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Khajje D, Devi SS, Subrahmanyam G, Kobayashi J, Sivaprasad V, Terenius O, Ponnuvel KM. Investigation on Pathological Aspects, Mode of Transmission, and Tissue Tropism of Antheraea proylei Nucleopolyhedrovirus Infecting Oak Tasar Silkworm. JOURNAL OF INSECT SCIENCE (ONLINE) 2022; 22:9. [PMID: 36208151 PMCID: PMC9543400 DOI: 10.1093/jisesa/ieac057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Indexed: 06/16/2023]
Abstract
The temperate oak tasar silkworm, Antheraea proylei, is frequently infested with Antheraea proylei nucleopolyhedrovirus (AnprNPV) causing tiger band disease. This disease is one of the key factors that obstructs production and productivity of oak tasar sericulture. The current study aimed to investigate the pathogenicity of AnprNPV, its mode of transmission, and detection of AnprNPV in different tissues. Transmission electron micrographs of AnprNPV showed single rod-shaped bodies and occlusion derived virus (ODV) enclosed within multiple envelopes. The infecting AnprNPV displayed tissue tropism with higher copy numbers detected in the insect fat body and ovary. The virus was observed to multiply in all developmental stages of the silkworm such as egg, larva, pupa, and moth, confirming its ability to spread throughout the silkworm lifecycle. Baculovirus isolated from infected A. proylei showed cross-infectivity in other Saturniidae wild silkworm species such as Antheraea pernyi, A. frithi, and Samia ricini, widening their probable host range for infection. Baculoviruses generally display a horizontal mode of transmission, mainly through ingestion of occlusion bodies (OBs); however, the present study revealed a trans-ovum vertical mode of transmission in addition to a horizontal mode. The observations made in this study aid a detailed understanding of the tiger band disease and its causative pathogen AnprNPV, which will support future studies and disease management in oak tasar sericulture.
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Affiliation(s)
- Diksha Khajje
- Genomic Division, Seri biotech Research Laboratory, Carmelaram Post, Kodathi, Bangalore 560035, India
- Department of Biotechnology, School of Sciences, Jain University, Bangalore 560027, India
| | | | - Gangavarapu Subrahmanyam
- Genomic Division, Seri biotech Research Laboratory, Carmelaram Post, Kodathi, Bangalore 560035, India
| | - Jun Kobayashi
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 1677-1, Yoshida, Yamaguchi 753-8515, Japan
| | - Vankadara Sivaprasad
- Genomic Division, Seri biotech Research Laboratory, Carmelaram Post, Kodathi, Bangalore 560035, India
| | | | - Kangayam M Ponnuvel
- Genomic Division, Seri biotech Research Laboratory, Carmelaram Post, Kodathi, Bangalore 560035, India
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Roy MC, Ahmed S, Mollah MMI, Kim Y. Antiviral Treatment Reveals a Cooperative Pathogenicity of Baculovirus and Iflavirus in Spodoptera exigua, a Lepidopteran Insect. J Microbiol Biotechnol 2021; 31:529-539. [PMID: 33526755 PMCID: PMC9723280 DOI: 10.4014/jmb.2012.12045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Revised: 01/16/2021] [Accepted: 01/18/2021] [Indexed: 12/15/2022]
Abstract
NPVThe beet armyworm, Spodoptera exigua, is a serious insect pest infesting various vegetable crops. Two infectious insect viruses, baculovirus and iflavirus, are known to induce epizootics in S. exigua populations. Indeed, some laboratory colonies have appeared to be covertly infected by these viruses. Diagnostic PCR tests detected two different viruses: Spodoptera exigua multiple nucleopolyhedrosis virus (SeMNPV) and iflaviruses (SeIfV1 and SeIfV2). Viral extract from dead larvae of S. exigua could infect Sf9 cells and produce occlusion bodies (OBs). Feeding OBs to asymptomatic larvae of S. exigua caused significant viral disease. Interestingly, both SeIfV1 and SeIfV2 increased their titers at late larval stages. Sterilization of laid eggs with 1% sodium hypochloride significantly reduced SeMNPV titers and increased larval survival rate. Doublestranded RNA (dsRNA) specific to SeIfV1 or SeIfV2 significantly reduced viral titers and increased larval survival rate. To continuously feed dsRNA, a recombinant Escherichia coli HT115 expressing SeIfV1-dsRNA was constructed with an L4440 expression vector. Adding this recombinant E. coli to the artificial diet significantly reduced the SeIfV1 titer and increased larval survival. These results indicate that laboratory colony collapse of S. exigua is induced by multiple viral infections. In addition, either suppression of SeMNPV or SeIfV infection significantly increased larval survival, suggesting a cooperative pathogenicity between baculovirus and iflavirus against S. exigua.
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Affiliation(s)
- Miltan Chandra Roy
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, Republic of Korea
| | - Shabbir Ahmed
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, Republic of Korea
| | - Md. Mahi Imam Mollah
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, Republic of Korea
| | - Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, Republic of Korea,Corresponding author E-mail:
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3
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Wilson K, Grzywacz D, Cory JS, Donkersley P, Graham RI. Trans-generational viral transmission and immune priming are dose-dependent. J Anim Ecol 2021; 90:1560-1569. [PMID: 33724454 DOI: 10.1111/1365-2656.13476] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 03/08/2021] [Indexed: 12/30/2022]
Abstract
It is becoming increasingly apparent that trans-generational immune priming (i.e. the transfer of the parental immunological experience to its progeny resulting in offspring protection from pathogens that persist across generations) is a common phenomenon not only in vertebrates, but also invertebrates. Likewise, it is known that covert pathogenic infections may become 'triggered' into an overt infection by various stimuli, including exposure to heterologous infections. Yet, rarely have both phenomena been explored in parallel. Using as a model system the African armyworm Spodoptera exempta, an eruptive agricultural pest and its endemic dsDNA virus (Spodoptera exempta nucleopolyhedrovirus, SpexNPV), the aim of this study was to explore the impact of parental inoculating-dose on trans-generational pathogen transmission and immune priming (in its broadest sense). Larvae were orally challenged with one of five doses of SpexNPV and survivors from these treatments were mated and their offspring monitored for viral mortality. Offspring from parents challenged with low viral doses showed evidence of 'immune priming' (i.e. enhanced survival following SpexNPV challenge); in contrast, offspring from parents challenged with higher viral doses exhibited greater susceptibility to viral challenge. Most offspring larvae died of the virus they were orally challenged with; in contrast, most offspring from parents that had been challenged with the highest doses were killed by the vertically transmitted virus (90%) and not the challenge virus. These results demonstrate that the outcome of a potentially lethal virus challenge is critically dependent on the level of exposure to virus in the parental generation-either increasing resistance at very low parental viral doses (consistent with trans-generational immune priming) or increasing susceptibility at higher parental doses (consistent with virus triggering). We discuss the implications of these findings for understanding both natural epizootics of baculoviruses and for using them as biological control agents.
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Affiliation(s)
- Kenneth Wilson
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
| | - David Grzywacz
- Department of Agriculture Health and Environment, Natural Resources Institute, University of Greenwich, Kent, UK
| | - Jenny S Cory
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
| | | | - Robert I Graham
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
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Akhanaev YB, Belousova IA, Lebedeva DA, Pavlushin SV, Martemyanov VV. A Comparison of the Vertical Transmission of High- and Low-Virulence Nucleopolyhedrovirus Strains in Lymantria Dispar L. INSECTS 2020; 11:E455. [PMID: 32698315 PMCID: PMC7411610 DOI: 10.3390/insects11070455] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 07/17/2020] [Accepted: 07/18/2020] [Indexed: 11/17/2022]
Abstract
Baculoviruses can persist in insect host organisms after infection and may be vertically transmitted to the next generation, in which they may be reactivated. The goal of the present study was to compare the efficiency of the vertical transmission of high- and low-virulence strains and the subsequent reactivation of Lymantria dispar multiple nucleopolyhedrovirus (LdMNPV) in the offspring of Lymantria dispar L. adults who survived after viral infection. As a result of parental infection, the fecundity of survived females, pupae weight, and fertility were significantly different compared to the untreated insects. However, differences in these parameters between high- and low-virulence strains were not observed. The prevalence of virus strains in the offspring measured by quantitative polymerase chain reaction also did not differ. When the larvae reached the fourth instar, they were starved to activate the vertically transmitted virus. The frequency of virus activation in the experiment was not dependent on the virulence of the virus strains. These results are helpful for understanding the strategy of virus survival in nature and for the selection of the most effective strains with transgenerational effects in the years following pest treatment.
