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Benning FMC, Jenni S, Garcia CY, Nguyen TH, Zhang X, Chao LH. Helical reconstruction of VP39 reveals principles for baculovirus nucleocapsid assembly. Nat Commun 2024; 15:250. [PMID: 38177118 PMCID: PMC10767040 DOI: 10.1038/s41467-023-44596-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 12/21/2023] [Indexed: 01/06/2024] Open
Abstract
Baculoviruses are insect-infecting pathogens with wide applications as biological pesticides, in vitro protein production vehicles and gene therapy tools. Its cylindrical nucleocapsid, which encapsulates and protects the circular double-stranded viral DNA encoding proteins for viral replication and entry, is formed by the highly conserved major capsid protein VP39. The mechanism for VP39 assembly remains unknown. We use electron cryomicroscopy to determine a 3.2 Å helical reconstruction of an infectious nucleocapsid of Autographa californica multiple nucleopolyhedrovirus, revealing how dimers of VP39 assemble into a 14-stranded helical tube. We show that VP39 comprises a distinct protein fold conserved across baculoviruses, which includes a Zinc finger domain and a stabilizing intra-dimer sling. Analysis of sample polymorphism shows that VP39 assembles in several closely-related helical geometries. This VP39 reconstruction reveals general principles for baculoviral nucleocapsid assembly.
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Affiliation(s)
- Friederike M C Benning
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Simon Jenni
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Coby Y Garcia
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, 02114, USA
- Harvard College, Cambridge, MA, 02138, USA
| | - Tran H Nguyen
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Xuewu Zhang
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Luke H Chao
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, 02114, USA.
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA.
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Benning FMC, Jenni S, Garcia CY, Nguyen TH, Zhang X, Chao LH. Helical reconstruction of VP39 reveals principles for baculovirus nucleocapsid assembly. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.15.545104. [PMID: 37398449 PMCID: PMC10312762 DOI: 10.1101/2023.06.15.545104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Baculoviruses are insect-infecting pathogens with wide applications as biological pesticides, in vitro protein production vehicles and gene therapy tools. Its cylindrical nucleocapsid, which encapsulates and protects the circular double-stranded viral DNA encoding proteins for viral replication and entry, is formed by the highly conserved major capsid protein VP39. The mechanism for VP39 assembly remains unknown. We determined a 3.2 Å electron cryomicroscopy helical reconstruction of an infectious nucleocapsid of Autographa californica multiple nucleopolyhedrovirus, revealing how dimers of VP39 assemble into a 14-stranded helical tube. We show that VP39 comprises a unique protein fold conserved across baculoviruses, which includes a Zinc finger domain and a stabilizing intra-dimer sling. Analysis of sample polymorphism revealed that VP39 assembles in several closely-related helical geometries. This VP39 reconstruction reveals general principles for baculoviral nucleocapsid assembly.
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Affiliation(s)
- Friederike M. C. Benning
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Simon Jenni
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Coby Y. Garcia
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Harvard College, Cambridge, MA 02138, USA
| | - Tran H. Nguyen
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Xuewu Zhang
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Luke H. Chao
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Genetics, Harvard Medical School, Boston, MA, USA
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3
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Bai H, Hu Y, Hu X, Li J, Mu J, Zhou Y, Chen X, Wang Y. Major capsid protein of Autographa californica multiple nucleopolyhedrovirus contributes to the promoter activity of the very late viral genes. Virus Res 2019; 273:197758. [PMID: 31541668 DOI: 10.1016/j.virusres.2019.197758] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 09/12/2019] [Accepted: 09/13/2019] [Indexed: 01/04/2023]
Abstract
The baculovirus expression vector system (BEVS) is one of the most powerful eukaryotic expression systems. Recombinant protein expression is usually controlled by promoters of the baculovirus very late genes (i.e., polyhedrin and p10); therefore, identifying novel regulatory factors for these promoters is key to increasing BEVS productivity. Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is the viral vector most frequently used in BEVS. VP39 is the major nucleocapsid protein of AcMNPV and plays a pivotal role in nucleocapsid assembly in the nucleus. In this study, we found that knocking out vp39 from the AcMNPV genome resulted in decreased protein abundance of polyhedrin and P10. Further assays revealed that the mRNA transcripts and the promoter activities of polyhedrin and p10 were decreased in the absence of vp39, suggesting that VP39 contributes to the activity of the very late viral gene promoters and may represent a means of optimizing the current BEVS.
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Affiliation(s)
- Huimin Bai
- Department of Basic Medicine and Forensic Medicine, Baotou Medical College, Baotou, China
| | - Yangyang Hu
- Shanghai Public Health Clinical Center, Fudan University, Shanghai, China
| | - Xue Hu
- State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Jing Li
- College of Pharmacy, Nankai University, Tianjin, China
| | - Jingfang Mu
- State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Yuan Zhou
- State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Xinwen Chen
- State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Yun Wang
- State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
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Saxena A, Byram PK, Singh SK, Chakraborty J, Murhammer D, Giri L. A structured review of baculovirus infection process: integration of mathematical models and biomolecular information on cell–virus interaction. J Gen Virol 2018; 99:1151-1171. [DOI: 10.1099/jgv.0.001108] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Abha Saxena
- 1Indian Institute of Technology Hyderabad, Chemical Engineering, Village Kandi, Sangareddy, Hyderabad, Telangana 502205, India
| | - Prasanna Kumar Byram
- 1Indian Institute of Technology Hyderabad, Chemical Engineering, Village Kandi, Sangareddy, Hyderabad, Telangana 502205, India
| | - Suraj Kumar Singh
- 1Indian Institute of Technology Hyderabad, Chemical Engineering, Village Kandi, Sangareddy, Hyderabad, Telangana 502205, India
| | - Jayanta Chakraborty
- 2Indian Institute of Technology Kharagpur, Chemical Engineering, Kharagpur, West Bengal 721302, India
| | - David Murhammer
- 3The University of Iowa, Department of Chemical and Biochemical Engineering, Iowa City, IA 52242-1527, USA
| | - Lopamudra Giri
- 1Indian Institute of Technology Hyderabad, Chemical Engineering, Village Kandi, Sangareddy, Hyderabad, Telangana 502205, India
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Abstract
Baculoviruses are large DNA viruses of insects that are highly pathogenic in many hosts. In the infection cycle, baculoviruses produce two types of virions. These virion phenotypes are physically and functionally distinct, and each serves a critical role in the biology of the virus. One phenotype, the occlusion-derived virus (ODV), is occluded within a crystallized protein that facilitates oral infection of the host. A large complex of at least nine ODV envelope proteins called per os infectivity factors are critically important for ODV infection of insect midgut epithelial cells. Viral egress from midgut cells is by budding to produce a second virus phenotype, the budded virus (BV). BV binds, enters, and replicates in most other tissues of the host insect. Cell recognition and entry by BV are mediated by a single major envelope glycoprotein: GP64 in some baculoviruses and F in others. Entry and egress by the two virion phenotypes occur by dramatically different mechanisms and reflect a life cycle in which ODV is specifically adapted for oral infection while BV mediates dissemination of the infection within the animal.
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Affiliation(s)
- Gary W Blissard
- Boyce Thompson Institute at Cornell University, Ithaca, New York 14853, USA;
| | - David A Theilmann
- Summerland Research and Development Center, Agriculture and Agri-Food Canada, Summerland, British Columbia V0H 1Z0, Canada;
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Zhang J, Feng M, Fan Y, Xu W, Zheng Q, Wu X. Networks of protein-protein interactions among structural proteins of budded virus of Bombyx mori nucleopolyhedrovirus. Virology 2018; 518:163-171. [PMID: 29510333 DOI: 10.1016/j.virol.2018.02.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 02/15/2018] [Accepted: 02/16/2018] [Indexed: 10/17/2022]
Abstract
The structural proteins of baculovirus are well studied, but the interactions between them remain unclear. In order to reveal protein-protein interactions among viral structural proteins and their associated proteins of the budded virus of Bombyx mori nucleopolyhedrovirus (BmNPV), the yeast two hybrid (Y2H) system was used to evaluate the interactions of 27 viral genes products. Fifty-seven interactions were identified with 51 binary interactions and 6 self-associations. Among them, 10 interactions were further confirmed by co-immunoprecipitation assays. Five interaction networks were formed based on the direct-cross Y2H assays. VP39, 38 K, and FP were identified to interact with most of the viral proteins, and may form major structural elements of the viral architecture. In addition, each envelope protein was detected to interact with more than one capsid protein. These results suggest how viral structural and structural associated proteins may assemble to form a complete virus through interacting with each other.
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Affiliation(s)
- Jianjia Zhang
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Min Feng
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Ying Fan
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Weifan Xu
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Qin Zheng
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Xiaofeng Wu
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, China.
