RESUMEN
High demand for antibodies as therapeutic interventions for various infectious, metabolic, autoimmune, neoplastic, and other diseases creates a growing need in developing efficient methods for recombinant antibody production. As of 2019, there were more than 70 FDA-approved monoclonal antibodies, and there is exponential growth potential. Despite their promise, limiting factors for widespread use are manufacturing costs and complexity. Potentially, plants offer low-cost, safe, and easily scalable protein manufacturing strategies. Plants like Nicotiana benthamiana not only can correctly fold and assemble complex mammalian proteins but also can add critical post-translational modifications similar to those offered by mammalian cell cultures. In this work, by using native GFP and an acid-stable variant of green fluorescent protein (GFP) fused to human monoclonal antibodies, we were able to visualize the entire transient antibody expression and purification process from N. benthamiana plants. Depending on the experiment's purpose, native GFP fusion can ensure easier visualization during the expression phase in the plants, while acid-stable GFP fusion allows for visualization during downstream processing. This scalable and straightforward procedure can be performed by a single researcher to produce milligram quantities of highly pure antibody or antibody fusion proteins in a matter of days using only a few small plants. Such a technique can be extended to the visualization of any type of antibody purification process and potentially many other proteins, both in plant and other expression systems. Moreover, these techniques can benefit virtual instructions and be executed in a teaching laboratory by undergraduate students possessing minimal prior experience with molecular biology techniques, providing a foundation for project-based exploration with real-world applications.
Asunto(s)
Inmunoglobulina G/biosíntesis , Nicotiana/genética , Proteínas Recombinantes de Fusión/biosíntesis , Agrobacterium tumefaciens/metabolismo , Animales , Anticuerpos Monoclonales/metabolismo , Secuencia de Bases , Cromatografía , Electroforesis en Gel de Poliacrilamida , Proteínas Fluorescentes Verdes/metabolismo , Humanos , Kanamicina/farmacología , Hojas de la Planta/microbiología , Plantas Modificadas Genéticamente , Nicotiana/crecimiento & desarrollo , Nicotiana/microbiología , Rayos UltravioletaRESUMEN
Cocaine use disorders include short-term and acute pathologies (e.g. overdose) and long-term and chronic disorders (e.g. intractable addiction and post-abstinence relapse). There is currently no available treatment that can effectively reduce morbidity and mortality associated with cocaine overdose or that can effectively prevent relapse in recovering addicts. One recently developed approach to treat these problems is the use of enzymes that rapidly break down the active cocaine molecule into inactive metabolites. In particular, rational design and site-directed mutagenesis transformed human serum recombinant butyrylcholinesterase (BChE) into a highly efficient cocaine hydrolase with drastically improved catalytic efficiency toward (-)-cocaine. A current drawback preventing the clinical application of this promising enzyme-based therapy is the lack of a cost-effective production strategy that is also flexible enough to rapidly scale-up in response to continuous improvements in enzyme design. Plant-based expression systems provide a unique solution as this platform is designed for fast scalability, low cost and the advantage of performing eukaryotic protein modifications such as glycosylation. A Plant-derived form of the Cocaine Super Hydrolase (A199S/F227A/S287G/A328W/Y332G) we designate PCocSH protects mice from cocaine overdose, counters the lethal effects of acute cocaine overdose, and prevents reinstatement of extinguished drug-seeking behavior in mice that underwent place conditioning with cocaine. These results demonstrate that the novel PCocSH enzyme may well serve as an effective therapeutic for cocaine use disorders in a clinical setting.