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Affiliation(s)
- Yuriy B. Akhanaev
- Laboratory of Ecological Physiology, Institute of Systematics and Ecology of Animals SB RAS, Frunze str. 11, Novosibirsk 630091, Russia; (I.A.B.); (D.A.L.); (S.V.P.)
| | - Irina A. Belousova
- Laboratory of Ecological Physiology, Institute of Systematics and Ecology of Animals SB RAS, Frunze str. 11, Novosibirsk 630091, Russia; (I.A.B.); (D.A.L.); (S.V.P.)
| | - Darya A. Lebedeva
- Laboratory of Ecological Physiology, Institute of Systematics and Ecology of Animals SB RAS, Frunze str. 11, Novosibirsk 630091, Russia; (I.A.B.); (D.A.L.); (S.V.P.)
| | - Sergey V. Pavlushin
- Laboratory of Ecological Physiology, Institute of Systematics and Ecology of Animals SB RAS, Frunze str. 11, Novosibirsk 630091, Russia; (I.A.B.); (D.A.L.); (S.V.P.)
| | - Vyacheslav V. Martemyanov
- Laboratory of Ecological Physiology, Institute of Systematics and Ecology of Animals SB RAS, Frunze str. 11, Novosibirsk 630091, Russia; (I.A.B.); (D.A.L.); (S.V.P.)
- Reshetnev Siberian State University of Science and Technology, Krasnoiarskii rabochii av. 31, Krasnoyarsk 630091, Russia
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5
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Abid AD, Saeed S, Zaka SM, Ali M, Shahzad MS, Khan KA, Iqbal N. Manifold passages in an assorted infection in a host could improve virulence of Helicoverpa armigera Nucleopolyhedrovirus (HaNPV). Saudi J Biol Sci 2020; 27:1419-1422. [PMID: 32489276 PMCID: PMC7253915 DOI: 10.1016/j.sjbs.2020.02.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 02/15/2020] [Accepted: 02/29/2020] [Indexed: 12/04/2022] Open
Abstract
Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) is serious pests of cotton and several other crops. Helicoverpa armigera Nucleopolyhedrovirus (HaNPV) can be important alternative to synthetic insecticides for the management of H. armigera. However, the efficacy of HaNPV can vary in horizontal and vertical transmission. In the current study, we evaluated the efficacy of HaNPV of a virulent strain (vertically transmitted up to six generations) and wild strains (used after isolation from the field infected larvae). Both strains were applied to the 2nd instar larvae of H. armigera @ 1 × 109 polyhedral inclusion bodies (PIB)/ml. There were six replications of each strain (strains). The results indicated higher mortalities in larvae exposed to virulent strains (68.33 ± 6.07%) as compared to wild strain (45 ± 2.24%). Virulent strains killed the larvae quite faster than wild strain. The lethal time (LT50) to kill 50% of the larvae by virulent strain was 7.15 days and for wild strain it was 19.47 days. The results showed that multiple passage of HaNPV through several generations enhances its efficacy to kill H. armigera larvae faster. The results of this study will be helpful to manage H. armigera and other related lepidopoterous pests.
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Affiliation(s)
- Allah Ditta Abid
- Department of Entomology, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan 60800, Pakistan.,Department of Plant Protection, Karachi Ministry of National Food Security, Pakistan
| | - Shafqat Saeed
- Department of Entomology, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan 60800, Pakistan.,Institute of Plant Protection, MNS-University of Agriculture, Multan (60000), Pakistan
| | - Syed Muhammad Zaka
- Department of Entomology, Bahauddin Zakariya University, Multan (60800), Pakistan
| | - Muhammad Ali
- Institute of Pure and Applied Biology, Bahauddin Zakariya University, Multan (60800), Pakistan.,Qauid-i-Azam University, Islamabad, Pakistan
| | | | - Khalid Ali Khan
- Unit of Bee Research and Honey Production, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia.,Biology Department, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia.,Research Center for Advanced Materials Science (RCAMS), King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia
| | - Naeem Iqbal
- Institute of Plant Protection, MNS-University of Agriculture, Multan (60000), Pakistan
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Rosario K, Mettel KA, Greco AM, Breitbart M. Prevalence of a vertically transmitted single-stranded DNA virus in spinybacked orbweavers (Gasteracantha cancriformis) from Florida, USA. J Gen Virol 2019; 100:1253-1265. [PMID: 31210632 DOI: 10.1099/jgv.0.001293] [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] [Indexed: 02/05/2023] Open
Abstract
Spiders (order Araneae, class Arachnida) are an important group of predatory arthropods in terrestrial ecosystems that have been recently identified as an untapped reservoir of single-stranded (ss)DNA viruses. Specifically, spiders harbour a diversity of ssDNA viruses encoding a replication-associated protein (Rep) within a circular genome. However, little is known about the ecology of novel circular Rep-encoding ssDNA (CRESS DNA) viruses. Here we investigated two CRESS DNA viruses recently identified in spinybacked orbweavers (Gasteracantha cancriformis), namely spinybacked orbweaver circular virus (SpOrbCV) 1 and 2. SpOrbCV-1 was detected in the majority (> 65 %) of spider specimens from all life stages, including eggs, spiderlings and adults, demonstrating that this virus is active within spinybacked orbweavers. In contrast, SpOrbCV-2 was only detected in adults at a lower (36 %) prevalence. Since we also detected SpOrbCV-2 in other spider species and this virus has been reported from a dragonfly, we suggest that SpOrbCV-2 is accumulated in these predators through common insect prey. The prevalence of SpOrbCV-1 in collected specimens allowed us to design assays to characterize this virus, which represents a new group of CRESS DNA viruses, the 'circularisviruses'. To our knowledge, SpOrbCV-1 is the first example of a vertically transmitted virus in spiders, which may explain its high prevalence in spinybacked orbweavers. Since vertically transmitted viruses infecting insects (class Insecta) can manipulate their host's behaviour and physiology, future studies should investigate the ecological role of vertically transmitted viruses in spiders.
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Affiliation(s)
- Karyna Rosario
- College of Marine Science, University of South Florida, 140 7th Avenue South, Saint Petersburg, FL, 33701, USA
| | - Kaitlin A Mettel
- College of Marine Science, University of South Florida, 140 7th Avenue South, Saint Petersburg, FL, 33701, USA
| | - Anthony M Greco
- College of Marine Science, University of South Florida, 140 7th Avenue South, Saint Petersburg, FL, 33701, USA
| | - Mya Breitbart
- College of Marine Science, University of South Florida, 140 7th Avenue South, Saint Petersburg, FL, 33701, USA
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8
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Wang L, Cappelle K, Santos D, Vanden Broeck J, Smagghe G, Swevers L. Short-term persistence precedes pathogenic infection: Infection kinetics of cricket paralysis virus in silkworm-derived Bm5 cells. JOURNAL OF INSECT PHYSIOLOGY 2019; 115:1-11. [PMID: 30905610 DOI: 10.1016/j.jinsphys.2019.03.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 02/16/2019] [Accepted: 03/16/2019] [Indexed: 06/09/2023]
Abstract
Next generation sequencing has revealed the widespread occurrence of persistent virus infections in insects but little is known regarding to what extent persistent infections can affect cellular physiology and how they might contribute to the development of disease. In contrast to the pathogenic infections occurring in Drosophila S2 cells, it was observed that Cricket Paralysis virus (CrPV; Dicistroviridae) causes persistent infections in 9 lepidopteran and 2 coleopteran cell lines. The status of the persistent infection was subsequently investigated in more detail using silkworm-derived Bm5 cells, where the infection eventually becomes pathogenic after 3-4 weeks. The short-term persistence period in Bm5 cells is characterized by low levels of viral replication and virion production as well as by the production of viral siRNAs. However, during this period cellular physiology also becomes altered since the cells become susceptible to infection by the nodavirus Flock House virus (FHV). Pathogenicity and widespread mortality at 4 weeks is preceded by a large increase in virion production and the transcriptional activation of immune-related genes encoding RNAi factors and transcription factors in the Toll, Imd and Jak-STAT pathways. During the infection of Bm5 cells, the infective properties of CrPV are not altered, indicating changes in the physiology of the host cells during the transition from short-term persistence to pathogenicity. The in vitro system of Bm5 cells persistently infected with CrPV can therefore be presented as an easily accessible model to study the nature of persistent virus infections and the processes that trigger the transition to pathogenicity, for instance through the application of different "omics" approaches (transcriptomics, proteomics, metabolomics). The different factors that can cause the transition from persistence to pathogenicity in the Bm5-CrPV infection model are discussed.
