Virus Nonstructural Protein Research Articles

Porcine reproductive and respiratory syndrome virus nonstructural protein 2 promotes the autophagic degradation of adaptor protein SH3KBP1 to antagonize host innate immune responses by enhancing K63-linked polyubiquitination of RIG-I.

Non-structural protein 2 (NSP2) of PRRSV is highly variable and plays crucial roles in the virus's life cycle. To elucidate the function of NSP2 during PRRSV infection, we identified SH3KBP1 as an NSP2-interacting host protein using mass spectrometry. Exogenous SH3KBP1 expression significantly inhibited PRRSV replication by enhancing IFN-I and related ISGs production. Conversely, SH3KBP1 knockdown promoted viral replication by downregulating IFN-I and ISGs levels. In vivo experiments revealed that Sh3kbp1-/- mice were more susceptible to VSV infection, exhibiting reduced serum IFN-β levels. Further investigation showed that SH3KBP1 enhances RIG-I signal transduction by increasing K63-linked polyubiquitination through interaction with the E3 ubiquitin ligase TRIM25. We also found that PRRSV infection and NSP2 overexpression induce the autophagic degradation of SH3KBP1, counteracting the host's innate immune response. A critical interaction site was identified within the third proline-rich motif in NSP2 (453PVPAPR458). Recombinant PRRSV lacking this motif displayed reduced virulence and decreased SH3KBP1 degradation. This study advances our understanding of how PRRSV interferes with the host immune response and offers valuable insights for development novel attenuated vaccines against PRRSV.

Non-lytic spread of poliovirus requires the nonstructural protein 3CD.

Non-enveloped viruses like poliovirus (PV) have evolved the capacity to spread by non-lytic mechanisms. For PV, this mechanism exploits the host secretory autophagy pathway. Virions are selectively incorporated into autophagosomes, double-membrane vesicles that travel to the plasma membrane, fuse, and release single-membrane vesicles containing virions. Loading of cellular cargo into autophagosomes relies on direct or indirect interactions with microtubule-associated protein 1B-light chain 3 (LC3) that are mediated by motifs referred to as LC3-interaction regions (LIRs). We have identified a PV mutant with a severe defect in non-lytic spread. An F-to-Y substitution in a putative LIR of the nonstructural protein 3CD prevented virion incorporation into LC3-positive autophagosomes and virion trafficking to the plasma membrane for release. Using high-angle annular dark-field scanning transmission electron microscopy to monitor PV-induced autophagosome biogenesis, for the first time, we show that virus-induced autophagic signals yield normal autophagosomes, even in the absence of virions. The F-to-Y derivative of PV 3CD was unable to support normal autophagosome biogenesis. Together, these studies make a compelling case for a direct role of a viral nonstructural protein in the formation and loading of the vesicular carriers used for non-lytic spread that may depend on the proper structure, accessibility, and/or dynamics of its LIR. The studies of PV 3CD protein reported here will hopefully provoke a more deliberate look at the presence and function of LIR motifs in viral proteins of viruses known to use autophagy as the basis for non-lytic spread.

Broad-Spectrum Antiviral Agents against SARS-CoV-2 Variants Inhibit the Conserved Viral Protein Nsp1-RNA Interaction.

The ongoing global threats posed by COVID-19 pandemic, catalyzed by SARS-CoV-2, underscores the pressing need for effective antiviral strategies. The viral non-structural protein 1 (Nsp1) significantly influences pathogenicity by impeding host protein expression and enhancing viral RNA translation through its interaction with the stem-loop 1 (SL1) in the 5' untranslated region (UTR). We have developed a novel dual-luciferase reporter assay, designed to investigate the critical Nsp1-SL1 interaction, and identified P23E02 as a potential inhibitor. Our investigation, combining molecular docking studies and alanine mutagenesis, has unveiled that P23E02 disrupts Nsp1-40S ribosomal subunit interaction, liberating translational inhibition and empowering host antiviral responses. P23E02 exhibits antiviral efficacy against various sarbecoviruses, making it a promising candidate for combatting COVID-19 and related diseases. This study underscores the therapeutic potential of targeting the Nsp1/SL1 axis and lays the foundation for innovative antiviral interventions, ultimately fortifying global preparedness against future viral threats.

Distinct chikungunya virus polymerase palm subdomains contribute to viral protein accumulation and virion production.

