D1133L protein of African swine fever virus promotes virus replication in pig macrophages by increasing vimentin phosphorylation in the host

Abstract:

African swine fever (ASF) caused by African swine fever virus (ASFV) is a severe infectious disease affecting both domestic pigs and wild boar. ASFV has a large genome, and the non-structural protein pD1133L is predicted to be one of the six helicases the genome encodes. We used the IP-MASS technology to screen the host proteins interacting with pD1133L and found that vimentin (VIM) is one of the host proteins that interacted with pD1133L. However, it remains unclear how the VIM affects ASFV replication. 【Objective】 To investigate the mutual regulation between ASFV and VIM and disclose the mechanism by which VIM enhances ASFV replication. 【Methods】 We employed the Co-IP assay to examine the interaction between pD1133L and VIM. Furthermore, we examined the effects of VIM on ASFV replication by designing and synthetizing VIM siRNAs and overexpressing VIM. Western blotting and quantitative real-time PCR (qPCR) were employed to determine the impact of ASFV on the protein and mRNA levels of VIM. Western blotting and indirect immunofluorescence assay (IFA) were used to explore the changes in the phosphorylation level and subcellular localization of VIM in macrophages infected with ASFV. The CCK-8 kit was used to determine the optimal concentration of KN-93, a VIM phosphorylation inhibitor, for treatment. The effects of KN-93 on the phosphorylation and subcellular localization of VIM and the replication of ASFV were examined by Western blotting and IFA. 【Results】 The overexpression of VIM promoted the replication of ASFV, while the knockdown of VIM inhibited ASFV replication. In addition, ASFV infection down-regulated both the protein and mRNA levels of VIM in a time-dependent manner. After ASFV infection, VIM was modified by phosphorylation and changed in subcellular localization, thereby promoting ASFV replication. 【Conclusion】 This study confirms the interaction between ASFV and the host protein VIM. After ASFV infection, pD1133L leads to the rearrangement of the subcellular localization of VIM towards paranuclear aggregation, which promotes ASFV replication.