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Affiliation(s)
- Luoluo Wang
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
| | - Kaat Cappelle
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
| | - Dulce Santos
- Molecular Developmental Physiology and Signal Transduction, KU Leuven, Leuven, Belgium.
| | - Jozef Vanden Broeck
- Molecular Developmental Physiology and Signal Transduction, KU Leuven, Leuven, Belgium.
| | - Guy Smagghe
- 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.
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Larem A, Ben Tiba S, Fritsch E, Undorf-Spahn K, Wennmann JT, Jehle JA. Effects of a Covert Infection with Phthorimaea operculella granulovirus in Insect Populations of Phthorimaea operculella. Viruses 2019; 11:E337. [PMID: 30970670 PMCID: PMC6520744 DOI: 10.3390/v11040337] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 03/27/2019] [Accepted: 04/04/2019] [Indexed: 01/27/2023] Open
Abstract
Virus infections of insects can easily stay undetected, neither showing typical signs of a disease, nor being lethal. Such a stable and most of the time covert infection with Phthorimaea operculella granulovirus (PhopGV) was detected in a Phthorimaea operculella laboratory colony, which originated from Italy (Phop-IT). This covert virus (named PhopGV-R) was isolated, purified and characterized at the genetic level by full genome sequencing. Furthermore, the insect colony Phop-IT was used to study the crowding effect, double infection with other PhopGV isolates (CR3 and GR1), and co-infection exclusion. An infection with a second homologous virus (PhopGV-CR3) activated the covert virus, while a co-infection with another virus isolate (PhopGV-GR1) led to its suppression. This study shows that stable virus infections can be common for insect populations and have an impact on population dynamics because they can suppress or enable co-infection with another virus isolate of the same species.
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Affiliation(s)
- Andreas Larem
- Institute for Biological Control, Federal Research Centre for Cultivated Plants, Julius Kühn Institute, Heinrichstraße 243, 64287 Darmstadt, Germany.
| | - Saoussen Ben Tiba
- Institute for Biological Control, Federal Research Centre for Cultivated Plants, Julius Kühn Institute, Heinrichstraße 243, 64287 Darmstadt, Germany.
| | - Eva Fritsch
- Institute for Biological Control, Federal Research Centre for Cultivated Plants, Julius Kühn Institute, Heinrichstraße 243, 64287 Darmstadt, Germany.
| | - Karin Undorf-Spahn
- Institute for Biological Control, Federal Research Centre for Cultivated Plants, Julius Kühn Institute, Heinrichstraße 243, 64287 Darmstadt, Germany.
| | - Jörg T Wennmann
- Institute for Biological Control, Federal Research Centre for Cultivated Plants, Julius Kühn Institute, Heinrichstraße 243, 64287 Darmstadt, Germany.
| | - Johannes A Jehle
- Institute for Biological Control, Federal Research Centre for Cultivated Plants, Julius Kühn Institute, Heinrichstraße 243, 64287 Darmstadt, Germany.
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Horta AB, Ardisson-Araujo DMP, da Silva LA, de Melo FL, da Silva Morgado F, Franco Lemos MV, Ribeiro ZA, Boiça AL, Wilcken CF, Ribeiro BM. Genomic analysis of a cypovirus isolated from the eucalyptus brown looper, Thyrinteina arnobia (Stoll, 1782) (Lepidoptera: Geometridae). Virus Res 2018; 253:62-67. [DOI: 10.1016/j.virusres.2018.05.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 05/24/2018] [Accepted: 05/30/2018] [Indexed: 11/26/2022]
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11
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Akhanaev YB, Belousova IA, Ershov NI, Nakai M, Martemyanov VV, Glupov VV. Comparison of tolerance to sunlight between spatially distant and genetically different strains of Lymantria dispar nucleopolyhedrovirus. PLoS One 2017; 12:e0189992. [PMID: 29261790 PMCID: PMC5738102 DOI: 10.1371/journal.pone.0189992] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 12/06/2017] [Indexed: 11/18/2022] Open
Abstract
Baculoviruses are a family of insect-specific pathogenic viruses can persist outside for long periods through the formation of occlusion bodies. In spite of this ability, the UV of sunlight is an essential factor that limits the survival of baculoviruses outside the host. In the current study, we compared the UV tolerance of two strains of Lymantria dispar multiple nucleopolyhedrovirus (LdMNPV), which were isolated in spatially different regions (LdMNPV-27/0 in Western Siberia (Russia) and LdMNPV-45/0 in North America (USA)) and dramatically differ in their potency. We exposed the studied strains to sunlight in an open area for 0.25, 0.5, 1, and 2 hours and later perorally inoculated host larvae with the same doses of virus (5x105) and with doses leading to same effect (LD90). We observed that strain LdMNPV-45/0, which previously showed high virulence against L. dispar larvae, was more sensitive to UV irradiation (estimated as the relative rate of inactivation (r, h -1) and as the half-life of the virus (τ1/2, h)) compared to LdMNPV-27/0. Exposure to sunlight induced a significant delay of LdMNPV-45/0-induced pathogenesis already after 0.25 h of sunlight exposure, while for LdMNPV-27/0 this delay was occurred only after 2 h exposure in spite of used concentrations. We also compared the sequences of the main structural proteins of the studied strains as UV light contributes not only to genome damage in viruses but also to structural protein damage. The most prominent genetic difference between the structural proteins of the strains was related to the loss of the virus enhancin factor-1 (vef-1) gene in the LdMNPV-27/0 strain. Thus initially highly potent viral strain (such as LdMNPV-45/0) is not recommend to use in the regions (or forest stand density) with high UV load. The role of virus enhancin factor-1 in baculovirus tolerance to UV needs for following studies.
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Affiliation(s)
- Yuriy B. Akhanaev
- Laboratory of Insect Pathology, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia
| | - Irina A. Belousova
- Laboratory of ecological parasitology, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia
- Institute of Biology, Irkutsk State University, Irkutsk, Russia
| | - Nikita I. Ershov
- Molecular Genetics Department, Institute of Cytology and Genetics SB RAS, Novosibirsk, Russia
| | - Madoka Nakai
- Institute of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, Japan
| | - Vyacheslav V. Martemyanov
- Laboratory of ecological parasitology, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia
- Biological Institute, National Research Tomsk State University, Tomsk, Russia
- * E-mail:
| | - Viktor V. Glupov
- Laboratory of Insect Pathology, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia
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Kasianov NS, Belousova IA, Pavlushin SV, Dubovskiy IM, Podgwaite JD, Martemyanov VV, Bakhvalov SA. The activity of phenoloxidase in haemolymph plasma is not a predictor of Lymantria dispar resistance to its baculovirus. PLoS One 2017; 12:e0183940. [PMID: 28854240 PMCID: PMC5576713 DOI: 10.1371/journal.pone.0183940] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 08/14/2017] [Indexed: 11/18/2022] Open
Abstract
Host innate immunity is one of the factors that determines the resistance of insects to their entomopathogens. In the research reported here we studied whether or not phenoloxidase (PO), a key enzyme in the melanogenesis component of humoral immunity of insects, plays a role in the protection of Lymantria dispar larvae from infection by L. dispar multiple nucleopolyhedrovirus. We studied two types of viral infection: overt and covert. The following lines of investigation were tested: i) the intravital individual estimation of baseline PO activity in haemolymph plasma followed by virus challenging; ii) the specific inhibition of PO activity in vivo by peroral treatment of infected larvae with phenylthiourea (PTU), a competitive inhibitor of PO; iii) the evaluation of PO activity in the haemolymph plasma after larval starvation. Starvation is a stress that activates the covert infection to an overt form. All of these experiments did not show a relationship between PO activity in haemolymph plasma of L. dispar larvae and larval susceptibility to baculovirus. Moreover, starvation-induced activation of covert viral infection to an overt form occurred in 70 percent of virus-carrying larvae against the background of a dramatic increase of PO activity in haemolymph plasma in the insects studied. Our conclusion is that in L. dispar larvae PO activity is not a predictor of host resistance to baculovirus.
