Development of PRRSV-1 specific monoclonal antibody and detection of PRRSV-1 infection

Porcine reproductive and respiratory syndrome virus (PRRSV) are responsible for reproductive failure in sows and respiratory diseases in pigs, inflicting significant economic losses worldwide. Due to continuous mutation and recombination, PRRSV exhibit remarkable genetic diversity, necessitating detection methods capable of recognizing PRRSV-2 and/or PRRSV-1 strains. In this study, four monoclonal antibodies (mAbs) targeting the PRRSV-1 nucleocapsid (N) protein were generated, and the precise and novel linear B-cell epitopes were identified as ⁵⁴PHFPL⁵⁸, ⁵³KPHFP⁵⁷, and ⁵⁹AAEDDIRHH⁶⁷, respectively. The epitopes ⁵⁴PHFPL⁵⁸ and ⁵³KPHFP⁵⁷ are highly conserved across all major PRRSV-2 lineages and PRRSV-1 subtypes, whereas the epitope ⁵⁹AAEDDIRHH⁶⁷ is relatively conserved only in PRRSV-1. Correspondingly, the PRRSV-1 specific mAb 6B4 showed reaction only with PRRSV-1 strains, but not with PRRSV-2 strains. The 6B4 peptide-based ELISA was developed for the detection of PRRSV-1 antibody, which showed an agreement rate of 83.6% with commercial PRRSV Ab ELISA kit in testing 55 clinical samples, indicating the potential of this peptide-based ELISA for preliminary application.