Emergence of a New Lineage 1C Variant of PRRSV-2 in the United States

 

2021 Oct 18;8:752938. doi: 10.3389/fvets.2021.752938. eCollection 2021.

Emergence of a New Lineage 1C Variant of Porcine Reproductive and Respiratory Syndrome Virus 2 in the United States

Mariana Kikuti  ¹ , Igor A D Paploski  ¹ , Nakarin Pamornchainavakul  ¹ , Catalina Picasso-Risso  ¹ , Mark Schwartz  ^{1   2} , Paul Yeske  ³ , Brad Leuwerke  ³ , Laura Bruner  ³ , Deborah Murray  ⁴ , Brian D Roggow  ⁵ , Pete Thomas  ⁶ , Lori Feldmann  ⁷ , Matt Allerson  ⁸ , Melissa Hensch  ⁹ , Tyler Bauman  ⁹ , Brent Sexton  ⁹ , Albert Rovira  ¹ , Kimberly VanderWaal  ¹ , Cesar A Corzo  ¹

Abstract

We report an ongoing regional outbreak of an emerging porcine reproductive and respiratory syndrome virus (PRRSV2) variant within Lineage 1C affecting 154 breeding and grow-finishing sites in the Midwestern U.S. Transmission seemed to have occurred in two waves, with the first peak of weekly cases occurring between October and December 2020 and the second starting in April 2021. Most of cases occurred within a 120 km radius. Both orf5 and whole genome sequencing results suggest that this represents the emergence of a new variant within Lineage 1C distinct from what has been previously circulating. A case-control study was conducted with 50 cases (sites affected with the newly emerged variant) and 58 controls (sites affected with other PRRSV variants) between October and December 2020. Sites that had a market vehicle that was not exclusive to the production system had 0.04 times the odds of being a case than a control. A spatial cluster (81.42 km radius) with 1.68 times higher the number of cases than controls was found. The average finishing mortality within the first 4 weeks after detection was higher amongst cases (4.50%) than controls (0.01%). The transmission of a highly similar virus between different farms carrying on trough spring rises concerns for the next high transmission season of PRRS.

Keywords: disease outbreak; epidemics; epidemiology; porcine reproductive and respiratory disease virus; swine diseases.

Copyright © 2021 Kikuti, Paploski, Pamornchainavakul, Picasso-Risso, Schwartz, Yeske, Leuwerke, Bruner, Murray, Roggow, Thomas, Feldmann, Allerson, Hensch, Bauman, Sexton, Rovira, VanderWaal and Corzo.