Whole-genome sequencing of 7 PRRSV-2 isolates revealed discordant phylogenetic placements compared to ORF5 sequencing in 4 isolates, driven by multiple recombination events.
Whole-genome surveillance is essential to accurately track PRRSV-2 viral diversity and detect recombinant strains, as traditional ORF5-based lineage classification overlooks key evolutionary events.
Porcine reproductive and respiratory syndrome virus remains one of the most economically significant pathogens in swine production, with PRRSV-2 being the dominant variant in the United States. While lineage classification has traditionally relied on ORF5 sequencing, recent studies suggest that this single-gene approach may overlook key evolutionary events such as recombination. In this study, we performed whole-genome sequencing and phylogenetic analysis of seven PRRSV-2 isolates collected in the U.S. between 2006 and 2024. Using reference-guided assembly, lineage assignment, and recombination detection with RDP5 and SIMplot, we identified discordant phylogenetic placements between ORF5 and whole genomes in four of the seven isolates. These discordances were explained by multiple recombination events affecting different genomic regions, particularly ORF2-ORF7. In contrast, three isolates showed phylogenetic concordance and no strong evidence of recombination. Our findings demonstrate that recombination plays a significant role in shaping PRRSV-2 evolution and highlight the limitations of ORF5-based lineage classification. Whole-genome surveillance is therefore essential to accurately track viral diversity, detect recombinant strains, and inform control strategies. This work underscores the need for a broader adoption of full-genome analysis in routine PRRSV surveillance and research.
Ferreira et al. (Tue,) conducted a other in Porcine reproductive and respiratory syndrome virus (PRRSV-2) (n=7). Whole-genome sequencing vs. ORF5 sequencing was evaluated on Discordant phylogenetic placements between ORF5 and whole genomes. Whole-genome sequencing of 7 PRRSV-2 isolates revealed discordant phylogenetic placements compared to ORF5 sequencing in 4 isolates, driven by multiple recombination events.