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At least 19 recordsLinked to original sources
PubMed1977

[Characteristics of the deletion mutant of plasmid R6K].

Deletion plasmide R6Kdelta with the mol wt of 17.2.10(6) dalton isolated from the E. coli chi 925 (R6K) is described. This plasmide expresses no resistance to streptomycin, is replicated in the E. coli K12 under relaxed control and is resistant to the treatment with the eliminating agents. Analysis of plasmide DNA with the aid of electrophoresis in agarose gel demonstrated that R6K delta has one site attacked by restriction endonucleases Eco. RI and Bam HI. These data were confirmed by the determination of the transforming activity of the corresponding DNA restrictors. It is supposed that the isolated plasmide was identical with plasmide RSF1040. A possibility of using R6K delta as a genetic vector for obtaining recombination DNA molecules in vitro is discussed.

DNA Restriction Enzymes↗
PubMed2014

Engineering adeno-associated viruses for clinical gene therapy.

Clinical gene therapy has been increasingly successful owing both to an enhanced molecular understanding of human disease and to progressively improving gene delivery technologies. Among these technologies, delivery vectors based on adeno-associated viruses (AAVs) have emerged as safe and effective and, in one recent case, have led to regulatory approval. Although shortcomings in viral vector properties will render extension of such successes to many other human diseases challenging, new approaches to engineer and improve AAV vectors and their genetic cargo are increasingly helping to overcome these barriers.

Capsid↗
PubMed2026

Distribution of transgene in the rodent choroid plexus after intracerebroventricular injection of adeno-associated virus.

Using adeno-associated virus to transfer genetic information to the choroid plexus has emerged as a promising route for long-term gene therapy in the brain for a variety of conditions. Overexpression of proteins has proved effective in small animal models but few attempts have been made to translate this technology to clinic, suppress the activity of a protein of interest, or further expand the limited capsid serotypes known to have choroid plexus tropism. We utilise transfer of green fluorescent protein to show choroid plexus epithelium tropism for novel AAV6 derived capsid ShH10Y445F in mouse, rat and porcine tissue explant cultures. In vivo tropism is shown in the mouse following stereotactic intracerebroventricular injection. We examined the distribution of viral transduction across the choroid plexus in all four ventricles following a single unilateral intracerebroventricular injection using both green fluorescent protein as a transgene, but also the CRISPR/Cas9 system to deliver permanent knockdown of apical water channel aquaporin-1. Quantitative immunofluorescence and SURVEYOR assay were used to statistically assess the magnitude and extent of choroid plexus knockdown across the ventricular system. We conclude that serotype ShH10Y445F targets choroid plexus epithelium in mouse, rat and pig; and when carrying the CRISPR/Cas9 system can reduce target protein expression in these cells. Transduced choroid plexus epithelial cells distribute unevenly with a bias toward the lateral ventricle on the injected side and a preferential infection of choroid plexus in the lateral over the third and fourth ventricles. Overcoming irregular distribution represents a challenge for clinical translation of this technology where clinical efficacy may require manipulation of the entire choroid plexus.

Animals↗
PubMed2026

A compact GAD67 promoter enables inhibitory neuron-targeted AAV gene therapy for seizure suppression.

Epilepsy arises from disruption of excitation-inhibition (E/I) balance, typically due to excessive excitatory activity. Despite available therapies, a substantial proportion of patients remain treatment resistant. Enhancing inhibitory neuron activity via gene therapy can restore E/I balance and may therefore provide a therapeutic strategy for treatment-resistant epilepsy. Here, we developed a compact 410-bp glutamic acid decarboxylase 67 promoter (cmGAD67) that enables strong, selective transgene expression in inhibitory neurons while preserving adeno-associated virus (AAV) packaging capacity. Systemic delivery of AAV vectors carrying cmGAD67 preferentially targeted parvalbumin interneurons and enabled efficient circuit modulation. To evaluate therapeutic potential, we expressed glutamic acid decarboxylase 65 (GAD65) under the control of cmGAD67 (AAV-GAD65). AAV-GAD65 suppressed abnormal delta oscillations, reduced seizure-like activity, normalized anxiety-like behavior, and improved survival in seizure models. Biochemical analyses confirmed increased GABA levels in the cortex and hippocampus, linking functional improvements to enhanced inhibitory neurotransmitter synthesis. Together, these findings establish the cmGAD67 promoter as a versatile platform for inhibitory neuron-targeted AAV gene delivery and identify AAV-GAD65 as a promising strategy for seizure control and disorders associated with E/I imbalance.