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Autographa californica Multiple Nucleopolyhedrovirus ac75 Is Required for the Nuclear Egress of Nucleocapsids and Intranuclear Microvesicle Formation. J Virol 2018; 92:JVI.01509-17. [PMID: 29212928 DOI: 10.1128/jvi.01509-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 11/27/2017] [Indexed: 01/15/2023] Open
Abstract
Autographa californica multiple nucleopolyhedrovirus (AcMNPV) orf75 (ac75) is a highly conserved gene of unknown function. In this study, we constructed an ac75 knockout AcMNPV bacmid and investigated the role of ac75 in the baculovirus life cycle. The expression and distribution of the Ac75 protein were characterized, and its interaction with another viral protein was analyzed to further understand its function. Our data indicated that ac75 was required for the nuclear egress of nucleocapsids, intranuclear microvesicle formation, and subsequent budded virion (BV) formation, as well as occlusion-derived virion (ODV) envelopment and embedding of ODVs into polyhedra. Western blot analyses showed that two forms, of 18 and 15 kDa, of FLAG-tagged Ac75 protein were detected. Ac75 was associated with both nucleocapsid and envelope fractions of BVs but with only the nucleocapsid fraction of ODVs; the 18-kDa form was associated with only BVs, whereas the 15-kDa form was associated with both types of virion. Ac75 was localized predominantly in the intranuclear ring zone during infection and exhibited a nuclear rim distribution during the early phase of infection. A phase separation assay suggested that Ac75 was not an integral membrane protein. A coimmunoprecipitation assay revealed an interaction between Ac75 and the integral membrane protein Ac76, and bimolecular fluorescence complementation assays identified the sites of the interaction within the cytoplasm and at the nuclear membrane and ring zone in AcMNPV-infected cells. Our results have identified ac75 as a second gene that is required for both the nuclear egress of nucleocapsids and the formation of intranuclear microvesicles.IMPORTANCE During the baculovirus life cycle, the morphogenesis of both budded virions (BVs) and occlusion-derived virions (ODVs) is proposed to involve a budding process at the nuclear membrane, which occurs while nucleocapsids egress from the nucleus or when intranuclear microvesicles are produced. However, the exact mechanism of virion morphogenesis remains unknown. In this study, we identified ac75 as a second gene, in addition to ac93, that is essential for the nuclear egress of nucleocapsids, intranuclear microvesicle formation, and subsequent BV formation, as well as ODV envelopment and embedding of ODVs into polyhedra. Ac75 is not an integral membrane protein. However, it interacts with an integral membrane protein (Ac76) and is associated with the nuclear membrane. These data enhance our understanding of the commonalities between nuclear egress of nucleocapsids and intranuclear microvesicle formation and may help to reveal insights into the mechanism of baculovirus virion morphogenesis.
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Protein composition analysis of polyhedra matrix of Bombyx mori nucleopolyhedrovirus (BmNPV) showed powerful capacity of polyhedra to encapsulate foreign proteins. Sci Rep 2017; 7:8768. [PMID: 28821766 PMCID: PMC5562830 DOI: 10.1038/s41598-017-08987-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 07/14/2017] [Indexed: 11/23/2022] Open
Abstract
Polyhedra can encapsulate other proteins and have potential applications as protein stabilizers. The extremely stable polyhedra matrix may provide a platform for future engineered micro-crystal devices. However, the protein composition of the polyhedra matrix remains largely unknown. In this study, the occlusion-derived virus (ODV)-removed BmNPV polyhedra matrix fraction was subjected to SDS-PAGE and then an LC-ESI-MS/MS analysis using a Thermo Scientific Q Exactive mass spectrometer. In total, 28 host and 91 viral proteins were identified. The host components were grouped into one of six categories, i.e., chaperones, ubiquitin and related proteins, host helicases, cytoskeleton-related proteins, RNA-binding proteins and others, according to their predicted Pfam domain(s). Most viral proteins may not be essential for polyhedra assembly, as evidenced by studies in the literature showing that polyhedra formation occurs in the nucleus upon the disruption of individual genes. The structural role of these proteins in baculovirus replication will be of significant interest in future studies. The immobilization of enhanced green fluorescent protein (eGFP) into the polyhedra by fusing with the C-terminus of BM134 that is encoded by open reading frame (ORF) 134 suggested that the polyhedra had a powerful capacity to trap foreign proteins, and BM134 was a potential carrier for incorporating proteins of interest into the polyhedra.
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Baculovirus FP25K Localization: Role of the Coiled-Coil Domain. J Virol 2016; 90:9582-9597. [PMID: 27512078 DOI: 10.1128/jvi.01241-16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2016] [Accepted: 08/03/2016] [Indexed: 11/20/2022] Open
Abstract
Two types of viruses are produced during the baculovirus life cycle: budded virus (BV) and occlusion-derived virus (ODV). A particular baculovirus protein, FP25K, is involved in the switch from BV to ODV production. Previously, FP25K from the model alphabaculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) was shown to traffic ODV envelope proteins. However, FP25K localization and the domains involved are inconclusive. Here we used a quantitative approach to study FP25K subcellular localization during infection using an AcMNPV bacmid virus that produces a functional AcMNPV FP25K-green fluorescent protein (GFP) fusion protein. During cell infection, FP25K-GFP localized primarily to the cytoplasm, particularly amorphous structures, with a small fraction being localized in the nucleus. To investigate the sequences involved in FP25K localization, an alignment of baculovirus FP25K sequences revealed that the N-terminal putative coiled-coil domain is present in all alphabaculoviruses but absent in betabaculoviruses. Structural prediction indicated a strong relatedness of AcMNPV FP25K to long interspersed element 1 (LINE-1) open reading frame 1 protein (ORF1p), which contains an N-terminal coiled-coil domain responsible for cytoplasmic retention. Point mutations and deletions of this domain lead to a change in AcMNPV FP25K localization from cytoplasmic to nuclear. The coiled-coil and C-terminal deletion viruses increased BV production. Furthermore, a betabaculovirus FP25K protein lacking this N-terminal coiled-coil domain localized predominantly to the nucleus and exhibited increased BV production. These data suggest that the acquisition of this N-terminal coiled-coil domain in FP25K is important for the evolution of alphabaculoviruses. Moreover, with the divergence of preocclusion nuclear membrane breakdown in betabaculoviruses and membrane integrity in alphabaculoviruses, this domain represents an alphabaculovirus adaptation for nuclear trafficking of occlusion-associated proteins. IMPORTANCE Baculovirus infection produces two forms of viruses: BV and ODV. Manufacturing of ODV involves trafficking of envelope proteins to the inner nuclear membrane, mediated partly through the FP25K protein. Since FP25K is present in alpha-, beta-, and gammabaculoviruses, it is uncertain if this trafficking function is conserved. In this study, we looked at alpha- and betabaculovirus FP25K trafficking by its localization. Alphabaculovirus FP25K localized primarily to the cytoplasm, whereas betabaculovirus FP25K localized to the nucleus. We found that an N-terminal coiled-coil domain present in all alphabaculovirus FP25K proteins, but absent in betabaculovirus FP25K, was critical for alphabaculovirus FP25K cytoplasmic localization. We believe that this represents an evolutionary process that partly led to the gain of function of this N-terminal coiled-coil domain in alphabaculovirus FP25K to aid in nuclear trafficking of occlusion-associated proteins. Due to betabaculovirus breakdown of the nuclear membrane before occlusion, this function is not needed, and the domain was lost or never acquired.
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Hou D, Chen X, Zhang LK. Proteomic Analysis of Mamestra Brassicae Nucleopolyhedrovirus Progeny Virions from Two Different Hosts. PLoS One 2016; 11:e0153365. [PMID: 27058368 PMCID: PMC4825930 DOI: 10.1371/journal.pone.0153365] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 03/29/2016] [Indexed: 01/31/2023] Open
Abstract
Mamestra brassicae nucleopolyhedrovirus (MabrNPV) has a wide host range replication in more than one insect species. In this study, a sequenced MabrNPV strain, MabrNPV-CTa, was used to perform proteomic analysis of both BVs and ODVs derived from two infected hosts: Helicoverpa armigera and Spodoptera exigua. A total of 82 and 39 viral proteins were identified in ODVs and BVs, respectively. And totally, 23 and 76 host proteins were identified as virion-associated with ODVs and BVs, respectively. The host proteins incorporated into the virus particles were mainly involved in cytoskeleton, signaling, vesicle trafficking, chaperone and metabolic systems. Some host proteins, such as actin, cyclophilin A and heat shock protein 70 would be important for viral replication. Several host proteins involved in immune response were also identified in BV, and a C-type lectin protein was firstly found to be associated with BV and its family members have been demonstrated to be involved in entry process of other viruses. This study facilitated the annotation of baculovirus genome, and would help us to understand baculovirus virion structure. Furthermore, the identification of host proteins associated with virions produced in vivo would facilitate investigations on the involvement of intriguing host proteins in virus replication.