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Affiliation(s)
- Nikita S. Kasianov
- Laboratory of ecological parasitology, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia
- Department of Natural science, Novosibirsk National Research State University, Novosibirsk, Russia
| | - Irina A. Belousova
- Laboratory of ecological parasitology, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia
- Institute of Biology, Irkutsk State University, Irkutsk, Russia
| | - Sergey V. Pavlushin
- Laboratory of ecological parasitology, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia
| | - Ivan M. Dubovskiy
- Laboratory of Insect Pathology, Institute of Systematics and Ecology of Animal SB RAS, Novosibirsk, Russia
- Novosibirsk State Agrarian University, Novosibirsk, Russia
| | - John D. Podgwaite
- Northern Research Station, USDA Forest Service, Hamden, CT, United States of America
| | - Vyacheslav V. Martemyanov
- Laboratory of ecological parasitology, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia
- Biological Institute, National Research Tomsk State University, Tomsk, Russia
| | - Stanislav A. Bakhvalov
- Laboratory of Insect Pathology, Institute of Systematics and Ecology of Animal SB RAS, Novosibirsk, Russia
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Williams T, Virto C, Murillo R, Caballero P. Covert Infection of Insects by Baculoviruses. Front Microbiol 2017; 8:1337. [PMID: 28769903 PMCID: PMC5511839 DOI: 10.3389/fmicb.2017.01337] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 07/03/2017] [Indexed: 12/19/2022] Open
Abstract
Baculoviruses (Baculoviridae) are occluded DNA viruses that are lethal pathogens of the larval stages of some lepidopterans, mosquitoes, and sawflies (phytophagous Hymenoptera). These viruses have been developed as biological insecticides for control of insect pests and as expression vectors in biotechnological applications. Natural and laboratory populations frequently harbor covert infections by baculoviruses, often at a prevalence exceeding 50%. Covert infection can comprise either non-productive latency or sublethal infection involving low level production of virus progeny. Latency in cell culture systems involves the expression of a small subset of viral genes. In contrast, covert infection in lepidopterans is associated with differential infection of cell types, modulation of virus gene expression and avoidance of immune system clearance. The molecular basis for covert infection may reside in the regulation of host-virus interactions through the action of microRNAs (miRNA). Initial findings suggest that insect nudiviruses and vertebrate herpesviruses may provide useful analogous models for exploring the mechanisms of covert infection by baculoviruses. These pathogens adopt mixed-mode transmission strategies that depend on the relative fitness gains that accrue through vertical and horizontal transmission. This facilitates virus persistence when opportunities for horizontal transmission are limited and ensures virus dispersal in migratory host species. However, when host survival is threatened by environmental or physiological stressors, latent or persistent infections can be activated to produce lethal disease, followed by horizontal transmission. Covert infection has also been implicated in population level effects on host-pathogen dynamics due to the reduced reproductive capacity of infected females. We conclude that covert infections provide many opportunities to examine the complexity of insect-virus pathosystems at the organismal level and to explore the evolutionary and ecological relationships of these pathogens with major crop and forest pests.
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Affiliation(s)
| | - Cristina Virto
- Bioinsecticidas Microbianos, Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas, Universidad Pública de NavarraMutilva, Spain
- Laboratorio de Entomología Agrícola y Patología de Insectos, Departamento de Producción Agraria, Universidad Pública de NavarraPamplona, Spain
| | - Rosa Murillo
- Bioinsecticidas Microbianos, Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas, Universidad Pública de NavarraMutilva, Spain
- Laboratorio de Entomología Agrícola y Patología de Insectos, Departamento de Producción Agraria, Universidad Pública de NavarraPamplona, Spain
| | - Primitivo Caballero
- Bioinsecticidas Microbianos, Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas, Universidad Pública de NavarraMutilva, Spain
- Laboratorio de Entomología Agrícola y Patología de Insectos, Departamento de Producción Agraria, Universidad Pública de NavarraPamplona, Spain
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14
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Maciel-Vergara G, Ros VID. Viruses of insects reared for food and feed. J Invertebr Pathol 2017; 147:60-75. [PMID: 28189501 DOI: 10.1016/j.jip.2017.01.013] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 01/26/2017] [Accepted: 01/31/2017] [Indexed: 02/07/2023]
Abstract
The use of insects as food for humans or as feed for animals is an alternative for the increasing high demand for meat and has various environmental and social advantages over the traditional intensive production of livestock. Mass rearing of insects, under insect farming conditions or even in industrial settings, can be the key for a change in the way natural resources are utilized in order to produce meat, animal protein and a list of other valuable animal products. However, because insect mass rearing technology is relatively new, little is known about the different factors that determine the quality and yield of the production process. Obtaining such knowledge is crucial for the success of insect-based product development. One of the issues that is likely to compromise the success of insect rearing is the outbreak of insect diseases. In particular, viral diseases can be devastating for the productivity and the quality of mass rearing systems. Prevention and management of viral diseases imply the understanding of the different factors that interact in insect mass rearing. This publication provides an overview of the known viruses in insects most commonly reared for food and feed. Nowadays with large-scale sequencing techniques, new viruses are rapidly being discovered. We discuss factors affecting the emergence of viruses in mass rearing systems, along with virus transmission routes. Finally we provide an overview of the wide range of measures available to prevent and manage virus outbreaks in mass rearing systems, ranging from simple sanitation methods to highly sophisticated methods including RNAi and transgenics.
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Affiliation(s)
- Gabriela Maciel-Vergara
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark.
| | - Vera I D Ros
- Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
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15
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Redman EM, Wilson K, Cory JS. Trade-offs and mixed infections in an obligate-killing insect pathogen. J Anim Ecol 2016; 85:1200-9. [PMID: 27155461 PMCID: PMC4988505 DOI: 10.1111/1365-2656.12547] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 04/24/2016] [Indexed: 02/01/2023]
Abstract
Natural populations of pathogens are frequently composed of numerous interacting strains. Understanding what maintains this diversity remains a key focus of research in disease ecology. In addition, within-host pathogen dynamics can have a strong impact on both infection outcome and the evolution of pathogen virulence, and thus, understanding the impact of pathogen diversity is important for disease management. We compared eight genetically distinguishable variants from Spodoptera exempta nucleopolyhedrovirus (SpexNPV) isolated from the African armyworm, Spodoptera exempta. NPVs are obligate killers, and the vast majority of transmission stages are not released until after the host has died. The NPV variants differed significantly in their virulence and could be clustered into two groups based on their dose-response curves. They also differed in their speed of kill and productivity (transmission potential) for S. exempta. The mixed-genotype wild-type (WT) SpexNPV, from which each variant was isolated, was significantly more virulent than any individual variant and its mean mortality rate was within the fastest group of individual variants. However, the WT virus produced fewer new infectious stages than any single variant, which might reflect competition among the variants. A survival analysis, combining the mortality and speed of kill data, confirmed the superiority of the genetically mixed WT virus over any single variant. Spodoptera exempta larvae infected with WT SpexNPV were predicted to die 2·7 and 1·9 times faster than insects infected with isolates from either of the two clusters of genotypes. Theory suggests that there are likely to be trade-offs between pathogen fitness traits. Across all larvae, there was a negative linear relationship between virus yield and speed of kill, such that more rapid host death carried the cost of producing fewer transmission stages. We also found a near-significant relationship for the same trend at the intervariant level. However, there was no evidence for a significant relationship between the induced level of mortality and transmission potential (virus yield) or speed of kill.
