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1.
Cell Host Microbe ; 31(1): 3-5, 2023 01 11.
Artigo em Inglês | MEDLINE | ID: mdl-36634621

RESUMO

Phage-inducible chromosomal islands (PICIs) steal structural proteins from helper phages. In two related studies, Penadés and coworkers reveal that PICIs are not parasites but mutualists. Some PICIs mobilize defense systems that restrict niche competitors, while other PICIs encode their own capsids and steal helper phage tails without affecting their fitness.


Assuntos
Bacteriófagos , Ilhas Genômicas , Bacteriófagos/genética , Capsídeo
2.
Int J Mol Sci ; 24(2)2023 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-36675014

RESUMO

(1) Multiple sclerosis (MS) is a chronic inflammatory disease of autoimmune origin. The Epstein-Barr virus (EBV) is associated with the onset of MS, as almost all patients have high levels of EBV-specific antibodies as a result of a previous infection. We evaluated longitudinally the effects of dimethyl fumarate (DMF), a first-line treatment of MS, on the quantity and quality of EBV-specific IgG in MS patients. (2) Serum samples from 17 MS patients receiving DMF were taken before therapy (T0) and after 1 week (T1) and 1 (T2), 3 (T3) and 6 (T4) months of treatment. Anti-EBV nuclear antigen (EBNA)-1 and capsid antigen (CA) IgG levels and anti-CA IgG avidity were measured in all samples. (3) Serum levels of anti-CA IgG were lower at T1 (p = 0.0341), T2 (p = 0.0034), T3 (p < 0.0001) and T4 (p = 0.0023) than T0. These differences were partially confirmed also in anti-EBNA-1 IgG levels (T3 vs. T0, p = 0.0034). All patients had high-avidity anti-CA IgG at T0, and no changes were observed during therapy. (4): DMF can reduce the amount but not the avidity of the anti-EBV humoral immune response in MS patients from the very early stages of treatment.


Assuntos
Infecções por Vírus Epstein-Barr , Esclerose Múltipla , Humanos , Herpesvirus Humano 4 , Antígenos Virais , Projetos Piloto , Fumarato de Dimetilo/farmacologia , Fumarato de Dimetilo/uso terapêutico , Capsídeo , Formação de Anticorpos , Imunoglobulina G , Anticorpos Antivirais , Proteínas do Capsídeo
3.
Proc Natl Acad Sci U S A ; 120(4): e2213727120, 2023 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-36656854

RESUMO

The myophage possesses a contractile tail that penetrates its host cell envelope. Except for investigations on the bacteriophage T4 with a rather complicated structure, the assembly pattern and tail contraction mechanism of myophage remain largely unknown. Here, we present the fine structure of a freshwater Myoviridae cyanophage Pam3, which has an icosahedral capsid of ~680 Å in diameter, connected via a three-section neck to an 840-Å-long contractile tail, ending with a three-module baseplate composed of only six protein components. This simplified baseplate consists of a central hub-spike surrounded by six wedge heterotriplexes, to which twelve tail fibers are covalently attached via disulfide bonds in alternating upward and downward configurations. In vitro reduction assays revealed a putative redox-dependent mechanism of baseplate assembly and tail sheath contraction. These findings establish a minimal myophage that might become a user-friendly chassis phage in synthetic biology.


Assuntos
Myoviridae , Montagem de Vírus , Bacteriófago T4/química , Capsídeo , Proteínas do Capsídeo/química , Microscopia Crioeletrônica , Myoviridae/química
4.
Mol Cell ; 83(2): 165-166, 2023 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-36669478

RESUMO

Zhang et al.1 reveal a previously unknown route to toxin activation whereby bacteriophage capsid proteins bind the antitoxin domain of the CapRel fused toxin-antitoxin system, triggering translational inhibition via pyrophosporylation of tRNAs and culminating in abortive infection-mediated phage resistance.