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Affiliation(s)
- Dianhai Hou
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Xi Chen
- Wuhan Institute of Biotechnology, Wuhan, P. R. China
| | - Lei-Ke Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
- * E-mail:
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Trichoplusia ni Kinesin-1 Associates with Autographa californica Multiple Nucleopolyhedrovirus Nucleocapsid Proteins and Is Required for Production of Budded Virus. J Virol 2016; 90:3480-95. [PMID: 26763996 DOI: 10.1128/jvi.02912-15] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 01/08/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The mechanism by which nucleocapsids of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) egress from the nucleus to the plasma membrane, leading to the formation of budded virus (BV), is not known. AC141 is a nucleocapsid-associated protein required for BV egress and has previously been shown to be associated with β-tubulin. In addition, AC141 and VP39 were previously shown by fluorescence resonance energy transfer by fluorescence lifetime imaging to interact directly with the Drosophila melanogaster kinesin-1 light chain (KLC) tetratricopeptide repeat (TPR) domain. These results suggested that microtubule transport systems may be involved in baculovirus nucleocapsid egress and BV formation. In this study, we investigated the role of lepidopteran microtubule transport using coimmunoprecipitation, colocalization, yeast two-hybrid, and small interfering RNA (siRNA) analyses. We show that nucleocapsid AC141 associates with the lepidopteran Trichoplusia ni KLC and kinesin-1 heavy chain (KHC) by coimmunoprecipitation and colocalization. Kinesin-1, AC141, and microtubules colocalized predominantly at the plasma membrane. In addition, the nucleocapsid proteins VP39, FP25, and BV/ODV-C42 were also coimmunoprecipitated with T. ni KLC. Direct analysis of the role of T. ni kinesin-1 by downregulation of KLC by siRNA resulted in a significant decrease in BV production. Nucleocapsids labeled with VP39 fused with three copies of the mCherry fluorescent protein also colocalized with microtubules. Yeast two-hybrid analysis showed no evidence of a direct interaction between kinesin-1 and AC141 or VP39, suggesting that either other nucleocapsid proteins or adaptor proteins may be required. These results further support the conclusion that microtubule transport is required for AcMNPV BV formation. IMPORTANCE In two key processes of the replication cycle of the baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV), nucleocapsids are transported through the cell. These include (i) entry of budded virus (BV) into the host cell and (ii) egress and budding of nucleocapsids newly produced from the plasma membrane. Prior studies have shown that the entry of nucleocapsids involves the polymerization of actin to propel nucleocapsids to nuclear pores and entry into the nucleus. For the spread of infection, progeny viruses must rapidly exit the infected cells, but the mechanism by which AcMNPV nucleocapsids traverse the cytoplasm is unknown. In this study, we examined whether nucleocapsids interact with lepidopteran kinesin-1 motor molecules and are potentially carried as cargo on microtubules to the plasma membrane in AcMNPV-infected cells. This study indicates that microtubule transport is utilized for the production of budded virus.
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Abstract
The development of baculovirus expression vector systems has accompanied a rapid expansion of our knowledge about the genes, their function and regulation in insect cells. Classification of these viruses has also been refined as we learn more about differences in gene content between isolates, how this affects virus structure and their replication in insect larvae. Baculovirus gene expression occurs in an ordered cascade, regulated by early, late and very late gene promoters. There is now a detailed knowledge of these promoter elements and how they interact first with host cell-encoded RNA polymerases and later with virus-encoded enzymes. The composition of this virus RNA polymerase is known. The virus replication process culminates in the very high level expression of both polyhedrin and p10 gene products in the latter stages of infection. It has also been realized that the insect host cell has innate defenses against baculoviruses in the form of an apoptotic response to virus invasion. Baculoviruses counter this by encoding apoptotic-suppressors, which also appear to have a role in determining the host range of the virus. Also of importance to our understanding of baculovirus expression systems is how the virus can accumulate mutations within genes that affect recombinant protein yield in cell culture. The summary in this chapter is not exhaustive, but should provide a good preparation to those wishing to use this highly successful gene expression system.
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Affiliation(s)
- Barbara J Kelly
- The Moyne Institute of Preventive Medicine, Trinity College, Dublin, Ireland
| | - Linda A King
- School of Biological and Molecular Sciences, Oxford Brookes University, Oxford, UK
| | - Robert D Possee
- NERC CEH (Oxford), Mansfield Road, Oxford, OX1, UK.
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK.
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The FP25K Acts as a Negative Factor for the Infectivity of AcMNPV Budded Virus. PLoS One 2015; 10:e0128471. [PMID: 26020780 PMCID: PMC4447387 DOI: 10.1371/journal.pone.0128471] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 04/27/2015] [Indexed: 01/11/2023] Open
Abstract
Baculoviruses generally produce two progeny phenotypes—the budded virus (BV) and the occlusion-derived virus (ODV)—and the intricate mechanisms that regulate the temporal synthesis of the two phenotypes are critical for the virus replication cycle, which are far from being clearly understood. FP25K was reported to be responsible for the regulation of BV/ODV, and the mutations within result in a decrease of normal ODVs formation and an increase of BVs production. In this study, we demonstrated that the increase of BV titer in an fp25k knockout recombinant (fp25k-negative) was a result of higher infectivity of BVs rather than an increased production of BVs. The constitution of the major structural proteins and genome of parental and fp25k-negative BVs were analyzed. The results showed that the integrity of the majority of DNA packaged into the fp25k-negative BVs was intact; i.e., the genomic DNA of fp25k-negative BV had better transformation and transfection efficiency than that of the parental virus, indicating more intact genomes in the virions. Although the analysis of proteins associated with BVs revealed that more envelope protein GP64 were incorporated into the fp25k-negative BVs, subsequent experiments suggested that overexpression of GP64 did not improve the titer of BVs. Thus, we conclude that the main reason for higher infectivity of BVs is due to better genome integrity, which benefits from the deletion of fp25k resulting in increased stability of the genome and produce a higher proportion of infectious BVs. FP25K acts as a negative factor for the infectivity of BV.
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14
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Ream DC, Murakami ST, Schmidt EE, Huang GH, Liang C, Friedberg I, Cheng XW. Comparative analysis of error-prone replication mononucleotide repeats across baculovirus genomes. Virus Res 2013; 178:217-25. [PMID: 24140718 DOI: 10.1016/j.virusres.2013.10.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 10/04/2013] [Accepted: 10/07/2013] [Indexed: 11/25/2022]
Abstract
Genome replication by the baculovirus DNA polymerase often generates errors in mononucleotide repeat (MNR) sequences due to replication slippage. This results in the inactivation of genes that affects different stages of the cell infection cycle. Here we mapped these MNRs in the 59 baculovirus genomes. We found that the MNR frequencies of baculovirus genomes are different and not correlated with the genome sizes. Although the average A/T content of baculoviruses is 58.67%, the A/T MNR frequency is significantly higher than that of the G/C MNRs. Furthermore, the A7/T7 MNRs are the most frequent of those we studied. Finally, MNR frequencies in different classes of baculovirus genes, such as immediate early genes, show differences between baculovirus genomes, suggesting that the distribution and frequency of different MNRs are unique to each baculovirus species or strain. Therefore, the results of this study can help select appropriate baculoviruses for the development of biological insecticides.
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Affiliation(s)
- David C Ream
- Department of Microbiology, Miami University, Oxford, OH, USA
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Luo XC, Wang SS, Zhang J, Qian DD, Wang SM, Li LL. Effects of Early or Overexpression of the Autographa californica Multiple Nucleopolyhedrovirus orf94 (ODV-e25) on Virus Replication. PLoS One 2013; 8:e65635. [PMID: 23825525 PMCID: PMC3688825 DOI: 10.1371/journal.pone.0065635] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2013] [Accepted: 04/25/2013] [Indexed: 11/19/2022] Open
Abstract
odv-e25(e25) is one of the core genes of baculoviruses. To investigate how it functions in the replication cycle of a baculovirus, a number of Autographa californica multiple nucleopolyhedrovirus recombinants with e25 under control of the promoter of immediate early gene ie1, or the promoter of the very late hyperexpressed gene p10, were constructed using a bacmid system, and the effects of early expression or overexpression of e25 on replication of the virus were evaluated. Microscopy and titration assays demonstrated that bacmids with e25 under control of ie1 promoter were unable to produce budded viruses; and that the recombinant viruses with e25 under control of p10 promoter generated budded virus normally, but formation of occlusion bodies were dramatically reduced and delayed in the infected cells. Electron microscopy showed that there were no mature virions or intact nucleocapsids present in the cells transfected with a recombinant bacmid with e25 under control of ie1 promoter. Quantitative real-time PCR analysis demonstrated that alteration of the e25 promoter did not affect viral DNA synthesis. The reporter gene expression from the promoter of the major capsid protein gene vp39 was reduced 63% by early expression of e25. Confocal microscopy revealed that E25 was predominantly localized in nuclei by 24 hours post infection with wild-type virus, but it remained in the cytoplasm in the cells transfected with a recombinant bacmid with e25 under control of the ie1 promoter, suggesting that the transport of E25 into nuclei was regulated in a specific and strict time dependent manner.
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Affiliation(s)
- Xiao-Chun Luo
- College of Life Sciences, Central China Normal University, Wuhan, China
| | - Shan-Shan Wang
- College of Life Sciences, Central China Normal University, Wuhan, China
| | - Jie Zhang
- College of Life Sciences, Central China Normal University, Wuhan, China
| | - Duo-Duo Qian
- College of Life Sciences, Central China Normal University, Wuhan, China
| | - Si-Min Wang
- College of Life Sciences, Central China Normal University, Wuhan, China
| | - Lu-Lin Li
- College of Life Sciences, Central China Normal University, Wuhan, China
- * E-mail:
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16
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Xiang X, Shen Y, Yang R, Chen L, Hu X, Wu X. Bombyx mori nucleopolyhedrovirus BmP95 plays an essential role in budded virus production and nucleocapsid assembly. J Gen Virol 2013; 94:1669-1679. [PMID: 23535571 DOI: 10.1099/vir.0.050583-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bombyx mori nucleopolyhedrovirus (BmNPV) BmP95 is a highly conserved gene that is found in all of the baculovirus genomes sequenced to date and is also found in nudiviruses. To investigate the role of BmP95 in virus infection in vitro, a BmP95 deletion virus (vBmP95-De) was generated by homologous recombination in Escherichia coli. Fluorescence and light microscopy and titration analysis indicated that the BmP95 deletion bacmid led to a defect in production of infectious budded virus (BV). However, deletion of BmP95 did not affect viral DNA replication. Electron microscopy showed that masses of aberrant tubular structures were present in cells transfected with the BmP95 deletion bacmid, indicating that deletion of BmP95 affected assembly of the nucleocapsid. This defect could be rescued by insertion of full-length BmP95 into the polyhedrin locus of the BmP95-knockout bacmid but not the N-terminal domain of BmP95. Together, these results showed that full-length BmP95 is essential for BV production and is required for nucleocapsid assembly.