Asunto(s)
Hidrolasas de Éster Carboxílico/uso terapéutico , Trastornos Relacionados con Cocaína/tratamiento farmacológico , Cocaína/envenenamiento , Sobredosis de Droga/tratamiento farmacológico , Comportamiento de Búsqueda de Drogas/efectos de los fármacos , Plantas/química , Proteínas Recombinantes/uso terapéutico , Animales , Butirilcolinesterasa/química , Butirilcolinesterasa/uso terapéutico , Condicionamiento Operante/efectos de los fármacos , Sobredosis de Droga/mortalidad , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Nicotiana/química , Nicotiana/metabolismoRESUMEN
Zika virus (ZIKV) reemergence poses a significant health threat especially due to its risks to fetal development, necessitating safe and effective vaccines that can protect pregnant women. Zika envelope domain III (ZE3) has been identified as a safe and effective vaccine candidate, however it is poorly immunogenic. We previously showed that plant-made recombinant immune complex (RIC) vaccines are a robust platform to improve the immunogenicity of weak antigens. In this study, we altered the antigen fusion site on the RIC platform to accommodate N-terminal fusion to the IgG heavy chain (N-RIC), and thus a wider range of antigens, with a resulting 40% improvement in RIC expression over the normal C-terminal fusion (C-RIC). Both types of RICs containing ZE3 were efficiently assembled in plants and purified to >95% homogeneity with a simple one-step purification. Both ZE3 RICs strongly bound complement receptor C1q and elicited strong ZE3-specific antibody titers that correlated with ZIKV neutralization. When either N-RIC or C-RIC was codelivered with plant-produced hepatitis B core (HBc) virus-like particles (VLP) displaying ZE3, the combination elicited 5-fold greater antibody titers (>1,000,000) and more strongly neutralized ZIKV than either RICs or VLPs alone, after only two doses without adjuvant. These findings demonstrate that antigens that require a free N-terminus for optimal antigen display can now be used with the RIC system, and that plant-made RICs and VLPs are highly effective vaccines targeting ZE3. Thus, the RIC platform can be more generally applied to a wider variety of antigens.
Asunto(s)
Vacunas de Partículas Similares a Virus , Infección por el Virus Zika , Virus Zika , Anticuerpos Neutralizantes , Anticuerpos Antivirales , Complejo Antígeno-Anticuerpo , Femenino , Humanos , Embarazo , Envoltura Viral , Virus Zika/genética , Infección por el Virus Zika/prevención & controlRESUMEN
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.
RESUMEN
Butyrylcholinesterase (BChE) is an enzyme with broad substrate and ligand specificities and may function as a generalized bioscavenger by binding and/or hydrolyzing various xenobiotic agents and toxicants, many of which target the central and peripheral nervous systems. Variants of BChE were rationally designed to increase the enzyme's ability to hydrolyze the psychoactive enantiomer of cocaine. These variants were cloned, and then expressed using the magnICON transient expression system in plants and their enzymatic properties were investigated. In particular, we explored the effects that these site-directed mutations have over the enzyme kinetics with various substrates of BChE. We further compared the affinity of various anticholinesterases including organophosphorous nerve agents and pesticides toward these BChE variants relative to the wild type enzyme. In addition to serving as a therapy for cocaine addiction-related diseases, enhanced bioscavenging against other harmful agents could add to the practicality and versatility of the plant-derived recombinant enzyme as a multivalent therapeutic.
Asunto(s)
Butirilcolinesterasa/química , Butirilcolinesterasa/metabolismo , Inhibidores de la Colinesterasa/farmacología , Cocaína/metabolismo , Proteínas de Plantas , Proteínas Recombinantes , Regulación Alostérica , Sitios de Unión , Butirilcolinesterasa/genética , Dominio Catalítico , Cocaína/química , Variación Genética , Hidrólisis , Mutación , Unión Proteica , EstereoisomerismoRESUMEN
Showing modest efficacy, the RV144 HIV-1 vaccine clinical trial utilized a non-replicating canarypox viral vector and a soluble gp120 protein boost. Here we built upon the RV144 strategy by developing a novel combination of a replicating, but highly-attenuated Vaccinia virus vector, NYVAC-KC, and plant-produced HIV-1 virus-like particles (VLPs). Both components contained the full-length Gag and a membrane anchored truncated gp41 presenting the membrane proximal external region with its conserved broadly neutralizing epitopes in the pre-fusion conformation. We tested different prime/boost combinations of these components in mice and showed that the group primed with NYVAC-KC and boosted with both the viral vectors and plant-produced VLPs have the most robust Gag-specific CD8 T cell responses, at 12.7% of CD8 T cells expressing IFN-γ in response to stimulation with five Gag epitopes. The same immunization group elicited the best systemic and mucosal antibody responses to Gag and dgp41 with a bias towards IgG1.