Assuntos
Antitoxinas , Toxinas Bacterianas , Bacteriófagos , Sistemas Toxina-Antitoxina , Bacteriófagos/metabolismo , Proteínas do Capsídeo/genética , Capsídeo/metabolismo , Bactérias/metabolismo , Antitoxinas/metabolismo , Toxinas Bacterianas/genética , Toxinas Bacterianas/metabolismo , Proteínas de Bactérias/metabolismo
5.
Antimicrob Agents Chemother ; 67(1): e0134822, 2023 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-36519892

RESUMO

The standard of care for the treatment of chronic hepatitis B (CHB) is typically lifelong treatment with nucleos(t)ide analogs (NAs), which suppress viral replication and provide long-term clinical benefits. However, infectious virus can still be detected in patients who are virally suppressed on NA therapy, which may contribute to the failure of these agents to cure most CHB patients. Accordingly, new antiviral treatment options are being developed to enhance the suppression of hepatitis B virus (HBV) replication in combination with NAs ("antiviral intensification"). Here, we describe GS-SBA-1, a capsid assembly modulator (CAM) belonging to class CAM-E, that demonstrates potent inhibition of extracellular HBV DNA in vitro (EC50 [50% effective concentration] = 19 nM) in HBV-infected primary human hepatocytes (PHHs) as well as in vivo in an HBV-infected immunodeficient mouse model. GS-SBA-1 has comparable activities across HBV genotypes and nucleos(t)ide-resistant mutants in HBV-infected PHHs. In addition, GS-SBA-1 demonstrated in vitro additivity in combination with tenofovir alafenamide (TAF). The administration of GS-SBA-1 to PHHs at the time of infection prevents covalently closed circular DNA (cccDNA) formation and, hence, decreases HBV RNA and antigen levels (EC50 = 80 to 200 nM). Furthermore, GS-SBA-1 prevents the production of extracellular HBV RNA-containing viral particles in vitro. Collectively, these data demonstrate that GS-SBA-1 is a potent CAM that has the potential to enhance viral suppression in combination with an NA.


Assuntos
Hepatite B Crônica , Hepatite B , Animais , Camundongos , Humanos , Hepatite B Crônica/tratamento farmacológico , Capsídeo , Vírus da Hepatite B , Antivirais/farmacologia , Antivirais/uso terapêutico , Proteínas do Capsídeo/genética , RNA , DNA Viral/genética , DNA Circular , Hepatite B/tratamento farmacológico
6.
Hum Gene Ther ; 34(1-2): 68-77, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36503264

RESUMO

A prototype strain of Coxsackievirus A21 (CVA21) is being evaluated as an oncolytic virus immunotherapy. CVA21 preferentially lyses cells that upregulate the expression of intercellular adhesion molecule 1, which includes some types of tumor cells. CVA21 has an icosahedral capsid structure made up of 60 protein subunits encapsidating a viral RNA genome with a particle diameter size of 30 nm. Rapid and robust analytical methods to quantify CVA21 total, empty, and full virus particles are important to support the process development, meet regulatory requirements, and validate manufacturing processes. In this study, we demonstrate the detection of all four CVA21 capsid proteins, VP1, VP2, VP3, and VP4, as well as VP0, a surrogate for empty particles, using in-house-generated antibodies. An automated and quantitative capillary Western blot assay, Simple Western, was developed using these antibodies to quantify CVA21 total particles through VP1, empty particles through VP0, relative ratio of empty to full particles through VP0 and VP4, and the absolute ratio of empty to total particles through VP0 and VP1. Finally, this Simple Western method was used to support CVA21 cell culture and purification process optimization as a high-throughput analytical tool to make rapid process decisions.


Assuntos
Capsídeo , Vírus Oncolíticos , Capsídeo/metabolismo , Vírus Oncolíticos/metabolismo , Proteínas Virais , Proteínas do Capsídeo/genética , Proteínas do Capsídeo/metabolismo
7.
Proc Natl Acad Sci U S A ; 119(50): e2203054119, 2022 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-36469786