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Affiliation(s)
- Xingwei Xiang
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, PR China
| | - Yunwang Shen
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, PR China
| | - Rui Yang
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, PR China
| | - Lin Chen
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, PR China
| | - Xiaolong Hu
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, PR China
| | - Xiaofeng Wu
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, PR China
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17
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Chen L, Yang R, Hu X, Xiang X, Yu S, Wu X. The formation of occlusion-derived virus is affected by the expression level of ODV-E25. Virus Res 2013; 173:404-14. [PMID: 23298549 DOI: 10.1016/j.virusres.2012.12.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 12/26/2012] [Accepted: 12/27/2012] [Indexed: 11/18/2022]
Abstract
Odv-e25 is a core gene of baculoviruses and encodes a 25.5 kDa protein located on both budded virus (BV) and occlusion-derived virus (ODV). Our previous study demonstrated that ODV-E25 was required for the formation of intranuclear microvesicles and ODV, and an odv-e25 deletion mutant could be rescued by re-expression of odv-e25 under its native promoter. To investigate the functions of ODV-E25 expression level on ODV formation, the promoter of ie-1 (pIE1), the odv-e25 native promoter, and the polyhedrin promoter (pPH) were used to direct odv-e25 expression. Our results showed that the production of ODV-E25 under its native promoter was higher than that under pIE1 but lower than that under pPH. Viral DNA replication and budded viruses (BVs) production showed that expression of odv-e25 under pIE1 and pPH could not completely repair the defects caused by the deletion of ODV-E25, while expression under its native promoter did. Electron microscopy showed that intranuclear microvesicles were found in all the constructs transfected cells except the odv-e25-null virus. However, mature ODVs only were detected in cells transfected with virus in which odv-e25 was expressed under its native or polyhedrin promoter. These results indicated that the formation occlusion-derived virus was affected by the expression level of ODV-E25.
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Affiliation(s)
- Lin Chen
- College of Animal Sciences, Zhejiang University, Hangzhou 310029, China
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18
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Cheng XH, Hillman CC, Zhang CX, Cheng XW. Reduction of polyhedrin mRNA and protein expression levels in Sf9 and Hi5 cell lines, but not in Sf21 cells, infected with Autographa californica multiple nucleopolyhedrovirus fp25k mutants. J Gen Virol 2013; 94:166-176. [DOI: 10.1099/vir.0.045583-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
During cell infection, the fp25k gene of baculoviruses frequently mutates, producing the few polyhedra (FP) per cell phenotype with reduced polyhedrin (polh) expression levels compared with wild-type baculoviruses. Here we report that the fp25k gene of the model baculovirus, Autographa californica multiple nucleopolyhedrovirus (AcMNPV), contains two hypermutable seven-adenine (A7) mononucleotide repeats (MNRs) that were mutated to A8 MNRs and a TTAA site that had host DNA insertions, producing fp25k mutants during Sf21 cell infection. The FP phenotype in Sf9 and Hi5 cells was more pronounced than in Sf21 cells. AcMNPV fp25k mutants produced similar levels of polyhedra or enhanced GFP, which were both under the control of the AcMNPV polh promoter for expression, in Sf21 cells but lower levels in Sf9 and Hi5 cells compared with AcMNPV with an intact fp25k gene. This correlated with the polh mRNA levels detected in each cell line. The majority of Sf21 cells infected with fp25 mutants showed high polh promoter-mediated GFP expression levels. Two cell lines subcloned from Sf21 cells that were infected with fp25k mutants showed different GFP expression levels. Furthermore, a small proportion of Hi5 cells infected with fp25k mutants showed higher production of polyhedra and GFP expression than the rest, and the latter was not correlated with increased m.o.i. Therefore, these data suggest that AcMNPV polh promoter-mediated gene expression activities differ in the three cell lines and are influenced by different cells within the cell line.
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Affiliation(s)
- Xin-Hua Cheng
- Department of Microbiology, Miami University, Oxford, OH 45056, USA
- Graduate Program in Cell, Molecular and Structural Biology, Miami University, Oxford, OH 45056, USA
| | | | - Chuan-Xi Zhang
- Agriculture Key Laboratory of Agricultural Entomology, Institute of Insect Science, Zhejiang University, Hangzhou 310058, PR China
| | - Xiao-Wen Cheng
- Department of Microbiology, Miami University, Oxford, OH 45056, USA
- Graduate Program in Cell, Molecular and Structural Biology, Miami University, Oxford, OH 45056, USA
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Dickison VL, Willis LG, Sokal NR, Theilmann DA. Deletion of AcMNPV ac146 eliminates the production of budded virus. Virology 2012; 431:29-39. [PMID: 22682215 DOI: 10.1016/j.virol.2012.05.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 02/02/2012] [Accepted: 05/04/2012] [Indexed: 12/22/2022]
Abstract
Autographa californica multiple nucleopolyhedrovirus (AcMNPV) ac146 is a highly conserved gene in the Alpha- and Betabaculovirus genera that has an unknown function. Northern blot analysis and transcript mapping showed that ac146 is transcribed at late times post infection as a 1.2 kb mRNA. To determine the role of ac146 in the baculovirus life cycle ac146 knock out viruses were constructed. Transfection and plaque assays showed that all the ac146 deletions produced a single cell phenotype indicating that no infectious budded virus (BV) was produced, however occlusion bodies were formed. The lack of BV production was confirmed by viral titration utilizing both qPCR and TCID₅₀. Analysis of BV and occlusion derived virus (ODV) revealed that AC146 is associated with both forms of the virus and is modified specifically in ODV. This study therefore demonstrates that AC146 is a late virion associated protein and is essential for the viral life cycle.
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Affiliation(s)
- Virginia L Dickison
- Irving K. Barber School of Arts and Sciences, Unit 2 Biology, University of British Columbia, Kelowna, B.C. V1V 1V7, Canada
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20
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Autographa californica multiple nucleopolyhedrovirus odv-e25 (Ac94) is required for budded virus infectivity and occlusion-derived virus formation. Arch Virol 2012; 157:617-25. [PMID: 22218963 DOI: 10.1007/s00705-011-1211-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Accepted: 11/24/2011] [Indexed: 10/14/2022]
Abstract
Autographa californica multiple nucleopolyhedrovirus (AcMNPV) odv-e25 is a core gene found in all lepidopteran baculoviruses, but its function is unknown. In this study, we generated an odv-e25-knockout AcMNPV and investigated the roles of ODV-E25 in the baculovirus life cycle. The odv-e25 knockout was subsequently rescued by reinserting the odv-e25 gene into the same virus genome. Fluorescence microscopy showed that transfection with the odv-e25-null bacmid vAcBac(KO) was insufficient for propagation in cell culture, whereas the 'repair' virus vAcBac(RE) was able to function in a manner similar to that of the control vAcBac. We found that odv-e25 was not essential for the release of budded viruses (BVs) into culture medium, although the absence of odv-e25 resulted in a 100-fold lower viral titer at 24 h post-transfection (p.t.). Analysis of viral DNA replication in the absence of odv-e25 showed that viral DNA replication was unaffected in the first 24 h p.t. Furthermore, electron microscopy revealed that polyhedra were found in the nucleus, while mature occlusion-derived viruses (ODVs) were not found in the nucleus or polyhedra in odv-e25 null transfected cells, which indicated that ODV-E25 was required for the formation of ODV.
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21
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Pedrini MRS, Reid S, Nielsen LK, Chan LCL. Kinetic characterization of the group II helicoverpa armigera nucleopolyhedrovirus propagated in suspension cell cultures: Implications for development of a biopesticides production process. Biotechnol Prog 2011; 27:614-24. [DOI: 10.1002/btpr.602] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 12/24/2010] [Indexed: 11/10/2022]
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22
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Xu F, Ince IA, Boeren S, Vlak JM, van Oers MM. Protein composition of the occlusion derived virus of Chrysodeixis chalcites nucleopolyhedrovirus. Virus Res 2011; 158:1-7. [PMID: 21354223 DOI: 10.1016/j.virusres.2011.02.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 02/17/2011] [Accepted: 02/17/2011] [Indexed: 11/27/2022]
Abstract
Chrysodeixis chalcites nucleopolyhedrovirus (ChchNPV) is a group II NPV and its genome has 151 predicted open reading frames. In this study, the protein composition of ChchNPV occlusion derived virus (ODV) was determined by LC-MS/MS. Fifty-three proteins were identified in ChchNPV ODV particles. One ODV-protein is encoded by a gene so far unique to ChchNPV (Chch105). The two DNA photolyases PHR1 and PHR2, which are characteristic for ChchNPV and thought to be involved in repairing UV damage in viral DNA, were not detected in the ODVs. Comparison of the ODV proteins identified in ChchNPV and in three other baculoviruses enabled the identification of ten conserved ODV proteins (ODV-E18, ODV-E56, ODV-EC27, ODV-EC43, P6.9, P33, P49, P74, GP41, and VP39). In addition, the baculovirus per os infectivity factors PIF1, PIF2 and PIF3 were all detected in ChchNPV and these should be considered as conserved ODV proteins as well as they are absolutely required for oral infection. With the LC-MS/MS method used 22 viral proteins were detected, which were not identified as ODV proteins in previous studies.
