Genomic analysis and pathogenic characterization of novel PRRSV-1 strain HBEU-328 in North China

Porcine reproductive and respiratory syndrome virus 1 (PRRSV-1) is an emerging threat to the Chinese swine industry, with limited pathogenic data available on the BJEU06-1-like subgroup in North China. In this study, we isolated PRRSV-1 strain HBEU-328 from an unvaccinated pig farm in Hebei Province, 2022. Whole-genome sequencing showed that its genome is 15,068 nucleotides long and that it belongs to the BJEU06-1-like subgroup, clustering with Henan isolates, indicating its cross-regional transmission. HBEU-328 has characteristic deletions in Nsp2 (4 + 1 amino acids), GP3 (unique 4 + 1 amino acids) and GP4 (six amino acids), and its GP5 protein has three N-glycosylation sites (N37, N46, N53; conserved N46 and N53) and epitope mutations. Animal experiments revealed that HBEU-328 causes persistent fever, reduced weight gain, and interstitial pneumonia in piglets, with the serum viral load peaking at 4.121 ± 0.237 log10 RNA copies/mL at 7 dpi, but no mortality, identifying it as a moderately pathogenic strain. Our findings supplement the molecular and pathogenic data on PRRSV-1 in North China and provide a basis for PRRSV-1 monitoring and control.