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International Journal of Molecular... May 2024Recombinant adeno-associated virus (rAAV) has emerged as a prominent vector for in vivo gene therapy, owing to its distinct advantages. Accurate determination of the...
Recombinant adeno-associated virus (rAAV) has emerged as a prominent vector for in vivo gene therapy, owing to its distinct advantages. Accurate determination of the rAAV genome titer is crucial for ensuring the safe and effective administration of clinical doses. The evolution of the rAAV genome titer assay from quantitative PCR (qPCR) to digital PCR (dPCR) has enhanced accuracy and precision, yet practical challenges persist. This study systematically investigated the impact of various operational factors on genome titration in a single-factor manner, aiming to address potential sources of variability in the quantitative determination process. Our findings revealed that a pretreatment procedure without genome extraction exhibits superior precision compared with titration with genome extraction. Additionally, notable variations in titration results across different brands of dPCR instruments were documented, with relative standard deviation (RSD) reaching 23.47% for AAV5 and 11.57% for AAV8. Notably, optimal operations about DNase I digestion were identified; we thought treatment time exceeding 30 min was necessary, and there was no need for thermal inactivation after digestion. And we highlighted that thermal capsid disruption before serial dilution substantially affected AAV genome titers, causing a greater than ten-fold decrease. Conversely, this study found that additive components of dilution buffer are not significant contributors to titration variations. Furthermore, we found that repeated freeze-thaw cycles significantly compromised AAV genome titers. In conclusion, a comprehensive dPCR titration protocol, incorporating insights from these impact factors, was proposed and successfully tested across multiple serotypes of AAV. The results demonstrate acceptable variations, with the RSD consistently below 5.00% for all tested AAV samples. This study provides valuable insights to reduce variability and improve the reproducibility of AAV genome titration using dPCR.
Topics: Dependovirus; Genome, Viral; Genetic Vectors; Humans; Polymerase Chain Reaction; HEK293 Cells; Genetic Therapy; Viral Load
PubMed: 38791184
DOI: 10.3390/ijms25105149 -
Molecular Therapy : the Journal of the... Jul 2024Sepsis-associated encephalopathy (SAE) is a frequent complication of severe systemic infection resulting in delirium, premature death, and long-term cognitive...
Sepsis-associated encephalopathy (SAE) is a frequent complication of severe systemic infection resulting in delirium, premature death, and long-term cognitive impairment. We closely mimicked SAE in a murine peritoneal contamination and infection (PCI) model. We found long-lasting synaptic pathology in the hippocampus including defective long-term synaptic plasticity, reduction of mature neuronal dendritic spines, and severely affected excitatory neurotransmission. Genes related to synaptic signaling, including the gene for activity-regulated cytoskeleton-associated protein (Arc/Arg3.1) and members of the transcription-regulatory EGR gene family, were downregulated. At the protein level, ARC expression and mitogen-activated protein kinase signaling in the brain were affected. For targeted rescue we used adeno-associated virus-mediated overexpression of ARC in the hippocampus in vivo. This recovered defective synaptic plasticity and improved memory dysfunction. Using the enriched environment paradigm as a non-invasive rescue intervention, we found improvement of defective long-term potentiation, memory, and anxiety. The beneficial effects of an enriched environment were accompanied by an increase in brain-derived neurotrophic factor (BDNF) and ARC expression in the hippocampus, suggesting that activation of the BDNF-TrkB pathway leads to restoration of the PCI-induced reduction of ARC. Collectively, our findings identify synaptic pathomechanisms underlying SAE and provide a conceptual approach to target SAE-induced synaptic dysfunction with potential therapeutic applications to patients with SAE.
Topics: Animals; Neuronal Plasticity; Mice; Cognitive Dysfunction; Sepsis-Associated Encephalopathy; Hippocampus; Brain-Derived Neurotrophic Factor; Disease Models, Animal; Cytoskeletal Proteins; Nerve Tissue Proteins; Dependovirus; Male; Long-Term Potentiation; Receptor, trkB; Genetic Vectors; Synapses
PubMed: 38788710
DOI: 10.1016/j.ymthe.2024.05.001 -
Veterinary Sciences Apr 2024Duck hepatitis B virus (DHBV) is widely prevalent in global ducks and has been identified in Chinese geese with a high prevalence; the available detection techniques are...
