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To facilitate the detection and management of potential clinical antiviral resistance, in vitro selection of drug-resistant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) against the virus Mpro inhibitor nirmatrelvir (Paxlovid active component) was conducted. Six Mpro mutation patterns containing T304I alone or in combination with T21I, L50F, T135I, S144A, or A173V emerged, with A173V+T304I and T21I+S144A+T304I mutations showing >20-fold resistance each. Biochemical analyses indicated inhibition constant shifts aligned to antiviral results, with S144A and A173V each markedly reducing nirmatrelvir inhibition and Mpro activity. SARS-CoV-2 surveillance revealed that in vitro resistance-associated mutations from our studies and those reported in the literature were rarely detected in the Global Initiative on Sharing All Influenza Data database. In the Paxlovid Evaluation of Protease Inhibition for COVID-19 in High-Risk Patients trial, E166V was the only emergent resistance mutation, observed in three Paxlovid-treated patients, none of whom experienced COVID-19-related hospitalization or death.
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Antivirales , Tratamiento Farmacológico de COVID-19 , Farmacorresistencia Viral , Mutación , SARS-CoV-2 , SARS-CoV-2/genética , SARS-CoV-2/efectos de los fármacos , Farmacorresistencia Viral/genética , Humanos , Antivirales/farmacología , Antivirales/uso terapéutico , COVID-19/virología , COVID-19/genética , COVID-19/epidemiología , Proteasas 3C de Coronavirus/genética , Proteasas 3C de Coronavirus/antagonistas & inhibidores , Lactamas , Leucina , Nitrilos , ProlinaRESUMEN
Variants of SARS-CoV-2 pose significant challenges in public health due to their increased transmissibility and ability to evade natural immunity, vaccine protection, and monoclonal antibody therapeutics. The emergence of the highly transmissible Omicron variant and subsequent subvariants, characterized by an extensive array of over 32 mutations within the spike protein, intensifies concerns regarding vaccine evasion. In response, multiple antiviral therapeutics have received FDA emergency use approval, targeting the SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) and main protease (Mpro) regions, known to have relatively fewer mutations across novel variants. In this study, we evaluated the efficacy of nirmatrelvir (PF-07321332) and other clinically significant SARS-CoV-2 antivirals against a diverse panel of SARS-CoV-2 variants, encompassing the newly identified Omicron subvariants XBB1.5 and JN.1, using live-virus antiviral assays. Our findings demonstrate that while the last Omicron subvariants exhibited heightened pathogenicity in our animal model, nirmatrelvir and other clinically relevant antivirals consistently maintained their efficacy against all tested variants, including the XBB1.5 subvariant.
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Despite the record-breaking discovery, development and approval of vaccines and antiviral therapeutics such as Paxlovid, coronavirus disease 2019 (COVID-19) remained the fourth leading cause of death in the world and third highest in the United States in 2022. Here, we report the discovery and characterization of PF-07817883, a second-generation, orally bioavailable, SARS-CoV-2 main protease inhibitor with improved metabolic stability versus nirmatrelvir, the antiviral component of the ritonavir-boosted therapy Paxlovid. We demonstrate the in vitro pan-human coronavirus antiviral activity and off-target selectivity profile of PF-07817883. PF-07817883 also demonstrated oral efficacy in a mouse-adapted SARS-CoV-2 model at plasma concentrations equivalent to nirmatrelvir. The preclinical in vivo pharmacokinetics and metabolism studies in human matrices are suggestive of improved oral pharmacokinetics for PF-07817883 in humans, relative to nirmatrelvir. In vitro inhibition/induction studies against major human drug metabolizing enzymes/transporters suggest a low potential for perpetrator drug-drug interactions upon single-agent use of PF-07817883.
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While somatic variants of TRAF7 (Tumor necrosis factor receptor-associated factor 7) underlie anterior skull-base meningiomas, here we report the inherited mutations of TRAF7 that cause congenital heart defects. We show that TRAF7 mutants operate in a dominant manner, inhibiting protein function via heterodimerization with wild-type protein. Further, the shared genetics of the two disparate pathologies can be traced to the common origin of forebrain meninges and cardiac outflow tract from the TRAF7-expressing neural crest. Somatic and inherited mutations disrupt TRAF7-IFT57 interactions leading to cilia degradation. TRAF7-mutant meningioma primary cultures lack cilia, and TRAF7 knockdown causes cardiac, craniofacial, and ciliary defects in Xenopus and zebrafish, suggesting a mechanistic convergence for TRAF7-driven meningiomas and developmental heart defects.
