scholarly journals Establishment of a Recombinant AAV2/HBoV1 Vector Production System in Insect Cells

Genes ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 439
Author(s):  
Xuefeng Deng ◽  
Wei Zou ◽  
Ziying Yan ◽  
Jianming Qiu
Keyword(s):  
Production System ◽  
Insect Cells ◽  
Capsid Proteins ◽  
Hek293 Cells ◽  
Sf9 Cells ◽  
Human Bocavirus ◽  
Transmission Electron Microscopy Analysis ◽  
Hek 293 ◽  
Highly Efficient ◽  
Baculovirus Expression Vector

We have previously developed an rAAV2/HBoV1 vector in which a recombinant adeno-associated virus 2 (rAAV2) genome is pseudopackaged into a human bocavirus 1 (HBoV1) capsid. Recently, the production of rAAV2/HBoV1 in human embryonic kidney (HEK) 293 cells has been greatly improved in the absence of any HBoV1 nonstructural proteins (NS). This NS-free production system yields over 16-fold more vectors than the original production system that necessitates NS expression. The production of rAAV with infection of baculovirus expression vector (BEV) in the suspension culture of Sf9 insect cells is highly efficient and scalable. Since the replication of the rAAV2 genome in the BEV system is well established, we aimed to develop a BEV system to produce the rAAV2/HBoV1 vector in Sf9 cells. We optimized the usage of translation initiation signals of the HBoV1 capsid proteins (Cap), and constructed a BEV Bac-AAV2Rep-HBoV1Cap, which expresses the AAV2 Rep78 and Rep52 as well as the HBoV1 VP1, VP2, and VP3 at the appropriate ratios. We found that it is sufficient as a trans helper to the production of rAAV2/HBoV1 in Sf9 cells that were co-infected with the transfer Bac-AAV2ITR-GFP-luc that carried a 5.4-kb oversized rAAV2 genome with dual reporters. Further study found that incorporation of an HBoV1 small NS, NP1, in the system maximized the viral DNA replication and thus the rAAV2/HBoV1 vector production at a level similar to that of the rAAV2 vector in Sf9 cells. However, the transduction potency of the rAAV2/HBoV1 vector produced from BEV-infected Sf9 cells was 5–7-fold lower in polarized human airway epithelia than that packaged in HEK293 cells. Transmission electron microscopy analysis found that the vector produced in Sf9 cells had a high percentage of empty capsids, suggesting the pseudopackage of the rAAV2 genome in HBoV1 capsid is not as efficient as in the capsids of AAV2. Nevertheless, our study demonstrated that the rAAV2/HBoV1 can be produced in insect cells with BEVs at a comparable yield to rAAV, and that the highly efficient expression of the HBoV1 capsid proteins warrants further optimization.

scholarly journals Nonstructural Protein NP1 of Human Bocavirus 1 Plays a Critical Role in the Expression of Viral Capsid Proteins

2016 ◽  
Vol 90 (9) ◽  
pp. 4658-4669 ◽  
Author(s):  
Wei Zou ◽  
Fang Cheng ◽  
Weiran Shen ◽  
John F. Engelhardt ◽  
Ziying Yan ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Capsid Protein ◽  
Nonstructural Protein ◽  
Critical Role ◽  
The Other ◽  
Capsid Proteins ◽  
Viral Capsid ◽  
Human Bocavirus ◽  
Human Airway ◽  
Viral Capsid Proteins