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Affiliation(s)
- Fang Xu
- Laboratory of Virology, Wageningen University, P.O. Box 629, 6700 AP Wageningen, The Netherlands
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23
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Sparks WO, Rohlfing A, Bonning BC. A peptide with similarity to baculovirus ODV-E66 binds the gut epithelium of Heliothis virescens and impedes infection with Autographa californica multiple nucleopolyhedrovirus. J Gen Virol 2011; 92:1051-1060. [PMID: 21228132 DOI: 10.1099/vir.0.028118-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Baculoviruses infect their lepidopteran hosts via the midgut epithelium through binding of occlusion-derived virus (ODV) and fusion between the virus envelope and microvillar membranes. To identify genes and sequences that are involved in this process, a random phage display library was screened for peptides that bound to brush border membrane vesicles (BBMV) derived from the midgut epithelium of Heliothis virescens. Seventeen peptides that bound to BBMV were recovered. Two of these, HV1 and HV2, had sequence similarity to the ODV envelope protein ODV-E66 that is found in five species of alphabaculoviruses. Chemically synthesized versions of HV1 and HV2, and two peptides (AcE66A and AcE66B) derived from similar sequences of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) ODV-E66, bound to unfixed cryosections of whole midgut tissues. AcE66A, but not HV1, bound to H. virescens gut BBMV proteins on a far-Western blot. Competition assays with HV1 and purified AcMNPV ODV resulted in decreased mortality of H. virescens larvae at a dose of 1 LD(50), and a significant increase in survival time at higher virus concentrations. These results suggest a role for ODV-E66 in baculovirus infection of lepidopteran larval midgut epithelium.
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Affiliation(s)
- Wendy O Sparks
- Department of Entomology and Program in Genetics, Iowa State University, Ames, IA 50011, USA
| | - Amy Rohlfing
- Department of Entomology and Program in Genetics, Iowa State University, Ames, IA 50011, USA
| | - Bryony C Bonning
- Department of Entomology and Program in Genetics, Iowa State University, Ames, IA 50011, USA
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24
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Nie Y, Fang M, Theilmann DA. Autographa californica multiple nucleopolyhedrovirus core gene ac92 (p33) is required for efficient budded virus production. Virology 2010; 409:38-45. [PMID: 20965540 DOI: 10.1016/j.virol.2010.09.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 09/15/2010] [Accepted: 09/22/2010] [Indexed: 11/26/2022]
Abstract
Autographa californica multiple nucleopolyhedrovirus (AcMNPV) ac92 is a core gene encoding a protein associated with occlusion derived virus (ODV), binds human P53 and also has flavin adenine dinucleotide linked sulfhydryl oxidase activity but its role in the virus life cycle is not known. To determine ac92 function a deletion virus (vAc(92KO)) was generated and transfected Sf9 cells revealed that vAc(92KO) infection was restricted primarily to single cells and budded virus (BV) titer was reduced over 99.99%. However, viral DNA replication was unaffected and development of occlusion bodies in vAc(92KO)-transfected cells evidenced progression to very late phases of viral infection. AC92 localized to both the cytoplasm and nucleus, and was also associated with BV as well as ODV. In BV AC92 was detected in BV envelope and nucleocapsid fractions. Finally it was shown that the ac92 homologue from the Group II alphabaculovirus Mamestra configurata NPV maco96 could only partially rescue vAc(92KO).
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Affiliation(s)
- Yingchao Nie
- Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, Box 5000, Summerland, BC, Canada
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25
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Giri L, Li H, Sandgren D, Feiss MG, Roller R, Bonning BC, Murhammer DW. Removal of transposon target sites from the Autographa californica multiple nucleopolyhedrovirus fp25k gene delays, but does not prevent, accumulation of the few polyhedra phenotype. J Gen Virol 2010; 91:3053-64. [PMID: 20810745 PMCID: PMC3052567 DOI: 10.1099/vir.0.024430-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Low-cost, large-scale production of the baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) using continuous insect cell culture is seriously hindered by the accumulation of AcMNPV mutants. Specifically, few-polyhedra (FP) mutants, with a reduced yield of occluded virus (polyhedra) and decreased infectivity, usually accumulate upon passaging in cell culture. FP mutations result from transposon insertions in the baculovirus fp25k gene, leading to significantly reduced levels of FP25K protein synthesis. This study evaluated the effects of removing the transposon insertion sites from the wild-type baculovirus fp25k gene; the mutated virus was denoted Ac-FPm. Specifically, this study involved a detailed comparison of wild-type (WT) AcMNPV and Ac-FPm with regard to the proportion of cells having polyhedra, number of polyhedra per cell, the fraction of empty polyhedra, number of occlusion-derived viruses per polyhedron, number of nucleocapsids in the nuclei, FP25K protein synthesis and genetic analysis of the fp25k gene. Removal of TTAA transposon insertion sites from the fp25k gene stabilized FP25K protein synthesis and delayed the appearance of the FP phenotype from passage 5 to passage 10. Electron micrographs revealed that more virus particles were found inside the nuclei of cells infected with Ac-FPm than in the nuclei of cells infected with WT AcMNPV (at passage 10). Abnormalities, however, were observed in envelopment of nucleocapsids and virus particle occlusion within Ac-FPm polyhedra. Thus, the FP phenotype appeared in spite of continued FP25K protein synthesis, suggesting that mechanisms other than fp25k gene disruption can lead to the FP phenotype.
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Affiliation(s)
- Lopamudra Giri
- University of Iowa, Department of Chemical and Biochemical Engineering, Iowa City, IA 52242-1527, USA
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Characterization of a Bombyx mori nucleopolyhedrovirus mutant lacking both fp25K and p35. Virus Genes 2010; 41:144-8. [PMID: 20508980 DOI: 10.1007/s11262-010-0492-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Accepted: 05/10/2010] [Indexed: 10/19/2022]
Abstract
Recent studies have shown that dual mutations in fp25K and p35 of Autographa californica nucleopolyhedrovirus (AcMNPV) result in a typical apoptotic infection on Trichoplusia ni cells, suggesting the involvement of FP25K on NPV-induced apoptosis. To examine the effect of fp25K deletion on Bombyx mori NPV (BmNPV)-induced apoptosis, we generated a BmNPV mutant, fp-p35D, in which both fp25K and p35 genes are deleted from the genome, and compared its phenotype with wild-type (T3), fp25K-deleted (fp-null), and p35-deleted (p35D) BmNPVs. In BmN cells, p35D, but not T3 or fp-null, caused apoptosis with caspase-3 activation. Infection with fp-p35D also resulted in caspase-3 activation, but the level was comparable to that of p35D. Also, we did not observe any apoptotic responses in hemocytes from larvae infected with p35D or fp-p35D. These results indicate that unlike AcMNPV, deletion of fp25K does not affect the pathway of p35D-induced apoptosis of BmN cells and B. mori larvae.
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Abstract
Baculoviruses produce two progeny phenotypes during their replication cycles. The occlusion-derived virus (ODV) is responsible for initiating primary infection in the larval midgut, and the budded virus (BV) phenotype is responsible for the secondary infection. The proteomics of several baculovirus ODVs have been revealed, but so far, no extensive analysis of BV-associated proteins has been conducted. In this study, the protein composition of the BV of Autographa californica nucleopolyhedrovirus (AcMNPV), the type species of baculoviruses, was analyzed by various mass spectrometry (MS) techniques, including liquid chromatography-triple quadrupole linear ion trap (LC-Qtrap), liquid chromatography-quadrupole time of flight (LC-Q-TOF), and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF). SDS-PAGE and MALDI-TOF analyses showed that the three most abundant proteins of the AcMNPV BV were GP64, VP39, and P6.9. A total of 34 viral proteins associated with the AcMNPV BV were identified by the indicated methods. Thirteen of these proteins, PP31, AC58/59, AC66, IAP-2, AC73, AC74, AC114, AC124, chitinase, polyhedron envelope protein (PEP), AC132, ODV-E18, and ODV-E56, were identified for the first time to be BV-associated proteins. Western blot analyses showed that ODV-E18 and ODV-E25, which were previously thought to be ODV-specific proteins, were also present in the envelop fraction of BV. In addition, 11 cellular proteins were found to be associated with the AcMNPV BV by both LC-Qtrap and LC-Q-TOF analyses. Interestingly, seven of these proteins were also identified in other enveloped viruses, suggesting that many enveloped viruses may commonly utilize certain conserved cellular pathways.
