Publications

Abstract

With the near eradication of poliovirus due to global vaccination campaigns, attention has shifted to other enteroviruses that can cause polio-like paralysis syndrome (now termed acute flaccid myelitis (AFM))1-3. In particular, enterovirus D68 (EV-D68) is believed to be the main driver of epidemic outbreaks of AFM in recent years4, yet not much is known about EV-D68 host interactions. EV-D68 is a respiratory virus5 but, in rare cases, can spread to the central nervous system to cause severe neuropathogenesis. Here, we used genome-scale CRISPR screens to identify the poorly characterized multipass membrane transporter MFSD6 as a host entry factor for EV-D68. Knockout of MFSD6 expression abrogated EV-D68 infection in cell lines and primary cells corresponding to respiratory and neural cells. MFSD6 localized to the plasma membrane and was required for viral entry into host cells. MFSD6 bound directly to EV-D68 particles via its third extracellular loop (L3). We determined the cryo-EM structure of EV-D68 in complex with L3 at 2.1 A resolution, revealing the interaction interface. A decoy receptor, engineered by fusing MFSD6(L3) to Fc, blocked EV-D68 infection of human primary lung epithelial cells, and provided near complete protection in a lethal mouse model of EV-D68 infection. Collectively, our results reveal MFSD6 as an entry receptor for EV-D68, and support targeting MFSD6 as a potential mechanism to combat infections by this emerging pathogen with pandemic potential.

View details for DOI 10.1038/s41586-025-08908-0

View details for PubMedID 40132641

Abstract

Vectors based on adeno-associated viruses (AAVs) are promising therapeutic modalities used in gene therapy. Robust cell-based assays that demonstrate and quantify the potency of AAV vectors in expressing their transgene are needed for clinical development. However, many AAV clinical serotypes poorly transduce cells in vitro and often contain cell-type-specific promoters inactive in commonly used cell lines. Here, we enhance the efficiency of in vitro AAV transduction by overexpressing the AAV receptor (AAVR/KIAA0319L), preventing transcriptional silencing by the HUSH complex, and using CRISPR activation (CRISPRa) to drive transgene expression. For the latter, we utilized guide RNAs targeting the conserved AAV2 inverted terminal repeat (ITR) sequence present in most AAV transfer vectors. Using this strategy, we engineered cell lines that showed marked increases in transduction by AAV vectors across a wide range of clinically relevant serotypes and containing cell-type-specific promoters. These improvements enabled the efficient determination of AAV functional titers (also referred to as transducing titers), which can be used to robustly monitor potency across diverse AAV preparations. The strongly enhanced susceptibility of these cell lines to transduction by a variety of divergent AAV vectors could facilitate the development of standardized in vitro quantitative assays for AAV-based gene therapy products.

View details for DOI 10.1016/j.omtm.2025.101416

View details for PubMedID 40008089

View details for PubMedCentralID PMC11851225

Abstract

Mosquito-borne flaviviruses, such as dengue virus (DENV), Zika virus (ZIKV), West Nile virus, and yellow fever virus, pose significant public health threats globally. Extensive efforts have led to the development of promising highly active compounds against DENV targeting viral non-structural protein 4B (NS4B) protein. However, due to the cocirculation of flaviviruses and to prepare for emerging flaviviruses, there is a need for more broadly acting antivirals. Host-directed therapy where one targets a host factor required for viral replication may be active against multiple viruses that use similar replication strategies. Here, we used a CRISPR-Cas9 library that we designed to target the druggable genome and identified signal peptide peptidase (SPP, encoded by Histocompatibility Minor 13, HM13), as a critical host factor in DENV infection. Genetic knockout or introducing mutations that disrupt the proteolytic activity of SPP markedly reduced the replication of multiple flaviviruses. Although their substrates differ, SPP has structural homology with γ-secretase, which has been pursued as a pharmacological target for Alzheimer's disease. Notably, SPP-targeting compounds exhibited potent anti-DENV activity at low nanomolar concentrations across multiple primary and disease-relevant cell types, acting specifically through SPP inhibition rather than γ-secretase inhibition. Importantly, SPP inhibitors were active at low nanomolar concentrations against flaviviruses other than DENV including ZIKV while DENV NS4B inhibitors lost activity. This study emphasizes the strong potential of SPP as a pan-flaviviral target and provides a framework for identifying host druggable targets to screen for broad-spectrum antivirals.