Glutamate Decarboxylase↗
PubMed2024

Chemical approaches to probe and engineer AAV vectors.

Adeno-associated virus (AAV) has emerged as the most promising vector for in vivo human gene therapy, with several therapeutic approvals in the last few years and countless more under development. Underlying this remarkable success are several attractive features that AAV offers, including lack of pathogenicity, low immunogenicity, long-term gene expression without genomic integration, the ability to infect both dividing and non-dividing cells, etc. However, the commonly used wild-type AAV capsids in therapeutic development present significant challenges, including inadequate tissue specificity and the need for large doses to attain therapeutic effectiveness, raising safety concerns. Additionally, significant preexisting adaptive immunity against most natural capsids, and the development of such anti-capsid immunity after the first treatment, represent major challenges. Strategies to engineer the AAV capsid are critically needed to address these challenges and unlock the full promise of AAV gene therapy. Chemical modification of the AAV capsid has recently emerged as a powerful new approach to engineer its properties. Unlike genetic strategies, which can be more disruptive to the delicate capsid assembly and packaging processes, "late-stage" chemical modification of the assembled capsid-whether at natural amino acid residues or site-specifically installed noncanonical amino acid residues-often enables a versatile approach to introducing new properties to the capsid. This review summarizes the significant recent progress in AAV capsid engineering strategies, with a particular focus on chemical modifications in advancing the next generation of AAV-based gene therapies.

Dependovirus↗
PubMed2024

Adeno-Associated Virus Engineering and Load Strategy for Tropism Modification, Immune Evasion and Enhanced Transgene Expression.

Gene therapy aims to add, replace or turn off genes to help treat disease. To date, the US Food and Drug Administration (FDA) has approved 14 gene therapy products. With the increasing interest in gene therapy, feasible gene delivery vectors are necessary for inserting new genes into cells. There are different kinds of gene delivery vectors including viral vectors like lentivirus, adenovirus, retrovirus, adeno-associated virus et al, and non-viral vectors like naked DNA, lipid vectors, polymer nanoparticles, exosomes et al, with viruses being the most commonly used. Among them, the most concerned vector is adeno-associated virus (AAV) because of its safety, natural ability to efficiently deliver gene into cells and sustained transgene expression in multiple tissues. In addition, the AAV genome can be engineered to generate recombinant AAV (rAAV) containing transgene sequences of interest and has been proven to be a safe gene vector. Recently, rAAV vectors have been approved for the treatment of various rare diseases. Despite these approvals, some major limitations of rAAV remain, namely nonspecific tissue targeting and host immune response. Additional problems include neutralizing antibodies that block transgene delivery, a finite transgene packaging capacity, high viral titer used for per dose and high cost. To deal with these challenges, several techniques have been developed. Based on differences in engineering methods, this review proposes three strategies: gene engineering-based capsid modification (capsid modification), capsid surface tethering through chemical conjugation (surface tethering), and other formulations loaded with AAV (virus load). In addition, the major advantages and limitations encountered in rAAV engineering strategies are summarized.

Dependovirus↗
PubMed1979

Entrapment of a bacterial plasmid in phospholipid vesicles: potential for gene transfer.

