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Granulovirus GP37 Facilitated ODVs Cross Insect Peritrophic Membranes and Fuse with Epithelia. Toxins (Basel) 2019; 11:toxins11030145. [PMID: 30836616 PMCID: PMC6468389 DOI: 10.3390/toxins11030145] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 02/13/2019] [Accepted: 02/23/2019] [Indexed: 01/28/2023] Open
Abstract
The Cydia pomonella granulovirus (CpGV) GP37 has synergistic effects on the infectivity of nucleopolyhedroviruses (NPVs), however, the mechanism employed is unclear. In this study, in vitro and in vivo binding assays indicated that GP37 efficiently bound to the midgut peritrophic membrane (PM) of Spodoptera exigua larvae. Treatment with GP37 led to the damage of the PM’s compacted structure and the generation of the PM perforations, and the enhancement of the PM’s permeability. qPCR results further demonstrated that GP37 increased the ability of occlusion-derived virions (ODV) to cross the PM. R18-labeling experiments exhibited that GP37 also promoted the fusion of ODVs and insect midgut epithelia. Altogether, our present results revealed that the synergistic mechanism of GP37 to the infectivity of NPV might involve two parts. GP37 damaged the integrity of the PM after binding, which enhanced the PM’s permeability and increased the ability of ODVs to cross the PM, finally facilitating the ODVs reaching the midgut. In addition, GP37 promoted the fusion of ODVs and insect midgut epithelia. Our data expand the understanding of the mechanism used by baculovirus synergistic factors and provide a foundation for the development of high-efficiency baculoviral insecticides.
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Marsberg T, Jukes MD, Krejmer-Rabalska M, Rabalski L, Knox CM, Moore SD, Hill MP, Szewczyk B. Morphological, genetic and biological characterisation of a novel alphabaculovirus isolated from Cryptophlebia peltastica (Lepidoptera: Tortricidae). J Invertebr Pathol 2018; 157:90-99. [PMID: 30102885 DOI: 10.1016/j.jip.2018.08.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 08/02/2018] [Accepted: 08/10/2018] [Indexed: 11/29/2022]
Abstract
Cryptophlebia peltastica is an agricultural pest of litchis and macadamias in South Africa with phytosanitary status for certain markets. Current control methods rely on chemical, cultural and classical biological control. However, a microbial control option has not been developed. An Alphabaculovirus from C. peltastica was recovered from a laboratory reared colony and morphologically characterised by transmission electron microscopy (TEM). Analysis of occlusion bodies indicated a single NPV (SNPV) varying in size from 421 to 1263 nm. PCR amplification and sequencing of the polh gene region using universal primers followed by BLAST analysis revealed a 93% similarity to a partial polh gene sequence from Epinotia granitalis NPV. Further genetic characterisation involving single restriction endonuclease (REN) digestion of genomic DNA was carried out to generate profiles for comparison against other baculovirus species and potential new isolates of the same virus. The complete genome of the virus was sequenced, assembled and analysed for a more comprehensive genetic analysis. The genome was 115728 base pairs (bp) in length with a GC content of 37.2%. A total of 126 open reading frames (ORFs) were identified with minimal overlap and no preference in orientation. Bioassays were used to determine the virulence of the NPV against C. peltastica. The NPV was virulent against C. peltastica with an LC50 value of 6.46 × 103 OBs/ml and an LC90 value of 2.46 × 105 OBs/ml, and time mortality ranging between 76.32 h and 93.49 h. This is the first study to describe the isolation and genetic characterisation of a novel SNPV from C. peltastica, which has potential for development into a biopesticide for the control of this pest in South Africa.
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Affiliation(s)
- Tamryn Marsberg
- Centre for Biological Control, Department of Zoology and Entomology, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa; Citrus Research International, P.O. Box 20285, Humewood, Port Elizabeth 6013 South Africa
| | - Michael D Jukes
- Department of Biochemistry and Microbiology, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa.
| | - Martyna Krejmer-Rabalska
- Laboratory of Recombinant Vaccines, Intercollegiate Faculty of Biotechnology of the University of Gdansk and Medical University of Gdansk, Abrahama 58 80-307 Gdansk, Poland
| | - Lukasz Rabalski
- Laboratory of Recombinant Vaccines, Intercollegiate Faculty of Biotechnology of the University of Gdansk and Medical University of Gdansk, Abrahama 58 80-307 Gdansk, Poland
| | - Caroline M Knox
- Department of Biochemistry and Microbiology, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa
| | - Sean D Moore
- Centre for Biological Control, Department of Zoology and Entomology, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa; Citrus Research International, P.O. Box 20285, Humewood, Port Elizabeth 6013 South Africa
| | - Martin P Hill
- Centre for Biological Control, Department of Zoology and Entomology, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa
| | - Boguslaw Szewczyk
- Laboratory of Recombinant Vaccines, Intercollegiate Faculty of Biotechnology of the University of Gdansk and Medical University of Gdansk, Abrahama 58 80-307 Gdansk, Poland
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Liu X, Ma X, Lei C, Xiao Y, Zhang Z, Sun X. Synergistic effects of Cydia pomonella granulovirus GP37 on the infectivity of nucleopolyhedroviruses and the lethality of Bacillus thuringiensis. Arch Virol 2011; 156:1707-15. [PMID: 21643992 DOI: 10.1007/s00705-011-1039-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Accepted: 05/19/2011] [Indexed: 10/18/2022]
Abstract
To initiate an efficient primary infection, it is important for baculovirus virions to penetrate through the peritrophic membrane (PM) of the host insect. It is frequently reported that enhancins of baculoviruses significantly enhance viral infection by degrading the various protein components of PMs. However, not all baculoviruses encode enhancins. GP37s of baculoviruses share high amino acid identity with fusolins, synergistic factors found in entomopoxviruses. In this study, a truncated Cydia pomonella granulovirus GP37 was expressed in Escherichia coli. The expressed GP37 effectively bound to chitin, and binding occurred predominantly within 3 h. GP37 altered the protein profiles of Spodoptera exigua PMs, from which a 50-kDa protein was dissociated. Droplet-feeding bioassays indicated that GP37 significantly enhanced the infectivity of nucleopolyhedroviruses (NPVs) and the lethality of Bacillus thuringiensis (Bt) in S. exigua larvae. This is the first demonstration of the enhancement of NPVs and Bt infection by a baculovirus GP37.
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Affiliation(s)
- Xiangyang Liu
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
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