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Human Gene Therapy Apr 2022In the past two decades, adeno-associated virus (AAV) vector manufacturing has made remarkable advancements to meet large-scale production demands for preclinical and...
In the past two decades, adeno-associated virus (AAV) vector manufacturing has made remarkable advancements to meet large-scale production demands for preclinical and clinical trials. In addition, AAV vectors have been extensively studied for their safety and efficacy. In particular, the presence of empty AAV capsids and particles containing "inaccurate" vector genomes in preparations has been a subject of concern. Several methods exist to separate empty capsids from full particles; but thus far, no single technique can produce vectors that are free of empty or partial (non-unit length) capsids. Unfortunately, the exact genome compositions of full, intermediate, and empty capsids remain largely unknown. In this work, we used AAV-genome population sequencing to explore the compositions of DNase-resistant, encapsidated vector genomes produced by two common production pipelines: plasmid transfection in human embryonic kidney cells (pTx/HEK293) and baculovirus expression vectors in insect cells (rBV/Sf9). Intriguingly, our results show that vectors originating from the same construct design that were manufactured by the rBV/Sf9 system produced a higher degree of truncated and unresolved species than those generated by pTx/HEK293 production. We also demonstrate that empty particles purified by cesium chloride gradient ultracentrifugation are not truly empty but are instead packaged with genomes composed of a single truncated and/or unresolved inverted terminal repeat (ITR). Our data suggest that the frequency of these "mutated" ITRs correlates with the abundance of inaccurate genomes in all fractions. These surprising findings shed new light on vector efficacy, safety, and how clinical vectors should be quantified and evaluated.
Topics: Animals; Baculoviridae; Dependovirus; Genetic Vectors; HEK293 Cells; Humans; Insecta
PubMed: 35293222
DOI: 10.1089/hum.2022.050 -
Viruses Jul 2019The baculovirus nucleocapsid is formed through a rod-like capsid encapsulating a genomic DNA molecule of 80~180 kbp. The viral capsid is a large oligomer composed of... (Review)
Review
The baculovirus nucleocapsid is formed through a rod-like capsid encapsulating a genomic DNA molecule of 80~180 kbp. The viral capsid is a large oligomer composed of many copies of various protein subunits. The assembly of viral capsids is a complex oligomerization process. The timing of expression of nucleocapsid-related proteins, transport pathways, and their interactions can affect the assembly process of preformed capsids. In addition, the selection of viral DNA and the injection of the viral genome into empty capsids are the critical steps in nucleocapsid assembly. This paper reviews the replication and recombination of baculovirus DNA, expression and transport of capsid proteins, formation of preformed capsids, DNA encapsulation, and nucleocapsid formation. This review will provide a basis for further study of the nucleocapsid assembly mechanism of baculovirus.
Topics: Baculoviridae; DNA, Viral; Genome, Viral; Nucleocapsid; Virus Assembly
PubMed: 31266177
DOI: 10.3390/v11070595 -
Viruses Jul 2023Baculovirology has been studied on the African continent for the development of insect virus-based biopesticides and, to a much lesser extent, vaccine production and... (Review)
Review
Baculovirology has been studied on the African continent for the development of insect virus-based biopesticides and, to a much lesser extent, vaccine production and delivery, since the 1960s. In this review, we focus only on baculoviruses as biopesticides for agricultural pests in Africa. At least 11 species of baculovirus have been discovered or studied on the African continent, some with several distinct isolates, with the objective in most cases being the development of a biopesticide. These include the nucleopolyhedroviruses of , , , , , and , as well as the granuloviruses of , , () , , and . Eleven different baculovirus-based biopesticides are recorded as being registered and commercially available on the African continent. Baculoviruses are recorded to have been isolated, researched, utilised in field trials, and/or commercially deployed as biopesticides in at least 13 different African countries. Baculovirus research is ongoing in Africa, and researchers are confident that further novel species and isolates will be discovered, to the benefit of environmentally responsible agricultural pest management, not only in Africa but also elsewhere.