RESUMO

Mammalian reovirus (reovirus) is a multilayered, turreted member of Reoviridae characterized by transcription of dsRNA genome within the innermost capsid shell. Here, we present high-resolution in situ structures of reovirus transcriptase complex in an intact double-layered virion, and in the uncoated single-layered core particles in the unloaded, reloaded, pre-elongation, and elongation states, respectively, obtained by cryo-electron microscopy and sub-particle reconstructions. At the template entry of RNA-dependent RNA polymerase (RdRp), the RNA-loading region gets flexible after uncoating resulting in the unloading of terminal genomic RNA and inactivity of transcription. However, upon adding transcriptional substrates, the RNA-loading region is recovered leading the RNAs loaded again. The priming loop in RdRp was found to play a critical role in regulating transcription, which hinders the elongation of transcript in virion and triggers the rearrangement of RdRp C-terminal domain (CTD) during elongation, resulting in splitting of template-transcript hybrid and opening of transcript exit. With the integration of these structures, a transcriptional model of reovirus with five states is proposed. Our structures illuminate the RdRp activation and regulation of the multilayered turreted reovirus.


Assuntos
RNA Viral , Reoviridae , Animais , Microscopia Crioeletrônica , RNA Viral/genética , Reoviridae/genética , RNA Polimerase Dependente de RNA/genética , Capsídeo , Mamíferos/genética
8.
Nat Commun ; 13(1): 7854, 2022 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-36543790

RESUMO

Coxsackievirus A16 (CVA16) causes hand, foot and mouth disease in infants and young children. However, no vaccine or anti-viral agent is currently available for CVA16. Here, the functions and working mechanisms of two CVA16-specific neutralizing monoclonal antibodies (MAbs), 9B5 and 8C4, are comprehensively investigated. Both 9B5 and 8C4 display potent neutralization in vitro and prophylactic and therapeutic efficacy in a mouse model of CVA16 infection. Mechanistically, 9B5 exerts neutralization primarily through inhibiting CVA16 attachment to cell surface via blockade of CVA16 binding to its attachment receptor, heparan sulfate, whereas 8C4 functions mainly at the post-attachment stage of CVA16 entry by interfering with the interaction between CVA16 and its uncoating receptor SCARB2. Cryo-EM studies show that 9B5 and 8C4 target distinct epitopes located at the 5-fold and 3-fold protrusions of CVA16 capsids, respectively, and exhibit differential binding preference to three forms of naturally occurring CVA16 particles. Moreover, 9B5 and 8C4 are compatible in formulating an antibody cocktail which displays the ability to prevent virus escape seen with individual MAbs. Together, our work elucidates the functional and structural basis of CVA16 antibody-mediated neutralization and protection, providing important information for design and development of effective CVA16 vaccines and antibody therapies.


Assuntos
Infecções por Coxsackievirus , Enterovirus Humano A , Enterovirus , Camundongos , Animais , Enterovirus Humano A/química , Anticorpos Neutralizantes , Capsídeo/química , Proteínas do Capsídeo/química , Enterovirus/química
9.
Viruses ; 14(12)2022 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-36560654

RESUMO

Upon infection, viruses hijack the cell machinery and remodel host cell structures to utilize them for viral proliferation. Since viruses are about a thousand times smaller than their host cells, imaging virus-host interactions at high spatial resolution is like looking for a needle in a haystack. Scouting gross cellular changes with fluorescent microscopy is only possible for well-established viruses, where fluorescent tagging is developed. Soft X-ray tomography (SXT) offers 3D imaging of entire cells without the need for chemical fixation or labeling. Here, we use full-rotation SXT to visualize entire human B cells infected by the herpes simplex virus 1 (HSV-1). We have mapped the temporospatial remodeling of cells during the infection and observed changes in cellular structures, such as the presence of cytoplasmic stress granules and multivesicular structures, formation of nuclear virus-induced dense bodies, and aggregates of capsids. Our results demonstrate the power of SXT imaging for scouting virus-induced changes in infected cells and understanding the orchestration of virus-host remodeling quantitatively.


