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Xue Q, Swevers L, Taning CNT. Plant and insect virus-like particles: emerging nanoparticles for agricultural pest management. PEST MANAGEMENT SCIENCE 2023; 79:2975-2991. [PMID: 37103223 DOI: 10.1002/ps.7514] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 04/20/2023] [Accepted: 04/27/2023] [Indexed: 06/05/2023]
Abstract
Virus-like particles (VLPs) represent a biodegradable, biocompatible nanomaterial made from viral coat proteins that can improve the delivery of antigens, drugs, nucleic acids, and other substances, with most applications in human and veterinary medicine. Regarding agricultural viruses, many insect and plant virus coat proteins have been shown to assemble into VLPs accurately. In addition, some plant virus-based VLPs have been used in medical studies. However, to our knowledge, the potential application of plant/insect virus-based VLPs in agriculture remains largely underexplored. This review focuses on why and how to engineer coat proteins of plant/insect viruses as functionalized VLPs, and how to exploit VLPs in agricultural pest control. The first part of the review describes four different engineering strategies for loading cargo at the inner or the outer surface of VLPs depending on the type of cargo and purpose. Second, the literature on plant and insect viruses the coat proteins of which have been confirmed to self-assemble into VLPs is reviewed. These VLPs are good candidates for developing VLP-based agricultural pest control strategies. Lastly, the concepts of plant/insect virus-based VLPs for delivering insecticidal and antiviral components (e.g., double-stranded RNA, peptides, and chemicals) are discussed, which provides future prospects of VLP application in agricultural pest control. In addition, some concerns are raised about VLP production on a large scale and the short-term resistance of hosts to VLP uptake. Overall, this review is expected to stimulate interest and research exploring plant/insect virus-based VLP applications in agricultural pest management. © 2023 Society of Chemical Industry.
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Affiliation(s)
- Qi Xue
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Luc Swevers
- Insect Molecular Genetics and Biotechnology, Institute of Biosciences and Applications, National Centre for Scientific Research "Demokritos", Athens, Greece
| | - Clauvis Nji Tizi Taning
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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2
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Zhao Z, Lin S, Wu W, Zhang Z, Wu P, Shen M, Qian H, Guo X. A cypovirus encoded microRNA negatively regulates the NF-κB pathway to enhance viral multiplication in Silkworm, Bombyx mori. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2022; 131:104382. [PMID: 35245604 DOI: 10.1016/j.dci.2022.104382] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 02/25/2022] [Accepted: 02/27/2022] [Indexed: 06/14/2023]
Abstract
MicroRNAs (miRNAs) are small non-coding RNAs that function as novel gene expression regulators at the post-transcriptional level. Not with standing that the biogenesis and function of miRNAs are well-understood in eukaryotes, little is known about RNA virus-encoded miRNAs. Bombyx mori cypovirus (BmCPV) is a double-stranded RNA virus with a segmented genome that causes cytoplasmic polyhedrosis disease in silkworm larvae. To date, the interaction between BmCPV and silkworm remains largely unclear. 22 candidate BmCPV-encoded miRNAs were identified in this study through small RNA sequencing, stem-loop RT-PCR and qRT-PCR. Then, generation and function analyses were conducted on one of the candidate miRNAs, BmCPV-miR-1, in the BmN cells and the silkworm larvae by RNA interference, quantitative PCR, dual-luciferase assay. Our results revealed that BmCPV-miR-1 was encoded by BmCPV genome RNA rather than the degraded fragments of the viral genome. Its generation depended on Dicer-1 and might also be correlated with Dicer-2, Argonaute-1 and Argonaute-2. Moreover, BmCPV-miR-1 could suppress the expression of the target gene, B. mori inhibitor of nuclear factor kappa-B kinase subunit beta (BmIKKβ), via binding to the target mRNA 3'-untranslated region, which fine-tuned the host NF-κB signaling pathway and consequently enhanced viral replication. Our results provide new evidence supporting the hypothesis that RNA viruses could generate miRNAs to modulate antiviral host defense.
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Affiliation(s)
- Ze Zhao
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, 212000, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, 212000, China
| | - Su Lin
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, 212000, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, 212000, China
| | - Wanming Wu
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, 212000, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, 212000, China
| | - Zhendong Zhang
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, 212000, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, 212000, China
| | - Ping Wu
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, 212000, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, 212000, China
| | - Manman Shen
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, 212000, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, 212000, China
| | - Heying Qian
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, 212000, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, 212000, China
| | - Xijie Guo
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, 212000, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, 212000, China.
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3
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Etebari K, Lenancker P, Powell KS, Furlong MJ. Transcriptomics Reveal Several Novel Viruses from Canegrubs (Coleoptera: Scarabaeidae) in Central Queensland, Australia. Viruses 2022; 14:649. [PMID: 35337056 PMCID: PMC8949096 DOI: 10.3390/v14030649] [Citation(s) in RCA: 4] [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: 01/31/2022] [Revised: 03/08/2022] [Accepted: 03/17/2022] [Indexed: 12/21/2022] Open
Abstract
Canegrubs (Coleoptera: Scarabaeidae) are major pests of sugarcane crops in Australia, but despite long-term and intensive research, no commercially viable biological control agents have been identified. We used the RNA-Seq approach to explore the viriomes of three different species of canegrubs from central Queensland, Australia to identify potential candidates for biological control. We identified six novel RNA viruses, characterized their genomes, and inferred their evolutionary relationships with other closely related viruses. These novel viruses showed similarity to other known members from picornaviruses, benyviruses, sobemoviruses, totiviruses, and reoviruses. The abundance of viral reads varied in these libraries; for example, Dermolepida albohirtum picorna-like virus (9696 nt) was built from 83,894 assembled reads while only 1350 reads mapped to Lepidiota negatoria beny-like virus (6371 nt). Future studies are essential to determine their natural incidence in different life stages of the host, biodiversity, geographical distributions, and potential as biological control agents for these important pests of sugarcane.
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Affiliation(s)
- Kayvan Etebari
- School of Biological Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia;
| | - Pauline Lenancker
- Sugar Research Australia, 71378 Bruce Highway, Gordonvale, QLD 4865, Australia; (P.L.); (K.S.P.)
| | - Kevin S. Powell
- Sugar Research Australia, 71378 Bruce Highway, Gordonvale, QLD 4865, Australia; (P.L.); (K.S.P.)
| | - Michael J. Furlong
- School of Biological Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia;
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4
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Zhu M, Pan J, Zhang M, Tong X, Zhang Y, Zhang Z, Liang Z, Zhang X, Hu X, Xue R, Cao G, Gong C. Bombyx mori cypovirus (BmCPV) induces PINK1-Parkin mediated mitophagy via interaction of VP4 with host Tom40. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2022; 126:104244. [PMID: 34450127 DOI: 10.1016/j.dci.2021.104244] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 08/24/2021] [Accepted: 08/24/2021] [Indexed: 06/13/2023]
Abstract
The mechanism by which infection by Bombyx mori cytoplasmic nucleopolyhedrosis virus (BmCPV) causes autophagy has not been studied in detail. Herein we have observed by electron microscopy that infection with BmCPV causes autophagosome and mitochondrial structure damage in Bombyx mori midgut. In BmN cells infected with BmCPV and expressing eGFP-LC3, fluorescence spots and LC3-II levels increased, suggesting that BmCPV infection causes autophagy. Autophagy inducer rapamycin (Rap) and autophagy inhibitor 3-methyladenine (3-MA) were used to monitor the effects of mitophagy on BmCPV proliferation. It was found BmCPV proliferation to be promoted by mitophagy. Transient transfection experiments in cultured BmN cells showed that mitophagy can be triggered by expression of BmCPV structural protein VP4. Moreover, VP4 caused upregulation of p-Drp1, PINK1 and Parkin proteins in the mitophagy pathway and downregulation of mitochondrial membrane protein Tom20. Furthermore, interaction between VP4 with Tom40 was confirmed by Co-IP, western blot and colocalization experiment, and overexpression of Tom40 reduce the level of mitochondrial autophagy induced by VP4. These results suggested that VP4 induced PINK1-Parkin-mediated mitophagy interacting with Tom40. These findings deepen our understanding of the interaction between BmCPV and silkworm and also provide a molecular target for screening anti-BmCPV drugs.
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Affiliation(s)
- Min Zhu
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China
| | - Jun Pan
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China
| | - Mingtian Zhang
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China
| | - Xinyu Tong
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China
| | - Yunshan Zhang
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China
| | - Ziyao Zhang
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China
| | - Zi Liang
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China
| | - Xing Zhang
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China
| | - Xiaolong Hu
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China
| | - Renyu Xue
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China
| | - Guangli Cao
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China.
| | - Chengliang Gong
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China.