ABSTRACTA novel chimeric parvoviral vector, rAAV2/HBoV1, in which the recombinant adeno-associated virus 2 (rAAV2) genome is pseudopackaged by the human bocavirus 1 (HBoV1) capsid, has been shown to be highly efficient in gene delivery to human airway epithelia (Z. Yan et al., Mol Ther 21:2181–2194, 2013,http://dx.doi.org/10.1038/mt.2013.92). In this vector production system, we used an HBoV1 packaging plasmid, pHBoV1NSCap, that harbors HBoV1 nonstructural protein (NS) and capsid protein (Cap) genes. In order to simplify this packaging plasmid, we investigated the involvement of the HBoV1 NS proteins in capsid protein expression. We found that NP1, a small NS protein encoded by the middle open reading frame, is required for the expression of the viral capsid proteins (VP1, VP2, and VP3). We also found that the other NS proteins (NS1, NS2, NS3, and NS4) are not required for the expression of VP proteins. We performed systematic analyses of the HBoV1 mRNAs transcribed from the pHBoV1NSCap packaging plasmid and its derivatives in HEK 293 cells. Mechanistically, we found that NP1 is required for both the splicing and the read-through of the proximal polyadenylation site of the HBoV1 precursor mRNA, essential functions for the maturation of capsid protein-encoding mRNA. Thus, our study provides a unique example of how a small viral nonstructural protein facilitates the multifaceted regulation of capsid gene expression.IMPORTANCEA novel chimeric parvoviral vector, rAAV2/HBoV1, expressing a full-length cystic fibrosis transmembrane conductance regulator (CFTR) gene, is capable of correcting CFTR-dependent chloride transport in cystic fibrosis human airway epithelium. Previously, an HBoV1 nonstructural and capsid protein-expressing plasmid, pHBoV1NSCap, was used to package the rAAV2/HBoV1 vector, but yields remained low. In this study, we demonstrated that the nonstructural protein NP1 is required for the expression of capsid proteins. However, we found that the other four nonstructural proteins (NS1 to -4) are not required for expression of capsid proteins. By mutating theciselements that function as internal polyadenylation signals in the capsid protein-expressing mRNA, we constructed a simple HBoV1 capsid protein-expressing gene that expresses capsid proteins as efficiently as pHBoV1NSCap does, and at similar ratios, but independently of NP1. Our study provides a foundation to develop a better packaging system for rAAV2/HBoV1 vector production.

Hairpin transfer-independent Parvovirus DNA Replication Produces Infectious Virus

2021 ◽  
Author(s):  
Weiran Shen ◽  
Zekun Wang ◽  
Kang Ning ◽  
Fang Cheng ◽  
John F. Engelhardt ◽  
...  
Keyword(s):  
Dna Replication ◽  
Hek293 Cells ◽  
Progeny Virus ◽  
Human Bocavirus ◽  
Viral Dna ◽  
Airway Epithelia ◽  
Viral Dna Replication ◽  
Human Airway ◽  
The Right ◽  
Human Airway Epithelia

Parvoviruses package a linear single-stranded DNA genome with hairpin structures at both ends. It has been thought that terminal hairpin sequences are indispensable for viral DNA replication. Here, we provide evidence that the hairpin-deleted duplex genomes of human bocavirus 1 (HBoV1) replicate in human embryonic kidney (HEK) 293 cells. We propose an alternative model for HBoV1 DNA replication in which the leading strand can initiate strand-displacement without “hairpin-transfer.” The transfection of the HBoV1 duplex genomes that retain a minimal replication origin at the right-end ( OriR ), but with extensive deletions in the right-end hairpin (REH), generated viruses in HEK293 cells at a level 10-20 times lower than the wild-type (WT) duplex genome. Importantly, these viruses that have a genome with various deletions after the OriR , but not the one retaining only the OriR , replicated in polarized human airway epithelia. We discovered that the 18-nt sequence (nt 5,403-5,420) beyond the OriR was sufficient to confer virus replication in polarized human airway epithelia, although its progeny virus production was ∼5 times lower than that of the WT virus. Thus, our study demonstrates that hairpin transfer-independent productive parvovirus DNA replication can occur. Importance Hairpin transfer-independent parvovirus replication was modeled with human bocavirus 1 (HBoV1) duplex genomes whose 5’ hairpin structure was ablated by various deletions. In HEK293 cells, these duplex viral genomes with ablated 5’/hairpin sequence replicated efficiently and generated viruses that productively infected polarized human airway epithelium. Thus, for the first time, we reveal a previously unknown phenomenon that the productive parvovirus DNA replication does not depend on the hairpin sequence at REH to initiate “rolling hairpin” DNA replication. Notably, the intermediates of viral DNA replication, as revealed two-dimensional electrophoresis, from transfections of hairpin sequence-deleted duplex genome and full-length genome in HEK293 cells, as well as from virus infection of polarized human airway epithelia are similar. Thus, the establishment of the hairpin transfer-independent parvoviral DNA replication deepens our understanding in viral DNA replication and may have implications in development of parvovirus-based viral vectors with alternative properties.

