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Viruses May 2024Newly emerging viruses, primarily zoonotic or vector-borne, pose a persistent threat to public health and have led to outbreaks of global concern [...].
Newly emerging viruses, primarily zoonotic or vector-borne, pose a persistent threat to public health and have led to outbreaks of global concern [...].
Topics: Alphavirus; Humans; Animals; Flavivirus; Alphavirus Infections; Flavivirus Infections
PubMed: 38932175
DOI: 10.3390/v16060882 -
Nature May 2018Arthritogenic alphaviruses comprise a group of enveloped RNA viruses that are transmitted to humans by mosquitoes and cause debilitating acute and chronic...
Arthritogenic alphaviruses comprise a group of enveloped RNA viruses that are transmitted to humans by mosquitoes and cause debilitating acute and chronic musculoskeletal disease . The host factors required for alphavirus entry remain poorly characterized . Here we use a genome-wide CRISPR-Cas9-based screen to identify the cell adhesion molecule Mxra8 as an entry mediator for multiple emerging arthritogenic alphaviruses, including chikungunya, Ross River, Mayaro and O'nyong nyong viruses. Gene editing of mouse Mxra8 or human MXRA8 resulted in reduced levels of viral infection of cells and, reciprocally, ectopic expression of these genes resulted in increased infection. Mxra8 bound directly to chikungunya virus particles and enhanced virus attachment and internalization into cells. Consistent with these findings, Mxra8-Fc fusion protein or anti-Mxra8 monoclonal antibodies blocked chikungunya virus infection in multiple cell types, including primary human synovial fibroblasts, osteoblasts, chondrocytes and skeletal muscle cells. Mutagenesis experiments suggest that Mxra8 binds to a surface-exposed region across the A and B domains of chikungunya virus E2 protein, which are a speculated site of attachment. Finally, administration of the Mxra8-Fc protein or anti-Mxra8 blocking antibodies to mice reduced chikungunya and O'nyong nyong virus infection as well as associated foot swelling. Pharmacological targeting of Mxra8 could form a strategy for mitigating infection and disease by multiple arthritogenic alphaviruses.
Topics: 3T3 Cells; Animals; Antibodies, Blocking; CRISPR-Cas Systems; Chikungunya virus; Chondrocytes; Fibroblasts; Humans; Immunoglobulins; Male; Membrane Proteins; Mice; Muscle, Skeletal; O'nyong-nyong Virus; Osteoblasts; Receptors, Fc; Receptors, Virus
PubMed: 29769725
DOI: 10.1038/s41586-018-0121-3 -
Cell Oct 2023MXRA8 is a receptor for chikungunya (CHIKV) and other arthritogenic alphaviruses with mammalian hosts. However, mammalian MXRA8 does not bind to alphaviruses that infect...
MXRA8 is a receptor for chikungunya (CHIKV) and other arthritogenic alphaviruses with mammalian hosts. However, mammalian MXRA8 does not bind to alphaviruses that infect humans and have avian reservoirs. Here, we show that avian, but not mammalian, MXRA8 can act as a receptor for Sindbis, western equine encephalitis (WEEV), and related alphaviruses with avian reservoirs. Structural analysis of duck MXRA8 complexed with WEEV reveals an inverted binding mode compared with mammalian MXRA8 bound to CHIKV. Whereas both domains of mammalian MXRA8 bind CHIKV E1 and E2, only domain 1 of avian MXRA8 engages WEEV E1, and no appreciable contacts are made with WEEV E2. Using these results, we generated a chimeric avian-mammalian MXRA8 decoy-receptor that neutralizes infection of multiple alphaviruses from distinct antigenic groups in vitro and in vivo. Thus, different alphaviruses can bind MXRA8 encoded by different vertebrate classes with distinct engagement modes, which enables development of broad-spectrum inhibitors.
Topics: Animals; Humans; Alphavirus; Chikungunya Fever; Chikungunya virus; Mammals; Receptors, Virus
PubMed: 37804831
DOI: 10.1016/j.cell.2023.09.007 -
Cell Jun 2023Alphaviruses are RNA viruses that represent emerging public health threats. To identify protective antibodies, we immunized macaques with a mixture of western, eastern,...