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Cardiopatías Congénitas , Neoplasias Meníngeas , Meningioma , Animales , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Cardiopatías Congénitas/genética , Neoplasias Meníngeas/genética , Meningioma/genética , Meningioma/patología , Mutación , Cráneo/metabolismo , Pez Cebra/genética , Pez Cebra/metabolismo , Proteínas de Pez Cebra/genética , Humanos , Péptidos y Proteínas Asociados a Receptores de Factores de Necrosis TumoralRESUMEN
Vero cells are widely used for antiviral tests and virology research for SARS-CoV-2 as well as viruses from various other families. However, Vero cells generally express high levels of multi-drug resistance 1 (MDR1) or Pgp protein, the efflux transporter of foreign substances including many antiviral compounds, affecting the antiviral activity as well as interpretation of data. To address this, a Pgp gene knockout VeroE6 cell line (VeroE6-Pgp-KO) was generated using CRISPR-CAS9 technology. These cells no longer expressed the Pgp protein as indicated by flow cytometry analysis following staining with a Pgp-specific monoclonal antibody. They also showed significantly reduced efflux transporter activity in the calcein acetoxymethyl ester (calcein AM) assay. The VeroE6-Pgp-KO cells and the parental VeroE6 cells were each infected with SARS-CoV-2 to test antiviral activities of remdesivir and nirmatrelvir, two known Pgp substrates, in the presence or absence of a Pgp inhibitor. The compounds showed antiviral activities in VeroE6-Pgp-KO cells similar to that observed in the presence of the Pgp inhibitor. Thus, the newly established VeroE6-Pgp-KO cell line adds a new in vitro virus infection system for SARS-CoV-2 and possibly other viruses to test antiviral therapies without a need to control the Pgp activity. Removal of the Pgp inhibitor for antiviral assays will lead to less data variation and prevent failed assays.
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Tratamiento Farmacológico de COVID-19 , SARS-CoV-2 , Humanos , Chlorocebus aethiops , Animales , SARS-CoV-2/genética , Antivirales/farmacología , Técnicas de Inactivación de Genes , Células Vero , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/genética , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/metabolismo , Línea CelularRESUMEN
Intracranial aneurysm (IA) rupture leads to subarachnoid hemorrhage, a sudden-onset disease that often causes death or severe disability. Although genome-wide association studies have identified common genetic variants that increase IA risk moderately, the contribution of variants with large effect remains poorly defined. Using whole-exome sequencing, we identified significant enrichment of rare, deleterious mutations in PPIL4, encoding peptidyl-prolyl cis-trans isomerase-like 4, in both familial and index IA cases. Ppil4 depletion in vertebrate models causes intracerebral hemorrhage, defects in cerebrovascular morphology and impaired Wnt signaling. Wild-type, but not IA-mutant, PPIL4 potentiates Wnt signaling by binding JMJD6, a known angiogenesis regulator and Wnt activator. These findings identify a novel PPIL4-dependent Wnt signaling mechanism involved in brain-specific angiogenesis and maintenance of cerebrovascular integrity and implicate PPIL4 gene mutations in the pathogenesis of IA.
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Encéfalo/irrigación sanguínea , Ciclofilinas/genética , Aneurisma Intracraneal/genética , Neovascularización Patológica/genética , Proteínas de Unión al ARN/genética , Ciclofilinas/fisiología , Humanos , Mutación , Proteínas de Unión al ARN/fisiología , Secuenciación del Exoma , Vía de Señalización Wnt/fisiologíaRESUMEN
The worldwide outbreak of COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic. Alongside vaccines, antiviral therapeutics are an important part of the healthcare response to countering the ongoing threat presented by COVID-19. Here, we report the discovery and characterization of PF-07321332, an orally bioavailable SARS-CoV-2 main protease inhibitor with in vitro pan-human coronavirus antiviral activity and excellent off-target selectivity and in vivo safety profiles. PF-07321332 has demonstrated oral activity in a mouse-adapted SARS-CoV-2 model and has achieved oral plasma concentrations exceeding the in vitro antiviral cell potency in a phase 1 clinical trial in healthy human participants.
