1
|
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.
Collapse
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.
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
Desheva Y, Petkova N, Losev I, Guzhov D, Go A, Chao YC, Tsai CH. Establishment of a Pseudovirus Platform for Neuraminidase Inhibiting Antibody Analysis. Int J Mol Sci 2023; 24:ijms24032376. [PMID: 36768700 PMCID: PMC9916614 DOI: 10.3390/ijms24032376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/18/2023] [Accepted: 01/21/2023] [Indexed: 01/27/2023] Open
Abstract
Neuraminidase (NA)-based immunity to influenza can be useful for protecting against novel antigenic variants. To develop safe and effective tools to assess NA-based immunity, we generated a baculovirus-based pseudotyped virus, N1-Bac, that expresses the full-length NA of the influenza A/California/07/2009 (H1N1)pdm09 strain. We evaluated the level of NA-inhibiting (NI) antibodies in the paired blood sera of influenza patients by means of an enzyme-linked lectin assay (ELLA) using the influenza virus or N1-Bac. Additionally, we evaluated the level of NA antibodies by means of the enzyme-linked immunosorbent assay (ELISA) with an N1-expressing Sf21 culture. We detected a strong correlation between our results from using the influenza virus and NA-Bac pseudoviruses to detect NI antibodies and a medium-strong correlation between NI antibodies and NA antibodies determined by an N1-cell ELISA, indicating that baculovirus-based platforms can be successfully used to evaluate NI or NA antibodies. Furthermore, animal experiments showed that immunization with N1-Bac protected against infection with a drift variant of the A/H1N1pdm09 influenza virus. Our results demonstrate that recombinant baculovirus can be an effective influenza pseudotype to evaluate influenza serologic immunity and protect against influenza virus infection.
Collapse
Affiliation(s)
- Yulia Desheva
- Virology Department, Federal State Budgetary Scientific Institution, Institute of Experimental Medicine, 197022 Saint Petersburg, Russia
| | - Nadezhda Petkova
- Virology Department, Federal State Budgetary Scientific Institution, Institute of Experimental Medicine, 197022 Saint Petersburg, Russia
| | - Igor Losev
- Virology Department, Federal State Budgetary Scientific Institution, Institute of Experimental Medicine, 197022 Saint Petersburg, Russia
| | - Dmitry Guzhov
- Clinical Infectious Diseases Hospital No. 30 Named after S.P. Botkin, 195067 Saint Petersburg, Russia
| | - Alexey Go
- Medical Center, St. Petersburg Research Institute of Epidemiology and Microbiology Named after Pasteur, 197101 Saint Petersburg, Russia
| | - Yu-Chan Chao
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
- Department of Entomology, National Chung-Hsing University, Taichung 402, Taiwan
- Department of Entomology, National Taiwan University, Taipei 106, Taiwan
- Correspondence: (Y.-C.C.); (C.-H.T.); Tel.: +886-4-2285-1522 (Y.-C.C.); +886-6-2353-535-5626 (C.-H.T.)
| | - Chih-Hsuan Tsai
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
- Correspondence: (Y.-C.C.); (C.-H.T.); Tel.: +886-4-2285-1522 (Y.-C.C.); +886-6-2353-535-5626 (C.-H.T.)
| |
Collapse
|
4
|
Hsu WT, Chang CY, Tsai CH, Wei SC, Lo HR, Lamis RJS, Chang HW, Chao YC. PEDV Infection Generates Conformation-Specific Antibodies That Can Be Effectively Detected by a Cell-Based ELISA. Viruses 2021; 13:v13020303. [PMID: 33671997 PMCID: PMC7919263 DOI: 10.3390/v13020303] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/05/2021] [Accepted: 02/09/2021] [Indexed: 02/07/2023] Open
Abstract
Porcine epidemic diarrhea virus (PEDV) is a coronavirus that causes serious and highly contagious enteric disease in swine worldwide. In this study, we constructed a recombinant baculovirus (S-Bac) expressing full-length spike protein of the virulent epidemic genotype 2b (G2b) PEDV strain for serological studies of infected pigs. We found that most spike-specific antibodies produced upon PEDV infection in pigs are conformation-specific and they could be detected on S-Bac-infected insect cells by immunofluorescent assay, but they were insensitive to Western blot analysis, the typical method for antiserum analysis. These results indicated that spike conformation is crucial for serum recognition. Since it is difficult to purify trimeric spike membrane protein for conventional enzyme-linked immunosorbent assay (ELISA), we used S-Bac to generate a novel cell-based ELISA for convenient PEDV detection. We analyzed 100 pig serum samples, and our cell-based ELISA exhibited a sensitivity of 100%, a specificity of 97%, and almost perfect agreement [Cohen’s kappa coefficient value (κ) = 0.98] with immunocytochemical staining results. Our cell-based ELISA rapidly presented antigen for proper detection of conformation-specific antibodies, making PEDV detection more convenient, and it will be useful for detecting many viral diseases in the future.