Entrapment of pBR322 DNA within liposomes was demonstrated by (i) its comigration with liposomes on Sepharose 4B columns, (ii) resistance of its biological activity to DNase digestion, and (iii) identification of plasmid DNA on agarose gels after lipid extraction. The biological activity of the liposome-entrapped plasmid was determined by transformation assays. The incubation of intact liposomes, containing entrapped pBR322, with competent Escherichia coli cells in the standard transformation mixture resulted in the appearance of tetracycline-resistant colonies at a frequency of 1% of the control frequency. Importantly, this frequency was unaffected by the addition of DNase to the incubation mixture, whereas transformation by free pBR322 DNA was totally eliminated after treatment with DNase.

Cytoplasm↗
PubMed2025

Generation of Biologically Contained Marburg Virus.

Wild-type Marburg virus (MARV) can only be handled in biosafety level 4 facilities. By removing an essential gene from the virus genome, deficient virus particles can be generated that are only capable of replication if the missing gene product is provided in trans. As a result, these viruses are restricted to specific cell lines, making them safe to handle at lower biosafety levels. Here, we provide a detailed overview of how to generate MARV in which the VP30 gene has been replaced by a green fluorescent reporter gene, as well as how to use lentiviral transduction to create stable cell lines expressing MARV VP30. These cell lines can be used for the propagation and confinement of the resulting reporter virus.

Marburgvirus↗
PubMed2026

Functional editing of the OTC locus by targeted integration with phenotype correction and restoration of endogenous expression patterns.

Here, we report highly efficient functional repair of the ornithine transcarbamylase (OTC) locus in mutant mouse and human hepatocytes in vivo using a dual adeno-associated virus system delivering CRISPR-Cas9 editing reagents and a promoterless donor for targeted integration. The approach was mutation agnostic and targeted intronic sequences to prevent inadvertent inactivation of hypomorphic alleles. Notably, in a murine model, we corrected the metabolic defect and simultaneously achieved liver-wide restoration of physiological metabolic zonation of Otc expression by capturing native cis-acting regulatory elements. The effectiveness of this approach was confirmed using a universally configured therapeutic cassette in patient-derived primary human hepatocytes in vivo. These data provide a powerful template to guide further optimization of this approach and, given the high editing efficacy required for phenotypic effect in OTC deficiency, have broader relevance to other liver disease phenotypes.

Animals↗
PubMed2025

Quantifying the mutational landscape of retroviral and lentiviral vectors in gene therapy patients.

Adenosine deaminase severe combined immunodeficiency (ADA-SCID) is a monogenic disorder caused by mutations in the ADA gene. Gene therapy using γ-retroviral and lentiviral vector gene addition approaches have shown curative results. We sequenced the ADA transgene in transduced CD3+ T cells, and in peripheral blood cells from patients treated with autologous CD34+ cells transduced with either a γ-retroviral or lentiviral ADA gene vector to assess transgene mutational profiles. In both CD3+ T cells and ADA-SCID patients' cells treated with the lentiviral vector, we observed significantly higher occurrences of guanine (G)-to-adenosine (A) base substitutions than with the γ-retroviral vector. We hypothesized that this G-to-A mutational signature was due to the APOBEC3 cytosine deaminase protein family. By knocking out APOBEC3 genes in HEK239T packaging cells, APOBEC3-mediated mutagenesis decreased by 91.2% along the transgene in CD34+ transduced cells in comparison to CD34+ cells transduced with lentiviral supernatant packaged in parental HEK293T cells.

Humans↗
PubMed2027

Lentiviral Transduction of Embryonic Stem Cells.

Lentiviral vectors provide an efficient and reliable method for stable gene knockdown in embryonic stem cells (ESCs) through RNA interference. Here, we describe a detailed protocol for lentiviral transduction of mouse ESCs using lentiviral shRNA expression vectors. The protocol encompasses lentiviral particle production in HEK-293T packaging cells, determination of viral titer, transduction of ESCs cultured under feeder-free conditions, and selection of stably transduced cells. Additionally, we describe methods for evaluating transduction efficiency using fluorescence microscopy and flow cytometry, as well as for assessing gene knockdown efficacy by quantitative real-time PCR (Q-RT-PCR). This protocol is suitable for functional genomic studies in pluripotent stem cells and can be adapted for other difficult-to-transfect cell types.