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28
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Comparative studies of lepidopteran baculovirus-specific protein FP25K: development of a novel Bombyx mori nucleopolyhedrovirus-based vector with a modified fp25K gene. J Virol 2010; 84:5191-200. [PMID: 20219904 DOI: 10.1128/jvi.00099-10] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lepidopteran baculovirus-specific protein FP25K performs many roles during the infection cycle, including functions in the production of occlusion bodies (OBs) and budded viruses (BVs), oral infection, and postmortem host degradation. To explore the common and specific functions of FP25K proteins among lepidopteran baculoviruses, we performed comparative analyses of FP25K proteins from group I and group II nucleopolyhedroviruses (NPVs) and granulovirus (GV). Using recombinant Bombyx mori NPVs (BmNPVs), we showed that the FP25Ks from NPVs were able to eliminate all the phenotypic defects observed in an infection with a BmNPV mutant lacking functional fp25K but that FP25K from GV did not show abilities to recover oral infectivity and postmortem host degradation. We also observed that introduction of Autographa californica multiple NPV (AcMNPV) fp25K into the BmNPV genome enhanced OB and BV production. According to these results, we generated a novel BmNPV-based expression vector with AcMNPV fp25K and examined its potential in BmN cells and B. mori larvae. Our results showed that the introduction of AcMNPV fp25K significantly increases the expression of foreign gene products in cultured cells and shortens the time for obtaining the secreted recombinant proteins from larval hemolymph.
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29
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Peng K, Wu M, Deng F, Song J, Dong C, Wang H, Hu Z. Identification of protein-protein interactions of the occlusion-derived virus-associated proteins of Helicoverpa armigera nucleopolyhedrovirus. J Gen Virol 2009; 91:659-70. [PMID: 19906939 DOI: 10.1099/vir.0.017103-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The purpose of this study was to identify protein-protein interactions among the components of the occlusion-derived virus (ODV) of Helicoverpa armigera nucleopolyhedrovirus (HearNPV), a group II alphabaculovirus in the family Baculoviridae. To achieve this, 39 selected genes of potential ODV structural proteins were cloned and expressed in the Gal4 yeast two-hybrid (Y2H) system. The direct-cross Y2H assays identified 22 interactions comprising 13 binary interactions [HA9-ODV-EC43, ODV-E56-38K, ODV-E56-PIF3, LEF3-helicase, LEF3-alkaline nuclease (AN), GP41-38K, GP41-HA90, 38K-PIF3, 38K-PIF2, VP80-HA100, ODV-E66-PIF3, ODV-E66-PIF2 and PIF3-PIF2] and nine self-associations (IE1, HA44, LEF3, HA66, GP41, CG30, 38K, PIF3 and P24). Five of these interactions - LEF3-helicase and LEF3-AN, and the self-associations of IE1, LEF3 and 38K - have been reported previously in Autographa californica multiple nucleopolyhedrovirus. As HA44 and HA100 were two newly identified ODV proteins of group II viruses, their interactions were further confirmed. The self-association of HA44 was verified with a His pull-down assay and the interaction of VP80-HA100 was confirmed by a co-immunoprecipitation assay. A summary of the protein-protein interactions of baculoviruses reported so far, comprising 68 interactions with 45 viral proteins and five host proteins, is presented, which will facilitate our understanding of the molecular mechanisms of baculovirus infection.
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Affiliation(s)
- Ke Peng
- State Key Laboratory of Virology and Joint Laboratory of Invertebrate Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China
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30
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Cohen DPA, Marek M, Davies BG, Vlak JM, van Oers MM. Encyclopedia of Autographa californica nucleopolyhedrovirus genes. Virol Sin 2009. [DOI: 10.1007/s12250-009-3059-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
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Nai YS, Wang TC, Chen YR, Lo CF, Wang CH. A new nucleopolyhedrovirus strain (LdMNPV-like virus) with a defective fp25 gene from Lymantria xylina (Lepidoptera: Lymantriidae) in Taiwan. J Invertebr Pathol 2009; 102:110-9. [PMID: 19616553 DOI: 10.1016/j.jip.2009.07.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Revised: 11/28/2008] [Accepted: 07/13/2009] [Indexed: 11/19/2022]
Abstract
A new multiple nucleopolyhedrovirus strain was isolated from casuarina moth, Lymantria xylina Swinhoe, (Lepidoptera: Lymantriidae) in Taiwan. This Lymantria-derived virus can be propagated in IPLB-LD-652Y and NTU-LY cell lines and showed a few polyhedra (occlusion bodies) CPE in the infected cells. The restriction fragment length polymorphism (RFLP) profiles of whole genome indicated that this virus is distinct from LyxyMNPV and the virus genome size was approximately 139 kbps, which was smaller than that of LyxyMNPV. The molecular phylogenetic analyses of three important genes (polyhedrin, lef-8 and lef-9) were performed. Polyhedrin, LEF-8 and LEF-9 putative amino acid analyses of this virus revealed that this virus belongs to Group II NPV and closely related to LdMNPV than to LyxyMNPV. The phylogenetic distance analysis was further clarified the relationship to LdMNPV and this virus provisionally named LdMNPV-like virus. A significant deletion of a 44bp sequence found in LdMNPV-like virus was noted in the fp25k sequences of LdMNPV and LyxyMNPV and may play an important role in the few polyhedra CPE. In ultrastructural observations, the nuclei of the infected LD host cells contained large occlusion bodies (OBs), and few OBs, which presented as one or two OBs in a nucleus that was otherwise filled with free nuclocapsids and virions. We concluded that this LdMNPV-like virus is a new LdMNPV strain from L. xylina.
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Affiliation(s)
- Yu-Shin Nai
- Department of Entomology, National Taiwan University, Taipei, Taiwan, ROC
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Nie Y, Fang M, Theilmann DA. AcMNPV AC16 (DA26, BV/ODV-E26) regulates the levels of IE0 and IE1 and binds to both proteins via a domain located within the acidic transcriptional activation domain. Virology 2009; 385:484-95. [PMID: 19150105 DOI: 10.1016/j.virol.2008.12.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Revised: 11/20/2008] [Accepted: 12/10/2008] [Indexed: 11/19/2022]
Abstract
IE0 and IE1 are the primary viral regulatory proteins of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) involved in the transactivation of early genes, stimulation of late gene expression, and viral DNA replication. The protein interactions required for IE0 or IE1 to achieve these varied roles are not well defined, so to identify proteins that interact with IE0 and IE1, tandem affinity purification (TAP) and LC-MS/MS was used. Analysis of purified proteins identified AC16 (DA26, BV/ODV-E26) from TAP tagged IE0 virus infected Sf9 cells. Co-immunoprecipitation confirmed that AC16 interacts with both IE0 and IE1 and yeast 2-hybrid analysis mapped the domain required for interaction with AC16. Mutation of the AC16 binding domain enhanced BV production by viruses expressing only IE0 but had no effect if only IE1 is expressed. An ac16 deletion virus was constructed and was shown not to affect the temporal expression of IE0 and IE1; however the relative level of IE0 to IE1 was significantly increased.
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Affiliation(s)
- Yingchao Nie
- Plant Science, Faculty of Land and Food Systems, University of British Columbia, Vancouver, B.C., Canada V6T 1Z4
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Katsuma S, Nakanishi T, Shimada T. Bombyx mori nucleopolyhedrovirus FP25K is essential for maintaining a steady-state level of v-cath expression throughout the infection. Virus Res 2009; 140:155-60. [PMID: 19100790 DOI: 10.1016/j.virusres.2008.11.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Revised: 11/25/2008] [Accepted: 11/25/2008] [Indexed: 11/16/2022]
Abstract
It has been previously reported that the fp25K product of Bombyx mori nucleopolyhedrovirus (BmNPV) is required for post-mortem host degradation, but the mechanism by which it regulates host degradation is still unknown. This study shows that disruption of BmNPV fp25K attenuates the expression of viral cathepsin gene (v-cath) at a late stage of infection, and thus reduces the secretion of its product V-CATH. Western blot analysis showed that secretion of V-CATH was severely reduced in BmN cells and B. mori larvae infected with Bm25KD, a BmNPV mutant lacking functional fp25K, compared to that of wild-type BmNPV. Also, reduced accumulation of pro-V-CATH in Bm25KD-infected cells was observed from 4 days postinfection (dpi), during which V-CATH was first detected in the medium of BmNPV-infected cells. qRT-PCR experiments showed that the expression levels of v-cath mRNA in wild-type- and Bm25KD-infected BmN cells were comparable at 3 dpi, but showed a marked decrease in Bm25KD-infected BmN cells at 4 dpi. Collectively, these results suggest that BmNPV FP25K is essential for the proper transcriptional regulation of v-cath and efficient secretion of V-CATH, and a steady-state level of v-cath expression during the period of V-CATH secretion (after 4 dpi) is required for post-mortem host degradation.
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Affiliation(s)
- Susumu Katsuma
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
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Bombyx mori nucleopolyhedrovirus ORF51 encodes a budded virus envelope associated protein. Virus Genes 2008; 38:171-7. [PMID: 19085095 DOI: 10.1007/s11262-008-0312-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Accepted: 11/26/2008] [Indexed: 10/21/2022]
Abstract
Bombyx mori nucleopolyhedrovirus (BmNPV) ORF 51 (Bm51) is a gene present in many lepidopteran NPVs, but its function is unknown. In this study, Bm51 was characterized. Transcripts of Bm51 were detected from 4.5 through 72 hour post infection (h p.i.) by RT-PCR. The corresponding protein was detected from 6 to 72 h p.i. in BmNPV-infected BmN cells by western blot analysis using a polyclonal antibody against Bm51. Western blot assay of occlusion-derived virus and budded virus (BV) preparations revealed that Bm51 encodes a 23-kDa structural protein that is associated with BV and is located in the envelope fraction of budded virions. The protein was temporarily called BV-E23. In addition immunofluorescence microscopy demonstrated that the protein was present within the cytoplasm and nuclei in virus-infected cells. In conclusion, the available data suggest that Bm51 is a functional ORF of BmNPV and encodes a protein expressed in the early stage of the infection cycle that is associated with the BV envelope.
