Host serine protease ACOT2 assists DENV proliferation by hydrolyzing viral polyproteins.

Dengue fever is a mosquito-borne tropical disease caused by the dengue virus (DENV). The replication of DENV relies on the processing of its genome-encoded polyprotein by both viral protease NS3 (NS3) and host proteases. However, the impact of host proteases on DENV proliferation is not well understood. In this study, we utilized fluorophosphonate-based probes (FPs) to investigate the up-regulation of host serine proteases during DENV infection in detail. Among the identified proteases, acyl-CoA thioesterase 2 (ACOT2), an enzyme that hydrolyzes acyl-CoA molecules to generate fatty acids and free CoA, exhibited cleavage activity against DENV polypeptide substrates. Enzymatic assays and virological experiments confirmed that ACOT2 contributes to DENV propagation during the replication stage by cleaving the viral polyprotein. Docking models provided insights into the binding pocket of viral polypeptides and the catalytic mechanism of ACOT2. Notably, this study is the first to demonstrate that ACOT2 functions as a serine protease to hydrolyze protein substrates. These findings offer novel insights into DENV infection, host response, as well as the potential development of innovative antiviral strategies.IMPORTANCEDENV, one of the major pathogens of Dengue fever, remains a significant public health concern in tropical and subtropical regions worldwide. How DENV efficiently hijacks the host and accesses its life cycle with delicate interaction remains to be elucidated. Here, we deconvoluted that the host protease ACOT2 assists the DENV replication and characterized the ACOT2 as a serine protease involved in the hydrolysis of the DENV polypeptide substrate. Our results not only further the understanding of the DENV life cycle but also provide a possibility for the usage of activity-based proteomics to reveal host-virus interactions.