practitioners.

References

Stevenson GW, Hoang H, Schwartz KJ, Burrough ER, Sun D, Madson D, Cooper VL, Pillatzki A, Gauger P, Schmitt BJ. 2013. Emergence of Porcine epidemic diarrhea virus in the United States: clinical signs, lesions, and viral genomic sequences. Journal of veterinary diagnostic investigation 25:649-654.                                                                                                                                                                                                                                                         

Related:Protecting America’s pork industry

Subscribe to Our Newsletters
National Hog Farmer is the source for hog production, management and market news

You May Also Like