Glyceraldehyde-3-Phosphate Dehydrogenase Restricted in Cytoplasmic Location by Viral GP5 Facilitates Porcine Reproductive and Respiratory Syndrome Virus Replication via Its Glycolytic Activity

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most important endemic swine pathogens, causing enormous losses in the global swine industry. Commercially available vaccines only partially prevent or counteract the virus infection and correlated losses. PRRSV's replication mechanism has not been well understood. In this study, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was screened to bind with the viral major envelope glycoprotein 5 (GP5) after PRRSV infection. The interacting sites are located within a 13-amino-acid (aa) region (aa 93 to 105) of GP5 and at Lys227 of GAPDH. Interestingly, viral GP5 restricts the translocation of GAPDH from the cytoplasm to the nucleus. Moreover, cytoplasmic GAPDH facilitates PRRSV replication by virtue of its glycolytic activity. The results suggest that PRRSV GP5 restricts GAPDH to the nucleus and exploits its glycolytic activity to stimulate virus replication. The data provide insight into the role of GAPDH in PRRSV replication and reveal a potential target for controlling viral infection. IMPORTANCE PRRSV poses a severe economic threat to the pig industry. PRRSV GP5, the major viral envelope protein, plays an important role in viral infection, pathogenicity, and immunity. However, interactions between GP5 and host proteins have not yet been well studied. Here, we show that GAPDH interacts with GP5 through binding a 13-aa sequence (aa 93 to 105) in GP5, while GP5 interacts with GAPDH at the K277 amino acid residue of GAPDH. We demonstrate that GP5 interacts with GAPDH in the cytoplasm during PPRSV infection, inhibiting GAPDH entry into the nucleus. PRRSV exploits the glycolytic activity of GAPDH to promote viral replication. These results enrich our understanding of PRRSV infection and pathogenesis and open a new avenue for antiviral prevention and PRRSV treatment strategies.