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5
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Wang Y, Lin S, Zhao Z, Xu P, Gao K, Qian H, Zhang Z, Guo X. Functional analysis of a putative Bombyx mori cypovirus miRNA BmCPV-miR-10 and its effect on virus replication. INSECT MOLECULAR BIOLOGY 2021; 30:552-565. [PMID: 34296485 DOI: 10.1111/imb.12725] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 07/11/2021] [Accepted: 07/13/2021] [Indexed: 06/13/2023]
Abstract
Bombyx mori cypovirus (BmCPV) is an important pathogen of silkworm (B. mori), the economically beneficial insect. The mechanism of its interaction with host immune defence system in the process of infection is still not yet completely clear. Researches have demonstrated that virus-encoded microRNAs (miRNA) play a crucial role in regulating host-pathogen interaction, but few reports are available so far on miRNAs encoded by insect viruses, especially the RNA viruses. In this study, a putative miRNA encoded by the 10th segment of BmCPV genomic RNA, BmCPV-miR-10, was identified and functionally analysed. The expression of the putative BmCPV-miR-10 could be detected via stem-loop RT-PCR (reverse transcription-Polymerase Chain Reaction) in the midgut of silkworm larvae infected with BmCPV. BmCSDE1 (B. mori cold shock domain E1 protein) gene was predicted to be a candidate target gene for BmCPV-miR-10 with the miRNA binding site located in 3' untranslated region of its mRNA. The regulation effect of the putative BmCPV-miR-10 on BmCSDE1 was verified in HEK293 cells by lentiviral expression system, in BmN cells by transfecting BmCPV-miR-10 mimics. The qRT-PCR (quantitative real-time PCR) results showed that the putative BmCPV-miR-10 could suppress the expression of BmCSDE1. By injection of BmCPV-miR-10 mimics into the silkworm larvae infected with BmCPV, it was further proved that the putative BmCPV-miR-10 could suppress the expression of BmCSDE1 in vivo, then inhibit the expression of BmApaf-1 (B. mori apoptotic protease activating factor 1), while enhance the replication of BmCPV genomic RNAs to a certain extent. These results implied that the putative BmCPV-miR-10 could down-regulate the expression of BmCSDE1, then suppress the expression of BmApaf-1, thereby created a favourable intracellular environment for virus replication and proliferation.
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Affiliation(s)
- Y Wang
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
| | - S Lin
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
| | - Z Zhao
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
| | - P Xu
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
| | - K Gao
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
| | - H Qian
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
- Sericulture Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
| | - Z Zhang
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
| | - X Guo
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
- Sericulture Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
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6
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Lin S, Wang Y, Zhao Z, Wu W, Su Y, Zhang Z, Shen M, Wu P, Qian H, Guo X. Two Putative Cypovirus-Encoded miRNAs Co-regulate the Host Gene of GTP-Binding Nuclear Protein Ran and Facilitate Virus Replication. Front Physiol 2021; 12:663482. [PMID: 34421632 PMCID: PMC8373394 DOI: 10.3389/fphys.2021.663482] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 07/13/2021] [Indexed: 01/08/2023] Open
Abstract
microRNA (miRNA) plays important roles in regulating various biological processes, including host-pathogen interaction. Recent studies have demonstrated that virus-encoded miRNAs can manipulate host gene expression to ensure viral effective multiplication. Bombyx mori cypovirus (BmCPV), a double-stranded RNA virus with a segmented genome, is one of the important pathogens for the economically important insect silkworm. Our present study indicated that two putative miRNAs encoded by BmCPV could promote viral replication by inhibiting the gene expression of B. mori GTP-binding nuclear protein Ran (BmRan), an essential component of the exportin-5-mediated nucleocytoplasmic transport of small RNAs. BmCPV-miR-1 and BmCPV-miR-3 are two of the BmCPV-encoded miRNAs identified in our previous studies. BmRan is a common target gene of them with binding sites all located in the 3′-untranslated region (3′-UTR) of its mRNA. The expression levels of the two miRNAs in the midgut of larvae infected with BmCPV gradually increased with the advance of infection, while the expression of the target gene BmRan decreased gradually. The miRNAs and the recombinant target gene consisting of reporter gene mCherry and 3′-UTR of BmRan mRNA were expressed in HEK293T cells for validating the interaction between the miRNAs and the target gene. qRT-PCR results revealed that BmCPV-miR-1 and BmCPV-miR-3 negatively regulate target gene expression not only separately but also cooperatively by binding to the 3′-UTR of BmRan mRNA. By transfecting miRNA mimics into BmN cells and injecting the mimics into the body of silkworm larvae, it was indicated that both BmCPV-miR-1 and BmCPV-miR-3 could repress the expression of BmRan in BmN cells and in the silkworm, and the cooperative action of the two miRNAs could enhance the repression of BmRan expression. Furthermore, the repression of BmRan could facilitate the replication of BmCPV genomic RNAs. It is speculated that BmCPV-miR-1 and BmCPV-miR-3 might reduce the generation of host miRNAs by inhibiting expression of BmRan, thus creating a favorable intracellular environment for virus replication. Our results are helpful to better understand the pathogenic mechanism of BmCPV to the silkworm, and provide insights into one of the evasion strategies used by viruses to counter the host defense for their effective multiplication.
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Affiliation(s)
- Su Lin
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China.,Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
| | - Yongsheng Wang
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China.,Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
| | - Ze Zhao
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China.,Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
| | - Wanming Wu
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China.,Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
| | - Yun Su
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China.,Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
| | - Zhendong Zhang
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China.,Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
| | - Manman Shen
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China.,Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
| | - Ping Wu
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China.,Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
| | - Heying Qian
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China.,Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
| | - Xijie Guo
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China.,Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
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7
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Tight junction protein claudin-2 promotes cell entry of Bombyx mori cypovirus. Appl Microbiol Biotechnol 2021; 105:6019-6031. [PMID: 34324010 DOI: 10.1007/s00253-021-11456-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 06/24/2021] [Accepted: 07/03/2021] [Indexed: 10/20/2022]
Abstract
Claudin-2 is a major component of tight junctions (TJs), which play an important role in reovirus entry into host cells. The Bombyx mori cytoplasmic polyhedosis virus (BmCPV) relates to the cypovirus strain of the reovirus family. So far, the role of claudin-2 in the process of BmCPV infection is not known. In the present study, it was observed that increasing expression of the claudin-2 gene (CLDN2) may concomitantly elevate BmCPV infection. Contrarily, knockdown of CLDN2 expression by siRNAs can reduce BmCPV infection. Similarly, antibody-based blockage of claudin-2 could also decrease BmCPV cell entry. These results suggest that claudin-2 can promote BmCPV infection in vitro. Moreover, immunofluorescence (IF) assays showed that claudin-2 can interact with BmCPV during viral infection. Specifically, co-immunoprecipitation experiments indicated that claudin-2 binds the BmCPV VP7 (instead of VP3 proteins). The interaction between VP7 and claudin-2 was further confirmed by bimolecular fluorescence complementation (BIFC). Altogether, our results suggest that BmCPV cell entry can be promoted upon interaction of VP7 with claudin-2. These findings provide new mechanistic insights related to BmCPV infection. KEY POINTS: •Claudin-2 could promote BmCPV infection of cells. •Claudin-2 interacted with BmCPV during BmCPV infection. •Claudin-2 could interact with BmCPV VP7 protein, but not with VP3 proteins.
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8
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Singh CP. Viral-encoded microRNAs in host-pathogen interactions in silkworm. Microrna 2021; 10:3-13. [PMID: 33475082 DOI: 10.2174/2211536610666210121154314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 09/30/2020] [Accepted: 11/27/2020] [Indexed: 11/22/2022]
Abstract
The mulberry silkworm Bombyx mori, apart from its well-known economic importance, has also emerged as an insect model to study host-pathogen interactions. The major concern for silkworm cultivation and the sericulture industry is the attack by various types of pathogens mainly includes viruses, fungi, bacteria and protozoa. Successful infection requires specific arsenals to counter the host immune response. MicroRNAs (miRNAs) are one of the potential arsenals which are encoded by viruses and effectively used during host-pathogen interactions. MiRNAs are short noncoding 19-25 nucleotides long endogenous RNAs that post-transcriptionally regulate expression of protein-coding genes in a sequencespecific manner. Most of the higher eukaryotes encode miRNAs and utilize them in the regulation of important cellular pathways. In silkworm, promising functions of miRNAs have been characterized in development, metamorphosis, immunity, and host-pathogen interactions. The viral miRNA-mediated fine-tuning of the viral, as well as cellular genes, is beneficial for making a cellular environment favorable for the virus proliferation. Baculovirus and cypovirus which infect silkworm have been shown to encode miRNAs and their functions are implicated in controlling the expression of both viral and host genes. In the present review, the author discusses the diverse functions of viral-encoded miRNAs in evasion of the host immune responses and reshaping of the silkworm cellular environment for replication. Besides, a basic overview of miRNA biogenesis and mechanism of action is also provided. Our increasing understanding of the viral miRNAs role in silkworm-virus interactions would not only assist us to get insights into the intricate pathways but also provide tools to deal with dreaded pathogens.
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Affiliation(s)
- C P Singh
- Department of Botany, University of Rajasthan, Jaipur-302004, Rajasthan. India
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9
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10
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Ren F, Swevers L, Lu Q, Zhao Y, Yan J, Li H, Sun J. Effect of mutations in capsid shell protein on the assembly of BmCPV virus-like particles. J Gen Virol 2020; 102. [PMID: 33331809 DOI: 10.1099/jgv.0.001542] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) is a typical single-layer capsid dsRNA virus belonging to the genus Cypovirus in the family Reoviridae. The results of cryo-electron microscopy showed that the BmCPV capsid consists of 60 asymmetric units, and each asymmetric unit contains one turret protein (TP), two large protrusion proteins (LPP) and two capsid shell proteins (CSP). CSP has the ability to self-assemble into virus-like particles (VLPs), and the small protrusion domain (SPD) in CSP may play an essential role in the assembly of viral capsids. In this study, three critical amino acid sites, D828, S829 and V945, in the SPD were efficiently mutated (point mutation) based on the principle of PCR circular mutagenesis. Moreover, a multi-gene expression system, Ac-MultiBac baculovirus, was used to produce eight different recombinant VLPs in vitro. Transmission electron microscopy showed that the single site and double site mutations had little effect on the efficiency and morphology of the assembly of VLPs. Still, the simultaneous mutation of the three sites had a significant impact. The experimental results demonstrate that the SPD of CSP plays an essential role in assembly of the viral capsid, which lays the foundation for further analysis of the molecular and structural mechanism of BmCPV capsid assembly.