Collapse
Affiliation(s)
- Wei-Ting Hsu
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan; (W.-T.H.); (C.-H.T.); (S.-C.W.); (H.-R.L.); (R.J.S.L.)
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan
| | - Chia-Yu Chang
- School of Veterinary Medicine, National Taiwan University, Taipei 106, Taiwan; (C.-Y.C.); (H.-W.C.)
| | - Chih-Hsuan Tsai
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan; (W.-T.H.); (C.-H.T.); (S.-C.W.); (H.-R.L.); (R.J.S.L.)
| | - Sung-Chan Wei
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan; (W.-T.H.); (C.-H.T.); (S.-C.W.); (H.-R.L.); (R.J.S.L.)
| | - Huei-Ru Lo
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan; (W.-T.H.); (C.-H.T.); (S.-C.W.); (H.-R.L.); (R.J.S.L.)
| | - Robert John S. Lamis
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan; (W.-T.H.); (C.-H.T.); (S.-C.W.); (H.-R.L.); (R.J.S.L.)
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan
- Molecular and Cell Biology, Taiwan International Graduate Program, Academia Sinica and Graduate Institute of Life Science, National Defense Medical Center, Taipei 115, Taiwan
| | - Hui-Wen Chang
- School of Veterinary Medicine, National Taiwan University, Taipei 106, Taiwan; (C.-Y.C.); (H.-W.C.)
- Graduate Institute of Molecular and Comparative Pathobiology, School of Veterinary Medicine, National Taiwan University, Taipei 106, Taiwan
| | - Yu-Chan Chao
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan; (W.-T.H.); (C.-H.T.); (S.-C.W.); (H.-R.L.); (R.J.S.L.)
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan
- Molecular and Cell Biology, Taiwan International Graduate Program, Academia Sinica and Graduate Institute of Life Science, National Defense Medical Center, Taipei 115, Taiwan
- Department of Entomology, National Chung Hsing University, Taichung 402, Taiwan
- Department of Plant Pathology and Microbiology, College of Bioresources and Agriculture, National Taiwan University, Taipei 106, Taiwan
- Correspondence:
| |
Collapse
|
5
|
Baculovirus IE2 Interacts with Viral DNA through Daxx To Generate an Organized Nuclear Body Structure for Gene Activation in Vero Cells. J Virol 2019; 93:JVI.00149-19. [PMID: 30728268 DOI: 10.1128/jvi.00149-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 01/31/2019] [Indexed: 12/14/2022] Open
Abstract
Upon virus infection of a cell, the uncoated DNA is usually blocked by the host intrinsic immune system inside the nucleus. Although it is crucial for the virus to counteract the host intrinsic immune system and access its genome, little is known about how viruses can knock down host restriction and identify their blocked genomes for later viral gene activation and replication. We found that upon baculovirus transduction into Vero E6 cells, the invading viral DNA is trapped by the cellular death domain-associated protein (Daxx) and histone H3.3 in the nucleus, resulting in gene inactivation. IE2, a baculovirus transactivator, targets host Daxx through IE2 SUMO-interacting motifs (SIMs) to indirectly access viral DNA and forms unique nuclear body structures, which we term clathrate cage-like apparatus (CCLAs), at the early transduction stage. At the later transduction stage, CCLAs gradually enlarge, and IE2 continues to closely interact with viral DNA but no longer associates with Daxx. The association with Daxx is essential for IE2 CCLA formation, and the enlarged CCLAs are capable of transactivating viral but not chromosomal DNA of Vero E6 cells. Our study reveals that baculovirus IE2 counteracts the cellular intrinsic immune system by specifically targeting Daxx and H3.3 to associate with viral DNA indirectly and efficiently. IE2 then utilizes this association with viral DNA to establish a unique CCLA cellular nanomachinery, which is visible under light microscopy as an enclosed environment for proper viral gene expression.IMPORTANCE The major breakthrough of this work is that viral protein IE2 localizes and transactivates its own viral DNA through a most unlikely route, i.e., host proteins Daxx and H3.3, which are designed to efficiently restrict viral DNA from expression. By interacting with these host intrinsic immune factors, IE2 can thus target the viral DNA and then form a unique spherical nuclear body, which we name the CCLA, to enclose the viral DNA and necessary factors to assist in high-level transactivation. Our study represents one of the most complete investigations of nuclear body formation. In addition, so far only RNA or protein molecules have been reported as potential nucleators for initiating nuclear body formation; our study may represent the first example showing that DNA can be a nucleator for a new class of nuclear body formation.