Alphaviruses are RNA viruses that represent emerging public health threats. To identify protective antibodies, we immunized macaques with a mixture of western, eastern, and Venezuelan equine encephalitis virus-like particles (VLPs), a regimen that protects against aerosol challenge with all three viruses. Single- and triple-virus-specific antibodies were isolated, and we identified 21 unique binding groups. Cryo-EM structures revealed that broad VLP binding inversely correlated with sequence and conformational variability. One triple-specific antibody, SKT05, bound proximal to the fusion peptide and neutralized all three Env-pseudotyped encephalitic alphaviruses by using different symmetry elements for recognition across VLPs. Neutralization in other assays (e.g., chimeric Sindbis virus) yielded variable results. SKT05 bound backbone atoms of sequence-diverse residues, enabling broad recognition despite sequence variability; accordingly, SKT05 protected mice against Venezuelan equine encephalitis virus, chikungunya virus, and Ross River virus challenges. Thus, a single vaccine-elicited antibody can protect in vivo against a broad range of alphaviruses.
Topics: Animals; Mice; Alphavirus; Encephalitis Virus, Venezuelan Equine; Antibodies, Viral; Viral Vaccines; Macaca
PubMed: 37295404
DOI: 10.1016/j.cell.2023.05.019 -
Cell May 2023Semliki Forest virus (SFV) is an alphavirus that uses the very-low-density lipoprotein receptor (VLDLR) as a receptor during infection of its vertebrate hosts and...
Semliki Forest virus (SFV) is an alphavirus that uses the very-low-density lipoprotein receptor (VLDLR) as a receptor during infection of its vertebrate hosts and insect vectors. Herein, we used cryoelectron microscopy to study the structure of SFV in complex with VLDLR. We found that VLDLR binds multiple E1-DIII sites of SFV through its membrane-distal LDLR class A (LA) repeats. Among the LA repeats of the VLDLR, LA3 has the best binding affinity to SFV. The high-resolution structure shows that LA3 binds SFV E1-DIII through a small surface area of 378 Å, with the main interactions at the interface involving salt bridges. Compared with the binding of single LA3s, consecutive LA repeats around LA3 promote synergistic binding to SFV, during which the LAs undergo a rotation, allowing simultaneous key interactions at multiple E1-DIII sites on the virion and enabling the binding of VLDLRs from divergent host species to SFV.
Topics: Alphavirus; Cryoelectron Microscopy; Semliki forest virus; Receptors, LDL; Receptors, Virus
PubMed: 37098345
DOI: 10.1016/j.cell.2023.03.032 -
Nature Communications Jan 2024Alphaviruses are arboviruses transmitted by mosquitoes and are pathogenic to humans and livestock, causing a substantial public health burden. So far, several receptors...
Alphaviruses are arboviruses transmitted by mosquitoes and are pathogenic to humans and livestock, causing a substantial public health burden. So far, several receptors have been identified for alphavirus entry; however, they cannot explain the broad host range and tissue tropism of certain alphaviruses, such as Getah virus (GETV), indicating the existence of additional receptors. Here we identify the evolutionarily conserved low-density lipoprotein receptor (LDLR) as a new cell entry factor for GETV, Semliki Forest virus (SFV), Ross River virus (RRV) and Bebaru virus (BEBV). Ectopic expression of LDLR facilitates cellular binding and internalization of GETV, which is mediated by the interaction between the E2-E1 spike of GETV and the ligand-binding domain (LBD) of LDLR. Antibodies against LBD block GETV infection in cultured cells. In addition, the GST-LBD fusion protein inhibits GETV infection both in vitro and in vivo. Notably, we identify the key amino acids in LDLR-LBD that played a crucial role in viral entry; specific mutations in the CR4 and CR5 domain of LDLR-LBD reduce viral entry to cells by more than 20-fold. These findings suggest that targeting the LDLR-LBD could be a potential strategy for the development of antivirals against multiple alphaviruses.
Topics: Animals; Humans; Alphavirus; Virus Internalization; Semliki forest virus; Alphavirus Infections; Culicidae
PubMed: 38245515
DOI: 10.1038/s41467-024-44872-5 -
Cell Jan 2024The very-low-density lipoprotein receptor (VLDLR) comprises eight LDLR type A (LA) domains and supports entry of distantly related alphaviruses, including Eastern equine...