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Affiliation(s)
- Elizabeth M Redman
- Molecular Ecology and Biocontrol Group, NERC Centre for Ecology and Hydrology, Mansfield Road, Oxford, OX1 3SR, UK
| | - Kenneth Wilson
- Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK
| | - Jenny S Cory
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, V5A 1S6, BC, Canada
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16
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Martemyanov VV, Kabilov MR, Tupikin AE, Baturina OA, Belousova IA, Podgwaite JD, Ilynykh AV, Vlassov VV. The enhancin gene: One of the genetic determinants of population variation in baculoviral virulence. DOKL BIOCHEM BIOPHYS 2016; 465:351-3. [DOI: 10.1134/s1607672915060022] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Indexed: 11/22/2022]
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17
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Myers JH, Cory JS. Ecology and evolution of pathogens in natural populations of Lepidoptera. Evol Appl 2016; 9:231-47. [PMID: 27087850 PMCID: PMC4780379 DOI: 10.1111/eva.12328] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 08/19/2015] [Indexed: 01/25/2023] Open
Abstract
Pathogens are ubiquitous in insect populations and yet few studies examine their dynamics and impacts on host populations. We discuss four lepidopteran systems and explore their contributions to disease ecology and evolution. More specifically, we elucidate the role of pathogens in insect population dynamics. For three species, western tent caterpillars, African armyworm and introduced populations of gypsy moth, infection by nucleopolyhedrovirus (NPV) clearly regulates host populations or reduces their outbreaks. Transmission of NPV is largely horizontal although low levels of vertical transmission occur, and high levels of covert infection in some cases suggest that the virus can persist in a nonsymptomatic form. The prevalence of a mostly vertically transmitted protozoan parasite, Ophryocystis elektroscirrha, in monarch butterflies is intimately related to their migratory behaviour that culls highly infected individuals. Virulence and transmission are positively related among genotypes of this parasite. These systems clearly demonstrate that the interactions between insects and pathogens are highly context dependent. Not only is the outcome a consequence of changes in density and genetic diversity: environmental factors, particularly diet, can have strong impacts on virulence, transmission and host resistance or tolerance. What maintains the high level of host and pathogen diversity in these systems, however, remains a question.
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Affiliation(s)
- Judith H. Myers
- Department of ZoologyUniversity of British ColumbiaVancouverBCCanada
| | - Jenny S. Cory
- Department of Biological SciencesSimon Fraser UniversityBurnabyBCCanada
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18
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Fleming-Davies AE, Dwyer G. Phenotypic Variation in Overwinter Environmental Transmission of a Baculovirus and the Cost of Virulence. Am Nat 2015; 186:797-806. [PMID: 26655986 DOI: 10.1086/683798] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
A pathogen's ability to persist in the environment is an ecologically important trait, and variation in this trait may promote coexistence of different pathogen strains. We asked whether naturally occurring isolates of the baculovirus that infects gypsy moth larvae varied in their overwinter environmental transmission and whether this variation was consistent with a trade-off or an upper limit to virulence that might promote pathogen diversity. We used experimental manipulations to replicate the natural overwinter infection process, using 16 field-collected isolates. Virus isolates varied substantially in the fraction of larvae infected, leading to differences in overwinter transmission rates. Furthermore, isolates that killed more larvae also had higher rates of early larval death in which no infectious particles were produced, consistent with a cost of high virulence. Our results thus support the existence of a cost that could impose an upper limit to virulence even in a highly virulent pathogen.
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Graham RI, Tummala Y, Rhodes G, Cory JS, Shirras A, Grzywacz D, Wilson K. Development of a Real-Time qPCR Assay for Quantification of Covert Baculovirus Infections in a Major African Crop Pest. INSECTS 2015; 6:746-59. [PMID: 26463414 PMCID: PMC4598664 DOI: 10.3390/insects6030746] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 08/14/2015] [Accepted: 08/19/2015] [Indexed: 12/24/2022]
Abstract
Many pathogens and parasites are present in host individuals and populations without any obvious signs of disease. This is particularly true for baculoviruses infecting lepidopteran hosts, where studies have shown that covert persistent viral infections are almost ubiquitous in many species. To date, the infection intensity of covert viruses has rarely been quantified. In this study, we investigated the dynamics of a covert baculovirus infection within the lepidopteran crop pest Spodoptera exempta. A real-time quantitative polymerase chain reaction (qPCR) procedure using a 5' nuclease hydrolysis (TaqMan) probe was developed for specific detection and quantification of Spodoptera exempta nucleopolyhedrovirus (SpexNPV). The qPCR assay indicated that covert baculovirus dynamics varied considerably over the course of the host life-cycle, with infection load peaking in early larval instars and being lowest in adults and final-instar larvae. Adult dissections indicated that, contrary to expectation, viral load aggregation was highest in the head, wings and legs, and lowest in the thorax and abdomen. The data presented here have broad implications relating to our understanding of transmission patterns of baculoviruses and the role of covert infections in host-pathogen dynamics.
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Affiliation(s)
- Robert I Graham
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
| | - Yamini Tummala
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
| | - Glenn Rhodes
- Lake Ecosystems Group, Centre for Ecology and Hydrology, Bailrigg, Lancaster LA1 4AP, UK.
| | - Jenny S Cory
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
| | - Alan Shirras
- Biomedical and Life Sciences, Lancaster University, Lancaster LA1 4YQ, UK.
| | - David Grzywacz
- Natural Resources Institute, University of Greenwich, Chatham Maritime, Kent ME4 4TB, UK.
| | - Kenneth Wilson
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
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20
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Martemyanov VV, Pavlushin SV, Dubovskiy IM, Yushkova YV, Morosov SV, Chernyak EI, Efimov VM, Ruuhola T, Glupov VV. Asynchrony between Host Plant and Insects-Defoliator within a Tritrophic System: The Role of Herbivore Innate Immunity. PLoS One 2015; 10:e0130988. [PMID: 26115118 PMCID: PMC4482610 DOI: 10.1371/journal.pone.0130988] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 05/26/2015] [Indexed: 11/18/2022] Open
Abstract
The effects of asynchrony in the phenology of spring-feeding insect-defoliators and their host plants on insects’ fitness, as well as the importance of this effect for the population dynamics of outbreaking species of insects, is a widespread and well-documented phenomenon. However, the spreading of this phenomenon through the food chain, and especially those mechanisms operating this spreading, are still unclear. In this paper, we study the effect of seasonally declined leafquality (estimated in terms of phenolics and nitrogen content) on herbivore fitness, immune parameters and resistance against pathogen by using the silver birch Betula pendula—gypsy moth Lymantria dispar—nucleopolyhedrovirus as the tritrophic system. We show that a phenological mismatch induced by the delay in the emergence of gypsy moth larvae and following feeding on mature leaves has negative effects on the female pupal weight, on the rate of larval development and on the activity of phenoloxidase in the plasma of haemolymph. In addition, the larval susceptibility to exogenous nucleopolyhydrovirus infection as well as covert virus activation were both enhanced due to the phenological mismatch. The observed effects of phenological mismatch on insect-baculovirus interaction may partially explain the strong and fast fluctuations in the population dynamics of the gypsy moth that is often observed in the studied part of the defoliator area. This study also reveals some indirect mechanisms of effect related to host plant quality, which operate through the insect innate immune status and affect resistance to both exogenous and endogenous virus.