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Tratamiento Farmacológico de COVID-19 , Lactamas/farmacología , Lactamas/uso terapéutico , Leucina/farmacología , Leucina/uso terapéutico , Nitrilos/farmacología , Nitrilos/uso terapéutico , Prolina/farmacología , Prolina/uso terapéutico , SARS-CoV-2/efectos de los fármacos , Inhibidores de Proteasa Viral/farmacología , Inhibidores de Proteasa Viral/uso terapéutico , Administración Oral , Animales , COVID-19/virología , Ensayos Clínicos Fase I como Asunto , Coronavirus/efectos de los fármacos , Modelos Animales de Enfermedad , Quimioterapia Combinada , Humanos , Lactamas/administración & dosificación , Lactamas/farmacocinética , Leucina/administración & dosificación , Leucina/farmacocinética , Ratones , Ratones Endogámicos BALB C , Pruebas de Sensibilidad Microbiana , Nitrilos/administración & dosificación , Nitrilos/farmacocinética , Prolina/administración & dosificación , Prolina/farmacocinética , Ensayos Clínicos Controlados Aleatorios como Asunto , Ritonavir/administración & dosificación , Ritonavir/uso terapéutico , SARS-CoV-2/fisiología , Inhibidores de Proteasa Viral/administración & dosificación , Inhibidores de Proteasa Viral/farmacocinética , Replicación Viral/efectos de los fármacosRESUMEN
Many RNA viruses encode a proof-reading deficient, low-fidelity RNA-dependent polymerase (RdRp), which generates genetically diverse populations that can adapt to changing environments and thwart antiviral therapies. 3Dpol, the RdRp of the foot-and-mouth disease virus (FMDV), is responsible for replication of viral genomes. The 3Dpol N terminus encodes a nuclear localization signal (NLS) sequence,MRKTKLAPT, important for import of the protein to host nucleus. Previous studies showed that substitutions at residues 18 and 20 of the NLS are defective in proper incorporation of nucleotides and RNA binding. Here, we use a systematic alanine scanning mutagenesis approach to understand the role of individual residues of the NLS in nuclear localization and nucleotide incorporation activities of 3Dpol We identify two residues of 3Dpol NLS, T19 and L21, that are important for the maintenance of enzyme fidelity. The 3Dpol NLS alanine substitutions of T19 and L21 results in aberrant incorporation of nucleoside analogs, conferring a low fidelity phenotype of the enzyme. A molecular dynamics simulation of RNA- and mutagen (RTP)-bound 3Dpol revealed that the T19 residue participates in a hydrogen bond network, including D165 in motif F and R416 at the C terminus of the FMDV 3Dpol and RNA template-primer. Based on these findings and previous studies, we conclude that at least the first six residues of theMRKTKLAPT sequence motif play a vital role in the maintenance of faithful RNA synthesis activity (fidelity) of FMDV 3Dpol, suggesting that the role of the NLS motif in similar viral polymerases needs to be revisited.IMPORTANCE In this study, we employed genetic and molecular dynamics approaches to analyze the role of individual amino acids of the FMDV 3Dpol nuclear localization signal (NLS). The NLS residues were mutated to alanine using a type A full-genome cDNA clone, and the virus progeny was analyzed for defects in growth and in competition with the parental virus. We identified two mutants in 3Dpol, T19A and L21A, that exhibited high rate of mutation, were sensitive to nucleotide analogs, and displayed reduced replicative fitness compared to the parental virus. Using molecular dynamics simulation, we demonstrated that residues T19 and L21 played a role in the structural configuration of the interaction network at the 3Dpol palm subdomain. Cumulatively, our data suggest that the T19 and L21 3Dpol amino acids are important for maintaining the fidelity of the FMDV polymerase and ensuring faithful replication of the FMDV genome.