Asunto(s)
Vacunas contra el SIDA/administración & dosificación , Proteína gp41 de Envoltorio del VIH/inmunología , Infecciones por VIH/inmunología , VIH-1/inmunología , Inmunización/métodos , Nicotiana/metabolismo , Virus Vaccinia/fisiología , Productos del Gen gag del Virus de la Inmunodeficiencia Humana/inmunología , Vacunas contra el SIDA/inmunología , Animales , Anticuerpos Neutralizantes/inmunología , Formación de Anticuerpos , Femenino , Vectores Genéticos/genética , Vectores Genéticos/fisiología , Anticuerpos Anti-VIH/inmunología , Proteína gp41 de Envoltorio del VIH/administración & dosificación , Proteína gp41 de Envoltorio del VIH/genética , Infecciones por VIH/prevención & control , Infecciones por VIH/virología , VIH-1/genética , Humanos , Inmunización Secundaria , Ratones , Ratones Endogámicos C57BL , Nicotiana/genética , Nicotiana/virología , Vacunas de Partículas Similares a Virus/genética , Vacunas de Partículas Similares a Virus/inmunología , Virus Vaccinia/genética , Replicación Viral , Productos del Gen gag del Virus de la Inmunodeficiencia Humana/administración & dosificación , Productos del Gen gag del Virus de la Inmunodeficiencia Humana/genéticaRESUMEN
Viral protein U (Vpu) is a type-III integral membrane protein encoded by Human Immunodeficiency Virus-1 (HIV- 1). It is expressed in infected host cells and plays several roles in viral progeny escape from infected cells, including down-regulation of CD4 receptors. But key structure/function questions remain regarding the mechanisms by which the Vpu protein contributes to HIV-1 pathogenesis. Here we describe expression of Vpu in bacteria, its purification and characterization. We report the successful expression of PelB-Vpu in Escherichia coli using the leader peptide pectate lyase B (PelB) from Erwinia carotovora. The protein was detergent extractable and could be isolated in a very pure form. We demonstrate that the PelB signal peptide successfully targets Vpu to the cell membranes and inserts it as a type I membrane protein. PelB-Vpu was biophysically characterized by circular dichroism and dynamic light scattering experiments and was shown to be an excellent candidate for elucidating structural models.
Asunto(s)
Proteínas del Virus de la Inmunodeficiencia Humana/metabolismo , Proteínas Reguladoras y Accesorias Virales/metabolismo , Clonación Molecular , Escherichia coli , Expresión Génica , Proteínas del Virus de la Inmunodeficiencia Humana/genética , Humanos , Pliegue de Proteína , Señales de Clasificación de Proteína , Proteínas Reguladoras y Accesorias Virales/genéticaRESUMEN
It is widely anticipated that a prophylactic vaccine may be needed to control the HIV/AIDS epidemic worldwide. Despite over two decades of research, a vaccine against HIV-1 remains elusive, although a recent clinical trial has shown promising results. Recent studies have focused on highly conserved domains within HIV-1 such as the membrane proximal external region (MPER) of the envelope glycoprotein, gp41. MPER has been shown to play critical roles in mucosal transmission of HIV-1, though this peptide is poorly immunogenic on its own. Here we provide evidence that plant-produced HIV-1 enveloped virus-like particles (VLPs) consisting of Gag and a deconstructed form of gp41 comprising the MPER, transmembrane, and cytoplasmic domains (Dgp41) provides an effective platform to display MPER for use as an HIV vaccine candidate. Prime-boost strategies combining systemic and mucosal priming with systemic boosting using two different vaccine candidates (VLPs and CTB-MPR--a fusion of MPER and the B-subunit of cholera toxin) were investigated in BALB/c mice. Serum antibody responses against both the Gag and gp41 antigens were elicited when systemically primed with VLPs. These responses could be recalled following systemic boosting with VLPs. In addition, mucosal priming with VLPs allowed for a boosting response against Gag and gp41 when boosted with either candidate. Importantly, the VLPs also induced Gag-specific CD4 and CD8 T-cell responses. This report on the immunogenicity of plant-based Gag/Dgp41 VLPs may represent an important milestone on the road towards a broadly efficacious and inexpensive subunit vaccine against HIV-1.