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Baculovirus data suggest a common but multifaceted pathway for sorting proteins to the inner nuclear membrane. J Virol 2008; 83:1280-8. [PMID: 19019955 DOI: 10.1128/jvi.01661-08] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Multiple unique protein markers sorted to the inner nuclear membrane (INM) from the Autographa californica nucleopolyhedrovirus occlusion-derived virus (ODV) envelope were used to decipher common elements of the sorting pathway of integral membrane proteins from their site of insertion into the membrane of the endoplasmic reticulum (ER) through their transit to the INM. The data show that during viral infection, the viral protein FP25K is a partner for all known ODV envelope proteins and that BV/ODV-E26 (designated E26) is a partner for some, but not all, such proteins. The association with the ER membrane of FP25K, E26, and the cellular INM-sorting protein importin-alpha-16 is not static; rather, these sorting proteins are actively recruited to the ER membrane based upon requirements of the proteins in transit to the INM. Colocalization analysis using an ODV envelope protein and importin-alpha-16 shows that during viral infection, importin-alpha-16 translocates across the pore membrane to the INM and then is incorporated into the virus-induced intranuclear membranes. Thus, the association of importin-alpha-16 and INM-directed proteins appears to remain at least through protein translocation across the pore membrane to the INM. Overall, the data suggest that multiple levels of regulation facilitate INM-directed protein trafficking, and that proteins participating in this sorting pathway have a dynamic relationship with each other and the membrane of the ER.
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Autographa californica multiple nucleopolyhedrovirus 38K is a novel nucleocapsid protein that interacts with VP1054, VP39, VP80, and itself. J Virol 2008; 82:12356-64. [PMID: 18922869 DOI: 10.1128/jvi.00948-08] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
It has been shown that the Autographa californica multiple nucleopolyhedrovirus (AcMNPV) 38K (ac98) is required for nucleocapsid assembly. However, the exact role of 38K in nucleocapsid assembly remains unknown. In the present study, we investigated the relationship between 38K and the nucleocapsid. Western blotting using polyclonal antibodies raised against 38K revealed that 38K was expressed in the late phase of infection in AcMNPV-infected Spodoptera frugiperda cells and copurified with budded virus (BV) and occlusion-derived virus (ODV). Biochemical fractionation of BV and ODV into the nucleocapsid and envelope components followed by Western blotting showed that 38K was associated with the nucleocapsids. Immunoelectron microscopic analysis revealed that 38K was specifically localized to the nucleocapsids in infected cells and appeared to be distributed over the cylindrical capsid sheath of nucleocapsid. Yeast two-hybrid assays were performed to examine potential interactions between 38K and nine known nucleocapsid shell-associated proteins (PP78/83, PCNA, VP1054, FP25, VLF-1, VP39, BV/ODV-C42, VP80, and P24), three non-nucleocapsid shell-associated proteins (P6.9, PP31, and BV/ODV-E26), and itself. The results revealed that 38K interacted with the nucleocapsid proteins VP1054, VP39, VP80, and 38K itself. These interactions were confirmed by coimmunoprecipitation assays in vivo. These data demonstrate that 38K is a novel nucleocapsid protein and provide a rationale for why 38K is essential for nucleocapsid assembly.
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Tang XD, Xu YP, Yu LL, Lang GJ, Tian CH, Zhao JF, Zhang CX. Characterization of a Bombyx mori nucleopolyhedrovirus with Bmvp80 disruption. Virus Res 2008; 138:81-8. [PMID: 18809445 DOI: 10.1016/j.virusres.2008.08.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2008] [Revised: 08/19/2008] [Accepted: 08/21/2008] [Indexed: 10/21/2022]
Abstract
A BmNPV Bacmid with the Bmvp80 gene disrupted was constructed using the ET-recombination system in Escherichia coli to investigate the role of Bmvp80 during the baculovirus life cycle. Disruption of Bmvp80 resulted in single cell infection phenotype, whereas a rescue BmBacmid restored budded virus titers to wild type levels; however, the homologous gene Ac104 (Acvp80) from AcMNPV could not complement the BmBacmid lacking a functional Bmvp80 gene. Electron microscopy of cells transfected with BmNPV lacking functional Bmvp80 revealed that the number of nucleocapsids was markedly lower. These results suggest that Bmvp80 is essential for normal budded virus production and nucleocapsid maturation, and is functionally divergent between baculovirus species.
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Affiliation(s)
- Xu-Dong Tang
- Institute of Insect Science, Zhejiang University, 268 Kaixuan Road, Hangzhou 310029, Zhejiang, China
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39
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Extended budded virus formation and induction of apoptosis by an AcMNPV FP-25/p35 double mutant in Trichoplusia ni cells. Virus Res 2008; 133:157-66. [DOI: 10.1016/j.virusres.2007.12.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Revised: 12/20/2007] [Accepted: 12/20/2007] [Indexed: 11/19/2022]
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40
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Fang M, Nie Y, Dai X, Theilmann DA. Identification of AcMNPV EXON0 (ac141) domains required for efficient production of budded virus, dimerization and association with BV/ODV-C42 and FP25. Virology 2008; 375:265-76. [DOI: 10.1016/j.virol.2008.01.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Revised: 12/29/2007] [Accepted: 01/28/2008] [Indexed: 11/30/2022]
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41
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Nuclear marginalization of host cell chromatin associated with expansion of two discrete virus-induced subnuclear compartments during baculovirus infection. J Virol 2008; 82:6409-18. [PMID: 18434402 DOI: 10.1128/jvi.00490-08] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Chromatin structure is strictly regulated during the cell cycle. DNA viruses occasionally disturb the spatial organization of the host cell chromatin due to formation of the viral DNA replication compartment. To examine chromatin behavior in baculovirus-infected cells, we constructed recombinant plasmids expressing fluorescent protein-tagged histone H4 molecules and visualized the intracellular localization of chromatin by their transient expression in live infected cells. Similar to other DNA viruses, the baculovirus Bombyx mori nucleopolyhedrovirus induced marginal relocation of chromatin within the nuclei of BmN cells, simultaneously with expansion of the viral DNA replication compartment, the virogenic stroma (VS). In the late stage of infection, however, the peristromal region (PR), another virus-induced subnuclear compartment, was also excluded from the chromatin-localizing area. Provided that late-gene products such as PR proteins (e.g., envelope proteins of the occlusion-derived virus) were expressed, blockage of viral DNA synthesis failed to inhibit chromatin relocation, despite abrogation of VS expansion. Instead, chromatin became marginalized concomitantly with PR expansion, suggesting that the PR contributes directly to chromatin replacement. In addition, chromatin was excluded from relatively large subnuclear structures that were induced in uninfected cells by cotransfection with four baculovirus genes, ie1, lef3, p143, and hr. Omission of any of the four genes, however, failed to result in formation of the large structures or chromatin exclusion. This correlation between compartmentalization and chromatin exclusion suggests the possibility that a chromatin-exclusive property of viral molecules, at least in part, supports nuclear compartmentalization of virus-infected cells.
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42
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McCarthy CB, Dai X, Donly C, Theilmann DA. Autographa californica multiple nucleopolyhedrovirus ac142, a core gene that is essential for BV production and ODV envelopment. Virology 2008; 372:325-39. [DOI: 10.1016/j.virol.2007.10.019] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Revised: 08/27/2007] [Accepted: 10/18/2007] [Indexed: 12/01/2022]
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43
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Ke J, Wang J, Deng R, Wang X. Autographa californica multiple nucleopolyhedrovirus ac66 is required for the efficient egress of nucleocapsids from the nucleus, general synthesis of preoccluded virions and occlusion body formation. Virology 2008; 374:421-31. [PMID: 18241908 DOI: 10.1016/j.virol.2007.12.033] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Revised: 11/20/2007] [Accepted: 12/18/2007] [Indexed: 11/29/2022]
Abstract
Although orf66 (ac66) of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is conserved in all sequenced lepidopteran baculovirus genomes, its function is not known. This paper describes generation of an ac66 knockout AcMNPV bacmid mutant and analyses of the influence of ac66 deletion on the virus replication in Sf-9 cells so as to determine the role of ac66 in the viral life cycle. Results indicated that budded virus (BV) yields were reduced over 99% in ac66-null mutant infected cells in comparison to that in wild-type virus infected cells. Optical microscopy revealed that occlusion body synthesis was significantly reduced in the ac66 knockout bacmid-transfected cells. In addition, ac66 deletion interrupted preoccluded virion synthesis. The mutant phenotype was rescued by an ac66 repair bacmid. On the other hand, real-time PCR analysis indicated that ac66 deletion did not affect the levels of viral DNA replication. Electron microscopy revealed that ac66 is not essential for nucleocapsid assembly, but for the efficient transport of nucleocapsids from the nucleus to the cytoplasm. These results suggested that ac66 plays an important role for the efficient exit of nucleocapsids from the nucleus to the cytoplasm for BV synthesis as well as for preoccluded virion and occlusion synthesis.
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Affiliation(s)
- Jianhao Ke
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, 510275 Guangzhou, China.
