African swine fever virus MGF360-9L promotes viral replication by degrading the host protein HAX1

Abstract

African swine fever virus (ASFV) infection causes African swine fever (ASF), a virulent infectious disease that threatens the safety of livestock worldwide. Studies have shown that MGF360–9 L is important for the virulence of ASFV and the host protein HS1-associated protein X-1 (HAX1) plays an important role in viral pathogenesis. This study aimed to clarify the mechanism by which HAX1 mediates ASFV replication through interactions with MGF360–9 L. The regions of interaction between MGF360–9 L and HAX1 were predicted and validated. HAX1 overexpression and RNA interference studies revealed that HAX1 is a host restriction factor that suppresses ASFV replication. Moreover, HAX1 expression was inhibited in ASFV-infected mature bone marrow–derived macrophages, and infection with the virulent MGF360–9 L gene deletion strain (∆MGF360–9 L) attenuated the inhibitory effect of the wild-type strain (WT) on HAX1 expression, suggesting a complex regulatory relationship between MGF360–9 L and HAX1. Furthermore, the E3 ubiquitin ligase RNF114 interacted with MGF360–9 L and HAX1, MGF360–9 L degraded HAX1 through the ubiquitin–proteasome pathway, and RNF114 facilitated the degradation of HAX1 by MGF360–9L-linked K48 ubiquitin chains through the ubiquitin–proteasome pathway, thereby facilitating ASFV replication. In conclusion, this study has enriched our understanding of the regulatory networks between ASFV proteins and host proteins and provided a reference for investigation into the pathogenesis and immune escape mechanism of ASFV.