Duck hepatitis B virus (DHBV) is widely prevalent in global ducks and has been identified in Chinese geese with a high prevalence; the available detection techniques are time-consuming and require sophisticated equipment. In this study, an assay combining multienzyme isothermal rapid amplification (MIRA) and lateral flow dipstick (LFD) was developed for the efficient and rapid detection of DHBV. The primary reaction condition of the MIRA assay for DHBV detection was 10 min at 38 °C without a temperature cycler. Combined with the LFD assay, the complete procedure of the newly developed MIRA assay for DHBV detection required only 15 min, which is about one-fourth of the reaction time for routine polymerase chain reaction assay. And electrophoresis and gel imaging equipment were not required for detection and to read the results. Furthermore, the detection limit of MIRA was 45.6 copies per reaction, which is approximately 10 times lower than that of a routine polymerase chain reaction assay. The primer set and probe had much simpler designs than loop-mediated isothermal amplification, and they were only specific to DHBV, with no cross-reactivity with duck hepatitis A virus subtype 1 and duck hepatitis A virus subtype 3, goose parvovirus, duck enteritis virus, duck circovirus, or . In this study, we offer a simple, fast, and accurate assay method to identify DHBV in clinical serum samples of ducks and geese, which would be suitable for widespread application in field clinics.
PubMed: 38787163
DOI: 10.3390/vetsci11050191 -
Euro Surveillance : Bulletin Europeen... May 2024In France, blood donations are tested in pools of 96 samples for parvovirus B19 (B19V) DNA to discard plasma for fractionation when it contains high viral loads. Between...
In France, blood donations are tested in pools of 96 samples for parvovirus B19 (B19V) DNA to discard plasma for fractionation when it contains high viral loads. Between January 2015 and March 2024, B19V-positive donations decreased during the COVID-19 pandemic, followed by a strong rebound in 2023 and unusually high circulation during winter 2023/24 (ca 10 times higher December 2023-March 2024 vs the pre-pandemic period). Variations over time are probably related to measures implemented to limit SARS-CoV-2 spread.
Topics: Humans; Blood Donation; Blood Donors; COVID-19; DNA, Viral; France; Mass Screening; Pandemics; Parvoviridae Infections; Parvovirus B19, Human; Seasons; Viral Load
PubMed: 38785091
DOI: No ID Found -
Current Gene Therapy 2024Osteoarthritis (OA) is a highly debilitating, degenerative pathology of cartilaginous joints affecting over 500 million people worldwide. The global economic burden of...
BACKGROUND
Osteoarthritis (OA) is a highly debilitating, degenerative pathology of cartilaginous joints affecting over 500 million people worldwide. The global economic burden of OA is estimated at $260-519 billion and growing, driven by aging global population and increasing rates of obesity. To date, only the multi-injection chondroanabolic treatment regimen of Fibroblast Growth Factor 18 (FGF18) has demonstrated clinically meaningful disease-modifying efficacy in placebo-controlled human trials. Our work focuses on the development of a novel single injection disease-modifying gene therapy, based on FGF18's chondroanabolic activity.
METHODS
OA was induced in Sprague-Dawley rats using destabilization of the medial meniscus (DMM) (3 weeks), followed by intra-articular treatment with 3 dose levels of AAV2-FGF18, rh- FGF18 protein, and PBS. Durability, redosability, and biodistribution were measured by quantifying nLuc reporter bioluminescence. Transcriptomic analysis was performed by RNA-seq on cultured human chondrocytes and rat knee joints. Morphological analysis was performed on knee joints stained with Safranin O/Fast Green and anti-PRG antibody.
RESULTS
Dose-dependent reductions in cartilage defect size were observed in the AAV2-FGF18- treated joints relative to the vehicle control. Total defect width was reduced by up to 76% and cartilage thickness in the thinnest zone was increased by up to 106%. Morphologically, the vehicle- treated joints exhibited pronounced degeneration, ranging from severe cartilage erosion and bone void formation, to subchondral bone remodeling and near-complete subchondral bone collapse. In contrast, AAV2-FGF18-treated joints appeared more anatomically normal, with only regional glycosaminoglycan loss and marginal cartilage erosion. While effective at reducing cartilage lesions, treatment with rhFGF18 injections resulted in significant joint swelling (19% increase in diameter), as well as a decrease in PRG4 staining uniformity and intensity. In contrast to early-timepoint RNA-seq analysis, which showed a high degree of concordance between protein- and gene therapy-treated chondrocytes, transcriptomic analysis, revealed few gene expression changes following protein treatment. On the other hand, the gene therapy treatment exhibited a high degree of durability and localization over the study period, upregulating several chondroanabolic genes while downregulating OA- and fibrocartilage-associated markers.
CONCLUSION
FGF18 gene therapy treatment of OA joints can provide benefits to both cartilage and subchondral bone, with a high degree of localization and durability.