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Affiliation(s)
- Feifei Ren
- Insect Molecular Genetics and Biotechnology, Institute of Biosciences and Applications, National Centre for Scientific Research Demokritos, Aghia Paraskevi, Athens, Greece.,Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China
| | - Luc Swevers
- Insect Molecular Genetics and Biotechnology, Institute of Biosciences and Applications, National Centre for Scientific Research Demokritos, Aghia Paraskevi, Athens, Greece
| | - Qiuyuan Lu
- Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China
| | - Yongchao Zhao
- Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China
| | - Jiming Yan
- Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China
| | - Haiyun Li
- Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China
| | - Jingchen Sun
- Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China
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11
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Guo JY, Wang YS, Chen T, Jiang XX, Wu P, Geng T, Pan ZH, Shang MK, Hou CX, Gao K, Guo XJ. Functional analysis of a miRNA-like small RNA derived from Bombyx mori cytoplasmic polyhedrosis virus. INSECT SCIENCE 2020; 27:449-462. [PMID: 30869181 DOI: 10.1111/1744-7917.12671] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 01/14/2019] [Accepted: 01/29/2019] [Indexed: 06/09/2023]
Abstract
Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) is a major pathogen of the economic insect silkworm, Bombyx mori. Virus-encoded microRNAs (miRNAs) have been proven to play important roles in host-pathogen interactions. In this study we identified a BmCPV-derived miRNA-like 21 nt small RNA, BmCPV-miR-1, from the small RNA deep sequencing of BmCPV-infected silkworm larvae by stem-loop quantitative real-time PCR (qPCR) and investigated its functions with qPCR and lentiviral expression systems. Bombyx mori inhibitor of apoptosis protein (BmIAP) gene was predicted by both target prediction software miRanda and Targetscan to be one of its target genes with a binding site for BmCPV-miR-1 at the 5' untranslated region. It was found that the expression of BmCPV-miR-1 and its target gene BmIAP were both up-regulated in BmCPV-infected larvae. At the same time, it was confirmed that BmCPV-miR-1 could up-regulate the expression of BmIAP gene in HEK293T cells with lentiviral expression systems and in BmN cells by transfecting mimics. Furthermore, BmCPV-miR-1 mimics could up-regulate the expression level of BmIAP gene in midgut and fat body in the silkworm. In the midgut of BmCPV-infected larvae, BmCPV-miR-1 mimics could be further up-regulated and inhibitors could lower the virus-mediated expression of BmIAP gene. With the viral genomic RNA segments S1 and S10 as indicators, BmCPV-miR-1 mimics could up-regulate and inhibitors down-regulate their replication in the infected silkworm. These results implied that BmCPV-miR-1 could inhibit cell apoptosis in the infected silkworm through up-regulating BmIAP expression, providing the virus with a better cell circumstance for its replication.
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Affiliation(s)
- Jian-Yong Guo
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
- Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
| | - Yong-Sheng Wang
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
- Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
| | - Tian Chen
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
| | - Xiao-Xu Jiang
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
| | - Ping Wu
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
- Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
| | - Tao Geng
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikoou, China
| | - Zhong-Hua Pan
- School of Biology & Basic Medical Science, Soochow University, Suzhou, China
| | - Meng-Ke Shang
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
| | - Cheng-Xiang Hou
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
- Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
| | - Kun Gao
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
- Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
| | - Xi-Jie Guo
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
- Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China
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Cui Y, Zhang Y, Zhou K, Sun J, Zhou ZH. Conservative transcription in three steps visualized in a double-stranded RNA virus. Nat Struct Mol Biol 2019; 26:1023-1034. [PMID: 31695188 DOI: 10.1038/s41594-019-0320-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 09/19/2019] [Indexed: 01/28/2023]
Abstract
Endogenous RNA transcription characterizes double-stranded RNA (dsRNA) viruses in the Reoviridae, a family that is exemplified by its simple, single-shelled member cytoplasmic polyhedrosis virus (CPV). Because of the lack of in situ structures of the intermediate stages of RNA-dependent RNA polymerase (RdRp) during transcription, it is poorly understood how RdRp detects environmental cues and internal transcriptional states to initiate and coordinate repeated cycles of transcript production inside the capsid. Here, we captured five high-resolution (2.8-3.5 Å) RdRp-RNA in situ structures-representing quiescent, initiation, early elongation, elongation and abortive states-under seven experimental conditions of CPV. We observed the 'Y'-form initial RNA fork in the initiation state and the complete transcription bubble in the elongation state. These structures reveal that de novo RNA transcription involves three major conformational changes during state transitions. Our results support an ouroboros model for endogenous conservative transcription in dsRNA viruses.
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Affiliation(s)
- Yanxiang Cui
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA
| | - Yinong Zhang
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA.,Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA.,Subtropical Sericulture and Mulberry Resources Protection and Safety Engineering Research Center, Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Kang Zhou
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA
| | - Jingchen Sun
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA. .,Subtropical Sericulture and Mulberry Resources Protection and Safety Engineering Research Center, Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, China.
| | - Z Hong Zhou
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA. .,Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA.
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Hu X, Chen F, Zhu L, Yu L, Zhu M, Liang Z, Zhang X, Xue R, Cao G, Gong C. Bombyx mori cypovirus encoded small peptide inhibits viral multiplication. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2019; 96:51-57. [PMID: 30822453 DOI: 10.1016/j.dci.2019.02.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 02/23/2019] [Accepted: 02/24/2019] [Indexed: 06/09/2023]
Abstract
Bombyx mori cypovirus (BmCPV) is one of the most infectious pathogen in sericulture and a member of the family Reoviridae. It specifically infects the midgut of silkworm. The BmCPV genome consists of 10 dsRNAs segments (S1-S10), which have generally been assumed to be monocistronic. In this study, a small open reading frame encoding the peptide S5-sORF, containing 27 amino acid residues, was predicted in a region of the negative (-) strand of BmCPV segment S5. An immunofluorescence assay detected S5-sORF in the cytoplasm and nuclei of BmCPV-infected cells, and it was also detected in the virion with western blotting, suggesting that S5-sORF may be assembled into the BmCPV virion. Viral gene expression was inhibited by overexpressed S5-sORF, and viral multiplication was dose-dependently suppressed by the S5-sORF peptide. A viable recombinant virus, BmCPV-S5-sORFmut, in which the start codon (ATG) of S5-sORF was mutated to a stop codon (TGA), was generated with reverse genetics. The proliferation of BmCPV was increased by the abolition of S5-sORF expression. Furthermore, the RNA transcript of S5-sORF and small peptide of S5-sORF were involved in BmCPV replication. The expression of genes related to the innate immune pathways and apoptosis in the silkworm were not significantly affected by S5-sORF overexpression. Our results suggest that a viral nucleotide sequence is utilized by the host to generate an antiviral peptide, which may be a novel strategy protecting the host from viral infection.
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Affiliation(s)
- Xiaolong Hu
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, China
| | - Fei Chen
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China
| | - Liyuan Zhu
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China
| | - Lei Yu
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China
| | - Min Zhu
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China
| | - Zi Liang
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China
| | - Xing Zhang
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China
| | - Renyu Xue
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, China
| | - Guangli Cao
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, China.
| | - Chengliang Gong
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China.
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Xu C, Wang J, Yang J, Lei C, Hu J, Sun X. NSP2 forms viroplasms during Dendrolimus punctatus cypovirus infection. Virology 2019; 533:68-76. [PMID: 31125854 DOI: 10.1016/j.virol.2019.05.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 05/14/2019] [Accepted: 05/15/2019] [Indexed: 10/26/2022]
Abstract
Reoviruses are thought to replicate and assemble in special cytoplasmic structures called 'viroplasms'. However, little is known about the viroplasms of the insect reoviruses, the cypoviruses. To investigate the viroplasm of Dendrolimus punctatus cypovirus (DpCPV), all proteins encoded by the 10 genomic segments of DpCPV were expressed in Sf9 cells using the Bac-to-Bac system. The viral nonstructural protein NSP2 formed viroplasm-like dots which showed close apposition with the endoplasmic reticulum and were surrounded by intracellular membranes during transfection. Colocalization and coimmunoprecipitation assays showed that NSP2 interacts with 4 of 6 structural proteins and another 2 nonstructural proteins, while NSP1 only colocalized with VP4, and NSP3 did not colocalize with any structural protein. Immunoelectron microscopy revealed that NSP2 were nearby the endoplasmic reticulum and mitochondria, and viral particles were present in the electron-dense inclusions formed by NSP2. We proposed that NSP2 is responsible for forming the viroplasms structures of DpCPV.