Collapse
|
6
|
Dong Z, Hu Z, Qin Q, Dong F, Huang L, Long J, Chen P, Lu C, Pan M. CRISPR/Cas9-mediated disruption of the immediate early-0 and 2 as a therapeutic approach to Bombyx mori nucleopolyhedrovirus in transgenic silkworm. INSECT MOLECULAR BIOLOGY 2019; 28:112-122. [PMID: 30120848 DOI: 10.1111/imb.12529] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The CRISPR/Cas9 system is a powerful tool for the treatment of infectious diseases. In our previous study, we knocked out the Bombyx mori nucleopolyhedrovirus (BmNPV) key genes and BmNPV-dependent host factor to generate transgenic antiviral strains. To further expand the range of target genes for BmNPV and more effectively prevent and control pathogenic infections, we performed gene editing and antiviral analysis by constructing a target-directed baculovirus early transcriptional activator immediate early-0 (ie-0) and 2 (ie-2) transgenic silkworm line. We hybridized it with Cas9 transgenic line to produce a double-positive transgenic Cas9(+)/sgIE0-sgIE2(+) line that could activate the CRISPR gene editing system. We first demonstrated that the system is capable of efficiently editing target genes and resulting in fragment deletions in the BmNPV genome. Survival rate of the transgenic Cas9(+)/sgIE0-sgIE2(+) line reached 65% after inoculation with 1 × 106 occlusion bodies/larva. Molecular analysis showed that BmNPV DNA replication and viral gene expression level in the transgenic Cas9(+)/sgIE0-sgIE2(+) line were significantly inhibited compared with the control Cas9(-)/sgIE0-sgIE2(-) line. These results indicated that IE-0 and IE-2, as baculovirus early transcriptional activators, can be used as target sites for gene therapy and that multigene editing could expand the range of target sites for research to create silkworm resistance breeds.
Collapse
Affiliation(s)
- Z Dong
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400716, China
| | - Z Hu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400716, China
| | - Q Qin
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400716, China
| | - F Dong
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400716, China
| | - L Huang
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400716, China
| | - J Long
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400716, China
| | - P Chen
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400716, China
| | - C Lu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400716, China
- Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, Chongqing, 400716, China
| | - M Pan
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400716, China
- Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, Chongqing, 400716, China
| |
Collapse
|
7
|
Baculovirus as a Tool for Gene Delivery and Gene Therapy. Viruses 2018; 10:v10090510. [PMID: 30235841 PMCID: PMC6164903 DOI: 10.3390/v10090510] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 09/14/2018] [Accepted: 09/14/2018] [Indexed: 12/13/2022] Open
Abstract
Based on its ability to express high levels of protein, baculovirus has been widely used for recombinant protein production in insect cells for more than thirty years with continued technical improvements. In addition, baculovirus has been successfully applied for foreign gene delivery into mammalian cells without any viral replication. However, several CpG motifs are present throughout baculoviral DNA and induce an antiviral response in mammalian cells, resulting in the production of pro-inflammatory cytokines and type I interferon through a Toll-like receptor (TLR)-dependent or -independent signaling pathway, and ultimately limiting the efficiency of transgene expression. On the other hand, by taking advantage of this strong adjuvant activity, recombinant baculoviruses encoding neutralization epitopes can elicit protective immunity in mice. Moreover, immunodeficient cells, such as hepatitis C virus (HCV)- or human immunodeficiency virus (HIV)-infected cells, are more susceptible to baculovirus infection than normal cells and are selectively eliminated by the apoptosis-inducible recombinant baculovirus. Here, we summarize the application of baculovirus as a gene expression vector and the mechanism of the host innate immune response induced by baculovirus in mammalian cells. We also discuss the future prospects of baculovirus vectors.