Abstract 423: Caveolin-3 Enriches and Dynamically Interacts With Swell1

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Daniel G Turner ◽  
Leonid Tyan ◽  
Sami Stroebel ◽  
Frank Deguire ◽  
Di Lang ◽  
...  
Keyword(s):  
Protein Expression ◽  
Hek293 Cells ◽  
Scaffolding Protein ◽  
Cell Swelling ◽  
Hypotonic Solution ◽  
Hek 293 ◽  
Dynamic Relationship ◽  
293 Cells ◽  
Fret Efficiency ◽  
Oxide Synthase

Caveolae are small (50-100nm) membrane invaginations formed by caveolin proteins enriched with cholesterol and lipids. Caveolae play a crucial role in mechanoprotection and mechano-electrical transduction by buffering membrane tension and facilitating activation of mechanosensitive ion channels, including a recently discovered swelling-activated chloride channel SWELL1 (also known as LRRC8A). However, the dynamic relationship between the muscle-specific caveolar scaffolding protein caveolin-3 (Cav3) and SWELL1 is poorly understood. The objective of this study was to determine how Cav3 interacts with SWELL1 channels and modulates their activity during mechano-electrical transduction. In HEK 293 cells transfected with Cav3, co-immunoprecipitation analysis recapitulated cardiac data showing association between SWELL1 and Cav3. Using transiently expressed Cav3-GFP and SWELL1-mCherry fusion proteins in HEK293 cells, we observed a high FRET efficiency between the two proteins in an isotonic (1T) solution, confirming their close (<5nm) proximity. In a hypotonic solution (0.7T, mimicking cell stretch), FRET efficiency decreased two-fold. Furthermore, FRET efficiency decreased two-fold to control levels when incubated with methyl-beta cyclodextrin, a cholesterol solubilizer. These data suggest that the relationship between Cav3 and SWELL1 is dependent on membrane mechanical tension and caveolae lipid raft integrity. Interestingly, in transfected cells, SWELL1 protein expression and whole cell swelling-activated chloride current ( I Cl,swell ) were increased four-fold and two-fold, respectively, while mRNA expression was reduced two-fold. This may indicate that caveolae formed by Cav3 expression enrich for SWELL1 and increase their half-life, thus requiring lower mRNA availability despite higher protein expression. Our findings indicate a close dynamic interplay between Cav3 and SWELL1, with a strong regulatory action of Cav3 on I Cl,swell activity. Given that I Cl,swell increases and interprotein FRET efficiency decreases in hypotonic solution, it is likely that Cav3 inhibits the activation of SWELL1 similarly to its known inhibition of nitric oxide synthase.

scholarly journals A Newly Designed EGFP-2A Peptide Monocistronic Baculoviral Vector for Concatenating the Expression of Recombinant Proteins in Insect Cells

Processes ◽  
2019 ◽  
Vol 7 (5) ◽  
pp. 291 ◽  
Author(s):  
Chih-Yu Wu ◽  
Chao-Wei Huang ◽  
Yu-Shin Nai ◽  
Pei-Yu Chu ◽  
Chung-Hsiung Wang ◽  
...  
Keyword(s):  
Recombinant Proteins ◽  
Posttranslational Modifications ◽  
Mammalian Cells ◽  
Insect Cells ◽  
Fluorescent Protein ◽  
Expression System ◽  
Recombinant Baculovirus ◽  
New Combination ◽  
Vector System ◽  
Baculovirus Expression Vector

Recombinant proteins produced by the baculovirus expression vector system (BVES) have been widely applied in the agricultural and medical fields. However, the procedure for protein expression is inefficient and needs to be improved. Herein, we propose a simple construct that incorporates a selectable marker (enhanced green fluorescent protein, EGFP) and a picorna viral-derived “self-cleaving” 2A-like peptide to separate the EGFP and target proteins in a monocistronic baculovirus vector to facilitate isolation of the recombinant baculovirus in the BVES. In this study, porcine adiponectin (ADN), a secreted, multimeric protein with insulin-sensitizing properties, was used to demonstrate its utility in our EGFP-2A-based expression system. EGFP and ADN were simultaneously expressed by a recombinant alphabaculovirus. Co-expression of EGFP facilitates the manipulation of the following processes, such as determining expression kinetics and harvesting ADN. The results showed that the 2A “self-cleaving” process does not interfere with EGFP activity or with signal peptide removal and the secretion of recombinant ADN. Posttranslational modifications, including glycosylation, of the recombinant ADN occurred in insect cells, and the formation of various multimers was further verified. Most importantly, the insect-produced ADN showed a similar bioactivity to that of mammalian cells. This concept provides a practical and economic approach that utilizes a new combination of alphabaculovirus/insect cell expression systems for future applications.

scholarly journals Relevance of Assembly-Activating Protein for Adeno-associated Virus Vector Production and Capsid Protein Stability in Mammalian and Insect Cells

2017 ◽  
Vol 91 (20) ◽  
Author(s):  
Stefanie Grosse ◽  
Magalie Penaud-Budloo ◽  
Anne-Kathrin Herrmann ◽  
Kathleen Börner ◽  
Julia Fakhiri ◽  
...  
Keyword(s):  
Protein Stability ◽  
Capsid Protein ◽  
Insect Cells ◽  
Critical Factor ◽  
Capsid Proteins ◽  
Wild Type ◽  
Particle Assembly ◽  
Adeno Associated Virus ◽  
Recombinant Vectors