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Virus de la Fiebre Aftosa/genética , Virus de la Fiebre Aftosa/fisiología , Señales de Localización Nuclear/genética , Señales de Localización Nuclear/metabolismo , Sustitución de Aminoácidos , Animales , Línea Celular , Genoma Viral , Simulación de Dinámica Molecular , Mutagénesis , Mutación , Señales de Localización Nuclear/química , Nucleótidos , Conformación Proteica , ARN Viral , Replicación ViralRESUMEN
Foot-and-mouth disease (FMD) is a highly contagious viral disease that severely impacts global food security and is one of the greatest constraints on international trade of animal products. Extensive viral population diversity and rapid, continuous mutation of circulating FMD viruses (FMDVs) pose significant obstacles to the control and ultimate eradication of this important transboundary pathogen. The current study investigated mechanisms contributing to within-host evolution of FMDV in a natural host species (cattle). Specifically, vaccinated and non-vaccinated cattle were infected with FMDV under controlled, experimental conditions and subsequently sampled for up to 35 days to monitor viral genomic changes as related to phases of disease and experimental cohorts. Consensus-level genomic changes across the entire FMDV coding region were characterized through three previously defined stages of infection: early, transitional, and persistent. The overall conclusion was that viral evolution occurred via a combination of two mechanisms: emergence of full-genomic minority haplotypes from within the inoculum super-swarm, and concurrent continuous point mutations. Phylogenetic analysis indicated that individuals were infected with multiple distinct haplogroups that were pre-existent within the ancestral inoculum used to infect all animals. Multiple shifts of dominant viral haplotype took place during the early and transitional phases of infection, whereas few shifts occurred during persistent infection. Overall, this work suggests that the establishment of the carrier state is not associated with specific viral genomic characteristics. These insights into FMDV population dynamics have important implications for virus sampling methodology and molecular epidemiology.
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Portador Sano/veterinaria , Evolución Molecular , Virus de la Fiebre Aftosa/genética , Fiebre Aftosa/virología , Genoma Viral/genética , Animales , Proteínas de la Cápside/genética , Portador Sano/inmunología , Portador Sano/virología , Bovinos , Enfermedades de los Bovinos/inmunología , Enfermedades de los Bovinos/prevención & control , Enfermedades de los Bovinos/virología , Fiebre Aftosa/inmunología , Fiebre Aftosa/prevención & control , Virus de la Fiebre Aftosa/inmunología , Virus de la Fiebre Aftosa/aislamiento & purificación , Haplotipos , Estudios Longitudinales , Mutación , Filogenia , ARN Viral/genética , Vacunas Virales/administración & dosificaciónRESUMEN
The highly contagious foot-and-mouth disease virus (FMDV) afflicts cloven-hoofed animals, resulting in significant costs because of loss of trade and recovery from disease. We developed a sensitive, specific, and rapid competitive ELISA (cELISA) to detect serum antibodies to FMDV. The cELISA utilized a monoclonal blocking antibody specific for a highly conserved FMDV nonstructural 3B epitope, a recombinant mutant FMDV 3ABC coating protein, and optimized format variables including serum incubation for 90 min at 20-25°C. Samples from 16 animals experimentally infected with one FMDV serotype (A, O, Asia, or SAT-1) demonstrated early detection capacity beginning 7 d post-inoculation. All samples from 55 vesicular stomatitis virus antibody-positive cattle and 44 samples from cloven-hoofed animals affected by non-FMD vesicular diseases were negative in the cELISA, demonstrating 100% analytical specificity. The diagnostic sensitivity was 100% against sera from 128 cattle infected with isolates of all FMDV serotypes, emphasizing serotype-agnostic results. Diagnostic specificities of U.S. cattle ( n = 1135) and swine ( n = 207) sera were 99.4% and 100%, respectively. High repeatability and reproducibility were demonstrated with 3.1% coefficient of variation in percent inhibition data and 100% agreement using 2 kit lots and 400 negative control serum samples, with no difference between bench and biosafety cabinet operation. Negative results from vaccinated, uninfected cattle, pig, and sheep sera confirmed the DIVA (differentiate infected from vaccinated animals) capability. This rapid (<3 h), select agent-free assay with high sensitivity and specificity, DIVA capability, and room temperature processing capability will serve as a useful tool in FMDV surveillance, emergency preparedness, response, and outbreak recovery programs.