View details for DOI 10.1073/pnas.2421573122

View details for PubMedID 39969998

Abstract

Human parechoviruses (PeV-A) are increasingly being recognized as a cause of infection in neonates and young infants, leading to a spectrum of clinical manifestations ranging from mild gastrointestinal and respiratory illnesses to severe sepsis and meningitis. However, the host factors required for parechovirus entry and infection remain poorly characterized. Here, using genome-wide CRISPR/Cas9 loss-of-function screens, we identify myeloid-associated differentiation marker (MYADM) as a host factor essential for the entry of several human parechovirus genotypes including PeV-A1, PeV-A2 and PeV-A3. Genetic knockout of MYADM confers resistance to PeV-A infection in cell lines and in human gastrointestinal epithelial organoids. Using immunoprecipitation, we show that MYADM binds to PeV-A1 particles via its fourth extracellular loop, and we identify critical amino acid residues within the loop that mediate binding and infection. The demonstrated interaction between MYADM and PeV-A1, and its importance specifically for viral entry, suggest that MYADM is a virus receptor. Knockout of MYADM does not reduce PeV-A1 attachment to cells pointing to a role at the post-attachment stage. Our study suggests that MYADM is a multi-genotype receptor for human parechoviruses with potential as an antiviral target to combat disease associated with emerging parechoviruses.

View details for DOI 10.1038/s41467-024-47825-0

View details for PubMedID 38658526

View details for PubMedCentralID 6893760

Abstract

The development of transgenic mouse models that express genes of interest in specific cell types has transformed our understanding of basic biology and disease. However, generating these models is time- and resource-intensive. Here we describe a model system, SELective Expression and Controlled Transduction In Vivo (SELECTIV), that enables efficient and specific expression of transgenes by coupling adeno-associated virus (AAV) vectors with Cre-inducible overexpression of the multi-serotype AAV receptor, AAVR. We demonstrate that transgenic AAVR overexpression greatly increases the efficiency of transduction of many diverse cell types, including muscle stem cells, which are normally refractory to AAV transduction. Superior specificity is achieved by combining Cre-mediated AAVR overexpression with whole-body knockout of endogenous Aavr, which is demonstrated in heart cardiomyocytes, liver hepatocytes and cholinergic neurons. The enhanced efficacy and exquisite specificity of SELECTIV has broad utility in development of new mouse model systems and expands the use of AAV for gene delivery in vivo.

View details for DOI 10.1038/s41592-023-01896-x

View details for PubMedID 37291262

View details for PubMedCentralID 3337962

Abstract

Lysosomes are key degradative compartments of the cell. Transport to lysosomes relies on GlcNAc-1-phosphotransferase-mediated tagging of soluble enzymes with mannose 6-phosphate (M6P). GlcNAc-1-phosphotransferase deficiency leads to the severe lysosomal storage disorder mucolipidosis II (MLII). Several viruses require lysosomal cathepsins to cleave structural proteins and thus depend on functional GlcNAc-1-phosphotransferase. Here, we used genome-scale CRISPR screens to identify Lysosomal Enzyme Trafficking factor (LYSET) as essential for infection by cathepsin-dependent viruses including SARS-CoV-2. LYSET deficiency resulted in global loss of M6P tagging and mislocalization of GlcNAc-1-phosphotransferase from the Golgi complex to lysosomes. Lyset knockout mice exhibited MLII-like phenotypes and human pathogenic LYSET alleles failed to restore lysosomal sorting defects. Thus, LYSET is required for correct functioning of the M6P trafficking machinery, and mutations in LYSET can explain the phenotype of the associated disorder.