ABSTRACT The discovery that adeno-associated virus 2 (AAV2) encodes an eighth protein, called assembly-activating protein (AAP), transformed our understanding of wild-type AAV biology. Concurrently, it raised questions about the role of AAP during production of recombinant vectors based on natural or molecularly engineered AAV capsids. Here, we show that AAP is indeed essential for generation of functional recombinant AAV2 vectors in both mammalian and insect cell-based vector production systems. Surprisingly, we observed that AAV2 capsid proteins VP1 to -3 are unstable in the absence of AAP2, likely due to rapid proteasomal degradation. Inhibition of the proteasome led to an increase of intracellular VP1 to -3 but neither triggered assembly of functional capsids nor promoted nuclear localization of the capsid proteins. Together, this underscores the crucial and unique role of AAP in the AAV life cycle, where it rapidly chaperones capsid assembly, thus preventing degradation of free capsid proteins. An expanded analysis comprising nine alternative AAV serotypes (1, 3 to 9, and rh10) showed that vector production always depends on the presence of AAP, with the exceptions of AAV4 and AAV5, which exhibited AAP-independent, albeit low-level, particle assembly. Interestingly, AAPs from all 10 serotypes could cross-complement AAP-depleted helper plasmids during vector production, despite there being distinct intracellular AAP localization patterns. These were most pronounced for AAP4 and AAP5, congruent with their inability to rescue an AAV2/AAP2 knockout. We conclude that AAP is key for assembly of genuine capsids from at least 10 different AAV serotypes, which has implications for vectors derived from wild-type or synthetic AAV capsids. IMPORTANCE Assembly of adeno-associated virus 2 (AAV2) is regulated by the assembly-activating protein (AAP), whose open reading frame overlaps with that of the viral capsid proteins. As the majority of evidence was obtained using virus-like particles composed solely of the major capsid protein VP3, AAP's role in and relevance for assembly of genuine AAV capsids have remained largely unclear. Thus, we established a trans-complementation assay permitting assessment of AAP functionality during production of recombinant vectors based on complete AAV capsids and derived from any serotype. We find that AAP is indeed a critical factor not only for AAV2, but also for generation of vectors derived from nine other AAV serotypes. Moreover, we identify a new role of AAP in maintaining capsid protein stability in mammalian and insect cells. Thereby, our study expands our current understanding of AAV/AAP biology, and it concomitantly provides insights into the importance of AAP for AAV vector production.

Applied Research on the Closed-Loop Control of Oil Production System with Progressing Cavity Pump

2012 ◽  
Vol 248 ◽  
pp. 119-123
Author(s):  
Duan Yin Zhu ◽  
Jian Ning Xu ◽  
Yan Xiong Gao ◽  
Wen Jie Lv
Keyword(s):  
Production System ◽  
Closed Loop ◽  
Frequency Conversion ◽  
Rotation Speed ◽  
Frequency Converter ◽  
Dynamic Change ◽  
Oil Production ◽  
Closed Loop Control ◽  
Loop Control ◽  
Highly Efficient

It aimed to dynamic change of oilfield productivity, maked sure that the progressing cavity pump is working in a highly efficient region. It combined variable frequency conversion technology and dynamic liquid level height control technology, the closed-loop control of oil production system with progressing cavity pump is made up of rotation-speed and torsion sensor, stepless motor, frequency converter, PLC and progressing cavity pump. The result show that the system can control the pump submergence depth by adjusting the rotation-speed and torsion of polish rod, and make sure the pump working in a highly efficient region finally. This system also can increase recovery efficiency and pump service life.

scholarly journals Fluorinated Galactoses Inhibit Galactose-1-Phosphate Uridyltransferase and Metabolically Induce Galactosemia-like Phenotypes in HEK-293 Cells

Cells ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 607 ◽  
Author(s):  
Verena Janes ◽  
Simona Grabany ◽  
Julien Delbrouck ◽  
Stephane P. Vincent ◽  
Johannes Gottschalk ◽  
...  
Keyword(s):  
Kinetic Studies ◽  
Surface Expression ◽  
Hek293 Cells ◽  
Galactose Metabolism ◽  
Galt Activity ◽  
Hek 293 ◽  
Classic Galactosemia ◽  
Developmental Impairment ◽  
The Unfolded Protein Response ◽  
Metabolic Induction