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Affiliation(s)
- Vyacheslav V. Martemyanov
- Laboratory of Insect Pathology, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia
- Biological Institute, National Research Tomsk State University, Tomsk, Russia
- * E-mail:
| | - Sergey V. Pavlushin
- Laboratory of Insect Pathology, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia
| | - Ivan M. Dubovskiy
- Laboratory of Insect Pathology, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia
| | - Yuliya V. Yushkova
- Laboratory of Ecological Research and Chromatographic Analysis, Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk, Russia
| | - Sergey V. Morosov
- Laboratory of Ecological Research and Chromatographic Analysis, Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk, Russia
| | - Elena I. Chernyak
- Laboratory of Ecological Research and Chromatographic Analysis, Novosibirsk Institute of Organic Chemistry SB RAS, Novosibirsk, Russia
| | - Vadim M. Efimov
- Laboratory of Molecular-Genetic Systems, Institute of Cytology and Genetics SB RAS, Novosibirsk, Russia
| | - Teija Ruuhola
- Department of Biology, University of Eastern Finland, Joensuu, Finland
| | - Victor V. Glupov
- Laboratory of Insect Pathology, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia
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21
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Is more better? Higher sterilization of infected hosts need not result in reduced pest population size. J Math Biol 2014; 70:1381-409. [PMID: 24929337 DOI: 10.1007/s00285-014-0800-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 05/22/2014] [Indexed: 10/25/2022]
Abstract
We analyze the effect of sterilization in the infected hosts in several epidemiological models involving infectious diseases that can be transmitted both vertically and horizontally. Sterilizing pathogens can be used as pest control agents by intentionally inoculating the target population, with the goal of reducing or eliminating it completely. Contrary to previous models that did not include vertical transmission we found that the population size at the endemic equilibrium may actually increase with higher levels of sterility. This effect is proved to exist for low to high efficiencies of vertical transmission. On the other hand, if the disease is sexually transmitted and the host reproduction and disease transmission are both consistently mediated by mating, we do not observe such a counter-intuitive effect and the population size in the stable endemic equilibrium is decreasing with higher levels of sterility. We suggest that models of the pest control techniques involving the release of sterilizing pathogens have to carefully consider the routes such pathogens use for transmission.
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22
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Virto C, Zárate CA, López-Ferber M, Murillo R, Caballero P, Williams T. Gender-mediated differences in vertical transmission of a nucleopolyhedrovirus. PLoS One 2013; 8:e70932. [PMID: 23940671 PMCID: PMC3733637 DOI: 10.1371/journal.pone.0070932] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Accepted: 06/25/2013] [Indexed: 11/24/2022] Open
Abstract
With the development of sensitive molecular techniques for detection of low levels of asymptomatic pathogens, it becoming clear that vertical transmission is a common feature of some insect pathogenic viruses, and likely to be essential to virus survival when opportunities for horizontal transmission are unfavorable. Vertical transmission of Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) is common in natural populations of S. exigua. To assess whether gender affected transgenerational virus transmission, four mating group treatments were performed using healthy and sublethally infected insects: i) healthy males (H♂)×healthy females (H♀); ii) infected males (I♂)×healthy females (H♀); iii) healthy males (H♂)×infected females (I♀) and iv) infected males (I♂)×infected females (I♀). Experimental adults and their offspring were analyzed by qPCR to determine the prevalence of infection. Both males and females were able to transmit the infection to the next generation, although female-mediated transmission resulted in a higher prevalence of infected offspring. Male-mediated venereal transmission was half as efficient as maternally-mediated transmission. Egg surface decontamination studies indicated that the main route of transmission is likely transovarial rather than transovum. Both male and female offspring were infected by their parents in similar proportions. Incorporating vertically-transmitted genotypes into virus-based insecticides could provide moderate levels of transgenerational pest control, thereby extending the periods between bioinsecticide applications.
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Affiliation(s)
- Cristina Virto
- Instituto de Agrobiotecnología, CSIC-Gobierno de Navarra, Mutilva Baja, Navarra, Spain
- Departamento de Producción Agraria, Universidad Pública de Navarra, Pamplona, Navarra, Spain
| | - Carlos A. Zárate
- Instituto de Agrobiotecnología, CSIC-Gobierno de Navarra, Mutilva Baja, Navarra, Spain
| | | | - Rosa Murillo
- Instituto de Agrobiotecnología, CSIC-Gobierno de Navarra, Mutilva Baja, Navarra, Spain
- Departamento de Producción Agraria, Universidad Pública de Navarra, Pamplona, Navarra, Spain
| | - Primitivo Caballero
- Instituto de Agrobiotecnología, CSIC-Gobierno de Navarra, Mutilva Baja, Navarra, Spain
- Departamento de Producción Agraria, Universidad Pública de Navarra, Pamplona, Navarra, Spain
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23
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Opoku-Debrah JK, Hill MP, Knox C, Moore SD. Overcrowding of false codling moth, Thaumatotibia leucotreta (Meyrick) leads to the isolation of five new Cryptophlebia leucotreta granulovirus (CrleGV-SA) isolates. J Invertebr Pathol 2013; 112:219-28. [DOI: 10.1016/j.jip.2012.12.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 12/15/2012] [Accepted: 12/17/2012] [Indexed: 10/27/2022]
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24
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Burke GR, Strand MR. Polydnaviruses of Parasitic Wasps: Domestication of Viruses To Act as Gene Delivery Vectors. INSECTS 2012; 3:91-119. [PMID: 26467950 PMCID: PMC4553618 DOI: 10.3390/insects3010091] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 01/07/2012] [Accepted: 01/16/2012] [Indexed: 12/21/2022]
Abstract
Symbiosis is a common phenomenon in which associated organisms can cooperate in ways that increase their ability to survive, reproduce, or utilize hostile environments. Here, we discuss polydnavirus symbionts of parasitic wasps. These viruses are novel in two ways: (1) they have become non-autonomous domesticated entities that cannot replicate outside of wasps; and (2) they function as a delivery vector of genes that ensure successful parasitism of host insects that wasps parasitize. In this review we discuss how these novelties may have arisen, which genes are potentially involved, and what the consequences have been for genome evolution.
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Affiliation(s)
- Gaelen R Burke
- Department of Entomology, The University of Georgia, 120 Cedar St., Athens, GA 30601, USA.
| | - Michael R Strand
- Department of Entomology, The University of Georgia, 120 Cedar St., Athens, GA 30601, USA.
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25
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Hajek AE, Tobin PC. Introduced pathogens follow the invasion front of a spreading alien host. J Anim Ecol 2011; 80:1217-26. [DOI: 10.1111/j.1365-2656.2011.01870.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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26
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Evidence for covert baculovirus infections in a Spodoptera exigua laboratory culture. J Gen Virol 2011; 92:1061-1070. [DOI: 10.1099/vir.0.028027-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A laboratory culture of Spodoptera exigua was examined to assess covert (latent or persistent) baculovirus infections and spontaneous disease outbreaks. Two nucleopolyhedrovirus (NPV) species were found to be reactivated from a covert state in a laboratory culture of S. exigua to fully lethal forms. These were identified as S. exigua multinucleopolyhedrovirus (SeMNPV) and Mamestra brassicae NPV (MbNPV) using restriction enzyme analysis of purified viral DNA. Sequence data derived from both overtly and covertly virus-infected insects revealed highly conserved sequences for lef-8, lef-9 and polyhedrin gene sequence (98–100 % nucleotide identity to SeMNPV published sequence). By monitoring spontaneous overt infections and quantifying viral DNA (by quantitative-PCR) in asymptomatic individuals over two generations we identified fluctuating trends in viral DNA levels from covert SeMNPV and MbNPV within an S. exigua host population. Virus levels per insect life stage ranged from 3.51±0.101×105 to 0.29±0.036 pg (detection limit at 0.06 pg). Bioassays performed with this culture of larvae showed a differential susceptibility to SeMNPV-like or MbNPV-like viruses, with SeMNPV superinfections being extremely virulent. The data presented has broad implications relating to our understanding of transmission patterns of baculovirus in the environment and the role of covert infections in host–pathogen interaction dynamics.
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27
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de Miranda JR, Genersch E. Deformed wing virus. J Invertebr Pathol 2009; 103 Suppl 1:S48-61. [PMID: 19909976 DOI: 10.1016/j.jip.2009.06.012] [Citation(s) in RCA: 309] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Accepted: 06/29/2009] [Indexed: 10/20/2022]
Abstract
Deformed wing virus (DWV; Iflaviridae) is one of many viruses infecting honeybees and one of the most heavily investigated due to its close association with honeybee colony collapse induced by Varroadestructor. In the absence of V.destructor DWV infection does not result in visible symptoms or any apparent negative impact on host fitness. However, for reasons that are still not fully understood, the transmission of DWV by V.destructor to the developing pupae causes clinical symptoms, including pupal death and adult bees emerging with deformed wings, a bloated, shortened abdomen and discolouration. These bees are not viable and die soon after emergence. In this review we will summarize the historical and recent data on DWV and its relatives, covering the genetics, pathobiology, and transmission of this important viral honeybee pathogen, and discuss these within the wider theoretical concepts relating to the genetic variability and population structure of RNA viruses, the evolution of virulence and the development of disease symptoms.
