TYPE Brief Research Report PUBLISHED 11 October 2022 DOI 10.3389/fvets.2022.986850 OPEN ACCESS EDITED BY Igor Paploski, University of Minnesota Twin Cities, United States REVIEWED BY Michael Zeller, Iowa State University, United States Juan Manuel Sanhueza, Catholic University of Temuco, Chile Ruwini Rupasinghe, University of California, Davis, United States *CORRESPONDENCE Krisztián Bányai bkrota@hotmail.com SPECIALTY SECTION This article was submitted to Veterinary Epidemiology and Economics, a section of the journal Frontiers in Veterinary Science RECEIVED 05 July 2022 ACCEPTED 23 September 2022 PUBLISHED 11 October 2022 CITATION Jakab S, Kaszab E, Marton S, Bányai K, Bálint Á, Nemes I and Szabó I (2022) Genetic diversity of imported PRRSV-2 strains, 2005–2020, Hungary. Front. Vet. Sci. 9:986850. doi: 10.3389/fvets.2022.986850 COPYRIGHT © 2022 Jakab, Kaszab, Marton, Bányai, Bálint, Nemes and Szabó. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Genetic diversity of imported PRRSV-2 strains, 2005–2020, Hungary Szilvia Jakab 1,2 , Eszter Kaszab 1,2 , Szilvia Marton 1,2 , Krisztián Bányai 1,2,3 *, Ádám Bálint 4 , Imre Nemes 5 and István Szabó 6 1 Veterinary Medical Research Institute, Budapest, Hungary, 2 National Laboratory for Infectious Animal Diseases, Antimicrobial Resistance, Veterinary Public Health and Food Chain Safety, Budapest, Hungary, 3 Department of Pharmacology and Toxicology, University of Veterinary Medicine, Budapest, Hungary, 4 Veterinary Diagnostic Directorate, National Food Chain Safety Office, Budapest, Hungary, 5 Hungarian Association for Porcine Health Management, Budapest, Hungary, 6 National PRRS Eradication Committee, Budapest, Hungary Porcine reproductive and respiratory syndrome virus 2 (PRRSV-2) remains sporadic in Europe. In this study, we investigated the molecular epidemiology of PRRSV-2 infections encompassing 15 years in Hungary. Partial (423 bp long) ORF5 sequences (n = 44) from 20 Hungarian pig herds were analyzed. The study strains fell into two genetic lineages, L1 and L5, being L5 strains more prevalent (88.6 vs. 11.4%). Pairwise sequence identities within Hungarian representative PRRSV-2 strains ranged between 84.7 to 100% (nucleotide, nt) and 85 to 100% (amino acid, aa). When compared with reference strains, identity values fell between 87 and 100% (L1, nt 87–91%, aa 87–93%, reference strain IAF-exp91; L5, nt 87–100%, aa 88–100%, reference strain Ingelvac MLV). Epidemiologic examination implied that the majority of L5 strains were imported repeatedly from other European countries where Ingelvac MLV was approved for routine use. The emergence of L1 strains was thought to be associated with a single introduction and subsequent dissemination between pig farms of a large integrator. Results presented here contribute to a better understanding of the epizootiology of PRRSV-2 infections and shed light on the genetic diversity of viral strains in non-endemic countries. KEYWORDS Betaarterivirus suid 2, molecular epidemiology, phylogenetic analysis, ORF5, vaccine virus Introduction Porcine reproductive and respiratory syndrome (PRRS) has become a major cause of economic losses for the global swine industry since its first description in Europe and North America (1, 2). PRRS virus (PRRSV), the causative agent, is divided into two species within the Arteriviridae family, Betaarterivirus suid 1 and Betaarterivirus suid 2 (PRRSV-1 and -2, respectively) (3). PRRSVs are enveloped, positive-sense, single- stranded RNA viruses with approximately 15 kb long genome which encodes at least 10 open reading frames (4). Reproductive failure and respiratory problems in affected sows and piglets are commonly seen irrespectively of the virus species (5), and comparable virulence has been observed in the reproductive disorder among sows (6). However, the respiratory disease is typically more severe in infections caused by PRRSV-2 (7–9). Frontiers in Veterinary Science 01 frontiersin.org