MYH9 Aggregation Induced by Direct Interaction With PRRSV GP5 Ectodomain Facilitates Viral Internalization by Permissive Cells

Abstract

Prevention and control of infection by porcine reproductive and respiratory syndrome virus (PRRSV) remains a challenge, due to our limited understanding of the PRRSV invasion mechanism. Our previous study has shown that PRRSV glycoprotein GP5 interacts with MYH9 C-terminal domain protein (PRA). Here we defined that the first ectodomain of GP5 (GP5-ecto-1) directly interacted with PRA and this interaction triggered PRA and endogenous MYH9 to form filament assembly. More importantly, MYH9 filament assembly was also formed in GP5-ecto-1-transfected MARC-145 cells. Notably, PRRSV infection of MARC-145 cells and porcine alveolar macrophages also induced endogenous MYH9 aggregation and polymerization that were required for subsequent PRRSV internalization. Moreover, overexpression of S100A4, a MYH9-specific disassembly inducer, in MARC-145 cells significantly resulted in diminished MYH9 aggregation and marked inhibition of subsequent virion internalization and infection by both <i>PRRSV-1</i> and <i>PRRSV-2</i> isolates. The collective results of this work reveal a novel molecular mechanism employed by MYH9 that helps PRRSV gain entry into permissive cells.