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Anticuerpos Antivirales/sangre , Ensayo de Inmunoadsorción Enzimática/veterinaria , Virus de la Fiebre Aftosa/aislamiento & purificación , Fiebre Aftosa/diagnóstico , Proteínas no Estructurales Virales/aislamiento & purificación , Animales , Bovinos , Enfermedades de los Bovinos/diagnóstico , Enfermedades de los Bovinos/virología , Ensayo de Inmunoadsorción Enzimática/métodos , Epítopos/inmunología , Fiebre Aftosa/virología , Ovinos , Enfermedades de las Ovejas/diagnóstico , Enfermedades de las Ovejas/virología , Porcinos , Enfermedades de los Porcinos/diagnóstico , Enfermedades de los Porcinos/virologíaRESUMEN
Viral genomes have evolved to maximize their potential of overcoming host defense mechanisms and to induce a variety of disease syndromes. Structurally, a genome of a virus consists of coding and noncoding regions, and both have been shown to contribute to initiation and progression of disease. Accumulated work in picornaviruses has stressed out the importance of the noncoding RNAs, or untranslated 5'- and 3'-regions (UTRs), in both replication and translation of viral genomes. Unsurprisingly, defects in these processes have been reported to cause viral attenuation and affect viral pathogenicity. However, substantial evidence suggests that these untranslated RNAs may influence the outcome of the host innate immune response. This review discusses the involvement of 5'- and 3'-terminus UTRs in induction and regulation of host immunity and its consequences for viral life cycle and virulence.
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The S fragment of the FMDV 5' UTR is predicted to fold into a long stem-loop structure and it has been implicated in virus-host protein interactions. In this study, we report the minimal S fragment sequence required for virus viability and show a direct correlation between the extent of the S fragment deletion mutations and attenuated phenotypes. Furthermore, we provide novel insight into the role of the S fragment in modulating the host innate immune response. Importantly, in an FMDV mouse model system, all animals survive the inoculation with the live A24 FMDV-S4 mutant, containing a 164 nucleotide deletion in the upper S fragment loop, at a dose 1000 higher than the one causing lethality by parental A24 FMDV, indicating that the A24 FMDV-S4 virus is highly attenuated in vivo. Additionally, mice exposed to high doses of live A24 FMDV-S4 virus are fully protected when challenged with parental A24 FMDV virus.
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Regiones no Traducidas 5'/genética , Virus de la Fiebre Aftosa/fisiología , Inmunidad Innata/fisiología , Replicación Viral/fisiología , Animales , Bovinos , Línea Celular , Cricetinae , Virus de la Fiebre Aftosa/genética , ARN Viral/genética , Eliminación de Secuencia , Replicación Viral/genéticaRESUMEN
Foot-and-mouth disease virus (FMDV) RNA-dependent RNA polymerase (RdRp) (3Dpol) catalyzes viral RNA synthesis. Its characteristic low fidelity and absence of proofreading activity allow FMDV to rapidly mutate and adapt to dynamic environments. In this study, we used the structure of FMDV 3Dpol in combination with previously reported results from similar picornaviral polymerases to design point mutations that would alter replication fidelity. In particular, we targeted Trp237 within conserved polymerase motif A because of the low reversion potential inherent in the single UGG codon. Using biochemical and genetic tools, we show that the replacement of tryptophan 237 with phenylalanine imparts higher fidelity, but replacements with isoleucine and leucine resulted in lower-fidelity phenotypes. Viruses containing these W237 substitutions show in vitro growth kinetics and plaque morphologies similar to those of the wild-type (WT) A24 Cruzeiro strain in BHK cells, and both high- and low-fidelity variants retained fitness during coinfection with the wild-type virus. The higher-fidelity W237F (W237FHF) mutant virus was more resistant to the mutagenic nucleoside analogs ribavirin and 5-fluorouracil than the WT virus, whereas the lower-fidelity W237I (W237ILF) and W237LLF mutant viruses exhibited lower ribavirin resistance. Interestingly, the variant viruses showed heterogeneous and slightly delayed growth kinetics in primary porcine kidney cells, and they were significantly attenuated in mouse infection experiments. These data demonstrate, for a single virus, that either increased or decreased RdRp fidelity attenuates virus growth in animals, which is a desirable feature for the development of safer and genetically more stable vaccine candidates.IMPORTANCE Foot-and-mouth disease (FMD) is the most devastating disease affecting livestock worldwide. Here, using structural and biochemical analyses, we have identified FMDV 3Dpol mutations that affect polymerase fidelity. Recombinant FMDVs containing substitutions at 3Dpol tryptophan residue 237 were genetically stable and displayed plaque phenotypes and growth kinetics similar to those of the wild-type virus in cell culture. We further demonstrate that viruses harboring either a W237FHF substitution or W237ILF and W237LLF mutations were highly attenuated in animals. Our study shows that obtaining 3Dpol fidelity variants by protein engineering based on polymerase structure and function could be exploited for the development of attenuated FMDV vaccine candidates that are safer and more stable than strains obtained by selective pressure via mutagenic nucleotides or adaptation approaches.