Assuntos
Herpesvirus Humano 1 , Humanos , Herpesvirus Humano 1/química , Tomografia por Raios X/métodos , Capsídeo
10.
Int J Mol Sci ; 23(23)2022 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-36499027

RESUMO

Macromolecular self-assembly is at the basis of many phenomena in material and life sciences that find diverse applications in technology. One example is the formation of virus-like particles (VLPs) that act as stable empty capsids used for drug delivery or vaccine fabrication. Similarly to the capsid of a virus, VLPs are protein assemblies, but their structural formation, stability, and properties are not fully understood, especially as a function of the protein modifications. In this work, we present a data-driven modeling approach for capturing macromolecular self-assembly on scales beyond traditional molecular dynamics (MD), while preserving the chemical specificity. Each macromolecule is abstracted as an anisotropic object and high-dimensional models are formulated to describe interactions between molecules and with the solvent. For this, data-driven protein-protein interaction potentials are derived using a Kriging-based strategy, built on high-throughput MD simulations. Semi-automatic supervised learning is employed in a high performance computing environment and the resulting specialized force-fields enable a significant speed-up to the micrometer and millisecond scale, while maintaining high intermolecular detail. The reported generic framework is applied for the first time to capture the formation of hepatitis B VLPs from the smallest building unit, i.e., the dimer of the core protein HBcAg. Assembly pathways and kinetics are analyzed and compared to the available experimental observations. We demonstrate that VLP self-assembly phenomena and dependencies are now possible to be simulated. The method developed can be used for the parameterization of other macromolecules, enabling a molecular understanding of processes impossible to be attained with other theoretical models.


Assuntos
Partículas Artificiais Semelhantes a Vírus , Vírus da Hepatite B , Substâncias Macromoleculares , Capsídeo/química , Proteínas do Capsídeo/química , Antígenos do Núcleo do Vírus da Hepatite B , Substâncias Macromoleculares/química , Partículas Artificiais Semelhantes a Vírus/química
11.
J Chem Phys ; 157(24): 244901, 2022 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-36586982

RESUMO

The promise of self-assembly to enable the bottom-up formation of materials with prescribed architectures and functions has driven intensive efforts to uncover rational design principles for maximizing the yield of a target structure. Yet, despite many successful examples of self-assembly, ensuring kinetic accessibility of the target structure remains an unsolved problem in many systems. In particular, long-lived kinetic traps can result in assembly times that vastly exceed experimentally accessible timescales. One proposed solution is to design non-equilibrium assembly protocols in which system parameters change over time to avoid such kinetic traps. Here, we develop a framework to combine Markov state model (MSM) analysis with optimal control theory to compute a time-dependent protocol that maximizes the yield of the target structure at a finite time. We present an adjoint-based gradient descent method that, in conjunction with MSMs for a system as a function of its control parameters, enables efficiently optimizing the assembly protocol. We also describe an interpolation approach to significantly reduce the number of simulations required to construct the MSMs. We demonstrate our approach with two examples; a simple semi-analytic model for the folding of a polymer of colloidal particles, and a more complex model for capsid assembly. Our results show that optimizing time-dependent protocols can achieve significant improvements in the yields of selected structures, including equilibrium free energy minima, long-lived metastable structures, and transient states.


Assuntos
Proteínas do Capsídeo , Capsídeo , Capsídeo/química , Polímeros/análise
12.
Int J Mol Sci ; 23(23)2022 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-36499678

RESUMO

TRIM5α is a host anti-retroviral restriction factor that destroys human immunodeficiency virus (HIV) virions and triggers innate immune signaling. TRIM5α also mediates the autophagic degradation of target proteins via TRIMosome formation. We previously showed that TRIM5α promotes Epstein-Barr virus (EBV) Rta ubiquitination and attenuates EBV lytic progression. In this study, we sought to elucidate whether TRIM5α can interact with and induce the degradation of EBV capsid proteins. Glutathione S-transferase (GST) pulldown and immunoprecipitation assays were conducted to identify interacting proteins, and mutants were generated to investigate key binding domains and ubiquitination sites. Results showed that TRIM5α binds directly with BORF1, an EBV capsid protein with a nuclear localization signal (NLS) that enables the transport of EBV capsid proteins into the host nucleus to facilitate capsid assembly. TRIM5α promotes BORF1 ubiquitination, which requires the surface patch region in the TRIM5α PRY/SPRY domain. TRIM5α expression also decreases the stability of BORF1(6KR), a mutant with all lysine residues mutated to arginine. However, chloroquine treatment restores the stability of BORF1(6KR), suggesting that TRIM5α destabilizes BORF1 via direct recognition of its substrate for autophagic degradation. These results reveal novel insights into the antiviral impact of TRIM5α beyond retroviruses.