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Affiliation(s)
- Congrui Xu
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jia Wang
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jian Yang
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chengfeng Lei
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China
| | - Jia Hu
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China
| | - Xiulian Sun
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China.
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15
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A Reverse Genetics System for Cypovirus Based on a Bacmid Expressing T7 RNA Polymerase. Viruses 2019; 11:v11040314. [PMID: 30939777 PMCID: PMC6521135 DOI: 10.3390/v11040314] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 03/27/2019] [Accepted: 03/28/2019] [Indexed: 12/14/2022] Open
Abstract
Dendrolimus punctatus cypovirus (DpCPV), belonging to the genus Cypovirus within the family Reoviridae, is considered the most destructive pest of pine forests worldwide. DpCPV has a genome consisting of 10 linear double-stranded RNA segments. To establish a reverse genetics system, we cloned cDNAs encoding the 10 genomic segments of DpCPV into three reverse genetics vectors in which each segment was transcribed under the control of a T7 RNA polymerase promoter and terminator tagged with a hepatitis delta virus ribozyme sequence. We also constructed a vp80-knockout Autographa californica multiple nucleopolyhedrovirus bacmid to express a T7 RNA polymerase codon-optimized for Sf9 cells. Following transfection of Sf9 cells with the three vectors and the bacmid, occlusion bodies (OBs) with the typical morphology of cypovirus polyhedra were observed by optical microscopy. The rescue system was verified by incorporation of a HindIII restriction enzyme site null mutant of the 9th genomic segment. Furthermore, when we co-transfected Sf9 cells with the reverse genetics vectors, the bacmid, and an additional vector bearing an egfp gene flanked with the 5′ and 3′ untranslated regions of the 10th genomic segment, aggregated green fluorescence co-localizing with the OBs was observed. The rescued OBs were able to infect Spodopetra exigua larvae, although their infectivity was significantly lower than that of wild-type DpCPV. This reverse genetics system for DpCPV could be used to explore viral replication and pathogenesis and to facilitate the development of novel bio-insecticides and expression systems for exogenous proteins.
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16
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Transcriptional response of immune-related genes after endogenous expression of VP1 and exogenous exposure to VP1-based VLPs and CPV virions in lepidopteran cell lines. Mol Genet Genomics 2019; 294:887-899. [DOI: 10.1007/s00438-019-01551-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 03/21/2019] [Indexed: 12/11/2022]
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17
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Zhu L, Hu X, Kumar D, Chen F, Feng Y, Zhu M, Liang Z, Huang L, Yu L, Xu J, Xue R, Cao G, Gong C. Both ganglioside GM2 and cholesterol in the cell membrane are essential for Bombyx mori cypovirus cell entry. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 88:161-168. [PMID: 30031014 DOI: 10.1016/j.dci.2018.07.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Revised: 07/10/2018] [Accepted: 07/11/2018] [Indexed: 06/08/2023]
Abstract
Bombyx mori cypovirus (BmCPV) enters permissive cells via clathrin-mediated endocytosis pathway. However, the distinct entry mechanism for BmCPV is still ambiguous. The aim of this study is to investigate the role of gangliosides and cholesterol in BmCPV cell entry. The number of BmCPV virions attached to the cell surface and the expression level of BmCPV vp1 gene was significantly decreased by digestion of terminal sialic acids in gangliosides with neuraminidase (NA). Preincubation of different concentration of ganglioside GM1, GM2 or GM3 with BmCPV prior to infection, the reduction of BmCPV infectivity was found by GM2-treated in a dose-depend manner. BmCPV virions were found to colocalize with GM2 in the cell surface. The infectivity of BmCPV was reduced by anti-GM2 antibody treatment cells. Moreover, BmCPV infection was impaired by depletion of membrane cholesterol with MβCD, but the inhibitory effect of MβCD was restored by supplementing with cholesterol. The number of viral particles attached on the BmN cells was significantly decreased by pretreated with MβCD, and BmCPV infection was inhibited by silencing the expression of 3-hydroxy-3-methylglutaryl-CoA reductase gene (Hmg-r) in cholesterol biosynthesis pathway. These results indicate that ganglioside GM2 and cholesterol in membrane lipid rafts are essential for BmCPV attachment to cell surface for its cell entry.
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Affiliation(s)
- Liyuan Zhu
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China
| | - Xiaolong Hu
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China
| | - Dhiraj Kumar
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China
| | - Fei Chen
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China
| | - Yongjie Feng
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China
| | - Min Zhu
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China
| | - Zi Liang
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China
| | - Lixu Huang
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China
| | - Lei Yu
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China
| | - Jian Xu
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China
| | - Renyu Xue
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China
| | - Guangli Cao
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China
| | - Chengliang Gong
- School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China; National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou, 215123, China.
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18
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Clathrin-mediated endocytosis is a candidate entry sorting mechanism for Bombyx mori cypovirus. Sci Rep 2018; 8:7268. [PMID: 29740149 PMCID: PMC5940776 DOI: 10.1038/s41598-018-25677-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 04/24/2018] [Indexed: 12/19/2022] Open
Abstract
Bombyx mori cypovirus (BmCPV), a member of the Reoviridae, specifically infects silkworms and causes extensive economic losses to the sericulture industry. To date, the entry mechanism of BmCPV into cells is unclear. Here we used electron microscopy to study the route of entry of BmCPV into cells, and the results demonstrated that the entry of BmCPV into BmN cells was mediated by endocytosis. Blocking the entry pathway with four endocytosis inhibitors, including dansylcadaverine, chlorpromazine, genistein, and PP2, significantly decreased the infectivity of BmCPV. This indicates that BmCPV enters BmN cells via endocytosis, and that clathrin-mediated sorting is the predominant entry method. After the relative expression levels of clathrin heavy chain (clathrin, GenBank accession No. NM_001142971.1) and the adaptor protein complex-1 gamma subunit AP-1 (AP-1, GenBank accession No. JQ824201.1), which are involved in clathrin-mediated endocytosis, were inhibited by RNA interference or abolishing the functions of clathrin and AP-1 with their corresponding antibodies, the infectivity of BmCPV was reduced significantly, which suggests that clathrin-mediated endocytosis contributed to the entry of BmCPV into cells. Our findings suggest that the clathrin-mediated endocytosis pathway is a candidate for the development of therapeutics for silkworm cytoplasmic polyhedrosis.
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Guo R, Cao G, Xue R, Kumar D, Chen F, Liu W, Jiang Y, Lu Y, Zhu L, Liang Z, Kuang S, Hu X, Gong C. Exogenous gene can be expressed by a recombinant Bombyx mori cypovirus. Appl Microbiol Biotechnol 2017; 102:1367-1379. [DOI: 10.1007/s00253-017-8667-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 11/16/2017] [Accepted: 11/17/2017] [Indexed: 12/25/2022]
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20
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Identification and characterization of two putative microRNAs encoded by Bombyx mori cypovirus. Virus Res 2017; 233:86-94. [DOI: 10.1016/j.virusres.2017.03.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Revised: 03/03/2017] [Accepted: 03/04/2017] [Indexed: 01/23/2023]
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21
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Viral Small-RNA Analysis of Bombyx mori Larval Midgut during Persistent and Pathogenic Cytoplasmic Polyhedrosis Virus Infection. J Virol 2015; 89:11473-86. [PMID: 26339065 DOI: 10.1128/jvi.01695-15] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 08/28/2015] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED The lepidopteran innate immune response against RNA viruses remains poorly understood, while in other insects several studies have highlighted an essential role for the exo-RNAi pathway in combating viral infection. Here, by using deep-sequencing technology for viral small-RNA (vsRNA) assessment, we provide evidence that exo-RNAi is operative in the silkworm Bombyx mori against both persistent and pathogenic infection of B. mori cytoplasmic polyhedrosis virus (BmCPV) which is characterized by a segmented double-stranded RNA (dsRNA) genome. Further, we show that Dicer-2 predominantly targets viral dsRNA and produces 20-nucleotide (nt) vsRNAs, whereas an additional pathway is responsive to viral mRNA derived from segment 10. Importantly, vsRNA distributions, which define specific hot and cold spot profiles for each viral segment, to a considerable degree overlap between Dicer-2-related (19 to 21 nt) and Dicer-2-unrelated vsRNAs, suggesting a common origin for these profiles. We found a degenerate motif significantly enriched at the cut sites of vsRNAs of various lengths which link an unknown RNase to the origins of vsRNAs biogenesis and distribution. Accordingly, the indicated RNase activity may be an important early factor for the host's antiviral defense in Lepidoptera. IMPORTANCE This work contributes to the elucidation of the lepidopteran antiviral response against infection of segmented double-stranded RNA (dsRNA) virus (CPV; Reoviridae) and highlights the importance of viral small-RNA (vsRNA) analysis for getting insights into host-pathogen interactions. Three vsRNA pathways are implicated in antiviral defense. For dsRNA, two pathways are proposed, either based on Dicer-2 cleavage to generate 20-nucleotide vsRNAs or based on the activity of an uncharacterized endo-RNase that cleaves the viral RNA substrate at a degenerate motif. The analysis also indicates the existence of a degradation pathway that targets the positive strand of segment 10.