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Antígenos Virales/genética , Antígenos Virales/metabolismo , Virus de la Fiebre Aftosa/enzimología , Virus de la Fiebre Aftosa/patogenicidad , Ingeniería de Proteínas , Proteínas no Estructurales Virales/genética , Proteínas no Estructurales Virales/metabolismo , Sustitución de Aminoácidos , Animales , Antivirales , Células Cultivadas , Cricetinae , Análisis Mutacional de ADN , Modelos Animales de Enfermedad , Farmacorresistencia Viral , Fluorouracilo/farmacología , Fiebre Aftosa/patología , Fiebre Aftosa/virología , Virus de la Fiebre Aftosa/genética , Virus de la Fiebre Aftosa/crecimiento & desarrollo , Ratones , Mutagénesis Sitio-Dirigida , Mutación Puntual , Ribavirina/farmacología , Porcinos , Triptófano/genética , Triptófano/metabolismo , Ensayo de Placa ViralRESUMEN
African swine fever virus (ASFV) is the etiological agent of a contagious and often lethal disease of domestic pigs that has significant economic consequences for the swine industry. The viral genome encodes for more than 150 genes, and only a select few of these genes have been studied in some detail. Here we report the characterization of open reading frame Ep152R that has a predicted complement control module/SCR domain. This domain is found in Vaccinia virus proteins that are involved in blocking the immune response during viral infection. A recombinant ASFV harboring a HA tagged version of the Ep152R protein was developed (ASFV-G-Ep152R-HA) and used to demonstrate that Ep152R is an early virus protein. Attempts to construct recombinant viruses having a deleted Ep152R gene were consistently unsuccessful indicating that Ep152R is an essential gene. Interestingly, analysis of host-protein interactions for Ep152R using a yeast two-hybrid screen, identified BAG6, a protein previously identified as being required for ASFV replication. Furthermore, fluorescent microscopy analysis confirms that Ep152R-BAG6 interaction actually occurs in cells infected with ASFV.
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Virus de la Fiebre Porcina Africana/fisiología , Fiebre Porcina Africana/metabolismo , Fiebre Porcina Africana/virología , Genes Esenciales , Chaperonas Moleculares/metabolismo , Proteínas Virales/genética , Proteínas Virales/metabolismo , Secuencia de Aminoácidos , Animales , Células Cultivadas , Secuencia Conservada , Interacciones Huésped-Patógeno , Macrófagos/metabolismo , Macrófagos/virología , Modelos Moleculares , Chaperonas Moleculares/química , Chaperonas Moleculares/genética , Sistemas de Lectura Abierta , Unión Proteica , Conformación Proteica , Mapeo de Interacción de Proteínas/métodos , Transporte de Proteínas , Eliminación de Secuencia , Porcinos , Técnicas del Sistema de Dos Híbridos , Proteínas Virales/química , Replicación ViralRESUMEN
Here, we engineered two FMD viruses with histidine residues inserted into or fused to the FMDV capsid. Both 6xHis viruses exhibited growth kinetics, plaque morphologies and antigenic characteristics similar to wild-type virus. The 6xHis tag allowed one-step purification of the mutant virions by Co(2+) affinity columns. Electron microscopy and biochemical assays showed that the 6xHis FMDVs readily assembled into antigen: adjuvant complexes in solution, by conjugating with Ni(2+)-chelated nanolipoprotein and monophosphoryl lipid A adjuvant (MPLA:NiNLP). Animals Immunized with the inactivated 6xHis-FMDV:MPLA:NiNLP vaccine acquired enhanced protective immunity against FMDV challenge compared to virions alone. Induction of anti-6xHis and anti-FMDV neutralizing antibodies in the immunized animals could be exploited in the differentiation of vaccinated from infected animals needed for the improvement of FMD control measures. The novel marker vaccine/nanolipid technology described here has broad applications for the development of distinctive and effective immune responses to other pathogens of importance.
