HSP27 Interacts with Nonstructural Proteins of Porcine Reproductive and Respiratory Syndrome Virus and Promotes Viral Replication

Heat shock protein 27 (HSP27) is a multifunctional protein and belongs to the small HSP family. It has been shown that HSP27 is involved in viral replication as a cellular chaperone, but the function of HSP27 during porcine reproductive and respiratory syndrome virus (PRRSV) infections remains unexplored. Here, we found that PRRSV replication can induce HSP27 expression and phosphorylation in vitro. HSP27 overexpression promoted PRRSV replication, whereas its knockdown reduced PRRSV proliferation. Additionally, suppressing HSP27 phosphorylation reduced PRRSV replication and the level of viral double-stranded RNA (dsRNA), a marker of the viral replication and transcription complexes (RTCs). Furthermore, HSP27 can interact with multiple viral nonstructural proteins (nsps), including nsp1α, nsp1β, nsp5, nsp9, nsp11 and nsp12. Suppressing the phosphorylation of HSP27 almost completely disrupted its interaction with nsp1β and nsp12. Altogether, our study revealed that HSP27 plays an important role in PRRSV replication.