Alphaviruses encode an error-prone RNA-dependent RNA polymerase (RdRp), nsP4, required for genome synthesis, yet how the RdRp functions in the complete alphavirus life cycle is not well-defined. Previous work using chikungunya virus has established the importance of the nsP4 residue cysteine 483 in replication. Given the location of residue C483 in the nsP4 palm domain, we hypothesized that other residues within this domain and surrounding subdomains would also contribute to polymerase function. To test this hypothesis, we designed a panel of nsP4 variants via homology modeling based on the coxsackievirus B3 3D polymerase. We rescued each variant in mammalian and mosquito cells and discovered that the palm domain and ring finger subdomain contribute to host-specific replication. In C6/36 cells, we found that while the nsP4 variants had replicase function similar to that of wild-type CHIKV, many variants presented changes in protein accumulation and virion production even when viral nonstructural and structural proteins were produced. Finally, we found that WT CHIKV and nsP4 variant replication and protein production could be enhanced in mammalian cells at 28°C, yet growing virus under these conditions led to changes in virus infectivity. Taken together, these studies highlight that distinct nsP4 subdomains are required for proper RNA transcription and translation, having major effects on virion production.

Avian deltacoronaviruses encode fusion-associated small transmembrane proteins that can induce syncytia formation

Fusion-associated small transmembrane (FAST) proteins are nonstructural viral proteins that induce cell-cell fusion. FAST proteins, which previously were identified in the genomes of double-stranded RNA viruses, typically contain an acylated N-terminal ectodomain, central transmembrane domain, and C-terminal endodomain with a polybasic region. Using sequence homology and protein motif prediction, we identified accessory proteins in a subset of avian deltacoronaviruses as putative FAST proteins. Transient expression of thrush coronavirus NS7b or common moorhen coronavirus NS7a, but not night heron coronavirus NS7b, induced cell-cell fusion. Syncytia were detected in primate kidney epithelial cells or fibroblasts but not chicken embryo fibroblasts, and addition of an N-terminal FLAG peptide to the proteins ablated fusion activity. These findings suggest that multiple avian deltacoronaviruses, positive-sense RNA viruses, encode nonstructural proteins that can mediate cell-cell fusion and share features with known FAST proteins. Additional studies are needed to understand contributions of these proteins to deltacoronavirus biology.

Cellular NS1-BP protein interacts with the mRNA export receptor NXF1 to mediate nuclear export of influenza virus M mRNAs

Influenza A viruses have eight genomic RNAs that are transcribed in the host cell nucleus. Two of the viral mRNAs undergo alternative splicing. The M1 mRNA encodes the matrix protein 1 (M1) and is also spliced into M2 mRNA, which encodes the proton channel matrix protein 2 (M2). Our previous studies have shown that the cellular NS1-binding protein (NS1-BP) interacts with the viral non-structural protein 1 (NS1) and M1 mRNA to promote M1 to M2 splicing. Another pool of NS1 protein binds the mRNA export receptor NXF1 (nuclear RNA export factor-1), leading to nuclear retention of cellular mRNAs. Here we show a series of biochemical and cell biological findings that suggest a model for nuclear export of M1 and M2 mRNAs despite the mRNA nuclear export inhibition imposed by the viral NS1 protein. NS1-BP competes with NS1 for NXF1 binding, allowing the recruitment of NXF1 to the M mRNAs after splicing. NXF1 then binds GANP (Germinal-center Associated Nuclear Protein), a member of the TRanscription and EXport complex (TREX)-2. Although both NS1 and NS1-BP remain in complex with GANP-NXF1, they dissociate once this complex docks at the nuclear pore complex (NPC), and the M mRNAs are translocated to the cytoplasm. Since this mRNA nuclear export pathway is key for expression of M1 and M2 proteins that function in viral intracellular trafficking and budding, these viral-host interactions are critical for influenza virus replication.

Zika virus NS3 drives the assembly of a viroplasm-like structure.

Zika virus (ZIKV) is a mosquito-transmitted flavivirus that caused an epidemic in 2015-2016 in the Americas and raised serious global health concerns due to its association with congenital brain developmental defects in infected pregnancies. Upon infection, ZIKV assembles virus particles in a virus-generated toroidal compartment next to the nucleus called the replication factory, or viroplasm, which forms by remodeling the host cell endoplasmic reticulum (ER). How the viral proteins control viroplasm assembly remains unknown. Here we show that the ZIKV non-structural protein 3 (NS3) is sufficient to drive the assembly of a viroplasm-like structure (VLS) in human cells. NS3 encodes a dual-function protease and RNA helicase. The VLS is similar to the ZIKV viroplasm in its assembly near centrosomes at the nuclear periphery, its deformation of the nuclear membrane, its recruitment of ER, Golgi, and dsRNA, and its association with microtubules at its surface. While sufficient to generate a VLS, NS3 is less efficient in several aspects compared to viroplasm formation upon ZIKV infection. We further show that the helicase domain and not the protease domain is required for optimal VLS assembly and dsRNA recruitment. Overall, this work advances our understanding of the mechanism of viroplasm assembly by ZIKV and likely will extend to other flaviviruses.