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22
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Pan ZH, Gao K, Hou CX, Wu P, Qin GX, Geng T, Guo XJ. dsRNA interference on expression of a RNA-dependent RNA polymerase gene of Bombyx mori cytoplasmic polyhedrosis virus. Gene 2015; 565:56-61. [PMID: 25839934 DOI: 10.1016/j.gene.2015.03.069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 03/20/2015] [Accepted: 03/28/2015] [Indexed: 10/23/2022]
Abstract
Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) is one of the major viral pathogens in silkworm. Its infection often results in significant losses to sericulture. Studies have demonstrated that RNAi is one of the important anti-viral mechanisms in organisms. In this study, three dsRNAs targeting the RNA-dependent RNA polymerase (RDRP) gene of BmCPV were designed and synthesized with 2'-F modification to explore their interference effects on BmCPV replication in silkworm larvae. The results showed that injecting dsRNA in the dosage of 4-6 ng per mg body weight into the 5th instar larvae can interfere with the BmCPV-RDRP expression by 93% after virus infection and by 99.9% before virus infection. In addition, the expression of two viral structural protein genes (genome RNA segments 1 and 5) was also decreased with the decrease of RDRP expression, suggesting that RNAi interference of BmCPV-RDRP expression could affect viral replication. The study provides an effective method for investigating virus replication as well as the virus-host interactions in the silkworm larvae using dsRNA.
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Affiliation(s)
- Zhong-Hua Pan
- Sericultural Research Institute, Jiangsu University of Science and Technology, Zhenjiang 212018, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang 212018, China; School of Biology & Basic Medical Science, Soochow University, Suzhou 215123, China
| | - Kun Gao
- Sericultural Research Institute, Jiangsu University of Science and Technology, Zhenjiang 212018, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang 212018, China
| | - Cheng-Xiang Hou
- Sericultural Research Institute, Jiangsu University of Science and Technology, Zhenjiang 212018, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang 212018, China
| | - Ping Wu
- Sericultural Research Institute, Jiangsu University of Science and Technology, Zhenjiang 212018, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang 212018, China
| | - Guang-Xing Qin
- Sericultural Research Institute, Jiangsu University of Science and Technology, Zhenjiang 212018, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang 212018, China
| | - Tao Geng
- Sericultural Research Institute, Jiangsu University of Science and Technology, Zhenjiang 212018, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang 212018, China
| | - Xi-Jie Guo
- Sericultural Research Institute, Jiangsu University of Science and Technology, Zhenjiang 212018, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang 212018, China.
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23
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Zhou Y, Qin T, Xiao Y, Qin F, Lei C, Sun X. Genomic and biological characterization of a new cypovirus isolated from Dendrolimus punctatus. PLoS One 2014; 9:e113201. [PMID: 25419713 PMCID: PMC4242531 DOI: 10.1371/journal.pone.0113201] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 10/24/2014] [Indexed: 11/18/2022] Open
Abstract
A novel cypovirus (designated DpCPV-MC) was isolated from the pine moth Dendrolimus punctatus using serial in vivo cloning procedures. DpCPV-MC occurs in typical polyhedral occlusion bodies, containing a number of spherical virions. Laboratory bioassays indicated that the infectivity of DpCPV-MC against second-instar Spodoptera exigua larvae does not differ significantly from that of Dendrolimus punctatus cypovirus 1. Full-length amplification of the DpCPV-MC cDNAs identified 16 dsRNA genome segments. Each segment encodes one open reading frame with unique conserved terminal sequences at the 5′ and 3′ ends, which differ from those of all previously reported cypoviruses. On a phylogenetic tree based on the amino acid sequences of the polyhedrin of 19 cypovirus species, DpCPV-MC was closest to the type-4 cypoviruses. Homology searches showed that ten segments of DpCPV-MC (S1, S2, S3, S4, S5, S7, S8, S9, S12, and S13) encode putative CPV structural and nonstructural proteins, three segments (S6, S10 and S14) encode putative insect proteins or other viral proteins, and the other three segments (S11, S15, and S16) encode proteins that have no obvious sequence similarity to any known protein. Based on RNA secondary structures analysis, two segments of them (S11 and S16) were predicted to possibly transcript less efficiently than the other segments. We speculate that DpCPV-MC is composed of several genotypes. The ten CPV-related segments constantly exist in all genotypes, and one or two of the six CPV-unrelated segments co-exist with the ten CPV-related segments in one DpCPV-MC genotype, thus each virion contains no more than 12 segments. Based on our results and the literature, DpCPV-MC is a new cypovirus (Cypovirus 22, strain DpCPV-22).
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Affiliation(s)
- Yin Zhou
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Tongcheng Qin
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Yuzhou Xiao
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Fujun Qin
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Chengfeng Lei
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Xiulian Sun
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China
- * E-mail:
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Cao G, Meng X, Xue R, Zhu Y, Zhang X, Pan Z, Zheng X, Gong C. Characterization of the complete genome segments from BmCPV-SZ, a novelBombyx moricypovirus 1 isolate. Can J Microbiol 2012; 58:872-83. [DOI: 10.1139/w2012-064] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A novel Bombyx mori cypovirus 1 isolated from infected silkworm larvae and tentatively assigned as Bombyx mori cypovirus 1 isolate Suzhou (BmCPV-SZ). The complete nucleotide sequences of genomic segments S1–S10 from BmCPV-SZ were determined. All segments possessed a single open reading frame; however, bioinformatic evidence suggested a short overlapping coding sequence in S1. Each BmCPV-SZ segment possessed the conserved terminal sequences AGUAA and GUUAGCC at the 5′ and 3′ ends, respectively. The conserved A/G at the –3 position in relation to the AUG codon could be found in the BmCPV-SZ genome, and it was postulated that this conserved A/G may be the most important nucleotide for efficient translation initiation in cypoviruses (CPVs). Examination of the putative amino acid sequences encoded by BmCPV-SZ revealed some characteristic motifs. Homology searches showed that viral structural proteins VP1, VP3, and VP4 had localized homologies with proteins of Rice ragged stunt virus , a member of the genus Oryzavirus within the family Reoviridae. A phylogenetic tree based on RNA-dependent RNA polymerase sequences demonstrated that CPV is more closely related to Rice ragged stunt virus and Aedes pseudoscutellaris reovirus than to other members of Reoviridae, suggesting that they may have originated from common ancestors.
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Affiliation(s)
- Guangli Cao
- School of Biology and Basic Medical Science, Soochow University, Suzhou 215123, People’s Republic of China
- National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123, People’s Republic of China
| | - Xiangkun Meng
- School of Biology and Basic Medical Science, Soochow University, Suzhou 215123, People’s Republic of China
| | - Renyu Xue
- School of Biology and Basic Medical Science, Soochow University, Suzhou 215123, People’s Republic of China
- National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123, People’s Republic of China
| | - Yuexiong Zhu
- School of Biology and Basic Medical Science, Soochow University, Suzhou 215123, People’s Republic of China
| | - Xiaorong Zhang
- School of Biology and Basic Medical Science, Soochow University, Suzhou 215123, People’s Republic of China
| | - Zhonghua Pan
- School of Biology and Basic Medical Science, Soochow University, Suzhou 215123, People’s Republic of China
| | - Xiaojian Zheng
- School of Biology and Basic Medical Science, Soochow University, Suzhou 215123, People’s Republic of China
| | - Chengliang Gong
- School of Biology and Basic Medical Science, Soochow University, Suzhou 215123, People’s Republic of China
- National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123, People’s Republic of China
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Electron tomography reveals polyhedrin binding and existence of both empty and full cytoplasmic polyhedrosis virus particles inside infectious polyhedra. J Virol 2011; 85:6077-81. [PMID: 21471233 DOI: 10.1128/jvi.00103-11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous studies have described the structure of purified cytoplasmic polyhedrosis virus (CPV) and that of polyhedrin protein. However, how polyhedrin molecules embed CPV particles inside infectious polyhedra is not known. By using electron tomography, we show that CPV particles are occluded within the polyhedrin crystalline lattice with a random spatial distribution and interact with the polyhedrin protein through the A-spike rather than as previously thought through the B-spike. Furthermore, both full (with RNA) and empty (no RNA) capsids were found inside polyhedra, suggesting a spontaneous RNA encapsidating process for CPV assembly in vivo.
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26
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Wu J, Du Z, Wang C, Cai L, Hu M, Lin Q, Wu Z, Li Y, Xie L. Identification of Pns6, a putative movement protein of RRSV, as a silencing suppressor. Virol J 2010; 7:335. [PMID: 21092155 PMCID: PMC3002307 DOI: 10.1186/1743-422x-7-335] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Accepted: 11/22/2010] [Indexed: 11/10/2022] Open
Abstract
RNA silencing is a potent antiviral response in plants. As a counterdefense, most plant and some animal viruses encode RNA silencing suppressors. In this study, we showed that Pns6, a putative movement protein of Rice ragged stunt virus (RRSV), exhibited silencing suppressor activity in coinfiltration assays with the reporter green fluorescent protein (GFP) in transgenic Nicotiana benthamiana line 16c. Pns6 of RRSV suppressed local silencing induced by sense RNA but had no effect on that induced by dsRNA. Deletion of a region involved in RNA binding abolished the silencing suppressor activity of Pns6. Further, expression of Pns6 enhanced Potato virus × pathogenicity in N. benthamiana. Collectively, these results suggested that RRSV Pns6 functions as a virus suppressor of RNA silencing that targets an upstream step of the dsRNA formation in the RNA silencing pathway. This is the first silencing suppressor to be identified from the genus Oryzavirus.