Assuntos
Proteínas do Capsídeo , Infecções por Vírus Epstein-Barr , Humanos , Proteínas do Capsídeo/genética , Proteínas do Capsídeo/metabolismo , Herpesvirus Humano 4/genética , Herpesvirus Humano 4/metabolismo , Infecções por Vírus Epstein-Barr/genética , Infecções por Vírus Epstein-Barr/metabolismo , Capsídeo/metabolismo , Ubiquitinação , Retroviridae , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo , Proteínas com Motivo Tripartido/genética , Proteínas com Motivo Tripartido/metabolismo
13.
Sci Rep ; 12(1): 21428, 2022 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-36504202

RESUMO

Marseilleviridae is a family of giant viruses, showing a characteristic internal membrane with extrusions underneath the icosahedral vertices. However, such large objects, with a maximum diameter of 250 nm are technically difficult to examine at sub-nanometre resolution by cryo-electron microscopy. Here, we tested the utility of 1 MV high-voltage cryo-EM (cryo-HVEM) for single particle structural analysis (SPA) of giant viruses using tokyovirus, a species of Marseilleviridae, and revealed the capsid structure at 7.7 Å resolution. The capsid enclosing the viral DNA consisted primarily of four layers: (1) major capsid proteins (MCPs) and penton proteins, (2) minor capsid proteins (mCPs), (3) scaffold protein components (ScPCs), and (4) internal membrane. The mCPs showed a novel capsid lattice consisting of eight protein components. ScPCs connecting the icosahedral vertices supported the formation of the membrane extrusions, and possibly act like tape measure proteins reported in other giant viruses. The density on top of the MCP trimer was suggested to include glycoproteins. This is the first attempt at cryo-HVEM SPA. We found the primary limitations to be the lack of automated data acquisition and software support for collection and processing and thus achievable resolution. However, the results pave the way for using cryo-HVEM for structural analysis of larger biological specimens.


Assuntos
Vírus Gigantes , Proteínas do Capsídeo , Microscopia Crioeletrônica , Capsídeo , Membranas
14.
Viruses ; 14(12)2022 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-36560770

RESUMO

Over 240 million people worldwide are chronically infected with Hepatitis B Virus (HBV), a hepatotropic DNA virus with an evolutionary root of over 400 million years. Persistent HBV infection exhibits distinct and diverse phases of disease, from minimal liver pathology to fulminant Hepatitis, that vary in duration and severity among individuals. Although huge progress has been made in HBV research which has yielded an effective prophylactic vaccine and potent antiviral therapy, our understanding of its virology and immunobiology is still far from complete. For example, the recent re-discovery of serum HBV RNA in chronic Hepatitis B (CHB) patients has led to the proposal of noncanonical viral particles such as RNA virion and capsid-derived immune complex (Capsid-Antibody-Complexes, CACs) that contradict long-established basic theory. Furthermore, the existence of capsid-derived immune complex may hint at novel mechanism of HBV-induced liver disease. Here, we summarize the past and recent literature on HBV-induced immune complex. We propose that the release of capsid-derived particles by HBV has its deep evolutionary origin, and the associated complement activation serves as an indispensable trigger for intrahepatic damage and a catalyst for further cell-mediated immunopathology.


Assuntos
Vírus da Hepatite B , Hepatite B Crônica , Humanos , Vírus da Hepatite B/genética , Capsídeo , Complexo Antígeno-Anticorpo , Proteínas do Capsídeo , RNA , DNA Viral , Replicação Viral
15.
PLoS One ; 17(11): e0272474, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36383523

