Vasudevan, S. G. | bioRxiv Science

bioRxiv2025

Host mRNA 3'-end processing machinery are critical binding partners during dengue virus infection

Dengue virus (DENV) causes a wide variety of dengue diseases that threaten over half of the worlds population. At present, there is no antiviral therapeutics against dengue. Virus infection and its associated pathologies are the result of a myriad of interactions between the virus and its host, of which most are protein-protein interactions (PPIs). Virus-encoded proteins modulate the host environment for the virus benefit by interacting with host proteins during infection. Thus studies of these virus-host PPIs are most informative when performed in the context of an infection. We undertook a comparative affinity purification-mass spectrometry approach to generate a DENV-host protein-protein interactome during DENV infection and identified mRNA 3-end processing protein complexes as novel interactors of DENV NS3. We demonstrated that the presence of the cleavage and polyadenylation specificity factor complex proteins, but not their enzymatic activity, is crucial for DENV replication, thus unveiling a potential new direction for the development of host-directed antiviral therapeutics.

microbiology↗

bioRxiv2022

Secreted dengue virus NS1 is predominantly dimeric and in complex with high-density lipoprotein

Severe dengue infections are characterized by endothelial dysfunction shown to be associated with the secreted nonstructural protein 1 (sNS1), making it an attractive vaccine antigen and biotherapeutic target. To uncover the biologically relevant structure of sNS1, we obtained infection-derived sNS1 (isNS1) from DENV-infected Vero cells through immunoffinity purification instead of recombinant sNS1 (rsNS1) overexpressed in insect or mammalian cell lines. We found that isNS1 appeared as an approximately 250 kDa complex of NS1 and ApoA1 and further determined the cryoEM structures of isNS1 and its complex with a monoclonal antibody/Fab. Indeed, we found that the major species of isNS1 is a complex of the NS1 dimer partially embedded in a High-Density Lipoprotein (HDL) particle. Cross-linking mass spectrometry (XL-MS) studies confirmed that the isNS1 interacts with the major HDL component ApoA1 through interactions that map to the NS1 wing and hydrophobic domains. Furthermore, our studies demonstrated that the sNS1 in sera from DENV-infected mice and a human patient form a similar complex as isNS1. Our results report the molecular architecture of a biological form of sNS1 which may have implications for the molecular pathogenesis of dengue. SummaryCryoEM structures of secreted dengue virus NS1 protein reveal dimers in complex with high-density lipoprotein.

microbiology↗