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Affiliation(s)
- Jianguo Wu
- Institute of Plant Virology, Fujian Agriculture and Forestry University , Key Laboratory of Plant Virology of Fujian Province, Fuzhou, Fujian, China.
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27
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Chakrabarti M, Ghorai S, Mani SKK, Ghosh AK. Molecular characterization of genome segments 1 and 3 encoding two capsid proteins of Antheraea mylitta cytoplasmic polyhedrosis virus. Virol J 2010; 7:181. [PMID: 20684765 PMCID: PMC2927528 DOI: 10.1186/1743-422x-7-181] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Accepted: 08/04/2010] [Indexed: 11/10/2022] Open
Abstract
Background Antheraea mylitta cytoplasmic polyhedrosis virus (AmCPV), a cypovirus of Reoviridae family, infects Indian non-mulberry silkworm, Antheraea mylitta, and contains 11 segmented double stranded RNA (S1-S11) in its genome. Some of its genome segments (S2 and S6-S11) have been previously characterized but genome segments encoding viral capsid have not been characterized. Results In this study genome segments 1 (S1) and 3 (S3) of AmCPV were converted to cDNA, cloned and sequenced. S1 consisted of 3852 nucleotides, with one long ORF of 3735 nucleotides and could encode a protein of 1245 amino acids with molecular mass of ~141 kDa. Similarly, S3 consisted of 3784 nucleotides having a long ORF of 3630 nucleotides and could encode a protein of 1210 amino acids with molecular mass of ~137 kDa. BLAST analysis showed 20-22% homology of S1 and S3 sequence with spike and capsid proteins, respectively, of other closely related cypoviruses like Bombyx mori CPV (BmCPV), Lymantria dispar CPV (LdCPV), and Dendrolimus punctatus CPV (DpCPV). The ORFs of S1 and S3 were expressed as 141 kDa and 137 kDa insoluble His-tagged fusion proteins, respectively, in Escherichia coli M15 cells via pQE-30 vector, purified through Ni-NTA chromatography and polyclonal antibodies were raised. Immunoblot analysis of purified polyhedra, virion particles and virus infected mid-gut cells with the raised anti-p137 and anti-p141 antibodies showed specific immunoreactive bands and suggest that S1 and S3 may code for viral structural proteins. Expression of S1 and S3 ORFs in insect cells via baculovirus recombinants showed to produce viral like particles (VLPs) by transmission electron microscopy. Immunogold staining showed that S3 encoded proteins self assembled to form viral outer capsid and VLPs maintained their stability at different pH in presence of S1 encoded protein. Conclusion Our results of cloning, sequencing and functional analysis of AmCPV S1 and S3 indicate that S3 encoded viral structural proteins can self assemble to form viral outer capsid and S1 encoded protein remains associated with it as inner capsid to maintain the stability. Further studies will help to understand the molecular mechanism of capsid formation during cypovirus replication.
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Affiliation(s)
- Mrinmay Chakrabarti
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, India
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28
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Ghorai S, Chakrabarti M, Roy S, Chavali VRM, Bagchi A, Ghosh AK. Molecular characterization of genome segment 2 encoding RNA dependent RNA polymerase of Antheraea mylitta cytoplasmic polyhedrosis virus. Virology 2010; 404:21-31. [PMID: 20488502 PMCID: PMC7111928 DOI: 10.1016/j.virol.2010.04.019] [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] [Received: 03/19/2010] [Revised: 04/14/2010] [Accepted: 04/20/2010] [Indexed: 12/04/2022]
Abstract
Genome segment 2 (S2) from Antheraea mylitta cypovirus (AmCPV) was converted into cDNA, cloned and sequenced. S2 consisted of 3798 nucleotides with a long ORF encoding a 1116 amino acid long protein (123 kDa). BLAST and phylogenetic analysis showed 29% sequence identity and close relatedness of AmCPV S2 with RNA dependent RNA polymerase (RdRp) of other insect cypoviruses, suggesting a common origin of all insect cypoviruses. The ORF of S2 was expressed as 123 kDa soluble His-tagged fusion protein in insect cells via baculovirus recombinants which exhibited RdRp activity in an in vitro RNA polymerase assay without any intrinsic terminal transferase activity. Maximum activity was observed at 37 °C at pH 6.0 in the presence of 3 mM MgCl2. Site directed mutagenesis confirmed the importance of the conserved GDD motif. This is the first report of functional characterization of a cypoviral RdRp which may lead to the development of anti-viral agents.
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Affiliation(s)
- Suvankar Ghorai
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, Kharagpur 721302, West Bengal, India
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29
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Marzban R, He Q, Liu X, Zhang Q. Effects of Bacillus thuringiensis toxin Cry1Ac and cytoplasmic polyhedrosis virus of Helicoverpa armigera (Hübner) (HaCPV) on cotton bollworm (Lepidoptera: Noctuidae). J Invertebr Pathol 2009; 101:71-6. [DOI: 10.1016/j.jip.2009.02.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Revised: 02/18/2009] [Accepted: 02/19/2009] [Indexed: 11/26/2022]
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30
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Jeger MJ, Madden LV, van den Bosch F. The effect of transmission route on plant virus epidemic development and disease control. J Theor Biol 2009; 258:198-207. [PMID: 19490879 DOI: 10.1016/j.jtbi.2009.01.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Revised: 01/06/2009] [Accepted: 01/06/2009] [Indexed: 10/21/2022]
Abstract
A model for indirect vector transmission and epidemic development of plant viruses is extended to consider direct transmission through vector mating. A basic reproduction number is derived which is the sum of the R(0) values specific for three transmission routes. We analyse the model to determine the effect of direct transmission on plant disease control directed against indirect transmission. Increasing the rate of horizontal sexual transmission means that vector control rate or indirect transmission rate must be increased/decreased substantially to maintain R(0) at a value less than 1. By contrast, proportionately increasing the probability of transovarial transmission has little effect. Expressions are derived for the steady-state values of the viruliferous vector population. There is clear advantage for an insect virus in indirect transmission to plants, especially where the sexual and transovarial transmission rates are low; however information on virulence-transmissibility relationships is required to explain the evolution of a plant virus from an insect virus.
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Affiliation(s)
- Michael J Jeger
- Division of Biology, Imperial College London, Silwood Park, Ascot SL5 7PY, UK.
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31
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Luke GA, Escuin H, Felipe PD, Ryan MD. 2A to the Fore – Research, Technology and Applications. Biotechnol Genet Eng Rev 2009; 26:223-60. [DOI: 10.5661/bger-26-223] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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32
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Structural evolution of reoviridae revealed by oryzavirus in acquiring the second capsid shell. J Virol 2008; 82:11344-53. [PMID: 18787002 DOI: 10.1128/jvi.02375-07] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The conservation of the core structure and diversification of the external features among the turreted reoviruses appear to be relevant to structural evolution in facilitating the infection of diverse host species. The structure of Rice ragged stunt virus (RRSV), in the genus Oryzavirus of the family Reoviridae, is determined to show a core composed of capsid shell, clamps, and long turrets. The RRSV core structure is equivalent to the core structure of Orthoreovirus and the virion structure of Cytoplasmic polyhedrosis virus (CPV). In RRSV, five peripheral trimers surround each long turret and sit at the Q trimer position in the T=13l icosahedral symmetry, a structural feature unique to turreted reoviruses. That is, the core of RRSV is partially covered by 60 copies of the peripheral trimer. In contrast, the core of Orthoreovirus is covered by 200 copies of the trimer that sit at the Q, R, S, and T trimer positions. Our results suggest that among the three viruses, RRSV has a structure intermediate between that of Orthoreovirus and the CPV virion. This conclusion coincides with the results of the phylogenetic analysis of amino acid sequences of RNA-dependent RNA polymerases.
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33
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Firth AE, Atkins JF. Bioinformatic analysis suggests that the Cypovirus 1 major core protein cistron harbours an overlapping gene. Virol J 2008; 5:62. [PMID: 18492230 PMCID: PMC2409309 DOI: 10.1186/1743-422x-5-62] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Accepted: 05/20/2008] [Indexed: 11/10/2022] Open
Abstract
Members of the genus Cypovirus (family Reoviridae) are common pathogens of insects. These viruses have linear dsRNA genomes divided into 10–11 segments, which have generally been assumed to be monocistronic. Here, bioinformatic evidence is presented for a short overlapping coding sequence (CDS) in the cypovirus genome segment encoding the major core capsid protein VP1, overlapping the 5'-terminal region of the VP1 ORF in the +1 reading frame. In Cypovirus type 1 (CPV-1), a 62-codon AUG-initiated open reading frame (hereafter ORFX) is present in all four available segment 1 sequences. The pattern of base variations across the sequence alignment indicates that ORFX is subject to functional constraints at the amino acid level (even when the constraints due to coding in the overlapping VP1 reading frame are taken into account; MLOGD software). In fact the translated ORFX shows greater amino acid conservation than the overlapping region of VP1. The genomic location of ORFX is consistent with translation via leaky scanning. A 62–64 codon AUG-initiated ORF is present in a corresponding location and reading frame in other available cypovirus sequences (2 CPV-14, 1 CPV-15) and an 87-codon ORFX homologue may also be present in Aedes pseudoscutellaris reovirus. The ORFX amino acid sequences are hydrophilic and basic, with between 12 and 16 Arg/Lys residues in each though, at 7.5–10.2 kDa, the putative ORFX product is too small to appear on typical published protein gels.