Genetic defects of human galactose-1-phosphate uridyltransferase (hGALT) and the partial loss of enzyme function result in an altered galactose metabolism with serious long-term developmental impairment of organs in classic galactosemia patients. In search for cellular pathomechanisms induced by the stressor galactose, we looked for ways to induce metabolically a galactosemia-like phenotype by hGALT inhibition in HEK293 cells. In kinetic studies, we provide evidence for 2-fluorinated galactose-1-phosphate (F-Gal-1-P) to competitively inhibit recombinant hGALT with a KI of 0.9 mM. Contrasting with hepatic cells, no alterations of N-glycoprofiles in MIG (metabolic induction of galactosemia)-HEK293 cells were revealed for an inducible secretory netrin-1 probe by MALDI-MS. Differential fluorescence-activated cell sorting demonstrated reduced surface expression of N-glycosylated CD109, EGFR, DPP4, and rhMUC1. Membrane raft proteomes exhibited dramatic alterations pointing to an affection of the unfolded protein response, and of targeted protein traffick. Most prominent, a negative regulation of oxidative stress was revealed presumably as a response to a NADPH pool depletion during reduction of Gal/F-Gal. Cellular perturbations induced by fluorinated galactoses in normal epithelial cells resemble proteomic changes revealed for galactosemic fibroblasts. In conclusion, the metabolic induction of galactosemia-like phenotypes in healthy epithelial/neuronal cells could support studies on the molecular pathomechanisms in classic galactosemia, in particular under conditions of low galactose stress and residual GALT activity.

scholarly journals Receptor-mediated activation of recombinant Trpl expressed in Sf9 insect cells

1995 ◽  
Vol 305 (2) ◽  
pp. 605-611 ◽  
Author(s):  
Y Hu ◽  
W P Schilling
Keyword(s):  
Photoreceptor Cell ◽  
Receptor Potential ◽  
Photoreceptor Cells ◽  
Sharp Contrast ◽  
Membrane Receptors ◽  
Cation Channels ◽  
Sf9 Cells ◽  
Baculovirus Expression ◽  
Baculovirus Expression Vector ◽  
Stimulation Of

The Drosophila proteins, Trp and Trpl, are suggested to be cation channels responsible for depolarization of the receptor potential associated with stimulation of insect photoreceptor cells by light. Consistent with this hypothesis, we recently showed that recombinant Trpl forms Ca(2+)- and Ba(2+)-permeable non-selective cation channels when expressed in Sf9 cells using the baculovirus expression vector. As Trpl may be activated in the photoreceptor cell after stimulation of phospholipase C, we hypothesized that a similar regulation of recombinant Trpl may be observed in the Sf9 cell after activation of heterologous membrane receptors linked to Ca(2+)-signal-transduction pathways. To test this hypothesis, Ca2+ signalling was examined in Fura-2-loaded Sf9 cells infected with baculovirus containing cDNA for the M5 muscarinic receptor alone (M5 cells) or in cells co-infected with both M5 and Trpl-containing baculoviruses (M5-Trpl cells). Addition of carbachol (100 microM) to M5 cells produced an increase in cytosolic free Ca2+ concentration ([Ca2+]i) (mean +/- S.D.; n = 17) from 101 +/- 20 to 762 +/- 178 nM which declined to a sustained elevated level of 384 +/- 102 nM after 3 min. The sustained component was eliminated by removal of extracellular Ca2+ or by addition of La3+ or Gd3+ (10 microM). In M5-Trpl cells, basal [Ca2+]i increased as a function of time after infection. To evaluate the contribution of Ca2+ influx to the overall profile observed, Ba2+, a Ca2+ surrogate that is not a substrate for the Ca2+ pump, was used. The increase in basal [Ca2+]i seen in M5-Trpl cells was associated with an increase in basal Ba2+ influx. Addition of carbachol to M5-Trpl cells at 30-36 h after infection produced a large increase in [Ca2+]i to a sustained value of 677 +/- 143 nM. This change in [Ca2+]i was (1) blocked by atropine, (2) attenuated in the absence of extracellular Ca2+, and (3) relatively insensitive to La3+, but blocked by Gd3+ in the 0.1-1 mM range. In the presence of 10 microM Gd3+ to block the endogenous-receptor-mediated Ca(2+)-influx in M5-Trpl cells. In sharp contrast increase in Ba2+ influx in M5-Trpl cells. In sharp contrast, neither Ca2+ nor Ba2+ influx through Trpl was affected by thapsigargin, a selective inhibitor of the endoplasmic reticulum Ca(2+)-ATPase pump.(ABSTRACT TRUNCATED AT 400 WORDS)

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