Asunto(s)
Vacunas contra el SIDA/inmunología , Proteína gp41 de Envoltorio del VIH/inmunología , VIH-1/inmunología , Nicotiana/metabolismo , Plantas Modificadas Genéticamente/metabolismo , Vacunas de Partículas Similares a Virus/inmunología , Productos del Gen gag del Virus de la Inmunodeficiencia Humana/inmunología , Animales , Formación de Anticuerpos/efectos de los fármacos , Formación de Anticuerpos/inmunología , Femenino , Infecciones por VIH/inmunología , Infecciones por VIH/prevención & control , Ratones , Ratones Endogámicos BALB CRESUMEN
The excessive use of antibiotics in food animal production has contributed to resistance in pathogenic bacteria, thereby triggering regulations and consumer demands to limit their use. Alternatives for disease control are therefore required that are cost-effective and compatible with intensive production. While vaccines are widely used and effective, they are available against a minority of animal diseases, and development of novel vaccines and other immunotherapeutics is therefore needed. Production of such proteins recombinantly in plants can provide products that are effective and safe, can be orally administered with minimal processing, and are easily scalable with a relatively low capital investment. The present report thus advocates the use of plants for producing vaccines and antibodies to protect farm animals from diseases that have thus far been managed with antibiotics; and highlights recent advances in product efficacy, competitiveness, and regulatory approval.
Asunto(s)
Inmunoterapia , Agricultura Molecular , Plantas , Proteínas Recombinantes , Medicina Veterinaria , Enfermedades de los Animales/inmunología , Enfermedades de los Animales/prevención & control , Animales , Biotecnología , Ganado , Plantas/genética , Plantas/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismoRESUMEN
The membrane proximal region (MPR, residues 649-683) and transmembrane domain (TMD, residues 684-705) of the gp41 subunit of HIV-1's envelope protein are highly conserved and are important in viral mucosal transmission, virus attachment and membrane fusion with target cells. Several structures of the trimeric membrane proximal external region (residues 662-683) of MPR have been reported at the atomic level; however, the atomic structure of the TMD still remains unknown. To elucidate the structure of both MPR and TMD, we expressed the region spanning both domains, MPR-TM (residues 649-705), in Escherichia coli as a fusion protein with maltose binding protein (MBP). MPR-TM was initially fused to the C-terminus of MBP via a 42 aa-long linker containing a TEV protease recognition site (MBP-linker-MPR-TM). Biophysical characterization indicated that the purified MBP-linker-MPR-TM protein was a monodisperse and stable candidate for crystallization. However, crystals of the MBP-linker-MPR-TM protein could not be obtained in extensive crystallization screens. It is possible that the 42 residue-long linker between MBP and MPR-TM was interfering with crystal formation. To test this hypothesis, the 42 residue-long linker was replaced with three alanine residues. The fusion protein, MBP-AAA-MPR-TM, was similarly purified and characterized. Significantly, both the MBP-linker-MPR-TM and MBP-AAA-MPR-TM proteins strongly interacted with broadly neutralizing monoclonal antibodies 2F5 and 4E10. With epitopes accessible to the broadly neutralizing antibodies, these MBP/MPR-TM recombinant proteins may be in immunologically relevant conformations that mimic a pre-hairpin intermediate of gp41.
Asunto(s)
Vacunas contra el SIDA/química , Proteína gp41 de Envoltorio del VIH/química , VIH-1/inmunología , Fragmentos de Péptidos/química , Vacunas contra el SIDA/inmunología , Vacunas contra el SIDA/aislamiento & purificación , Dicroismo Circular , Electroforesis en Gel de Poliacrilamida , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/inmunología , Proteína gp41 de Envoltorio del VIH/inmunología , Fragmentos de Péptidos/inmunología , Proteínas de Unión Periplasmáticas/química , Proteínas de Unión Periplasmáticas/inmunología , Resonancia por Plasmón de Superficie , Proteínas Virales de Fusión/química , Proteínas Virales de Fusión/inmunología , Proteínas Virales de Fusión/aislamiento & purificaciónRESUMEN
OBJECTIVES: This short commentary examines the factors that led to Food and Drug Administration's approval of the first plant-derived biologic. RESULTS: In 2012, the first plant-derived protein pharmaceutical (biologic) was approved for commercial use in humans. The product, a recombinant form of human ß-glucocerebrosidase marketed as ELELYSO, was developed by Protalix Biotherapeutics (Carmiel, Israel). The foresight to select this particular therapeutic product for development, flawless production pipeline, and serendipity seem to provide the key in explaining how ELELYSO became the first plant-derived biologic to achieve approval by Food and Drug Administration. CONCLUSIONS: While the circumstances that enabled Protalix and its scientists to become the first to arrive at this historic milestone are perhaps unique, it is anticipated that more biologics will follow suit in winning regulatory endorsement.