Collapse
|
8
|
Chang CY, Hsu WT, Chao YC, Chang HW. Display of Porcine Epidemic Diarrhea Virus Spike Protein on Baculovirus to Improve Immunogenicity and Protective Efficacy. Viruses 2018; 10:v10070346. [PMID: 29954081 PMCID: PMC6071207 DOI: 10.3390/v10070346] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 06/15/2018] [Accepted: 06/15/2018] [Indexed: 01/23/2023] Open
Abstract
A new variant of the porcine epidemic diarrhea virus (PEDV) is an emerging swine disease, killing considerable numbers of neonatal piglets in North America and Asia in recent years. To generate immunogens mimicking the complex spike (S) protein folding with proper posttranslational modification to mount a robust immune response against the highly virulent PEDV, two baculoviruses displaying the full-length S protein (S-Bac) and the S1 protein (S1-Bac) of the virulent Taiwan genotype 2b (G2b) PEDV Pintung 52 (PEDV-PT) strain were constructed. Intramuscular immunizations of mice and piglets with the S-Bac and S1-Bac demonstrated significantly higher levels of systemic anti-PEDV S-specific IgG, as compared with control group. Our results also showed that piglets in the S-Bac group elicited superior PEDV-specific neutralizing antibodies than those of the S1-Bac and control groups. The highly virulent PEDV-PT strain challenge experiment showed that piglets immunized with S-Bac and S1-Bac showed milder clinical symptoms with significantly less fecal viral shedding as compared with non-immunized control piglets. More importantly, piglets immunized with the S-Bac exhibited no to mild clinical signs, with a delayed, minimal viral shedding. Our results demonstrated that the S-Bac could serve as a safe, easy to manipulate, and effective vaccine candidate against the PEDV infection.
Collapse
Affiliation(s)
- Chia-Yu Chang
- School of Veterinary Medicine, National Taiwan University, Taipei 106, Taiwan.
| | - Wei-Ting Hsu
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei 115, Taiwan.
| | - Yu-Chan Chao
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei 115, Taiwan.
| | - Hui-Wen Chang
- School of Veterinary Medicine, National Taiwan University, Taipei 106, Taiwan.
- Graduate Institute of Molecular and Comparative Pathobiology, School of Veterinary Medicine, National Taiwan University, Taipei 106, Taiwan.
| |
Collapse
|
9
|
The Heteroaryldihydropyrimidine Bay 38-7690 Induces Hepatitis B Virus Core Protein Aggregates Associated with Promyelocytic Leukemia Nuclear Bodies in Infected Cells. mSphere 2018; 3:3/2/e00131-18. [PMID: 29669885 PMCID: PMC5907649 DOI: 10.1128/mspheredirect.00131-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 03/24/2018] [Indexed: 02/07/2023] Open
Abstract
Heteroaryldihydropyrimidines (HAPs) are compounds that inhibit hepatitis B virus (HBV) replication by modulating viral capsid assembly. While their biophysical effects on capsid assembly in vitro have been previously studied, the effect of HAP treatment on capsid protein (Cp) in individual HBV-infected cells remains unknown. We report here that the HAP Bay 38-7690 promotes aggregation of recombinant Cp in vitro and causes a time- and dose-dependent decrease of Cp in infected cells, consistent with previously studied HAPs. Interestingly, immunofluorescence analysis showed Cp aggregating in nuclear foci of Bay 38-7690-treated infected cells in a time- and dose-dependent manner. We found these foci to be associated with promyelocytic leukemia (PML) nuclear bodies (NBs), which are structures that affect many cellular functions, including DNA damage response, transcription, apoptosis, and antiviral responses. Cp aggregation is not an artifact of the cell system used, as it is observed in HBV-expressing HepAD38 cells, in HepG2 cells transfected with an HBV-expressing plasmid, and in HepG2-NTCP cells infected with HBV. Use of a Cp overexpression vector without HBV sequences shows that aggregation is independent of viral replication, and use of an HBV-expressing plasmid harboring a HAP resistance mutation in Cp abrogated the aggregation, demonstrating that the effect is due to direct compound-Cp interactions. These studies provide novel insight into the effects of HAP-based treatment at a single-cell level.IMPORTANCE Despite the availability of effective vaccines and treatments, HBV remains a significant global health concern, with more than 240 million individuals chronically infected. Current treatments are highly effective at controlling viral replication and disease progression but rarely cure infections. Therefore, much emphasis is being placed on finding therapeutics with new drug targets, such as viral gene expression, covalently closed circular DNA formation and stability, capsid formation, and host immune modulators, with the ultimate goal of an HBV cure. Understanding the mechanisms by which novel antiviral agents act will be imperative for the development of curative HBV therapies.