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Affiliation(s)
- Andrew E Firth
- BioSciences Institute, University College Cork, Cork, Ireland.
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34
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Chavali VRM, Madhurantakam C, Ghorai S, Roy S, Das AK, Ghosh AK. Genome segment 6 of Antheraea mylitta cypovirus encodes a structural protein with ATPase activity. Virology 2008; 377:7-18. [PMID: 18486179 DOI: 10.1016/j.virol.2008.03.038] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 03/11/2008] [Accepted: 03/31/2008] [Indexed: 11/30/2022]
Abstract
The genome segment 6 (S6) of the 11 double stranded RNA genomes from Antheraea mylitta cypovirus was converted into cDNA, cloned and sequenced. S6 consisted of 1944 nucleotides with an ORF of 607 amino acids and could encode a protein of 68 kDa, termed P68. Motif scan and molecular docking analysis of P68 showed the presence of two cystathionine beta synthase (CBS) domains and ATP binding sites. The ORF of AmCPV S6 was expressed in E. coli as His-tag fusion protein and polyclonal antibody was raised. Immunoblot analysis of virus infected gut cells and purified polyhedra using raised anti-p68 polyclonal antibody showed that S6 encodes a viral structural protein. Fluorescence and ATPase assay of soluble P68 produced in Sf-9 cells via baculovirus expression system showed its ability to bind and cleave ATP. These results suggest that P68 may bind viral RNA through CBS domains and help in replication and transcription through ATP binding and hydrolysis.
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Affiliation(s)
- Venkata R M Chavali
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, Kharagpur 721302, West Bengal, India
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35
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Tan L, Zhang J, Li Y, Li Y, Jiang H, Cao X, Hu Y. The complete nucleotide sequence of the type 5 Helicoverpa armigera cytoplasmic polyhedrosis virus genome. Virus Genes 2008; 36:587-93. [PMID: 18368473 DOI: 10.1007/s11262-008-0222-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2007] [Accepted: 03/11/2008] [Indexed: 12/01/2022]
Abstract
The S1-6, S8, and S9 segments of the type 5 Helicoverpa armigera cytoplasmic polyhedrosis virus (HaCPV-5, Chinese strain) were cloned and sequenced, completing the HaCPV-5 genome. We found that each HaCPV-5 segment exhibits the conserved terminal sequences AGUU and UUGC located at the 5' and 3' ends, respectively. We also analyzed the translation initiation codon of the HaCPV-5 genome and compared it with the available cypovirus sequences in GenBank. We postulated that the conserved purine at the -3 position in relation to the AUG codon is probably the most important nucleotide for efficient translation initiation in cypovirus. Although the nucleotide sequences of the HaCPV-5 segments S1-10 exhibit no significant similarity to other viruses, blast searches did reveal some similarities between predicted HaCPV-5 amino acid sequences and those of other viruses.
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Affiliation(s)
- Li Tan
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei, 430072, China
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36
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Green TB, White S, Rao S, Mertens PPC, Adler PH, Becnel JJ. Biological and molecular studies of a cypovirus from the black fly Simulium ubiquitum (Diptera: Simuliidae). J Invertebr Pathol 2007; 95:26-32. [PMID: 17224161 DOI: 10.1016/j.jip.2006.10.006] [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: 07/20/2006] [Revised: 10/05/2006] [Accepted: 10/24/2006] [Indexed: 11/29/2022]
Abstract
A cypovirus from the black fly Simulium ubiquitum (SuCPV) was isolated and examined using biological and molecular techniques. SuCPV produces small (typically 0.25mum), polyhedral shaped inclusion bodies (polyhedra), in which the virus particles become multiply embedded. SuCPV is the third cypovirus isolated from Diptera, but the first from Simuliidae that has been characterized using molecular analyses. SuCPV has a genome composed of 10 segments of dsRNA, with an electrophoretic migration pattern that is different from those of recent UsCPV-17 and CrCPV-17 isolates from the mosquitoes Uranotaenia sapphirina and Culex restuans, respectively. The SuCPV electropherotype appears to show significant differences from those of the previously characterized lepidopteran cypoviruses. Sequence analysis of SuCPV segment 10 shows that it is unrelated to either of the two CPV isolates from Diptera or to the CPV species for which Seg-10 has been previously characterized from Lepidoptera. A comparison of the terminal regions of SuCPV genome segments to those of CPV-1, 2, 4, 5 14, 15, 16, 17, 18, and 19 also revealed only low levels of conservation. We therefore, propose that SuCPV is classified within a new Cypovirus species, which we have tentatively identified as Cypovirus-20. We have therefore referred to this virus isolate as S. ubiquitum CPV-20 (SuCPV-20).
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Affiliation(s)
- Terry B Green
- ARS, CMAVE, 1600-1700 S.W. 23rd Drive, Gainesville, FL 32608, USA
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37
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Chen W, Hu Y, Li Y, Yu Z, Dong C, Cai D, Zhang J. Characterization of the RNA-binding regions in protein p36 of Heliothis armigera cypovirus 14. Virus Res 2007; 125:211-8. [PMID: 17350708 DOI: 10.1016/j.virusres.2007.01.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2006] [Revised: 01/10/2007] [Accepted: 01/12/2007] [Indexed: 10/23/2022]
Abstract
Some proteins of cypovirus (CPV) bind to RNA, probably contributing to the replication of viral genome. However, little is known about whether any protein from Heliothis armigera cypovirus (HaCPV) could bind to RNA. In this study, we cloned the ORF of segment 9 (S9) of HaCPV, serotype 14, into pMAL-c2X for the generation and purification of maltose binding protein (MBP) fused protein p36 (MBP-p36). The analysis of the RNA-binding properties of MBP-p36 revealed that p36, but not MBP alone, bound to ssRNA of CPV. Furthermore, the ssRNA-binding activities of p36 were significantly inhibited or completely eliminated by protein denaturants or unsuitable concentrations of NaCl. Importantly, the formation of ssRNA/p36 was only competitively inhibited by a heavy dose of competitive non-viral ssRNA or dsRNA, but not by ssDNA and dsDNA, suggesting that p36 bound to both ssRNA and dsRNA, but not DNA. Moreover, the characterization of different mutants of p36 revealed that the regions 1-26aa, 154-170aa, and 229-238aa, but not region 291-320aa, may be crucial for the ssRNA-binding ability of p36. Conceivably, the sensitivity of p36 to denaturants and the synergetic effect of different regions suggest that the RNA-binding ability of p36 may be conformation-dependent. Thus, our findings provide new insights into understanding the genomic function of HaCPV-14.
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Affiliation(s)
- Wuguo Chen
- State Key Laboratory of Virology and Department of Biotechnology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, PR China
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38
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. SRJ, . MC, . AKG. Molecular Cloning, Expression and Analysis of Antheraea mylitta Cypovirus Genome Segments 8 and 11. ACTA ACUST UNITED AC 2007. [DOI: 10.3923/ijv.2007.60.72] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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39
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Li Y, Zhang J, Li Y, Tan L, Chen W, Luo H, Hu Y. Phylogenetic analysis of Heliothis armigera cytoplasmic polyhedrosis virus type 14 and a series of dwarf segments found in the genome. J Gen Virol 2007; 88:991-997. [PMID: 17325373 DOI: 10.1099/vir.0.82673-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Full-length nucleotide sequences for the genome segments (S1-S6) of Heliothis armigera cytoplasmic polyhedrosis virus type 14 (HaCPV-14) have been characterized. Each segment consists of a single open reading frame with conserved motifs AGAA and AGCU at the 5' and 3' ends, respectively. Comparison of the proteins of HaCPV-14 with those of other members of the family Reoviridae suggests that S1 encodes an RNA-dependent RNA polymerase (RdRp), whilst S2 encodes a major capsid protein of the virus. Phylogenetic analysis of RdRps from 16 viruses in the family Reoviridae reveals that the genera Cypovirus and Oryzavirus may have originated from a common insect virus ancestor. A series of viable dwarf segments originating from S5 of HaCPV-14 has been identified. Analysis of the predicted secondary structures for these dwarf segments suggests that the signals essential for replication and packaging are located within the terminal sequences of these segments.