Topics: Animals; Biological Control Agents; Baculoviridae; Moths; Nucleopolyhedroviruses; Africa; Spodoptera
PubMed: 37515205
DOI: 10.3390/v15071519 -
Current Issues in Molecular Biology 2020constitutes a family of insect-specific, large DNA viruses with a unique life cycle characterized by the production of two morphologically distinct virions, the budded... (Review)
Review
constitutes a family of insect-specific, large DNA viruses with a unique life cycle characterized by the production of two morphologically distinct virions, the budded virus (BV) and the occlusion-derived virus (ODV). ODV and BV, with different tissue tropisms, have been widely applied in the areas of biological control and biotechnology, respectively. In nature, baculovirus infection of susceptible host larvae is initiated by ODV-mediated primary infection, followed by the production of BV for spreading infection within larval body. Across millions of years of co-evolution with their hosts, baculoviruses have developed dedicated mechanisms for efficient entry/egress, genome replication/transcription, and virion assembly by employing either their own proteins or host machineries. They have also adopted versatile strategies to precisely regulate the immunity, behaviors and physiology of hosts to facilitate their own replication and dispersal. In this chapter, research advances relating to key aspects of the baculovirus life cycle are reviewed, and the application of a newly-developed baculovirus synthetic biology technology is introduced. Finally, future avenues for baculovirus research are discussed.
Topics: Baculoviridae; Biological Evolution; Gene Expression Regulation, Viral; Genome, Viral; Genomics; Host-Pathogen Interactions; Life Cycle Stages; Molecular Biology; Open Reading Frames; Structure-Activity Relationship; Viral Proteins; Virus Physiological Phenomena; Virus Replication
PubMed: 31167961
DOI: 10.21775/cimb.034.183 -
Trends in Microbiology May 2017Increasing evidence indicates that viruses do not simply propagate as independent virions among cells, organs, and hosts. Instead, viral spread is often mediated by... (Review)
Review
Increasing evidence indicates that viruses do not simply propagate as independent virions among cells, organs, and hosts. Instead, viral spread is often mediated by structures that simultaneously transport groups of viral genomes, such as polyploid virions, aggregates of virions, virion-containing proteinaceous structures, secreted lipid vesicles, and virus-induced cell-cell contacts. These structures increase the multiplicity of infection, independently of viral population density and transmission bottlenecks. Collective infectious units may contribute to the maintenance of viral genetic diversity, and could have implications for the evolution of social-like virus-virus interactions. These may include various forms of cooperation such as immunity evasion, genetic complementation, division of labor, and relaxation of fitness trade-offs, but also noncooperative interactions such as negative dominance and interference, potentially leading to conflict.
Topics: Animals; Baculoviridae; Biological Evolution; Genetic Variation; Virion; Virus Diseases
PubMed: 28262512
DOI: 10.1016/j.tim.2017.02.003 -
Frontiers in Immunology 2021Insects are the largest group of animals. Nearly all organisms, including insects, have viral pathogens. An important domesticated economic insect is the silkworm moth .... (Review)
Review
Insects are the largest group of animals. Nearly all organisms, including insects, have viral pathogens. An important domesticated economic insect is the silkworm moth . (BmNPV) is a typical baculovirus and a primary silkworm pathogen. It causes major economic losses in sericulture. Baculoviruses are used in biological pest control and as a bioreactor. Silkworm and baculovirus comprise a well-established model of insect-virus interactions. Several recent studies have focused on this model and provided novel insights into viral infections and host defense. Here, we focus on baculovirus invasion, silkworm immune response, baculovirus evasion of host immunity, and enhancement of antiviral efficacy. We also discuss major issues remaining and future directions of research on silkworm antiviral immunity. Elucidation of the interaction between silkworm and baculovirus furnishes a theoretical basis for targeted pest control, enhanced pathogen resistance in economically important insects, and bioreactor improvement.
Topics: Animals; Bombyx; Immune Evasion; Nucleopolyhedroviruses; Pest Control, Biological
PubMed: 33633750
DOI: 10.3389/fimmu.2021.628151 -
Viruses Apr 2015Baculoviruses are widely encountered in nature and a great deal of data is available about their safety and biology. Recently, these versatile, insect-specific viruses... (Review)
Review
Baculoviruses are widely encountered in nature and a great deal of data is available about their safety and biology. Recently, these versatile, insect-specific viruses have demonstrated their usefulness in various biotechnological applications including protein production and gene transfer. Multiple in vitro and in vivo studies exist and support their use as gene delivery vehicles in vertebrate cells. Recently, baculoviruses have also demonstrated high potential in RNAi applications in which several advantages of the virus make it a promising tool for RNA gene transfer with high safety and wide tropism.