The greasy finger region of DTMUV NS1 plays an essential role in NS1 secretion and viral proliferation

Duck Tembusu virus (DTMUV) of the Orthoflavivirus genus poses a significant threat to waterfowl aquaculture. Nonstructural protein 1 (NS1), a multifunctional glycoprotein, exists in various oligomeric forms and performs diverse functions. The Greasy Finger (GF) region within NS1 of other flaviviruses has been shown to be a crucial component of the hydrophobic protrusion aiding in anchoring NS1 to the endoplasmic reticulum (ER). However, detailed studies on the role of the GF region in viral proliferation in vitro and the biological properties of NS1 remain scarce. A series of recombinant DTMUV (rDTMUV) with mutations in the GF region, including NS1-F158A, G159A, F160A, G161A, V162A, L163A, F160R, multipoint mutations (GF-4M), or regional deletions (ΔGF), were rescued using a DNA-based reverse genetics system. Only five rDTMUV variants (G159A, F160A, G161A, V162A, and L163A) could be rescued successfully, and these mutations were found to impair replication, reduce virulence, and decrease plaque size, as shown by growth kinetics, duck embryo virulence, and plaque assays, respectively. Upon examining NS1 expression by western blot, we discovered that secreted NS1 (sNS1) presented in large quantities in the supernatant of cells infected with rDTMUV-NS1-G159A, whereas intracellular NS1 was less abundant. These mutations also impacted the primary forms and secretion rates of NS1 in cases of overexpression by western blot and indirect ELISA. Exception for F160A and G161A, which showed decreased secretion rates, all other mutations increased sNS1 expression, with the most pronounced increase observed in F158A and ΔGF, and rDTMUV with these mutations can't be rescued. Co-localization studies of NS1 with the ER demonstrated that the ΔGF mutation attenuated NS1 anchoring to the ER, thereby inhibiting its intracellular residence and promoting secretion. Although these effects vary between flaviviruses, our data reveal that the GF region of NS1 is crucial for viral proliferation and NS1 secretion.

High-throughput peptide array analysis and computational techniques for serological profiling of flavivirus infections: Implications for diagnostics and vaccine development.

Arthropod-borne viruses, such as dengue virus (DENV), pose significant global health threats, with DENV alone infecting around 400 million people annually and causing outbreaks beyond endemic regions. This study aimed to enhance serological diagnosis and discover new drugs by identifying immunogenic protein regions of DENV. Utilizing a comprehensive approach, the study focused on peptides capable of distinguishing DENV from other flavivirus infections through serological analyses. Over 200 patients with confirmed arbovirus infection were profiled using high-density pan flavivirus peptide arrays comprising 6253 peptides and the computational method matrix of local coupling energy (MLCE). Twenty-four peptides from nonstructural and structural viral proteins were identified as specifically recognized by individuals with DENV infection. Six peptides were confirmed to distinguish DENV from Zika virus (ZIKV), West Nile virus (WNV), Yellow Fever virus (YFV), Usutu virus (USUV), and Chikungunya virus (CHIKV) infections, as well as healthy controls. Moreover, the combination of two immunogenic peptides emerged as a potential serum biomarker for DENV infection. These peptides, mapping to highly accessible regions on protein structures, show promise for diagnostic and prophylactic strategies against flavivirus infections. The described methodology holds broader applicability in the serodiagnosis of infectious diseases.

Drupacine as a potent SARS-CoV-2 replication inhibitor in vitro

Despite the availability of vaccines and antiviral treatments, the continued emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants and breakthrough infections underscores the need for new, potent antiviral therapies. In a previous study, we established a transcription and replication-competent SARS-CoV-2 virus-like particle (trVLP) system that recapitulates the complete viral life cycle. In this study, we combined high-content screening (HCS) with the SARS-CoV-2 trVLP cell culture system, providing a powerful phenotype-oriented approach to assess the antiviral potential of compounds on a large scale. We screened a library of 3,200 natural compounds and identified drupacine as a potential candidate against SARS-CoV-2 infection. Furthermore, we utilized a SARS-CoV-2 replicon system to demonstrate that drupacine could inhibit viral genome transcription and replication. However, in vitro, enzymatic assays revealed that the inhibition could not be attributed to conventional antiviral targets, such as the viral non-structural proteins nsp5 (MPro) or nsp12 (RdRp). In conclusion, our findings position drupacine as a promising antiviral candidate against SARS-CoV-2, providing a novel scaffold for developing anti-coronavirus disease 2019 (COVID-19) therapeutics. Further investigation is required to pinpoint its precise target and mechanism of action.