Collapse
|
10
|
Wang CH, Naik NG, Liao LL, Wei SC, Chao YC. Global Screening of Antiviral Genes that Suppress Baculovirus Transgene Expression in Mammalian Cells. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2017; 6:194-206. [PMID: 28831401 PMCID: PMC5554962 DOI: 10.1016/j.omtm.2017.07.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Accepted: 07/13/2017] [Indexed: 12/31/2022]
Abstract
Although baculovirus has been used as a safe and convenient gene delivery vector in mammalian cells, baculovirus-mediated transgene expression is less effective in various mammalian cell lines. Identification of the negative regulators in host cells is necessary to improve baculovirus-based expression systems. Here, we performed high-throughput shRNA library screening, targeting 176 antiviral innate immune genes, and identified 43 host restriction factor genes in a human A549 lung carcinoma cell line. Among them, suppression of receptor interaction protein kinase 1 (RIP1, also known as RIPK1) significantly increased baculoviral transgene expression without resulting in significant cell death. Silencing of RIP1 did not affect viral entry or cell viability, but it did inhibit nuclear translocation of the IRF3 and NF-κB transcription factors. Also, activation of downstream signaling mediators (such as TBK1 and IRF7) was affected, and subsequent interferon and cytokine gene expression levels were abolished. Further, Necrostatin-1 (Nec-1)—an inhibitor of RIP1 kinase activity—dramatically increased baculoviral transgene expression in RIP1-silenced cells. Using baculovirus as a model system, this study presents an initial investigation of large numbers of human cell antiviral innate immune response factors against a “nonadaptive virus.” In addition, our study has made baculovirus a more efficient gene transfer vector for some of the most frequently used mammalian cell systems.
Collapse
Affiliation(s)
- Chia-Hung Wang
- Department of Life Science and Institute of Genome Science, National Yang Ming University, No. 115, Section 2, Linong St., Beitou District, Taipei 112, Taiwan.,Institute of Molecular Biology, Academia Sinica, No. 128, Sec. 2, Academia Road, Nankang, Taipei 115, Taiwan
| | - Nenavath Gopal Naik
- Institute of Molecular Biology, Academia Sinica, No. 128, Sec. 2, Academia Road, Nankang, Taipei 115, Taiwan
| | - Lin-Li Liao
- Institute of Molecular Biology, Academia Sinica, No. 128, Sec. 2, Academia Road, Nankang, Taipei 115, Taiwan
| | - Sung-Chan Wei
- Institute of Molecular Biology, Academia Sinica, No. 128, Sec. 2, Academia Road, Nankang, Taipei 115, Taiwan
| | - Yu-Chan Chao
- Institute of Molecular Biology, Academia Sinica, No. 128, Sec. 2, Academia Road, Nankang, Taipei 115, Taiwan
| |
Collapse
|
11
|
Baculovirus IE2 Stimulates the Expression of Heat Shock Proteins in Insect and Mammalian Cells to Facilitate Its Proper Functioning. PLoS One 2016; 11:e0148578. [PMID: 26863132 PMCID: PMC4749218 DOI: 10.1371/journal.pone.0148578] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 01/19/2016] [Indexed: 02/02/2023] Open
Abstract