RESUMO

Hepatitis B virus (HBV) morphogenesis is characterized by a large over-production of subviral particles and recently described new forms in parallel of complete viral particles (VP). This study was designed to depict circulating viral forms in HBV infected patient plasmas, using velocity gradients and most sensitive viral markers. Plasmas from chronic hepatitis B (CHB) patients, HBeAg positive or negative, genotype D or E, were fractionated on velocity and equilibrium gradients with or without detergent treatment. Antigenic and molecular markers were measured in plasma and in each collected fraction. Fast Nycodenz velocity gradients revealed good reproducibility and provided additional information to standard equilibrium sucrose gradients. HBV-RNAs circulated as enveloped particles in all plasmas, except one, and at lesser concentrations than VP. Calculations based on standardized measurements and relative virion and subviral particle molecular stoichiometry allowed to refine the experimental approach. For the HBeAg-positive plasma, VP were accompanied by an overproduction of enveloped capsids, either containing HBs, likely corresponding to empty virions, or for the main part, devoid of this viral envelope protein. Similarly, in the HBeAg-negative sample, HBs enveloped capsids, likely corresponding to empty virions, were detected and the presence of enveloped capsids devoid of HBs protein was suspected but not clearly evidenced due to the presence of contaminating high-density subviral particles. While HBeAg largely influences HBcrAg measurement and accounts for two-thirds of HBcrAg reactivity in HBeAg-positive patients, it remains a 10 times more sensitive marker than HBsAg to characterize VP containing fractions. Using Nycodenz velocity gradients and standardized biomarkers, our study proposes a detailed characterization of circulating viral forms in chronically HBV infected patients. We provide evidence for an excess of capsids in fractions enriched in Dane particles, likely due to the presence of empty virions but also by capsids enveloped by an HBs free lipid layer. Identification of this new circulating viral particle sets the basis for studies around the potential role of these entities in hepatitis B pathogeny and their physiological regulation.


Assuntos
Hepatite B Crônica , Hepatite B , Humanos , Vírus da Hepatite B/genética , Capsídeo/metabolismo , Antígenos E da Hepatite B/metabolismo , Iohexol/metabolismo , Reprodutibilidade dos Testes , Antígenos de Superfície da Hepatite B , DNA Viral/metabolismo
16.
Molecules ; 27(21)2022 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-36363990

RESUMO

DNA nanostructures are well-established vectors for packaging diversified payloads for targeted cellular delivery. Here, DNA origami rectangular sheets were combined with Herpes Simplex Virus 1 (HSV1) capsids to demonstrate surface coverage of the particle via electrostatic interactions. The optimized origami:HSV1 molar ratios led to characteristic packaging geometries ranging from dispersed "HSV1 pockets" to agglomerated "HSV1 sleeves". "Pockets" were disguised from cells in HeLa and B16F10 cells and were 44.2% less infective than naked HSV1 particles. However, the pockets were 117% more infective than naked HSV1 particles when the origami sheets were coated with folic acid. We observed infectivity from naked origami, but they are 99.1% less infective with respect to HSV1 and 99.6% less infective with respect to the pocket complexes. This work suggests that DNA origami can selectively modulate virus infectivity.


Assuntos
Herpes Simples , Herpesvirus Humano 1 , Humanos , Virulência , Capsídeo , DNA/genética , Proteínas do Capsídeo/química
17.
Nat Commun ; 13(1): 7241, 2022 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-36433970

RESUMO

The Klebsiella jumbo myophage ϕKp24 displays an unusually complex arrangement of tail fibers interacting with a host cell. In this study, we combine cryo-electron microscopy methods, protein structure prediction methods, molecular simulations, microbiological and machine learning approaches to explore the capsid, tail, and tail fibers of ϕKp24. We determine the structure of the capsid and tail at 4.1 Šand 3.0 Šresolution. We observe the tail fibers are branched and rearranged dramatically upon cell surface attachment. This complex configuration involves fourteen putative tail fibers with depolymerase activity that provide ϕKp24 with the ability to infect a broad panel of capsular polysaccharide (CPS) types of Klebsiella pneumoniae. Our study provides structural and functional insight into how ϕKp24 adapts to the variable surfaces of capsulated bacterial pathogens, which is useful for the development of phage therapy approaches against pan-drug resistant K. pneumoniae strains.