View details for DOI 10.1126/science.abn5648

View details for PubMedID 36074821

Abstract

Enteroviruses cause a number of medically relevant and widespread human diseases with no approved antiviral therapies currently available. Host-directed therapies present an enticing option for this diverse genus of viruses. We have previously identified the actin histidine methyltransferase SETD3 as a critical host factor physically interacting with the viral protease 2A. Here, we report the 3.5 Å cryo-EM structure of SETD3 interacting with coxsackievirus B3 2A at two distinct interfaces, including the substrate-binding surface within the SET domain. Structure-function analysis revealed that mutations of key residues in the SET domain resulted in severely reduced binding to 2A and complete protection from enteroviral infection. Our findings provide insight into the molecular basis of the SETD3-2A interaction and a framework for the rational design of host-directed therapeutics against enteroviruses.

View details for DOI 10.1038/s41467-022-32758-3

View details for PubMedID 36075902

Abstract

Flaviviruses, including dengue virus (DENV) and Zika virus (ZIKV), cause severe human disease. Co-opting cellular factors for viral translation and viral genome replication at the endoplasmic reticulum is a shared replication strategy, despite different clinical outcomes. Although the protein products of these viruses have been studied in depth, how the RNA genomes operate inside human cells is poorly understood. Using comprehensive identification of RNA-binding proteins by mass spectrometry (ChIRP-MS), we took an RNA-centric viewpoint of flaviviral infection and identified several hundred proteins associated with both DENV and ZIKV genomic RNA in human cells. Genome-scale knockout screens assigned putative functional relevance to the RNA-protein interactions observed by ChIRP-MS. The endoplasmic-reticulum-localized RNA-binding proteins vigilin and ribosome-binding protein 1 directly bound viral RNA and each acted at distinct stages in the life cycle of flaviviruses. Thus, this versatile strategy can elucidate features of human biology that control the pathogenesis of clinically relevant viruses.

View details for DOI 10.1038/s41564-019-0518-2

View details for PubMedID 31384002

Abstract

Enteroviruses (EVs) comprise a large genus of positive-sense, single-stranded RNA viruses whose members cause a number of important and widespread human diseases, including poliomyelitis, myocarditis, acute flaccid myelitis and the common cold. How EVs co-opt cellular functions to promote replication and spread is incompletely understood. Here, using genome-scale CRISPR screens, we identify the actin histidine methyltransferase SET domain containing 3 (SETD3) as critically important for viral infection by a broad panel of EVs, including rhinoviruses and non-polio EVs increasingly linked to severe neurological disease such as acute flaccid myelitis (EV-D68) and viral encephalitis (EV-A71). We show that cytosolic SETD3, independent of its methylation activity, is required for the RNA replication step in the viral life cycle. Using quantitative affinity purification-mass spectrometry, we show that SETD3 specifically interacts with the viral 2A protease of multiple enteroviral species, and we map the residues in 2A that mediate this interaction. 2A mutants that retain protease activity but are unable to interact with SETD3 are severely compromised in RNA replication. These data suggest a role of the viral 2A protein in RNA replication beyond facilitating proteolytic cleavage. Finally, we show that SETD3 is essential for in vivo replication and pathogenesis in multiple mouse models for EV infection, including CV-A10, EV-A71 and EV-D68. Our results reveal a crucial role of a host protein in viral pathogenesis, and suggest targeting SETD3 as a potential mechanism for controlling viral infections.

View details for DOI 10.1038/s41564-019-0551-1

View details for PubMedID 31527793

Abstract

Necroptosis is an important form of lytic cell death triggered by injury and infection, but whether mixed lineage kinase domain-like (MLKL) is sufficient to execute this pathway is unknown. In a genetic selection for human cell mutants defective for MLKL-dependent necroptosis, we identified mutations in IPMK and ITPK1, which encode inositol phosphate (IP) kinases that regulate the IP code of soluble molecules. We show that IP kinases are essential for necroptosis triggered by death receptor activation, herpesvirus infection, or a pro-necrotic MLKL mutant. In IP kinase mutant cells, MLKL failed to oligomerize and localize to membranes despite proper receptor-interacting protein kinase-3 (RIPK3)-dependent phosphorylation. We demonstrate that necroptosis requires IP-specific kinase activity and that a highly phosphorylated product, but not a lowly phosphorylated precursor, potently displaces the MLKL auto-inhibitory brace region. These observations reveal control of MLKL-mediated necroptosis by a metabolite and identify a key molecular mechanism underlying regulated cell death.

View details for PubMedID 29883610