Baculoviruses have gained popularity as pest control agents and for protein production in insect systems. These viruses are also becoming popular for gene expression, tissue engineering and gene therapy in mammalian systems. Baculovirus infection triggers a heat shock response, and this response is crucial for its successful infection of host insect cells. However, the viral protein(s) or factor(s) that trigger this response are not yet clear. Previously, we revealed that IE2-an early gene product of the baculovirus-could form unique nuclear bodies for the strong trans-activation of various promoters in mammalian cells. Here, we purified IE2 nuclear bodies from Vero E6 cells and investigated the associated proteins by using mass spectrometry. Heat shock proteins (HSPs) were found to be one of the major IE2-associated proteins. Our experiments show that HSPs are greatly induced by IE2 and are crucial for the trans-activation function of IE2. Interestingly, blocking both heat shock protein expression and the proteasome pathway preserved the IE2 protein and its nuclear body structure, and revived its function. These observations reveal that HSPs do not function directly to assist the formation of the nuclear body structure, but may rather protect IE2 from proteasome degradation. Aside from functional studies in mammalian cells, we also show that HSPs were stimulated and required to determine IE2 protein levels, in insect cells infected with baculovirus. Upon inhibiting the expression of heat shock proteins, baculovirus IE2 was substantially suppressed, resulting in a significantly suppressed viral titer. Thus, we demonstrate a unique feature in that IE2 can function in both insect and non-host mammalian cells to stimulate HSPs, which may be associated with IE2 stabilization and lead to the protection of the its strong gene activation function in mammalian cells. On the other hand, during viral infection in insect cells, IE2 could also strongly stimulate HSPs and ultimately affect viral replication.
Collapse
|
12
|
Cetkovská K, Šustová H, Kosztyu P, Uldrijan S. A Novel Interaction between TFII-I and Mdm2 with a Negative Effect on TFII-I Transcriptional Activity. PLoS One 2015; 10:e0144753. [PMID: 26656605 PMCID: PMC4676684 DOI: 10.1371/journal.pone.0144753] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 11/23/2015] [Indexed: 11/24/2022] Open
Abstract
Williams-Beuren syndrome-associated transcription factor TFII-I plays a critical regulatory role in bone and neural tissue development and in immunity, in part by regulating cell proliferation in response to mitogens. Mdm2, a cellular oncogene responsible for the loss of p53 tumor suppressor activity in a significant proportion of human cancers, was identified in this study as a new binding partner for TFII-I and a negative regulator of TFII-I-mediated transcription. These findings suggest a new p53-independent mechanism by which increased Mdm2 levels found in human tumors could influence cancer cells. In addition to that, we present data indicating that TFII-I is an important cellular regulator of transcription from the immediate-early promoter of human cytomegalovirus, a promoter sequence frequently used in mammalian expression vectors, including vectors for gene therapy. Our observation that Mdm2 over-expression can decrease the ability of TFII-I to activate the CMV promoter might have implications for the efficiency of experimental gene therapy based on CMV promoter–derived vectors in cancers with Mdm2 gene amplification.