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Affiliation(s)
- Joachim R de Miranda
- Department of Ecology, Swedish University of Agricultural Sciences, 750-07 Uppsala, Sweden
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28
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29
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Cory JS, Myers JH. Within and between population variation in disease resistance in cyclic populations of western tent caterpillars: a test of the disease defence hypothesis. J Anim Ecol 2009; 78:646-55. [DOI: 10.1111/j.1365-2656.2008.01519.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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30
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Vilaplana L, Wilson K, Redman EM, Cory JS. Pathogen persistence in migratory insects: high levels of vertically-transmitted virus infection in field populations of the African armyworm. Evol Ecol 2009. [DOI: 10.1007/s10682-009-9296-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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31
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Vilaplana L, Redman EM, Wilson K, Cory JS. Density-related variation in vertical transmission of a virus in the African armyworm. Oecologia 2007; 155:237-46. [PMID: 18038154 DOI: 10.1007/s00442-007-0914-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Accepted: 10/29/2007] [Indexed: 11/24/2022]
Abstract
Larvae of the African armyworm, Spodoptera exempta, are darker and more resistant to baculovirus infection when reared in groups (gregarious form) compared to being reared singly (solitary form). Lepidoptera that survive virus challenge as larvae could potentially retain a sublethal virus infection which is then transmitted vertically to the next generation. Here we examine whether gregarious and solitary forms of the armyworm differ in the costs of surviving virus infection and in their capacity to transmit an active baculovirus infection to their offspring. Pupae of larvae reared gregariously that survived virus challenge weighed significantly less than uninfected individuals, but this was not so for those reared solitarily. This did not, however, translate into differences in fecundity, at least under laboratory conditions. As found in previous studies, pre-oviposition period was shorter for solitary than gregarious insects, and it was also shorter for females that had been challenged with virus as larvae. Both the prevalence of egg batches containing larvae that died from nucleopolyhedrovirus (NPV) infection and the proportion of infected larvae within each egg batch were significantly increased (approximately doubled) when parental moths were previously challenged with the virus during their larval state. This demonstrates that horizontal transmission in one generation can elevate vertical transmission to the next generation. Moreover, prevalence of overt infection in the offspring generation was two to three times greater when parental moths were reared solitarily as larvae than when reared gregariously. Disease prevalence and proportional infection were both independent of the sex of the infected parent and whether or not the egg batch was surface-sterilized to remove potential contaminants. This suggests that the eggs are infected internally (transovarial) rather than externally (transovum). These results help to shed light on the observed temporal pattern of virus epizootics in eastern Africa.
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Affiliation(s)
- Lluisa Vilaplana
- Molecular Ecology and Biocontrol Group, NERC Centre for Ecology and Hydrology, Mansfield Road, OX1 3SR Oxford, UK
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Yue C, Schröder M, Gisder S, Genersch E. Vertical-transmission routes for deformed wing virus of honeybees (Apis mellifera). J Gen Virol 2007; 88:2329-2336. [PMID: 17622639 DOI: 10.1099/vir.0.83101-0] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Deformed wing virus (DWV) is a viral pathogen of the European honeybee (Apis mellifera), associated with clinical symptoms and colony collapse when transmitted by the ectoparasitic mite Varroa destructor. In the absence of V. destructor, DWV infection does not result in visible symptoms, suggesting that mite-independent transmission results in covert infections. True covert infections are a known infection strategy for insect viruses, resulting in long-term persistence of the virus in the population. They are characterized by the absence of disease symptoms in the presence of the virus and by vertical transmission of the virus. To demonstrate vertical transmission and, hence, true covert infections for DWV, a detailed study was performed on the vertical-transmission routes of DWV. In total, 192 unfertilized eggs originating from eight virgin queens, and the same number of fertilized eggs from the same queens after artificial insemination with DWV-negative (three queens) or DWV-positive (five queens) semen, were analysed individually. The F0 queens and drones and F1 drones and workers were also analysed for viral RNA. By in situ hybridization, viral sequences were detected in the ovary of an F0 queen that had laid DWV-positive unfertilized eggs and was inseminated with DWV-positive semen. In conclusion, vertical transmission of DWV from queens and drones to drone and worker offspring through unfertilized and fertilized eggs, respectively, was demonstrated. Viral sequences in fertilized eggs can originate from the queen, as well as from drones via DWV-positive semen.
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Affiliation(s)
- Constanze Yue
- Institute for Bee Research, Friedrich-Engels-Str. 32, D-16540 Hohen Neuendorf, Germany
| | - Marion Schröder
- Institute for Bee Research, Friedrich-Engels-Str. 32, D-16540 Hohen Neuendorf, Germany
| | - Sebastian Gisder
- Institute for Bee Research, Friedrich-Engels-Str. 32, D-16540 Hohen Neuendorf, Germany
| | - Elke Genersch
- Institute for Bee Research, Friedrich-Engels-Str. 32, D-16540 Hohen Neuendorf, Germany
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Thorne CM, Otvos IS, Conder N, Levin DB. Development and evaluation of methods to detect nucleopolyhedroviruses in larvae of the Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough). Appl Environ Microbiol 2007; 73:1101-6. [PMID: 17189436 PMCID: PMC1828647 DOI: 10.1128/aem.01958-06] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Accepted: 12/11/2006] [Indexed: 11/20/2022] Open
Abstract
Various molecular methods are used to detect pathogenic microorganisms and viruses within their hosts, but these methods are rarely validated by direct comparison. Southern hybridization, enzyme-linked immunosorbent assay (ELISA), and a novel DNA extraction/PCR assay were used to detect Orgyia pseudotsugata multiple nucleopolyhedrovirus (OpMNPV) in Douglas-fir tussock moth larvae. PCR was more sensitive than Southern hybridization and ELISA at detecting semipurified virus. ELISA, however, was the most accurate method for detecting virus within larvae, given that Southern hybridization and PCR produced false-negative results (31% and 2.5%, respectively). ELISA may be preferable in some applications because virus infections can be quantified (r(2) = 0.995). These results may be applicable to both applied and academic research that seeks to accurately identify the incidence of viruses and microorganisms that regulate insect populations.
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Affiliation(s)
- Christine M Thorne
- Department of Biosystems Engineering, University of Manitoba, Winnipeg, Manitoba R3T 5V6, Canada
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Burden JP, Possee RD, Sait SM, King LA, Hails RS. Phenotypic and genotypic characterisation of persistent baculovirus infections in populations of the cabbage moth (Mamestra brassicae) within the British Isles. Arch Virol 2005; 151:635-49. [PMID: 16328143 DOI: 10.1007/s00705-005-0657-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2005] [Accepted: 10/09/2005] [Indexed: 11/29/2022]
Abstract
The genotypic relatedness of persistent baculovirus infections within UK populations of Mamestra brassicae was assessed by sequencing amplified regions from polyhedrin and ie1. Most populations harboured Mamestra brassicae (Mb) nucleopolyhedrosis virus (NPV) which showed very little genotypic variation between populations. However, one population harboured a virus that closely resembled a baculovirus found previously only in Pine Beauty Moth (Panolis flammea) populations in Scotland. Persistent baculoviruses that had emerged spontaneously as lethal, overt infections from two of the insect populations were compared with the type strain of MbNPV and a mixture of P. flammea (Pafl) NPV strains, isolated from a single host, by bioassay in virus-free Spodoptera exigua larvae. Reactivated baculoviruses were as pathogenic as the stock virus and showed phenotypic characteristics closest to the type strain they most resembled genetically. Sequence data from the insect host cytochrome oxidase genes were compared and showed a high degree of sequence conservation between populations and it was not possible to determine whether the persistent baculovirus infections had arisen on many occasions or whether they represented a single initial infection that had spread with the host. However, the presence of two distinct virus genotypes in separate M. brassicae populations suggests multiple colonisations of the host are a possibility.
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Affiliation(s)
- J P Burden
- NERC Centre for Ecology and Hydrology, Oxford, UK.
