RAP1 is essential for PRRSV replication and the synthesis of the viral genome.

Since its emergence, porcine reproductive and respiratory syndrome (PRRS) has caused enormous economic losses to the global swine industry. The pathogenesis of PRRS remains under investigation. The porcine reproductive and respiratory syndrome virus (PRRSV) causes reproductive disorders in pigs and respiratory in piglets, which is a 15 kb RNA virus that encodes 16 viral proteins, most of which exhibit multiple functions during the virus lifecycle. RAP1 (Ras-proximate-1), a small GTPase, is known to regulates cell adhesion across different cell types and is one of the most conserved telomere proteins. Thus, this study explored the effect of RAP1 after PRRSV infection. In this study, RAP1 did not participate in the adsorption and internalization process of PRRSV, however, it promoted viral RNA synthesis and enhanced PRRSV replication. Additionally, we discovered that RAP1 interacted with Nsp10 and the N protein. Specifically, the Myb domain of RAP1 primarily bound to the viral genome interacted with the N-terminal structural domain of the N protein, which contains an RNA-binding domain. Additionally, the C-terminal region of RAP1 interacted with the N-terminal domain of Nsp10. These results suggested that RAP1 is a critical factor in the PRRSV infection process, particularly in the context of viral RNA synthesis. RAP1 could be a potential target for the prevention and control of PRRSV.