Asunto(s)
Productos Biológicos , Agricultura Molecular , Proteínas de Plantas , Glucosilceramidasa , Humanos , Estados Unidos , United States Food and Drug AdministrationRESUMEN
CTB-MPR is a fusion protein between the B subunit of cholera toxin (CTB) and the membrane-proximal region of gp41 (MPR), the transmembrane envelope protein of Human immunodeficiency virus 1 (HIV-1), and has previously been shown to induce the production of anti-HIV-1 antibodies with antiviral functions. To further improve the design of this candidate vaccine, X-ray crystallography experiments were performed to obtain structural information about this fusion protein. Several variants of CTB-MPR were designed, constructed and recombinantly expressed in Escherichia coli. The first variant contained a flexible GPGP linker between CTB and MPR, and yielded crystals that diffracted to a resolution of 2.3â Å, but only the CTB region was detected in the electron-density map. A second variant, in which the CTB was directly attached to MPR, was shown to destabilize pentamer formation. A third construct containing a polyalanine linker between CTB and MPR proved to stabilize the pentameric form of the protein during purification. The purification procedure was shown to produce a homogeneously pure and monodisperse sample for crystallization. Initial crystallization experiments led to pseudo-crystals which were ordered in only two dimensions and were disordered in the third dimension. Nanocrystals obtained using the same precipitant showed promising X-ray diffraction to 5â Å resolution in femtosecond nanocrystallography experiments at the Linac Coherent Light Source at the SLAC National Accelerator Laboratory. The results demonstrate the utility of femtosecond X-ray crystallography to enable structural analysis based on nano/microcrystals of a protein for which no macroscopic crystals ordered in three dimensions have been observed before.
RESUMEN
The transmembrane subunit (gp41) of the envelope glycoprotein of HIV-1 associates noncovalently with the surface subunit (gp120) and together they play essential roles in viral mucosal transmission and infection of target cells. The membrane proximal region (MPR) of gp41 is highly conserved and contains epitopes of broadly neutralizing antibodies. The transmembrane (TM) domain of gp41 not only anchors the envelope glycoprotein complex in the viral membrane but also dynamically affects the interactions of the MPR with the membrane. While high-resolution X-ray structures of some segments of the MPR were solved in the past, they represent the post-fusion forms. Structural information on the TM domain of gp41 is scant and at low resolution. Here we describe the design, expression and purification of a protein construct that includes MPR and the transmembrane domain of gp41 (MPR-TMTEV-6His), which reacts with the broadly neutralizing antibodies 2F5 and 4E10 and thereby may represent an immunologically relevant conformation mimicking a prehairpin intermediate of gp41. The expression level of MPR-TMTEV-6His was improved by fusion to the C-terminus of Mistic protein, yielding â¼ 1 mg of pure protein per liter. The isolated MPR-TMTEV-6His protein was biophysically characterized and is a monodisperse candidate for crystallization. This work will enable further investigation into the structure of MPR-TMTEV-6His, which will be important for the structure-based design of a mucosal vaccine against HIV-1.
Asunto(s)
Proteína gp41 de Envoltorio del VIH/química , Proteína gp41 de Envoltorio del VIH/aislamiento & purificación , Proteínas Recombinantes/química , Proteínas Recombinantes/aislamiento & purificación , Secuencia de Aminoácidos , Anticuerpos Monoclonales/metabolismo , Anticuerpos Antivirales/metabolismo , Proteína gp41 de Envoltorio del VIH/genética , Proteína gp41 de Envoltorio del VIH/metabolismo , Luz , Datos de Secuencia Molecular , Estructura Terciaria de Proteína , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Dispersión de Radiación , Resonancia por Plasmón de SuperficieRESUMEN
Plants have a proven track record for the expression of biopharmaceutically interesting proteins. Importantly, plants and mammals share a highly conserved secretory pathway that allows similar folding, assembly and posttranslational modifications of proteins. Human butyrylcholinesterase (BChE) is a highly sialylated, tetrameric serum protein, investigated as a bioscavenger for organophosphorous nerve agents. Expression of recombinant BChE (rBChE) in Nicotiana benthamiana results in accumulation of both monomers as well as assembled oligomers. In particular, we show here that co-expression of BChE with a novel gene-stacking vector, carrying six mammalian genes necessary for in planta protein sialylation, resulted in the generation of rBChE decorated with sialylated N-glycans. The N-glycosylation profile of monomeric rBChE secreted to the apoplast largely resembles the plasma-derived orthologue. In contrast, rBChE purified from total soluble protein extracts was decorated with a significant portion of ER-typical oligomannosidic structures. Biochemical analyses and live-cell imaging experiments indicated that impaired N-glycan processing is due to aberrant deposition of rBChE oligomers in the endoplasmic reticulum or endoplasmic-reticulum-derived compartments. In summary, we show the assembly of rBChE multimers, however, also points to the need for in-depth studies to explain the unexpected subcellular targeting of oligomeric BChE in plants.