Collapse
Affiliation(s)
- Kateřina Cetkovská
- International Clinical Research Center—Center of Biomolecular and Cellular Engineering, St. Anne's University Hospital, Brno, Czech Republic
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Hana Šustová
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Pavlína Kosztyu
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Stjepan Uldrijan
- International Clinical Research Center—Center of Biomolecular and Cellular Engineering, St. Anne's University Hospital, Brno, Czech Republic
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
- * E-mail:
| |
Collapse
|
13
|
Identification of a high-efficiency baculovirus DNA replication origin that functions in insect and mammalian cells. J Virol 2014; 88:13073-85. [PMID: 25187548 DOI: 10.1128/jvi.01713-14] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED The p143 gene from Autographa californica multinucleocapsid nucleopolyhedrovirus (AcMNPV) has been found to increase the expression of luciferase, which is driven by the polyhedrin gene promoter, in a plasmid with virus coinfection. Further study indicated that this is due to the presence of a replication origin (ori) in the coding region of this gene. Transient DNA replication assays showed that a specific fragment of the p143 coding sequence, p143-3, underwent virus-dependent DNA replication in Spodoptera frugiperda IPLB-Sf-21 (Sf-21) cells. Deletion analysis of the p143-3 fragment showed that subfragment p143-3.2a contained the essential sequence of this putative ori. Sequence analysis of this region revealed a unique distribution of imperfect palindromes with high AT contents. No sequence homology or similarity between p143-3.2a and any other known ori was detected, suggesting that it is a novel baculovirus ori. Further study showed that the p143-3.2a ori can replicate more efficiently in infected Sf-21 cells than baculovirus homologous regions (hrs), the major baculovirus ori, or non-hr oris during virus replication. Previously, hr on its own was unable to replicate in mammalian cells, and for mammalian viral oris, viral proteins are generally required for their proper replication in host cells. However, the p143-3.2a ori was, surprisingly, found to function as an efficient ori in mammalian cells without the need for any viral proteins. We conclude that p143 contains a unique sequence that can function as an ori to enhance gene expression in not only insect cells but also mammalian cells. IMPORTANCE Baculovirus DNA replication relies on both hr and non-hr oris; however, so far very little is known about the latter oris. Here we have identified a new non-hr ori, the p143 ori, which resides in the coding region of p143. By developing a novel DNA replication-enhanced reporter system, we have identified and located the core region required for the p143 ori. This ori contains a large number of imperfect inverted repeats and is the most active ori in the viral genome during virus infection in insect cells. We also found that it is a unique ori that can replicate in mammalian cells without the assistance of baculovirus gene products. The identification of this ori should contribute to a better understanding of baculovirus DNA replication. Also, this ori is very useful in assisting with gene expression in mammalian cells.
Collapse
|
14
|
Wu Y, Wu Y, Wu Y, Tang H, Wu H, Zhang G, Wang W. Screening of candidate proteins interacting with IE-2 of Bombyx mori nucleopolyhedrovirus. Mol Biol Rep 2013; 40:5797-804. [DOI: 10.1007/s11033-013-2683-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Accepted: 09/14/2013] [Indexed: 10/26/2022]
|
15
|
Autographa californica multiple nucleopolyhedrovirus orf114 is not essential for virus replication in vitro, but its knockout reduces per os infectivity in vivo. Virus Genes 2012; 45:360-9. [PMID: 22739701 DOI: 10.1007/s11262-012-0777-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Accepted: 06/11/2012] [Indexed: 12/22/2022]
Abstract
Autographa californica multiple nucleopolyhedrovirus (AcMNPV) orf114 (ac114) is one of the highly conserved unique genes in the lepidopteran group I nucleopolyhedrovirus. So far, the biological function of ac114 is unknown. To study the function of ac114 in the virus life cycle, an ac114 knockout baculovirus shuttle vector (bacmid) was generated. Fluorescence and light microscopy showed that the ac114 knockout mutant was able to produce infectious budded viruses (BVs) and occlusion bodies (OBs). Titration assays demonstrated that the ac114 knockout virus had similar growth kinetics to the control virus during the infection phase. Electron microscopy indicated that ac114 did not affect the morphogenesis of BVs and occlusion-derived viruses (ODVs); however, the numbers of ODVs per OB of the ac114 knockout virus were significantly lower than those of the control virus. RT-PCR demonstrated that ac114 was a late stage expression gene and that its transcription initiated at an A residue, 16 nucleotides upstream of the ATG start codon. Intracellular localization analysis revealed that the Ac114-GFP fusion protein localized predominantly as punctate patches in the cytoplasm of infected Sf9 cells. Bioassays showed that the ac114 knockout did not change the killing speed of AcMNPV in Spodoptera exigua larvae, but reduced its viral infectivity significantly. Taken together, these data indicate that ac114 is an auxiliary gene that facilitates embedding of ODVs into OBs, thus affecting the per os infectivity of the virus.
