Genetic and Pathogenic Characteristic of High Pathogenic Korean NADC34-Like Porcine Reproductive and Respiratory Syndrome Virus

A novel NADC34-like strain of porcine reproductive and respiratory syndrome virus (PRRSV), named SNUVP231106, was isolated from a farm where pigs experienced respiratory symptoms and abortions. In this study, a SNUVP231106 strain was fully sequenced and evaluated for its pathogenicity. The genomic sequence of SNUVP231106 was NADC34-like PRRSV which was classified as sublineage 1.5 with 100 amino acid (aa) continuous deletions in nsp2. The Korean NADC34-like PRRSV strain SNUVP231106 is a restriction fragment polymorphism pattern of 1-6-4 according to the genetic analysis of the open reading frame (ORF) 5 gene. Recombination analysis revealed that the Korean NADC34-like PRRSV strain SNUVP231106 is a recombinant strain, with IA/2014/NADC34 as the major parent and both RespPRRS-MLV and NADC30 as minor parents. Animal studies demonstrated that infection with the NADC34-like PRRSV strain SNUVP231106 resulted in 100% morbidity and 37.5% mortality, accompanied by high viremia, elevated fever, and significant weight loss. Pathological findings included interstitial pneumonia, thymus atrophy, and perivascular cuffing in the brain. These experimental results confirm that the NADC34-like PRRSV strain SNUVP231106 exhibits high pathogenicity in piglets.