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Affiliation(s)
- Yanqiu Li
- Laboratory of Insect Virology, State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, China
| | - Jiamin Zhang
- Laboratory of Insect Virology, State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, China
| | - Yang Li
- Laboratory of Insect Virology, State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, China
| | - Li Tan
- Laboratory of Insect Virology, State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, China
| | - Wuguo Chen
- Laboratory of Insect Virology, State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, China
| | - Haishan Luo
- Laboratory of Insect Virology, State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, China
| | - Yuanyang Hu
- Laboratory of Insect Virology, State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, China
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40
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Chavali VRM, Ghosh AK. Molecular cloning, sequence analysis and expression of genome segment 7 (S7) of Antheraea mylitta cypovirus (AmCPV) that encodes a viral structural protein. Virus Genes 2007; 35:433-41. [PMID: 17253125 DOI: 10.1007/s11262-006-0070-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2006] [Accepted: 08/07/2006] [Indexed: 10/23/2022]
Abstract
The Genome segment 7 (S7) of the 11 double stranded RNA genomes from Antheraea mylitta cypovirus (AmCPV) was converted to cDNA, cloned and sequenced. The nucleotide sequence showed that segment 7 consisted of 1789 nucleotides with an ORF of 530 amino acids and could encode a protein of approximately 61 kDa, termed P61. The 5' terminal sequence, AGTAAT and the 3' terminal sequence, AGAGC of the plus strand was found to be the same as genome segment 10 of AmCPV encoding polyhedrin. No sequence similarity was found by searching nucleic acid and protein sequence databases using BLAST. The secondary structure prediction showed the presence of 17 alpha-helices, 18 extended beta-sheets along the entire length of P61. The ORF of segment 7 was expressed in E. coli as His-tagged fusion protein, purified through Ni-NTA chromatography, and polyclonal antibody was raised in rabbit indicating that P61 is immunogenic. Immunoblot analysis using this antibody on viral infected cells as well as purified polyhedra showed that P61 is a viral structural protein. Motif scan search showed some similarity of P61 with Inosine monophosphate dehydrogenase (IMPDH) cystathionine-beta-synthase (CBS) domain at the C-terminus and it was hypothesized that by binding to single stranded viral RNA through its CBS domain P61 may help in virus replication or transcription.
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41
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Li Y, Tan L, Li Y, Chen W, Zhang J, Hu Y. Identification and genome characterization of Heliothis armigera cypovirus types 5 and 14 and Heliothis assulta cypovirus type 14. J Gen Virol 2006; 87:387-394. [PMID: 16432026 DOI: 10.1099/vir.0.81435-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Genomic characterization of Heliothis armigera cypovirus (HaCPV) isolated from China showed that insects were co-infected with several cypoviruses (CPVs). One of the CPVs (HaCPV-5) could be separated from the others by changing the rearing conditions of the Heliothis armigera larvae. This finding was further confirmed by nucleotide sequencing analysis. Genomic sequences of segments S10-S7 from HaCPV-14, S10 and S7 from HaCPV-5, and S10 from Heliothis assulta CPV-14 were compared. Results from database searches showed that the nucleotide sequences and deduced amino acid sequences of the newly identified CPVs had high levels of identity with those of reported CPVs of the same type, but not with CPVs of different types. Putative amino acid sequences of HaCPV-5 S7 were similar to that of the protein from Rice ragged stunt virus (genus Oryzavirus, family Reoviridae), suggesting that CPVs and oryzaviruses are related more closely than other genera of the family Reoviridae. Conserved motifs were also identified at the ends of each RNA segment of the same virus type: type 14, 5'-AGAAUUU...CAGCU-3'; and type 5, 5'-AGUU...UUGC-3'. Our results are consistent with classification of CPV types based on the electrophoretic patterns of CPV double-stranded RNA.
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Affiliation(s)
- Yang Li
- Laboratory of Insect Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Li Tan
- Laboratory of Insect Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yanqiu Li
- Laboratory of Insect Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Wuguo Chen
- Laboratory of Insect Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Jiamin Zhang
- Laboratory of Insect Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yuanyang Hu
- Laboratory of Insect Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
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Green TB, Shapiro A, White S, Rao S, Mertens PPC, Carner G, Becnel JJ. Molecular and biological characterization of a Cypovirus from the mosquito Culex restuans. J Invertebr Pathol 2006; 91:27-34. [PMID: 16376932 DOI: 10.1016/j.jip.2005.10.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Revised: 10/06/2005] [Accepted: 10/11/2005] [Indexed: 10/25/2022]
Abstract
A cypovirus from the mosquito Culex restuans (named CrCPV) was isolated and its biology, morphology, and molecular characteristics were investigated. CrCPV is characterized by small (0.1-1.0 microm), irregularly shaped inclusion bodies that are multiply embedded. Laboratory studies demonstrated that divalent cations influenced transmission of CrCPV to Culex quinquefasciatus larvae; magnesium enhanced CrCPV transmission by approximately 30% while calcium inhibited transmission. CrCPV is the second cypovirus from a mosquito that has been confirmed by using molecular analysis. CrCPV has a genome composed of 10 dsRNA segments with an electropherotype similar to the recently discovered UsCPV-17 from the mosquito Uranotaenia sapphirina, but distinct from the lepidopteran cypoviruses BmCPV-1 (Bombyx mori) and TnCPV-15 (Trichoplusia ni). Nucleotide and deduced amino acid sequence analysis of CrCPV segment 10 (polyhedrin) suggests that CrCPV is closely related (83% nucleotide sequence identity and 87% amino acid sequence identity) to the newly characterized UsCPV-17 but is unrelated to the 16 remaining CPV species from lepidopteran hosts. A comparison of the terminal segment regions of CrCPV and UsCPV-17, an additional method for differentiating various Cypovirus species, revealed a high level of conservation. Therefore, we propose that CrCPV is a member of the Cypovirus-17 group and designate this species as CrCPV-17.
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Zhao SL, Liang CY, Zhang WJ, Tang XC, Peng HY. Characterization of the RNA-binding domain in the Dendrolimus punctatus cytoplasmic polyhedrosis virus nonstructural protein p44. Virus Res 2005; 114:80-8. [PMID: 16023751 DOI: 10.1016/j.virusres.2005.06.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2005] [Revised: 06/01/2005] [Accepted: 06/06/2005] [Indexed: 11/24/2022]
Abstract
Dendrolimus punctatus cytoplasmic polyhedrosis virus (DpCPV-1) belongs to the Cypovirus genus in the Reoviridae family. The ORF of genome segment 8 (S8) of DpCPV-1 was cloned into vector pMAL-c2X and used to express a 44kDa protein (p44) in E. coli, which was detected by Western blotting. The gel mobility shift assays showed that p44 had ssRNA-binding activity. Competitive assay indicated that this protein only bind to ssRNA and could not interact with DNA and dsRNA. The binding of p44 to ssRNA is sequence non-specific. To identify the domain(s) important for RNA binding of the protein, a number of deletions were made. These truncated proteins were expressed in E. coli and purified. The affinity of each truncated protein towards ssRNA was then assayed by electrophoretic mobility shift assays and northwestern blot. The results indicated that glutamic acid-rich domain in the central region of p44 from residues 104 to 201 was the ssRNA-binding domain.
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Affiliation(s)
- S L Zhao
- Laboratory for Biological Control, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
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Shapiro A, Green T, Rao S, White S, Carner G, Mertens PPC, Becnel JJ. Morphological and molecular characterization of a Cypovirus (Reoviridae) from the mosquito Uranotaenia sapphirina (Diptera: Culicidae). J Virol 2005; 79:9430-8. [PMID: 16014906 PMCID: PMC1181557 DOI: 10.1128/jvi.79.15.9430-9438.2005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel cypovirus has been isolated from the mosquito Uranotaenia sapphirina (UsCPV) and shown to cause a chronic infection confined to the cytoplasm of epithelial cells of the gastric ceca and posterior stomach. The production of large numbers of virions and inclusion bodies and their arrangement into paracrystalline arrays gives the gut of infected insects a distinctive blue iridescence. The virions, which were examined by electron microscopy, are icosahedral (55 to 65 nm in diameter) with a central core that is surrounded by a single capsid layer. They are usually packaged individually within cubic inclusion bodies (polyhedra, approximately 100 nm across), although two to eight virus particles were sometimes occluded together. The virus was experimentally transmitted per os to several mosquito species. The transmission rate was enhanced by the presence of magnesium ions but was inhibited by calcium ions. Most of the infected larvae survived to adulthood, and the adults retained the infection. Electrophoretic analysis of the UsCPV genome segments (using 1% agarose gels) generated a migration pattern (electropherotype) that is different from those of the 16 Cypovirus species already recognized. UsCPV genome segment 10 (Seg-10) showed no significant nucleotide sequence similarity to the corresponding segment of the other cypoviruses that have previously been analyzed, and it has different "conserved" termini. A BLAST search of the UsCPV deduced amino acid sequence also showed little similarity to Antheraea mylitta CPV-4 (67 of 290 [23%]) or Choristoneura fumiferana CPV-16 (33 of 111 [29%]). We conclude that UsCPV should be recognized as a member of a new Cypovirus species (Cypovirus 17, strain UsCPV-17).
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Affiliation(s)
- Alexandra Shapiro
- Center for Medical, Agricultural and Veterinary Entomology, USDA/ARS, Gainesville, FL 32604, USA
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Hagiwara K, Naitow H. Assembly into single-shelled virus-like particles by major capsid protein VP1 encoded by genome segment S1 of Bombyx mori cypovirus 1. J Gen Virol 2003; 84:2439-2441. [PMID: 12917465 DOI: 10.1099/vir.0.19216-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The major capsid protein VP1 encoded by genome segment S1 of Bombyx mori cypovirus 1 was expressed in a baculovirus system. In the absence of any other capsid proteins, VP1 was found to assemble into single-shelled virus-like particles. The VP1 particles were more sensitive to acidic conditions than were intact particles.
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Affiliation(s)
- Kyoji Hagiwara
- Laboratory of Virology, National Agricultural Research Center, Tsukuba, Ibaraki 305-8666, Japan
| | - Hisashi Naitow
- Division of Bio-Crystallography Technology, RIKEN Harima Institute, Sayo-gun, Hyogo 679-5148, Japan
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