Antiviral Activity of Chlorophyll Extracts from Tetraselmis sp., a Marine Microalga, Against Zika Virus Infection.

Recent advancements in the large-scale cultivation of Tetraselmis sp. in Korea have enabled year-round production of this marine microalgae. This study explores the potential industrial applications of Tetraselmis sp. biomass by investigating the antiviral properties of its extracts and primary components. The antiviral effects of Tetraselmis sp. extracts were evaluated in Zika virus (ZIKV)-infected cells. Following extensive isolation and purification, the main compounds were characterized using liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) analyses. Their antiviral activities were confirmed using in vitro and in silico tests. Tetraselmis sp. extracts reduced infectious viral particles and non-structural protein 1 messenger RNA levels in ZIKV-infected cells without inducing cytotoxicity. Additionally, they modulated the interferon-mediated immune system responses. Tetraselmis sp. extracts are composed of four main chlorophylls: chlorophyll a, chlorin e6-131-152-dimethyl-173-phytyl ester, hydroxychlorophyll a, and hydroxypheophytin a. Among them, chlorophyll a, chlorin e6-131-152-dimethyl-173-phytyl ester, and hydroxypheophytin showed the antiviral activities in ZIKV-infected cells and molecular docking simulations predicted interactions between these chlorophylls and ZIKV. Our findings suggest that Tetraselmis sp. chlorophyll extracts exert antiviral effects against ZIKV and could serve as potential therapeutic candidates against ZIKV infection.

Membrane Retention of West Nile Virus NS5 Depends on NS1 or NS3 for Enzymatic Activity.

West Nile virus (WNV) nonstructural protein 5 (NS5) possesses multiple enzymatic domains essential for viral RNA replication. During infection, NS5 predominantly localizes to unique replication organelles (ROs) at the rough endoplasmic reticulum (RER), known as vesicle packets (VPs) and convoluted membranes (CMs), with a portion of NS5 accumulating in the nucleus. NS5 is a soluble protein that must be in the VP, where its enzymatic activities are required for viral RNA synthesis. However, the mechanistic processes behind the recruitment of NS5 from the cytoplasm to the RER membrane remain unclear. Here, we utilize high-resolution confocal microscopy and sucrose density gradient ultracentrifugation to investigate whether the association of NS5 with other NS proteins contributes to its membrane recruitment and retention. We demonstrate that NS1 or NS3 partially influences the NS5 association with the membrane. We further demonstrate that processed NS5 is predominantly in the cytoplasm and nucleus, indicating that the processing of NS5 from the viral polyprotein does not contribute to its membrane localization. These observations suggest that other host or viral factors, such as the enwrapment of NS5 by the RO, may also be necessary for the complete membrane retention of NS5. Therefore, studies on the inhibitors that disrupt the membrane localization of WNV NS5 are warranted for antiviral drug development.

Employing Machine Learning-Based QSAR for Targeting Zika Virus NS3 Protease: Molecular Insights and Inhibitor Discovery.

Zika virus infection is a mosquito-borne viral disease that has become a global health concern recently. Zika virus belongs to the Flavivirus genus and is primarily transmitted by Aedes mosquitoes. Prevention of Zika virus infection involves avoiding mosquito bites by using repellent, wearing protective clothing, and staying in screened areas, especially for pregnant women. Treatment focuses on managing symptoms with rest, fluids, and acetaminophen, with close monitoring for pregnant women. Currently, there is no specific antiviral treatment or vaccine for the Zika virus, highlighting the importance of prevention strategies to control its spread. Therefore, in this study, the Zika virus non-structural protein NS3 was targeted to inhibit Zika infection by identifying the novel inhibitor through an in silico approach. Here, 2864 natural compounds were screened using a machine learning-based QSAR model, and later docking was performed to select the potential target. Subsequently, Tanimoto similarity and clustering were performed to obtain the potential target. The three most potential compounds were obtained: (a) 5297, (b) 432449, and (c) 85137543. The protein-ligand complex's stability and flexibility were then investigated by dynamic modelling. The 300 ns simulation showed that 5297 exhibited the steadiest deviation and constant creation of hydrogen bonds. Compared to the other compounds, 5297 demonstrated a superior binding free energy (ΔG = -20.81 kcal/mol) with the protein when the MM/GBSA technique was used. The study determined that 5297 showed significant therapeutic potential and justifies further experimental investigation as a possible inhibitor of the NS2B-NS3 protease target implicated in Zika virus infection.

