Porcine reproductive and respiratory syndrome virus (PRRSV) causes reproductive failure in sows and respiratory disease in growing pigs, leading to significant economic losses worldwide. Due to the constant mutation and recombination, PRRSV exhibits significant genetic diversity, the general detection of all PRRSV-2 and PRRSV-1 strains is thus needed. In our study, four monoclonal antibodies (mAbs) against PRRSV nucleocapsid (N) protein were generated and the precise and novel B cell epitopes (