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Adyuvantes Inmunológicos , Virus de la Fiebre Aftosa/inmunología , Fiebre Aftosa/inmunología , Fiebre Aftosa/prevención & control , Iones , Metales , Nanopartículas , Vacunas Virales/inmunología , Animales , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Antígenos Virales/inmunología , Virus de la Fiebre Aftosa/genética , Orden Génico , Genoma Viral , Lipoproteínas/inmunología , Modelos Moleculares , Mutación , Unión Proteica , Conformación Proteica , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/inmunología , Vacunas Virales/genéticaRESUMEN
A companion study reported Jumonji-C domain containing protein 6 (JMJD6) is involved in an integrin- and HS-independent pathway of FMDV infection in CHO cells. JMJD6 localization was investigated in animal tissues from cattle infected with either wild type A24-FMDV (A24-WT) or mutant FMDV (JMJD6-FMDV) carrying E95K/S96L and RGD to KGE mutations in VP1. Additionally, pathogenesis of mutant JMJD6-FMDV was investigated in cattle through aerosol and intraepithelial lingual (IEL) inoculation. Interestingly, JMJD6-FMDV pathogenesis was equivalent to A24-WT administered by IEL route. In contrast, JMJD6-FMDV aerosol-infected cattle did not manifest signs of FMD and animals showed no detectable viremia. Immunofluorescent microscopy of post-mortem tissue revealed JMJD6-FMDV exclusively co-localized with JMJD6(+) cells while A24-WT was occasionally found in JMJD6(+) cells. In vitro, chemical uptake inhibitors demonstrated JMJD6-FMDV entered cells via clathrin-coated pit endocytosis. In vivo, JMJD6-FMDV exhibited preference for JMJD6(+) cells, but availability of this alternative receptor likely depends on route of inoculation.
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Enfermedades de los Bovinos/prevención & control , Virus de la Fiebre Aftosa/inmunología , Fiebre Aftosa/prevención & control , Histona Demetilasas con Dominio de Jumonji/inmunología , Vacunación , Administración por Inhalación , Animales , Células CHO , Bovinos , Enfermedades de los Bovinos/inmunología , Enfermedades de los Bovinos/patología , Enfermedades de los Bovinos/virología , Línea Celular , Vesículas Cubiertas por Clatrina/metabolismo , Cricetulus , Endocitosis , Células Epiteliales/virología , Fiebre Aftosa/inmunología , Fiebre Aftosa/patología , Fiebre Aftosa/virología , Virus de la Fiebre Aftosa/genética , Virus de la Fiebre Aftosa/metabolismo , Expresión Génica , Interacciones Huésped-Patógeno , Humanos , Integrinas/genética , Integrinas/metabolismo , Histona Demetilasas con Dominio de Jumonji/antagonistas & inhibidores , Histona Demetilasas con Dominio de Jumonji/genética , Histona Demetilasas con Dominio de Jumonji/metabolismo , Mutagénesis , Mutación , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Receptores Virales/genética , Receptores Virales/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Proteínas Recombinantes/metabolismo , LenguaRESUMEN
BACKGROUND: The nuclear protein Src-associated protein of 68 kDa in mitosis (Sam68) is known to bind RNA and be involved in cellular processes triggered in response to environmental stresses, including virus infection. Interestingly, Sam68 is a multi-functional protein implicated in the life cycle of retroviruses and picornaviruses and is also considered a marker of virus-induced stress granules (SGs). Recently, we demonstrated the partial redistribution of Sam68 to the cytoplasm in FMDV infected cells, its interaction with viral protease 3C(pro), and found a significant reduction in viral titers as consequence of Sam68-specific siRNA knockdowns. Despite of that, details of how it benefits FMDV remains to be elucidated. METHODS: Sam68 cytoplasmic localization was examined by immunofluorescent microscopy, counterstaining with antibodies against Sam68, a viral capsid protein and markers of SGs. The relevance of RAAA motifs in the IRES was investigated using electromobility shift assays with Sam68 protein and parental and mutant FMDV RNAs. In addition, full genome WT and mutant or G-luc replicon RNAs were tested following transfection in mammalian cells. The impact of Sam68 depletion to virus protein and RNA synthesis was investigated in a cell-free system. Lastly, through co-immunoprecipitation, structural modeling, and subcellular fractionation, viral protein interactions with Sam68 were explored. RESULTS: FMDV-induced cytoplasmic redistribution of Sam68 resulted in it temporarily co-localizing with SG marker: TIA-1. Mutations that disrupted FMDV IRES RAAA motifs, with putative affinity to Sam68 in domain 3 and 4 cause a reduction on the formation of ribonucleoprotein complexes with this protein and resulted in non-viable progeny viruses and replication-impaired replicons. Furthermore, depletion of Sam68 in cell-free extracts greatly diminished FMDV RNA replication, which was restored by addition of recombinant Sam68. The results here demonstrated that Sam68 specifically co-precipitates with both FMDV 3D(pol) and 3C(pro) consistent with early observations of FMDV 3C(pro)-induced cleavage of Sam68. CONCLUSION: We have found that Sam68 is a specific binding partner for FMDV non-structural proteins 3C(pro) and 3D(pol) and showed that mutations at RAAA motifs in IRES domains 3 and 4 cause a decrease in Sam68 affinity to these RNA elements and rendered the mutant RNA non-viable. Interestingly, in FMDV infected cells re-localized Sam68 was transiently detected along with SG markers in the cytoplasm. These results support the importance of Sam68 as a host factor co-opted by FMDV during infection and demonstrate that Sam68 interact with both, FMDV RNA motifs in the IRES and viral non-structural proteins 3C(pro) and 3D(pol).