Assuntos
Bacteriófagos , Microscopia Crioeletrônica , Klebsiella pneumoniae , Klebsiella , Capsídeo , Proteínas do Capsídeo
18.
AAPS J ; 25(1): 3, 2022 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-36414847

RESUMO

The genome content of adeno-associated virus (AAV) vectors is critical to the safety and potency of AAV-based gene therapy products. Empty capsids are considered a product-related impurity and a critical quality attribute (CQA) of the drug product, thus requiring characterization throughout the production process to demonstrate they are controlled to acceptable levels in the final drug product. Anion exchange chromatography has been used to achieve separation between empty and full capsids, but requires method development and gradient optimization for different serotypes and formulations. Here, we describe an alternative approach to quantitation that does not rely on achieving separation between empty and full capsids, but instead uses the well-established relationship between absorbance at UV A260/A280 and relation to DNA/protein content, in combination with anion-exchange chromatography to allow one to calculate the relative proportion of empty and full capsids in AAV samples from a single peak. We call this approach ACUVRA: Anion-exchange Chromatography UV-Ratio Analysis, and show the applicability of the method through a case study with recombinant AAV2 (rAAV2) process intermediates and drug substance. Method qualification and GMP validation in a quality control (QC) laboratory results show that ACUVRA is a fit-for-purpose method for process development support and characterization, while also being a QC-friendly option for GMP release testing at all stages of clinical development. Graphical abstract.


Assuntos
Capsídeo , Dependovirus , Dependovirus/genética , Capsídeo/química , Vetores Genéticos , Cromatografia , Ânions/análise , Controle de Qualidade
19.
Nat Commun ; 13(1): 7104, 2022 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-36402777

RESUMO

TRIM5α is an E3 ubiquitin ligase of the TRIM family that binds to the capsids of primate immunodeficiency viruses and blocks viral replication after cell entry. Here we investigate how synthesis of K63-linked polyubiquitin is upregulated by transient proximity of three RING domains in honeycomb-like assemblies formed by TRIM5α on the surface of the retroviral capsid. Proximity of three RINGs creates an asymmetric arrangement, in which two RINGs form a catalytic dimer that activates E2-ubiquitin conjugates and the disordered N-terminus of the third RING acts as the substrate for N-terminal autoubiquitylation. RING dimerization is required for activation of the E2s that contribute to the antiviral function of TRIM5α, UBE2W and heterodimeric UBE2N/V2, whereas the proximity of the third RING enhances the rate of each of the two distinct steps in the autoubiquitylation process: the initial N-terminal monoubiquitylation (priming) of TRIM5α by UBE2W and the subsequent extension of the K63-linked polyubiquitin chain by UBE2N/V2. The mechanism we describe explains how recognition of infection-associated epitope patterns by TRIM proteins initiates polyubiquitin-mediated downstream events in innate immunity.


Assuntos
Poliubiquitina , Ubiquitina-Proteína Ligases , Animais , Poliubiquitina/metabolismo , Proteínas com Motivo Tripartido/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo , Capsídeo/metabolismo , Ubiquitina/metabolismo
20.
Structure ; 30(12): 1573-1581.e3, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36417907

RESUMO

Despite their worldwide prevalence and association with human disease, the molecular bases of human astrovirus (HAstV) infection and evolution remain poorly characterized. Here, we report the structure of the capsid protein spike of the divergent HAstV MLB clade (HAstV MLB). While the structure shares a similar folding topology with that of classical-clade HAstV spikes, it is otherwise strikingly different. We find no evidence of a conserved receptor-binding site between the MLB and classical HAstV spikes, suggesting that MLB and classical HAstVs utilize different receptors for host-cell attachment. We provide evidence for this hypothesis using a novel HAstV infection competition assay. Comparisons of the HAstV MLB spike structure with structures predicted from its sequence reveal poor matches, but template-based predictions were surprisingly accurate relative to machine-learning-based predictions. Our data provide a foundation for understanding the mechanisms of infection by diverse HAstVs and can support structure determination in similarly unstudied systems.


Assuntos
Capsídeo , Mamastrovirus , Humanos , Mamastrovirus/genética , Proteínas do Capsídeo , Sítios de Ligação , Aprendizado de Máquina
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