Insect ribosome-rescuer Pelo-Hbs1 complex on sperm surface mediates paternal arbovirus transmission

Arboviruses can be paternally transmitted by male insects to offspring for long-term persistence, but the mechanism remains largely unknown. Here, we use a model system of a destructive rice reovirus and its leafhopper vector to find that insect ribosome-rescuer Pelo-Hbs1 complex expressed on the sperm surface mediates paternal arbovirus transmission. This occurs through targeting virus-containing tubules constituted by viral nonstructural protein Pns11 to sperm surface via Pns11-Pelo interaction. Tubule assembly is dependent on Hsp70 activity, while Pelo-Hbs1 complex inhibits tubule assembly via suppressing Hsp70 activity. However, virus-activated ubiquitin ligase E3 mediates Pelo ubiquitinated degradation, synergistically causing Hbs1 degradation. Importantly, Pns11 effectively competes with Pelo for binding to E3, thus antagonizing E3-mediated Pelo-Hbs1 degradation. These processes cause a slight reduction of Pelo-Hbs1 complex in infected testes, promoting effective tubule assembly. Our findings provide insight into how insect sperm-specific Pelo-Hbs1 complex is modulated to promote paternal virus transmission without disrupting sperm function.

Computational Investigations to Identify Potent Natural Flavonoid Inhibitors of the Nonstructural Protein (NSP) 16/10 Complex Against Coronavirus.

Globally, the viral pandemic has spread rapidly, resulting in widespread infections. The coronavirus family (CoVs) is one of the various viral families capable of infecting mammals, causing diseases related to the gastrointestinal, neurological, and respiratory systems. Flavonoid compounds have been identified as potentially effective antiviral agents, specifically targeting the virus's nonstructural protein (NSP) 16/10. Flavonoids have also been shown to inhibit virus replication and viral attachment to host cells, making them a promising candidate for antiviral treatment. Further research is needed to understand the full potential of flavonoids as antiviral agents. This study investigated natural compounds derived from medicinal plants using in silico screening. In addition to assessing drug-likeness, pharmacokinetics, docking, molecular dynamics simulation, bioavailability assessment, and exploration of molecular targets, the screening process entailed analyses of molecular targets and bioavailability. The molecular properties and potential antiviral efficacy of these phytochemical candidates were determined by analyzing them as drug candidates. The results of the study showed that these compounds had potential antiviral activity and could be developed as therapeutic agents. Furthermore, the study showed that the compounds had good bioavailability, suggesting that they are suitable for use as therapeutic agents. An in silico method was used to identify flavonoid compounds for potent antiviral drug molecules against the coronavirus protein complex NSP16/10 protein. The NSP16/10 complex protein binding energy values were -6.14 for isoquercetin, -6.902 for narirutin, -6.052 for myricetin, -7.10 for hesperidin, -4.392 for silibinin, -3.997 for baicalein, -3.712 for taxifolin, and -3.321 for petunidin. Molecular dynamics simulations showed that isoquercetin, hesperidin, and narirutin flavonoids interacted with the COVID-19 virus protein complex NSP16/10 protease up to 100 nanoseconds.

Impact of Zika virus non-structural protein mutations on hippocampal damage.

Impact of Zika virus non-structural protein mutations on hippocampal damage.

