Proteomic analysis of the nonstructural protein 2-host protein interactome reveals a novel regulatory role of SH3 domain-containing kinase-binding protein 1 in porcine reproductive and respiratory syndrome virus replication and apoptosis.

Virus-host protein interaction is critical for successful completion of viral replication cycles. As the largest nonstructural protein (NSP) of porcine reproductive and respiratory syndrome virus (PRRSV), NSP2 plays multiple and critical roles in viral replication, antiviral immunity, cellular tropism and virulence. An interactome of this protein with host proteins would be instrumental in full understanding of these multifunctional roles. In this study, we report the identification of 120 NSP2-interacting host proteins by co-immunoprecipitation coupled liquid chromatography mass spectrometry, via rescuing and utilizing a recombinant PRRSV expressing an HA-tagged NSP2. By comparing and subtracting with cells infected with parental virus, a comprehensive interactome was constructed. Bioinformatics analysis revealed that these host factors are mainly involved in translation regulation, metabolism, signal transduction and innate immunity signaling pathways. Selection of five host proteins (CtBP1, CtBP2, HSPA2, PPP1CA, SH3KBP1) for further verification and characterization confirmed their interactions with NSP2 and differential effects on PRRSV replication. Intriguingly, interaction of NSP2 and SH3KBP1 led to specific cleavage of SH3KBP1, antagonizing its pro-apoptotic activity. Taken together, this study provides overarching views on the NSP2-host interactome, paving a solid foundation for functional studies of host proteins in PRRSV biology and their potential as targets for novel therapeutics development.