Asunto(s)
Butirilcolinesterasa/metabolismo , Nicotiana/metabolismo , Butirilcolinesterasa/genética , Butirilcolinesterasa/aislamiento & purificación , Vectores Genéticos/metabolismo , Glicosilación , Humanos , Plantas Modificadas Genéticamente/metabolismo , Ingeniería de Proteínas , Procesamiento Proteico-Postraduccional , Transporte de Proteínas , Proteínas Recombinantes/metabolismo , Nicotiana/genéticaRESUMEN
Human butyrylcholinesterase (BChE) is considered a candidate bioscavenger of nerve agents for use in pre- and post-exposure treatment. However, the presence and functional necessity of complex N-glycans (i.e. sialylated structures) is a challenging issue in respect to its recombinant expression. Here we transiently co-expressed BChE cDNA in the model plant Nicotiana benthamiana with vectors carrying the genes necessary for in planta protein sialylation. Site-specific sugar profiling of secreted recombinant BChE (rBChE) collected from the intercellular fluid revealed the presence of mono- and di-sialylated N-glycans, which largely resembles to the plasma-derived orthologue. Attempts to increase that sialylation content of rBChE by the over-expression of an additional glycosylation enzyme that generates branched N-glycans (i.e. ß1,4-N-acetylglucosaminyl-transferase IV), allowed the production of rBChE decorated with tri-sialylated structures (up to 70%). Sialylated and non-sialylated plant-derived rBChE exhibited functional in vitro activity comparable to that of its commercially available equine-derived counterpart. These results demonstrate the ability of plants to generate valuable proteins with designed sialylated glycosylation profiles optimized for therapeutic efficacy. Moreover, the efficient synthesis of carbohydrates present only in minute amounts on the native protein (tri-sialylated N-glycans) facilitates the generation of a product with superior efficacies and/or new therapeutic functions.
Asunto(s)
Butirilcolinesterasa/química , Butirilcolinesterasa/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Butirilcolinesterasa/genética , Butiriltiocolina/análisis , Butiriltiocolina/metabolismo , Glicosilación , Humanos , Ácido N-Acetilneuramínico , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/metabolismo , Ingeniería de Proteínas , Proteínas Recombinantes/genética , Nicotiana/genética , Nicotiana/metabolismoRESUMEN
The VLPNPV 2014 Conference that was convened at the Salk institute was the second conference of its kind to focus on advances in production, purification, and delivery of virus-like particles (VLPs) and nanoparticles. Many exciting developments were reported and discussed in this interdisciplinary arena, but here we report specifically on the contributions of plant-based platforms to VLP vaccine technology as reported in the section of the conference devoted to the topic as well in additional presentations throughout the meeting. The increasing popularity of plant production platforms is due to their lower cost, scalability, and lack of contaminating animal pathogens seen with other systems. Reports include production of complex VLPs consisting of 4 proteins expressed at finely-tuned expression levels, a prime-boost strategy for HIV vaccination using plant-made VLPs and a live viral vector, and the characterization and development of plant viral nanoparticles for use in cancer vaccines, drug delivery, and bioimaging.
