Non-structural protein 2 of the porcine reproductive and respiratory syndrome (PRRS) virus: A crucial protein in viral pathogenesis, immunity and diagnosis

Porcine reproductive and respiratory syndrome (PRRS) is a swine disease of significant economic importance that causes reproductive and respiratory problems in pigs. The replicase non-structural protein 2 (Nsp2) of the porcine reproductive and respiratory syndrome virus (PRRSV) is recognized as the most variable region within the PRRSV genome. This review discusses the molecular characteristics and biological and immunological functions of the PRRSV Nsp2 and its involvement in the virus’s pathogenesis. The role of Nsp2 in cell and tissue tropism, replication and growth, and variation and pathogenicity of PRRSV and the differences in virulence among different strains are described in the present review. Nsp2 is an ideal marker for monitoring genetic variation and for developing differential diagnostic tests.