Topics: Animals; Fibroblast Growth Factors; Genetic Therapy; Rats; Rats, Sprague-Dawley; Humans; Osteoarthritis; Disease Models, Animal; Cartilage, Articular; Dependovirus; Chondrocytes; Genetic Vectors; Male
PubMed: 38783531
DOI: 10.2174/0115665232275532231213063634 -
Genome Biology May 2024Dilated cardiomyopathy (DCM) is one of the most common causes of heart failure. Multiple identified mutations in nexilin (NEXN) have been suggested to be linked with...
BACKGROUND
Dilated cardiomyopathy (DCM) is one of the most common causes of heart failure. Multiple identified mutations in nexilin (NEXN) have been suggested to be linked with severe DCM. However, the exact association between multiple mutations of Nexn and DCM remains unclear. Moreover, it is critical for the development of precise and effective therapeutics in treatments of DCM.
RESULTS
In our study, Nexn global knockout mice and mice carrying human equivalent G645del mutation are studied using functional gene rescue assays. AAV-mediated gene delivery is conducted through systemic intravenous injections at the neonatal stage. Heart tissues are analyzed by immunoblots, and functions are assessed by echocardiography. Here, we identify functional components of Nexilin and demonstrate that exogenous introduction could rescue the cardiac function and extend the lifespan of Nexn knockout mouse models. Similar therapeutic effects are also obtained in G645del mice, providing a promising intervention for future clinical therapeutics.
CONCLUSIONS
In summary, we demonstrated that a single injection of AAV-Nexn was capable to restore the functions of cardiomyocytes and extended the lifespan of Nexn knockout and G645del mice. Our study represented a long-term gene replacement therapy for DCM that potentially covers all forms of loss-of-function mutations in NEXN.
Topics: Animals; Cardiomyopathy, Dilated; Mice, Knockout; Mice; Genetic Therapy; Humans; Dependovirus; Myocytes, Cardiac; Disease Models, Animal; Mutation; Genetic Vectors; Gene Transfer Techniques
PubMed: 38783323
DOI: 10.1186/s13059-024-03283-x -
rAAV capsid mutants eliminate leaky expression from DNA donor template for homologous recombination.Nucleic Acids Research Jun 2024Precise genomic editing through the combination of CRISPR/Cas systems and recombinant adeno-associated virus (rAAV)-delivered homology directed repair (HDR) donor...
Precise genomic editing through the combination of CRISPR/Cas systems and recombinant adeno-associated virus (rAAV)-delivered homology directed repair (HDR) donor templates represents a powerful approach. However, the challenge of effectively suppressing leaky transcription from the rAAV vector, a phenomenon associated to cytotoxicity, persists. In this study, we demonstrated substantial promoter activities of various homology arms and inverted terminal repeats (ITR). To address this issue, we identified a novel rAAV variant, Y704T, which not only yields high-vector quantities but also effectively suppresses in cis mRNA transcription driven by a robust promoter. The Y704T variant maintains normal functionality in receptor interaction, intracellular trafficking, nuclear entry, uncoating, and second-strand synthesis, while specifically exhibiting defects in transcription. Importantly, this inhibitory effect is found to be independent of ITR, promoter types, and RNA polymerases. Mechanistic studies unveiled the involvement of Valosin Containing Protein (VCP/p97) in capsid-mediated transcription repression. Remarkably, the Y704T variant delivers HDR donor templates without compromising DNA replication ability and homologous recombination efficiency. In summary, our findings enhance the understanding of capsid-regulated transcription and introduce novel avenues for the application of the rAAV-CRISPR/Cas9 system in human gene therapy.
Topics: Dependovirus; Humans; Promoter Regions, Genetic; Gene Editing; Homologous Recombination; HEK293 Cells; Capsid Proteins; Capsid; Mutation; Genetic Vectors; Transcription, Genetic; CRISPR-Cas Systems; Recombinational DNA Repair; Terminal Repeat Sequences; DNA Replication
PubMed: 38783157
DOI: 10.1093/nar/gkae401 -
Pediatric Nephrology (Berlin, Germany) May 2024A 13-year-old girl who had a kidney transplant four weeks prior presented with a 10-day history of fatigue, paleness, and headache. On physical examination, tachycardia...
A 13-year-old girl who had a kidney transplant four weeks prior presented with a 10-day history of fatigue, paleness, and headache. On physical examination, tachycardia and paleness were noted. Laboratory testing was notable for severe anemia and mild leukopenia and thrombocytopenia. Polymerase chain reaction (PCR) test for Epstein-Barr virus (EBV) and cytomegalovirus (CMV) were negative and for parvovirus B19 (PVB19) was positive. Despite lower immunosuppression and administration of intravenous immunoglobulin (IVIG) it persisted for 15 months, and frequent red blood cell transfusions were needed. PVB19 is a less common but significant complication. The patient's clinical course demonstrates the importance of this complication and the challenges in its management. A notable void exists in the literature regarding standardized treatment protocols for PVB19-induced recurrent anemia after kidney transplant. This case indicates the need for further research and consensus to guide effective clinical interventions in similar cases.