Lentivirus↗
PubMed2026

Evaluation of transduction properties and vaccine efficacy of a simian adenovirus type 25-based vector.

Although human adenovirus serotype 5 (Ad5) is widely used as a vaccine vector for infectious diseases due to its high transduction efficiency, pre-existing immunity to Ad5 in many people reduces vaccine efficacy. To address this limitation, simian Ad vectors, such as ChAdOx1 and ChAdOx2, have been explored as alternative vaccine platforms. ChAdOx2 is based on simian Ad25 (SAd25), but the fundamental characteristics of gene transduction by SAd25-based vectors have not been fully elucidated. This study aimed to characterize the gene transduction efficiency, tissue distribution, and immunogenicity of an SAd25-based vector in comparison with those of the Ad5 vector following various routes of administration. Compared with intravenous administration of the Ad5 vector, intravenous administration of the SAd25 vector showed distinct biodistribution patterns, including reduced liver accumulation and predominant expression in the lung. Transduction by the SAd25 vector was not inhibited by human serum, whereas transduction by the Ad5 vector was inhibited, indicating that the SAd25 vector, but not the Ad5 vector, can evade pre-existing Ad immunity. Although intramuscular administration of the SAd25 vector induced lower transgene product-specific antibody production than intramuscular administration of the Ad5 vector, gene expression and Ad genome distribution mediated by the SAd25 vector, but not the Ad5 vector, were localized only to the muscle at the administration site. Intranasal administration of the SAd25 vector induced an antigen-specific antibody response in serum more rapidly than intranasal administration of the Ad5 vector. The SAd25 vector induced antigen-specific antibody production in bronchoalveolar lavage fluid (BALF) that was comparable to that induced by the Ad5 vector. These findings provide essential insights into the biological characteristics of the SAd25 vector, supporting its potential as a safe and effective vaccine vector.

Animals↗
PubMed2026

Adaptation of lentiviral vectors for viral gene therapy and their impact on host cell biology.

BACKGROUND: Lentiviral vectors (LVVs) are used as a viral gene therapeutic and were derived from human immunodeficiency virus subtype 1 (HIV-1). LVVs are used to deliver and induce the stable expression of transgenes through genome integration. Current clinical LVV delivery systems do not include HIV-1 major accessory genes; however, critical structural and non-structural HIV-1 proteins are encoded by the 4-plasmid combination that composes the 3rd generation LVV transduction systems. LVVs use HIV-1-like mechanisms for viral genome integration and both transgene delivery and expression. LVVs rely on host cell machinery to transcribe and translate transgenes for either knocking down disease-causing genes and/or supplying functional genes in a targeted disease. LVVs integrate into host intronic and intergenic regions due to genomic accessibility, but there are no known biases toward specific target integration motifs. MAIN BODY: Investigation of LVV integration has uncovered the generation of chimeric LVV-host transcripts and altered host transcript splicing patterns. Several Food and Drug Administration (FDA)-approved LVV-derived therapies are used for treating diseases ranging from beta thalassemia to sickle cell anemia. An increasingly popular application of LVV is in the generation of chimeric antigen receptor (CAR) T cell therapies, which change and enhance T cell antigen specificity and effector function in liquid cancers. In November 2023, all CAR T cell therapies were placed under FDA investigation due to higher-than-expected rates of malignant transformation, hospitalization, and death in treated individuals. LVV integrations driving oncogene expression could be a cause for malignancy development. Current methods for resolving LVV integration patterns are technically limited by the sequencing approach applied allowing for only limited characterization of LVV integration profiles and altered host gene regulation. CONCLUSIONS: A comprehensive understanding of LVV integration and its consequences is necessary for understanding how these events influence host cell gene regulation and splicing, possibly identifying tunable variables for enhanced positive clinical outcomes. Here, we review the development of LVV systems, what is known about LVV integration patterns, technologies used to characterize patterns of LVV integration, and what is understood about the subsequent impact on host cell gene regulation and its potential linkage to patient malignancies.

Humans↗