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44
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Abstract
The development of baculovirus expression vector systems has accompanied a rapid expansion of our knowledge about the genes, their function, and regulation in insect cells. Classification of these viruses has also been refined as we learn more about differences in gene content between isolates, how this affects virus structure, and their replication in insect larvae. Baculovirus gene expression occurs in an ordered cascade, regulated by early, late, and very late gene promoters. There is now a detailed knowledge of these promoter elements and how they interact first with host cell-encoded RNA polymerases and later with virus-encoded enzymes. The composition of this virus RNA polymerase is known. The virus replication process culminates in the very high level expression of both polyhedrin and p10 gene products in the latter stages of infection. It has also been realized that the insect host cell has innate defenses against baculoviruses in the form of an apoptotic response to virus invasion. Baculoviruses counter this by encoding apoptotic-suppressors, which also appear to have a role in determining the host range of the virus. Also of importance to our understanding of baculovirus expression systems is how the virus can accumulate mutations within genes that affect recombinant protein yield in cell culture. The summary in this chapter is not exhaustive, but should provide a good preparation to those wishing to use this highly successful gene expression system.
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45
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Fang M, Dai X, Theilmann DA. Autographa californica multiple nucleopolyhedrovirus EXON0 (ORF141) is required for efficient egress of nucleocapsids from the nucleus. J Virol 2007; 81:9859-69. [PMID: 17626083 PMCID: PMC2045402 DOI: 10.1128/jvi.00588-07] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Autographa californica multiple nucleopolyhedrovirus (AcMNPV) exon0 (orf141) has been shown to be required for the efficient production of budded virus (BV). The deletion of exon0 reduces the level of BV production by up to 99% (X. Dai, T. M. Stewart, J. A. Pathakamuri, Q. Li, and D. A. Theilmann, J. Virol. 78:9633-9644, 2004); however, the function or mechanism by which EXON0 affects BV production is unknown. In this study, we further elucidated the function of EXON0 by investigating the localization of EXON0 in infected Sf9 cells and in virions and by identifying interactions between EXON0 and other viral proteins. In addition, electron microscopy was used to study the cellular localization of nucleocapsids in cells transfected with an exon0 knockout (KO) virus. The results showed that EXON0 was localized to both the cytoplasm and the nuclei of infected Sf9 cells throughout the infection. Western blotting results also showed that EXON0 was purified along with BV and occlusion-derived virus (ODV). The fractionation of BV into the nucleocapsid and envelope components showed that EXON0 localized to the BV nucleocapsid. Yeast two-hybrid screening, coimmunoprecipitation, and confocal microscopy revealed that it interacted with nucleocapsid proteins FP25 and BV/ODV-C42. Cells transfected with the exon0 KO virus exhibited normally appearing nucleocapsids in the nuclei in numbers equal to those in the nuclei of cells transfected with the EXON0 repaired virus. In contrast, the numbers of nucleocapsids in the cytoplasm of cells transfected with the exon0 KO virus were significantly lower than those in the cytoplasm of cells transfected with the repaired virus. These results support the conclusion that EXON0 is required in the BV pathway for the efficient egress of nucleocapsids from the nucleus to the cytoplasm.
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Affiliation(s)
- Minggang Fang
- Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, Box 5000, Summerland, BC, Canada
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46
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Li X, Song J, Jiang T, Liang C, Chen X. The N-terminal hydrophobic sequence of Autographa californica nucleopolyhedrovirus PIF-3 is essential for oral infection. Arch Virol 2007; 152:1851-8. [PMID: 17585368 DOI: 10.1007/s00705-007-1012-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2007] [Accepted: 05/21/2007] [Indexed: 10/23/2022]
Abstract
The Autographa californica nucleopolyhedrovirus (AcMNPV) open reading frame 115 has been identified as a per os infection factor (pif-3) and is essential for oral infection. Here, we have characterized the pif-3 of AcMNPV in more detail. The pif-3 transcripts were detected from 12 to 96 h post-infection (hpi) in Sf9 cells infected with AcMNPV. Polyclonal antiserum first recognized a 25-kDa protein at 36 hpi. Western blot analysis indicated that PIF-3 is a component of occlusion-derived virus but not of budded virus. The subcellular localization demonstrated that the 21-amino-acid (aa) N-terminal hydrophobic domain of PIF-3, which is conserved in PIF-1, PIF2 and PIF-3, acts as a nuclear location signal and is essential for trafficking the protein to the nucleus. Deletion of either pif-3 or the 21-aa N-terminal hydrophobic domain of pif-3 from AcMNPV abolished per os infectivity but had no effect on the infectivity of the budded virus phenotype.
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Affiliation(s)
- X Li
- State Key Laboratory of Virology, Wuhan Institute of Virology, The Chinese Academy of Sciences, Wuhan, PR China
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47
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Li L, Kim YS, Hwang DS, Seo JH, Jung HJ, Du J, Cha HJ. High and compact formation of baculoviral polyhedrin-induced inclusion body by co-expression of baculoviral FP25 in Escherichia coli. Biotechnol Bioeng 2007; 96:1183-90. [PMID: 17004271 DOI: 10.1002/bit.21193] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Previously, we found that baculoviral polyhedrin (Polh) can successfully be used in Escherichia coli as a fusion partner for the expression of special foreign proteins as inclusion bodies, and the resulting, easily isolatable Polh-induced fusion inclusion bodies had almost the same characteristics as the native Polh. Here, we investigated the effects of co-expression of baculoviral FP25 protein on Polh-induced inclusion-body production in an E. coli expression system, as FP25 is known to be involved specifically in polyhedra formation. Using several analytical tools, including SDS-PAGE, pronase proteolysis, solubilization under alkaline conditions, and electron microscopy, we found that co-expressed FP25 was associated with Polh-induced inclusion bodies and that its co-expression led to formation of compact inclusion bodies as well as high production levels. We confirmed that FP25 co-expression induced higher production levels of other heterologous protein, antimicrobial peptide Hal18, fused with aggregation-prone Polh. Therefore, co-expression of baculoviral FP25 can be promisingly used to increase the levels of baculoviral Polh-fused foreign proteins, especially harmful proteins, expressed as inclusion bodies in an E. coli expression system.
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Affiliation(s)
- Lin Li
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
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48
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Wen R, Ou R, Chen B. Molecular characterization and genetic organization of the inhibitor of apoptosis gene (iap-5) region of the Pieris rapae granulovirus. Virus Genes 2007; 35:443-8. [PMID: 17354063 DOI: 10.1007/s11262-007-0086-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Accepted: 02/14/2007] [Indexed: 10/23/2022]
Abstract
Pieris rapae granulovirus (PiraGV) is a baculovirus pathogenic to the insect P. rapae (Pieridae, Lepidoptera). Though being known for decades, information on the genetic organization of this virus remains limited. In an effort to characterize this virus, an 11.8 kb BamHI restriction fragment that harbors the inhibitor of apoptosis gene (iap-5) was sequenced. Our results indicate that this region contains important genes such as dnapol, lef-3, lef-9, and dnaligase that are involved in transcription and replication of the virus. The gene content and synteny in this region are highly conserved among granulovirus genomes. Phylogenetic analysis showed that PiraGV genes are more closely related to the Choristoneura occidentalis granulovirus (ChocGV) than other characterized granulovirus (GVs).
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Affiliation(s)
- Ronghui Wen
- Guangxi Key Laboratory of Subtropical Bioresources Conservation and Utilization, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China
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49
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Abstract
Baculoviruses play an important ecological role regulating the size of insect populations. For many years, baculoviruses have been applied as targeted biocontrol agents against forestry and agriculture pests. Baculovirus insecticides are effective against insect pests such as velvetbean caterpillar (Anticarsia gemmatalis ), cotton bollworm (Helicoverpa zea ), and gypsy moth (Lymantria dispar ). Baculoviruses are transmitted to insects by the oral route mediated by the occlusion-derived virus (ODV). The ODV is also specialized to exploit the insect midgut that is one of the most extreme biological environments where the viruses are subject to caustic pH and digestive proteases. The molecular biology of the ODV reveals new frontiers in protein chemistry. Finally, ODVs establishes infection in insect gut tissues that are virtually nonsupportive to virus replication and which are continuously sloughed away. ODVs carry with them a battery of proteins that enable them to rapidly exploit and harness these unstable cells for virus replication.
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Affiliation(s)
- Jeffery Slack
- Laboratory for Molecular Virology, Great Lakes Forestry Centre, Sault Ste. Marie, Ontario, Canada
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50
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Burks JK, Summers MD, Braunagel SC. BV/ODV-E26: a palmitoylated, multifunctional structural protein of Autographa californica nucleopolyhedrovirus. Virology 2006; 361:194-203. [PMID: 17169392 DOI: 10.1016/j.virol.2006.11.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Revised: 10/30/2006] [Accepted: 11/06/2006] [Indexed: 11/18/2022]
Abstract
Autographa californica nucleopolyhedrovirus Ac16 is 1 of 17 genes conserved within Type 1 nucleopolyhedroviruses. This report demonstrates that multiple isoforms of the protein encoded by Ac16, BV/ODV-E26 (E26), are present in the infected cell. One form of E26 associates with viral DNA or DNA-binding proteins, while a second form associates with intracellular membranes and this is likely due to palmitoylation. The different forms of E26 present unique epitopes that can be discriminated by antiserum produced to bacterially or virally produced antigen. A summation of the data now available on E26 suggests that it is a multifunctional protein and the functional states assume unique conformations that can be discriminated by differing antisera.
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Affiliation(s)
- Jared K Burks
- Department of Biology, Texas A&M University, TX, USA
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