Collapse
|
16
|
Chen HZ, Liu CYY, Kost TA, Chao YC. Sucrose and fetal bovine serum maintain stability and activity of the budded baculovirus during dehydration. Eur J Pharm Sci 2012; 45:311-9. [DOI: 10.1016/j.ejps.2011.11.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Revised: 10/28/2011] [Accepted: 11/28/2011] [Indexed: 12/28/2022]
|
17
|
Chen CY, Lin CY, Chen GY, Hu YC. Baculovirus as a gene delivery vector: recent understandings of molecular alterations in transduced cells and latest applications. Biotechnol Adv 2011; 29:618-31. [PMID: 21550393 PMCID: PMC7126054 DOI: 10.1016/j.biotechadv.2011.04.004] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 04/15/2011] [Accepted: 04/15/2011] [Indexed: 12/13/2022]
Abstract
Baculovirus infects insects in nature and is non-pathogenic to humans, but can transduce a broad range of mammalian and avian cells. Thanks to the biosafety, large cloning capacity, low cytotoxicity and non-replication nature in the transduced cells as well as the ease of manipulation and production, baculovirus has gained explosive popularity as a gene delivery vector for a wide variety of applications. This article extensively reviews the recent understandings of the molecular mechanisms pertinent to baculovirus entry and cellular responses, and covers the latest advances in the vector improvements and applications, with special emphasis on antiviral therapy, cancer therapy, regenerative medicine and vaccine.
Collapse
Affiliation(s)
- Chi-Yuan Chen
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | | | | | | |
Collapse
|
18
|
Chen HZ, Wu CP, Chao YC, Liu CYY. Membrane penetrating peptides greatly enhance baculovirus transduction efficiency into mammalian cells. Biochem Biophys Res Commun 2011; 405:297-302. [PMID: 21219863 PMCID: PMC7092845 DOI: 10.1016/j.bbrc.2011.01.032] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Accepted: 01/06/2011] [Indexed: 12/25/2022]
Abstract
The baculovirus group of insect viruses is widely used for foreign gene introduction into mammalian cells for gene expression and protein production; however, the efficiency of baculovirus entry into mammalian cells is in general still low. In this study, two recombinant baculoviruses were engineered and their ability to improve viral entry was examined: (1) cytoplasmic transduction peptide (CTP) was fused with baculovirus envelope protein, GP64, to produce a cytoplasmic membrane penetrating baculovirus (vE-CTP); and (2) the protein transduction domain (PTD) of HIV TAT protein was fused with the baculovirus capsid protein VP39 to form a nuclear membrane penetrating baculovirus (vE-PTD). Transduction experiments showed that both viruses had better transduction efficiency than vE, a control virus that only expresses EGFP in mammalian cells. Interestingly, vE-CTP and vE-PTD were also able to improve the transduction efficiency of a co-transduced baculovirus, resulting in higher levels of gene expression. Our results have described new routes to further enhance the development of baculovirus as a tool for gene delivery into mammalian cells.
Collapse
Affiliation(s)
- Hong-Zhang Chen
- Institute of Biotechnology, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan, ROC
| | | | | | | |
Collapse
|
19
|
Autographa californica multiple nucleopolyhedrovirus LEF-2 is a capsid protein required for amplification but not initiation of viral DNA replication. J Virol 2010; 84:5015-24. [PMID: 20219928 DOI: 10.1128/jvi.02423-09] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The late expression factor 2 gene (lef-2) of baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) has been identified as one of the factors essential for origin-dependent DNA replication in transient expression assays and has been shown to be involved in late/very late gene expression. To study the function of lef-2 in the life cycle of AcMNPV, lef-2 knockout and repair bacmids were generated by homologous recombination in Escherichia coli. Growth curve analysis showed that lef-2 was essential for virus production. Interestingly, a DNA replication assay indicated that lef-2 is not required for the initiation of viral DNA replication and that, rather, it is required for the amplification of DNA replication. lef-2 is also required for the expression of late and very late genes, as the expression of these genes was abolished by lef-2 deletion. Temporal and spatial distributions of LEF-2 protein in infected cells were also analyzed, and the data showed that LEF-2 protein was localized to the virogenic stroma in the nuclei of the infected cells. Analysis of purified virus particles revealed that LEF-2 is a viral protein component of both budded and occlusion-derived virions, predominantly in the nucleocapsids of the virus particles. This observation suggests that LEF-2 may be required immediately after virus entry into host cells for efficient viral DNA replication.
Collapse
|
20
|
X-linked mental retardation gene CASK interacts with Bcl11A/CTIP1 and regulates axon branching and outgrowth. J Neurosci Res 2010; 88:2364-73. [DOI: 10.1002/jnr.22407] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|