PubMed: 38775967
DOI: 10.1007/s00467-024-06378-6 -
Journal of Virology Jun 2024Adeno-associated viruses (AAVs) package a single-stranded (ss) DNA genome of 4.7 kb in their capsid of ~20 nm in diameter. AAV replication requires co-infection of a...
UNLABELLED
Adeno-associated viruses (AAVs) package a single-stranded (ss) DNA genome of 4.7 kb in their capsid of ~20 nm in diameter. AAV replication requires co-infection of a helper virus, such as adenovirus. During the optimization of recombinant AAV production, a small viral nonstructural protein, membrane-associated accessory protein (MAAP), was identified. However, the function of the MAAP in the context of AAV infection remains unknown. Here, we investigated the expression strategy and function of the MAAP during infection of both AAV2 and AAV5 in human embryonic kidney (HEK)293 cells. We found that AAV2 MAAP2 and AAV5 MAAP5 are expressed from the capsid gene ()-transcribing mRNA spliced from the donor to the second splice site that encodes VP2 and VP3. Thus, this AAV gene transcribes a multicistronic mRNA that can be translated to four viral proteins, MAAP, VP2, AAP, and VP3 in order. In AAV2 infection, MAAP2 predominantly localized in the cytoplasm, alongside the capsid, near the nuclear and plasma membranes, but a fraction of MAAP2 exhibited nuclear localization. In AAV5 infection, MAAP5 revealed a distinct pattern, predominantly localizing within the nucleus. In the cells infected with an MAAP knockout mutant of AAV2 or AAV5, both viral DNA replication and virus replication increased, whereas virus egress decreased, and the decrease in virus egress can be restored by providing MAAP . In summary, MAAP, a novel AAV nonstructural protein translated from a multicistronic viral mRNA, not only facilitates cellular egress of AAV but also likely negatively affects viral DNA replication during infection.
IMPORTANCE
Recombinant adeno-associated virus (rAAV) has been used as a gene delivery vector in clinical gene therapy. In current gene therapies employing rAAV, a high dose of the vector is required. Consequently, there is a high demand for efficient and high-purity vector production systems. In this study, we demonstrated that membrane-associated accessory protein (MAAP), a small viral nonstructural protein, is translated from the same viral mRNA transcript encoding VP2 and VP3. In AAV-infected cells, apart from its prevalent expression in the cytoplasm with localization near the plasma and nuclear membranes, the MAAP also exhibits notable localization within the nucleus. During AAV infection, MAAP expression increases the cellular egress of progeny virions and decreases viral DNA replication and progeny virion production. Thus, the choice of MAAP expression has pros and cons during AAV infection, which could provide a guide to rAAV production.
Topics: Humans; Dependovirus; HEK293 Cells; Virus Replication; Capsid Proteins; Viral Nonstructural Proteins; Parvoviridae Infections; Capsid
PubMed: 38775479
DOI: 10.1128/jvi.00633-24 -
Cell Jun 2024Leveraging AAVs' versatile tropism and labeling capacity, we expanded the scale of in vivo CRISPR screening with single-cell transcriptomic phenotyping across embryonic...
Leveraging AAVs' versatile tropism and labeling capacity, we expanded the scale of in vivo CRISPR screening with single-cell transcriptomic phenotyping across embryonic to adult brains and peripheral nervous systems. Through extensive tests of 86 vectors across AAV serotypes combined with a transposon system, we substantially amplified labeling efficacy and accelerated in vivo gene delivery from weeks to days. Our proof-of-principle in utero screen identified the pleiotropic effects of Foxg1, highlighting its tight regulation of distinct networks essential for cell fate specification of Layer 6 corticothalamic neurons. Notably, our platform can label >6% of cerebral cells, surpassing the current state-of-the-art efficacy at <0.1% by lentivirus, to achieve analysis of over 30,000 cells in one experiment and enable massively parallel in vivo Perturb-seq. Compatible with various phenotypic measurements (single-cell or spatial multi-omics), it presents a flexible approach to interrogate gene function across cell types in vivo, translating gene variants to their causal function.
Topics: Animals; Female; Humans; Mice; Cerebral Cortex; CRISPR-Cas Systems; Dependovirus; Forkhead Transcription Factors; Gene Regulatory Networks; Genetic Vectors; Mice, Inbred C57BL; Nerve Tissue Proteins; Neurons; Single-Cell Analysis; Transcriptome; Cell Line; Transcription, Genetic
PubMed: 38772369
DOI: 10.1016/j.cell.2024.04.050