The very-low-density lipoprotein receptor (VLDLR) comprises eight LDLR type A (LA) domains and supports entry of distantly related alphaviruses, including Eastern equine encephalitis virus (EEEV) and Semliki Forest virus (SFV). Here, by resolving multiple cryo-electron microscopy structures of EEEV-VLDLR complexes and performing mutagenesis and functional studies, we show that EEEV uses multiple sites (E1/E2 cleft and E2 A domain) to engage more than one LA domain simultaneously. However, no single LA domain is necessary or sufficient to support efficient EEEV infection. Whereas all EEEV strains show conservation of two VLDLR-binding sites, the EEEV PE-6 strain and a few other EEE complex members feature a single amino acid substitution that enables binding of LA domains to an additional site on the E2 B domain. These structural and functional analyses informed the design of a minimal VLDLR decoy receptor that neutralizes EEEV infection and protects mice from lethal challenge.
Topics: Animals; Mice; Alphavirus; Cryoelectron Microscopy; Encephalitis Virus, Eastern Equine; Encephalomyelitis, Equine; Horses; Protein Binding; Receptors, LDL
PubMed: 38176410
DOI: 10.1016/j.cell.2023.11.031 -
Methods in Molecular Biology (Clifton,... 2016Alphavirus vectors based on Semliki Forest virus, Sindbis virus, and Venezuelan equine encephalitis virus have been widely applied for vaccine development. Naked RNA...
Alphavirus vectors based on Semliki Forest virus, Sindbis virus, and Venezuelan equine encephalitis virus have been widely applied for vaccine development. Naked RNA replicons, recombinant viral particles, and layered DNA vectors have been subjected to immunization in preclinical animal models with antigens for viral targets and tumor antigens. Moreover, a limited number of clinical trials have been conducted in humans. Vaccination with alphavirus vectors has demonstrated efficient immune responses and has showed protection against challenges with lethal doses of virus and tumor cells, respectively. Moreover, vaccines have been developed against alphaviruses causing epidemics such as Chikungunya virus.
Topics: Alphavirus; Animals; Blotting, Western; Carcinoembryonic Antigen; Chromatography, Affinity; Cloning, Molecular; DNA, Recombinant; Electroporation; Fluorescent Antibody Technique; Genetic Engineering; Genetic Vectors; Green Fluorescent Proteins; Immunization; Macaca; Mice; RNA, Viral; Transcription, Genetic; Ultracentrifugation; Vaccines
PubMed: 27076308
DOI: 10.1007/978-1-4939-3389-1_22 -
Methods in Molecular Biology (Clifton,... 2017Alphavirus-based vectors have been engineered from Semliki Forest virus, Sindbis virus, and Venezuelan equine encephalitis virus and applied for vaccine development....
Alphavirus-based vectors have been engineered from Semliki Forest virus, Sindbis virus, and Venezuelan equine encephalitis virus and applied for vaccine development. Immunization in preclinical animal models has been conducted with naked RNA replicons, recombinant viral particles and layered DNA-RNA vectors. Most commonly, the targets for the immunization have been viral surface proteins and tumor antigens, which have elicited strong immune responses and even provided protection against challenges with lethal doses of virus and tumor cells, respectively. As alphaviruses also cause epidemics, vaccines have been developed against Chikungunya virus. Despite the success in several animal smodels only a few clinical trials have been conducted in humans, so far.
Topics: Alphavirus; Animals; CHO Cells; COS Cells; Cell Line; Chlorocebus aethiops; Cricetinae; Cricetulus; HEK293 Cells; Humans; Mice; Plasmids; Vaccination; Viral Vaccines
PubMed: 28374252
DOI: 10.1007/978-1-4939-6869-5_13 -
Methods in Molecular Biology (Clifton,... 2021Alphavirus-based vectors present an efficient approach for antigen preparation applied for vaccine development. Semliki Forest virus, Sindbis virus, and Venezuelan...
Alphavirus-based vectors present an efficient approach for antigen preparation applied for vaccine development. Semliki Forest virus, Sindbis virus, and Venezuelan equine encephalitis virus have been engineered for high-level expression of antigens targeting infectious diseases and tumors. Alphaviruses possess a large application range as vectors can be delivered as naked RNA replicons, recombinant viral particles, and layered DNA plasmids. Immunization studies in animal models have provided protection against challenges with lethal doses of pathogenic infectious agents and tumor cells. So far, a limited number of clinical trials have been conducted for alphavirus vectors in humans.
Topics: Alphavirus; Animals; Antigens; Cell Line; Cloning, Molecular; Genetic Engineering; Genetic Vectors; Humans; Immunization; Mice; Plasmids; RNA, Viral; Replicon; Transfection; Vaccines, DNA; Vaccines, Virus-Like Particle
PubMed: 32959241
DOI: 10.1007/978-1-0716-0795-4_6