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Antígenos Virales/metabolismo , Cisteína Endopeptidasas/metabolismo , Proteínas de Unión al ADN/metabolismo , Virus de la Fiebre Aftosa/fisiología , Fiebre Aftosa/patología , Fiebre Aftosa/virología , Interacciones Huésped-Patógeno , Proteínas de Unión al ARN/metabolismo , Proteínas no Estructurales Virales/metabolismo , Proteínas Virales/metabolismo , Proteasas Virales 3C , Animales , Antígenos Virales/química , Línea Celular , Cisteína Endopeptidasas/química , Citoplasma/química , Análisis Mutacional de ADN , Inmunoprecipitación , Sitios Internos de Entrada al Ribosoma , Microscopía Fluorescente , Modelos Moleculares , Unión Proteica , Conformación Proteica , ARN Viral/genética , ARN Viral/metabolismo , Proteínas no Estructurales Virales/química , Proteínas Virales/químicaRESUMEN
Bovine rhinitis viruses (BRVs) cause mild respiratory disease of cattle. In this study, a near full-length genome sequence of a virus named RS3X (formerly classified as bovine rhinovirus type 1), isolated from infected cattle from the UK in the 1960s, was obtained and analyzed. Compared to other closely related Aphthoviruses, major differences were detected in the leader protease (L(pro)), P1, 2B, and 3A proteins. Phylogenetic analysis revealed that RS3X was a member of the species bovine rhinitis A virus (BRAV). Using different codon-based and branch-site selection models for Aphthoviruses, including BRAV RS3X and foot-and-mouth disease virus, we observed no clear evidence for genomic regions undergoing positive selection. However, within each of the BRV species, multiple sites under positive selection were detected. The results also suggest that the probability (determined by Recombination Detection Program) for recombination events between BRVs and other Aphthoviruses, including foot-and-mouth disease virus was not significant. In contrast, within BRVs, the probability of recombination increases. The data reported here provide genetic information to assist in the identification of diagnostic signatures and research tools for BRAV.
RESUMEN
In this study we describe the adaptive changes fixed on the capsid of several foot-and-mouth disease virus serotype A strains during propagation in cell monolayers. Viruses passaged extensively in three cell lines (BHK-21, LFBK and IB-RS-2) consistently gained positively charged amino acids in the putative heparin-sulfate-binding pocket (VP2 ßE-ßF loop, VP1 C-terminus and VP3 ß-B knob) surrounding the fivefold symmetry axis (VP1 ßF-ßG loop) and at other discrete sites on the capsid (VP3 ßG-ßH loop, VP1 C-terminus, VP2 ßC strand and VP1 ßG-ßH loop). A lysine insertion in the VP1 ßF-ßG loop of two of the BHK-21-adapted viruses supports the biological advantage of positively charged residues acquired in cell culture. The charge transitions occurred irrespective of cell line, suggesting their possible role in ionic interaction with ubiquitous negatively charged cell-surface molecules such as glycosaminoglycans (GAG). This was supported by the ability of the cell-culture-adapted variants to replicate in the integrin-deficient, GAG-positive CHO-K1 cells and their superior fitness in competition assays compared with the lower passage viruses with WT genotypes. Substitutions fixed in the VP1 ßG-ßH loop (-3, -2 and +2 'RGD' positions) or in the structural element known to be juxtaposed against that loop (VP1 ßB-ßC loop) suggest their possible role in modulating the efficiency and specificity of interaction of the 'RGD' motif with αv-integrin receptors. The nature and location of the substitutions described in this study could be applied in the rapid cell culture adaptation of viral strains for vaccine production.