Topics: Animals; Arthropods; Baculoviridae; Gene Transfer Techniques; Genetic Vectors; RNA Interference; Transduction, Genetic; Vertebrates
PubMed: 25912715
DOI: 10.3390/v7042099 -
Virology Feb 2015Negatively-supercoiled-ds DNA molecules, including the genomes of baculoviruses, spontaneously wrap around cores of histones to form nucleosomes when present within... (Review)
Review
Negatively-supercoiled-ds DNA molecules, including the genomes of baculoviruses, spontaneously wrap around cores of histones to form nucleosomes when present within eukaryotic nuclei. Hence, nucleosome management should be essential for baculovirus genome replication and temporal regulation of transcription, but this has not been documented. Nucleosome mobilization is the dominion of ATP-dependent chromatin-remodeling complexes. SWI/SNF and INO80, two of the best-studied complexes, as well as chromatin modifier TIP60, all contain actin as a subunit. Retrospective analysis of results of AcMNPV time course experiments wherein actin polymerization was blocked by cytochalasin D drug treatment implicate actin-containing chromatin modifying complexes in decatenating baculovirus genomes, shutting down host transcription, and regulating late and very late phases of viral transcription. Moreover, virus-mediated nuclear localization of actin early during infection may contribute to nucleosome management.
Topics: Animals; Baculoviridae; Genome, Viral; Insect Proteins; Insecta; Nucleosomes; Virus Replication
PubMed: 25569454
DOI: 10.1016/j.virol.2014.12.022 -
Biotechnology Journal Jan 2019To stop the spread of future epidemics and meet infant vaccination demands in low- and middle-income countries, flexible, rapid and low-cost vaccine development and... (Review)
Review
To stop the spread of future epidemics and meet infant vaccination demands in low- and middle-income countries, flexible, rapid and low-cost vaccine development and manufacturing technologies are required. Vaccine development platform technologies that can produce a wide range of vaccines are emerging, including: a) humanized, high-yield yeast recombinant protein vaccines; b) insect cell-baculovirus ADDomer vaccines; c) Generalized Modules for Membrane Antigens (GMMA) vaccines; d) RNA vaccines. Herein, existing and future platforms are assessed in terms of addressing challenges of scale, cost, and responsiveness. To assess the risk and feasibility of the four emerging platforms, the following six metrics are applied: 1) technology readiness; 2) technological complexity; 3) ease of scale-up; 4) flexibility for the manufacturing of a wide range of vaccines; 5) thermostability of the vaccine product at tropical ambient temperatures; and 6) speed of response from threat identification to vaccine deployment. The assessment indicated that technologies in the order of increasing feasibility and decreasing risk are the yeast platform, ADDomer platform, followed by RNA and GMMA platforms. The comparative strengths and weaknesses of each technology are discussed in detail, illustrating the associated development and manufacturing needs and priorities.
Topics: Baculoviridae; Biotechnology; Humans; Technology, Pharmaceutical; Vaccination; Vaccines
PubMed: 30537361
DOI: 10.1002/biot.201800376 -
Trends in Biotechnology Sep 2015DNA transposons offer an efficient nonviral method of permanently modifying the genomes of mammalian cells. The piggyBac transposon system has proven effective in... (Review)
Review
DNA transposons offer an efficient nonviral method of permanently modifying the genomes of mammalian cells. The piggyBac transposon system has proven effective in genomic engineering of mammalian cells for preclinical applications, including gene discovery, simultaneous multiplexed genome modification, animal transgenesis, gene transfer in vivo achieving long-term gene expression in animals, and the genetic modification of clinically relevant cell types, such as induced pluripotent stem cells and human T lymphocytes. piggyBac has many desirable features, including seamless excision of transposons from the genomic DNA and the potential to target integration events to desired DNA sequences. In this review, we explore these recent applications and also highlight the unique advantages of using piggyBac for developing new molecular therapeutic strategies.
Topics: Animals; Baculoviridae; Genetic Engineering; Genetic Vectors; Genome; Humans; Mice
PubMed: 26211958
DOI: 10.1016/j.tibtech.2015.06.009