Retrospective study on the dengue fever outbreak in Puntland State, Somalia

BackgroundDengue infection is a mosquito-borne, endemic viral disease, particularly in developing countries. Here, we report the results of the clinicodemographic, serologic profile and the monthly occurrence of a recent dengue fever outbreak in Puntland State (Somalia).MethodologyWe analyzed the data of 956 dengue-suspected patients who were investigated using the rapid diagnostic testing (RDT) method for detecting NS1 (dengue virus non-structural protein) and IgM antibodies employing the SD Biosensor Dengue Dou NS Ag and IgM test kit (Germany) at the Puntland Public Health Referral Laboratory from November 21, 2022, to May 27, 2023.ResultsWe found that 118 cases were positive for dengue among the suspected patients enrolled in the present study. Of these cases, 76.2% were dengue NSI positive, 13.6% were dengue IgM positive, and 10.2% were both NSI and IgM positive. The number of females and males in the confirmed cases was equal, and most (48.3%) were aged 20 years or less. 43.1% of them lived in the Nugal region, particularly in Garowe. Clinically, fever was the most frequent symptom (88.9%). The cases peaked in December 2022 but dropped from January to March, with a slight rise in February, and then increased in April and May 2023.ConclusionThis study highlights the clinicodemographic characteristics, seroprevalence, and monthly occurrence of dengue in Puntland. We recommend improving vector control measures, enhancing case management, strengthening dengue surveillance, developing an early warning system, and conducting future studies to characterize the circulating strains.

NS2 induces an influenza A RNA polymerase hexamer and acts as a transcription to replication switch.

Genome transcription and replication of influenza A virus (FluA), catalyzed by viral RNA polymerase (FluAPol), are delicately controlled across the virus life cycle. A switch from transcription to replication occurring at later stage of an infection is critical for progeny virion production and viral non-structural protein NS2 has been implicated in regulating the switch. However, the underlying regulatory mechanisms and the structure of NS2 remained elusive for years. Here, we determine the cryo-EM structure of the FluAPol-NS2 complex at ~3.0 Å resolution. Surprisingly, three domain-swapped NS2 dimers arrange three symmetrical FluPol dimers into a highly ordered barrel-like hexamer. Further structural and functional analyses demonstrate that NS2 binding not only hampers the interaction between FluAPol and the Pol II CTD because of steric conflicts, but also impairs FluAPol transcriptase activity by stalling it in the replicase conformation. Moreover, this is the first visualization of the full-length NS2 structure. Our findings uncover key molecular mechanisms of the FluA transcription-replication switch and have implications for the development of antivirals.

Repurposing of FDA-approved drugs against oligomerization domain of dengue virus NS1 protein: a computational approach.

Dengue fever is a serious health hazard on a global scale and its primary causative agent is the dengue virus (DENV). The non-structural protein 1 (NS1) of DENV plays a pivotal role in pathogenesis. It is associated with several autoimmune events, endothelial cell apoptosis, and vascular leakage, which increase mainly during the critical phase of infection. In this study, important residues of the oligomerization domain of NS1 protein were identified by literature searches. Virtual screening has been conducted using the entire dataset of the DrugBank database and the potential small-molecule inhibitors against the NS1 protein have been chosen on the basis of binding energy values. This is succeeded by molecular dynamics (MD) simulations of the shortlisted compounds, ultimately giving rise to five compounds. These five compounds were further subjected to RAMD simulations by applying a random direction force of specific magnitude on the ligand center of mass in order to push the ligand out of the protein-binding pocket, for the quantitative estimation of their binding energy values to determine the interaction strength between protein and ligand which prevents ligand unbinding from its binding site, ultimately leading to the selection of three major compounds, DB00826 (Natamycin), DB11274 (Dihydro-alphaergocryptine), and DB11275 (Epicriptine), with the DB11274 having a role against idiopathic Parkinson's disease, and thus may have possible important roles in the prevention of dengue-associated Parkinsonism. These compounds may act as prospective drugs against dengue, by preventing the oligomerization of the NS1 protein, thereby preventing disease progression and pathogenesis.

The glycoprotein quality control factor Malectin promotes coronavirus replication and viral protein biogenesis.

Coronaviruses (CoV) rewire host protein homeostasis (proteostasis) networks through interactions between viral nonstructural proteins (nsps) and host factors to promote infection. With the emergence of SARS-CoV-2, it is imperative to characterize host interactors shared across nsp homologs. Using quantitative proteomics and functional genetic screening, we identify conserved proteostasis interactors of nsp2 and nsp4 that serve pro-viral roles during infection of murine hepatitis virus - a model betacoronavirus. We uncover a glycoprotein quality control factor, Malectin (MLEC), which significantly reduces infectious titers when knocked down. During infection, nsp2 interacts with MLEC-associated proteins and the MLEC-interactome is drastically altered, stabilizing association with the Oligosaccheryltransferase (OST) complex, a crucial component of viral glycoprotein production. MLEC promotes viral protein levels and genome replication through its quality control activity. Lastly, we show MLEC promotes SARS-CoV-2 replication. Our results reveal a role for MLEC in mediating CoV infection and identify a potential target for pan-CoV antivirals.