Asunto(s)
Virus de la Lengua Azul/inmunología , Proteínas de la Cápside/biosíntesis , Antígenos del Núcleo de la Hepatitis B/biosíntesis , Plantas/metabolismo , Productos del Gen gag del Virus de la Inmunodeficiencia Humana/biosíntesis , Proteínas de la Cápside/inmunología , Antígenos del Núcleo de la Hepatitis B/inmunología , Humanos , Nanopartículas , Vacunas de Partículas Similares a Virus/inmunología , Vacunas de Partículas Similares a Virus/uso terapéutico , Productos del Gen gag del Virus de la Inmunodeficiencia Humana/inmunologíaRESUMEN
The transmembrane HIV-1 envelope protein gp41 has been shown to play critical roles in the viral mucosal transmission and infection of CD4⺠cells. Gag is a structural protein configuring the enveloped viral particles and has been suggested to constitute a target of the cellular immunity that may control viral load. We hypothesized that HIV enveloped virus-like particles (VLPs) consisting of Gag and a deconstructed form of gp41 comprising the membrane proximal external, transmembrane and cytoplasmic domains (dgp41) could be expressed in plants. To this end, plant-optimized HIV-1 genes were constructed and expressed in Nicotiana benthamiana by stable transformation, or transiently using a Tobamovirus-based expression system or a combination of both. Our results of biophysical, biochemical and electron microscopy characterization demonstrates that plant cells could support not only the formation of enveloped HIV-1 Gag VLPs, but also the accumulation of VLPs that incorporated dgp41. These findings provide further impetus for the journey towards a broadly efficacious and inexpensive subunit vaccine against HIV-1.
Asunto(s)
Proteína gp41 de Envoltorio del VIH/metabolismo , VIH-1/metabolismo , Nicotiana/virología , Productos del Gen gag del Virus de la Inmunodeficiencia Humana/metabolismo , Regulación de la Expresión Génica de las Plantas , Genes Sintéticos , Hojas de la Planta/ultraestructura , Hojas de la Planta/virología , Plantas Modificadas Genéticamente , Nicotiana/genética , Virión/ultraestructuraRESUMEN
BACKGROUND: Concerns about the safety of paralytics such as succinylcholine to facilitate endotracheal intubation limit their use in prehospital and emergency department settings. The ability to rapidly reverse paralysis and restore respiratory drive would increase the safety margin of an agent, thus permitting the pursuit of alternative intubation strategies. In particular, patients who carry genetic or acquired deficiency of butyrylcholinesterase, the serum enzyme responsible for succinylcholine hydrolysis, are susceptible to succinylcholine-induced apnea, which manifests as paralysis, lasting hours beyond the normally brief half-life of succinylcholine. We hypothesized that intravenous administration of plant-derived recombinant BChE, which also prevents mortality in nerve agent poisoning, would rapidly reverse the effects of succinylcholine. METHODS: Recombinant butyrylcholinesterase was produced in transgenic plants and purified. Further analysis involved murine and guinea pig models of succinylcholine toxicity. Animals were treated with lethal and sublethal doses of succinylcholine followed by administration of butyrylcholinesterase or vehicle. In both animal models vital signs and overall survival at specified intervals post succinylcholine administration were assessed. RESULTS: Purified plant-derived recombinant human butyrylcholinesterase can hydrolyze succinylcholine in vitro. Challenge of mice with an LD100 of succinylcholine followed by BChE administration resulted in complete prevention of respiratory inhibition and concomitant mortality. Furthermore, experiments in symptomatic guinea pigs demonstrated extremely rapid succinylcholine detoxification with complete amelioration of symptoms and no apparent complications. CONCLUSIONS: Recombinant plant-derived butyrylcholinesterase was capable of counteracting and reversing apnea in two complementary models of lethal succinylcholine toxicity, completely preventing mortality. This study of a protein antidote validates the feasibility of protection and treatment of overdose from succinylcholine as well as other biologically active butyrylcholinesterase substrates.
Asunto(s)
Apnea/inducido químicamente , Apnea/tratamiento farmacológico , Butirilcolinesterasa/administración & dosificación , Proteínas Recombinantes/administración & dosificación , Succinilcolina/efectos adversos , Animales , Apnea/prevención & control , Catálisis , Cobayas , Humanos , Masculino , Ratones , Especificidad por Sustrato , Succinilcolina/metabolismo , Succinilcolina/toxicidadRESUMEN
Acetylcholinesterase is an enzyme that is intimately associated with regulation of synaptic transmission in the cholinergic nervous system and in neuromuscular junctions of animals. However the presence of cholinesterase activity has been described also in non-metazoan organisms such as slime molds, fungi and plants. More recently, a gene purportedly encoding for acetylcholinesterase was cloned from maize. We have cloned the Arabidopsis thaliana homolog of the Zea mays gene, At3g26430, and studied its biochemical properties. Our results indicate that the protein encoded by the gene exhibited lipase activity with preference to long chain substrates but did not hydrolyze choline esters. The At3g26430 protein belongs to the SGNH clan of serine hydrolases, and more specifically to the GDS(L) lipase family.