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Cossentine JE, Jensen LBM, Eastwell KC. Incidence and transmission of a granulovirus in a large codling moth [Cydia pomonella L. (Lepidoptera: Tortricidae)] rearing facility. J Invertebr Pathol 2005; 90:187-92. [PMID: 16303132 DOI: 10.1016/j.jip.2005.09.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2005] [Revised: 09/21/2005] [Accepted: 09/28/2005] [Indexed: 11/24/2022]
Abstract
Incidences of potential per os Cydia pomonella granulovirus (CpGV) transmission within a large codling moth colony were identified. CpGV was detected in the water which is used to wash egg sheets. When pre-neonates were extracted from eggs prior to emergence and tested for the presence of CpGV, 40% were found to carry amounts of CpGV detectable by a polymerase chain reaction (PCR) assay, suggesting possible transovarial transmission of the virus. Although symptoms typical of virus infection and larval death were found infrequently within communal rearing trays, the frequency with which CpGV DNA was detected by PCR assays increased from a mean of 31% of 10-day-old larvae to 94% of 25-day-old larvae. CpGV in codling moth cadavers remained virulent after being held at 60 degrees C for 3 days under conditions similar to the treatment of spent diet at the rearing facility before its disposal. PCR tests of surface samples taken from air filters and rearing rooms of the rearing facility were found to contain CpGV. Bioassays of surface samples from the diet trash bin and a filter through which outside air is passed before entering the rearing chambers resulted in significant codling moth neonate mortality. The virulence of CpGV in dust from the spent diet and the original inadvertent positioning of the diet trash bin directly below one of the air intake ducts are suggested as a possible additional source of CpGV contamination within the facility.
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Affiliation(s)
- J E Cossentine
- Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre, Summerland, BC, Canada V0H 1Z0.
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Szewczyk B, Hoyos-Carvajal L, Paluszek M, Skrzecz I, Lobo de Souza M. Baculoviruses-- re-emerging biopesticides. Biotechnol Adv 2005; 24:143-60. [PMID: 16257169 DOI: 10.1016/j.biotechadv.2005.09.001] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2005] [Revised: 08/19/2005] [Accepted: 09/09/2005] [Indexed: 11/28/2022]
Abstract
Biological control of agricultural pests has gained importance in recent years due to increased pressure to reduce the use of agrochemicals and their residues in the environment and food. Viruses of a few families are known to infect insects but only those belonging to the highly specialized family Baculoviridae have been used as biopesticides. They are safe to people and wildlife, their specificity is very narrow. Their application as bioinsecticides was limited until recently because of their slow killing action and technical difficulties for in vitro commercial production. Two approaches for the wider application of baculoviruses as biopesticides will be implemented in future. In countries where use of genetically modified organisms is restricted, the improvements will be mainly at the level of diagnostics, in vitro production and changes in biopesticide formulations. In the second approach, the killing activity of baculoviruses may be augmented by genetic modifications of the baculovirus genome with genes of another natural pathogen. It is expected that the baculoviruses improved by genetic modifications will be gradually introduced in countries which have fewer concerns towards genetically modified organisms.
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Affiliation(s)
- Boguslaw Szewczyk
- Department of Molecular Virology, Intercollegiate Faculty of Biotechnology of the University of Gdansk and Medical University of Gdansk, Kladki 24, 80-822 GDANSK, Poland.
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Zhou M, Sun X, Sun X, Vlak JM, Hu Z, van der Werf W. Horizontal and vertical transmission of wild-type and recombinant Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus. J Invertebr Pathol 2005; 89:165-75. [PMID: 15893760 DOI: 10.1016/j.jip.2005.03.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2004] [Revised: 02/28/2005] [Accepted: 03/25/2005] [Indexed: 10/25/2022]
Abstract
Transmission plays a central role in the ecology of baculoviruses and the population dynamics of their hosts. Here, we report on the horizontal and vertical transmission dynamics of wild-type Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus (HaSNPV-WT) and a genetically modified variant (HaSNPV-AaIT) with enhanced speed of action through the expression of an insect-selective scorpion toxin (AaIT). In caged field plots, horizontal transmission of both HaSNPV variants was greatest when inoculated 3rd instar larvae were used as infectors, transmission was intermediate with 2nd instar infectors and lowest with 1st instar infectors. Transmission was greater at a higher density of infectors (1 per plant) than at a lower density (1 per 4 plants); however, the transmission coefficient (number of new infections per initial infector) was lower at the higher density of infectors than at the lower density. HaSNPV-AaIT exhibited a significantly lower rate of transmission than HaSNPV-WT in the field cages. This was also the case in open field experiments. In the laboratory, the vertical transmission of HaSNPV-AaIT from infected females to offspring of 16.7+/-2.1% was significantly lower than that of HaSNPV-WT (30.9+/-2.9%). Likewise, in the field, vertical transmission of HaSNPV-AaIT (8.4+/-1.1%) was significantly lower than that of HaSNPV-WT (12.6+/-2.0%). The results indicate that the recombinant virus will be transmitted at lower rates in H. armigera populations than the wild-type virus. This may potentially affect negatively its long-term efficacy as compared to wild-type virus, but contributing positively to its biosafety.
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Affiliation(s)
- Mingzhe Zhou
- Joint-Laboratory of Invertebrate Virology, Key Laboratory of Molecular Virology and State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071 Hubei, China
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BONSALL MB, SAIT SM, HAILS RS. Invasion and dynamics of covert infection strategies in structured insect-pathogen populations. J Anim Ecol 2005. [DOI: 10.1111/j.1365-2656.2005.00945.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Martínez AM, Williams T, López-Ferber M, Caballero P. Optical brighteners do not influence covert baculovirus infection of Spodoptera frugiperda. Appl Environ Microbiol 2005; 71:1668-70. [PMID: 15746377 PMCID: PMC1065160 DOI: 10.1128/aem.71.3.1668-1670.2005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Covert infection with Spodoptera frugiperda multiple nucleopolyhedrovirus, detected by reverse transcription-PCR of virus gene transcripts (ie-0 and polh), was not significantly affected by the presence of an optical brightener (Tinopal UNPA-GX), indicating no change in virus virulence. Detection of the covert infection was dependent on insect life stage and the viral mRNA used for diagnosis.
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Affiliation(s)
- Ana-Mabel Martínez
- Departamento de Producción Agraria, Universidad Pública de Navarra, Pamplona, Spain
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42
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Ecology of Nuclear Polyhedrosis Virus in Western Siberian Populations of the Gypsy Moth (Lymantria dispar L.). RUSS J ECOL+ 2005. [DOI: 10.1007/s11184-005-0059-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Khurad AM, Mahulikar A, Rathod MK, Rai MM, Kanginakudru S, Nagaraju J. Vertical transmission of nucleopolyhedrovirus in the silkworm, Bombyx mori L. J Invertebr Pathol 2004; 87:8-15. [PMID: 15491594 DOI: 10.1016/j.jip.2004.05.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2003] [Accepted: 05/26/2004] [Indexed: 11/23/2022]
Abstract
Nucleopolyhedrovirus (NPV) was tested for vertical transmission in the silkworm, Bombyx mori. Fifth instar larvae were exposed to four different dosages of BmNPV (830, 1300, 1800, and 2000OBs/larva) and a dosage of about 2000OBs/larva was found suitable for obtaining infected adults. Histopathological studies revealed the infection in susceptible tissues and organs initially, and at later stages of infection cycles the spermatocytes and nurse cells in the young oocytes were infected in the larval rudiments of testis and ovary, respectively. The mating of infected females with uninfected males resulted in significant reduction in fecundity (P < 0.01) and hatching of eggs (P < 0.001) due to transovarial transmission of BmNPV. Mating tests of uninfected females and infected males also confirmed venereal transmission as there was a significant reduction in hatching of eggs (P < 0.01). Further, among the F1 hybrid offspring (infected female x uninfected male) that were infected transovarially, larval progeny died at first and second instar stages, whereas those infected venereally developed acute lethal infection late and died by the end of third and fourth instar stage. PCR amplification and sequencing of 473bp of immediate early-1 (ie-1) gene of BmNPV isolated from the viral-infected parent and the F1 offspring confirmed that the viral infection is vertically transmitted to the progeny.
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Affiliation(s)
- A M Khurad
- Department of Zoology, Nagpur University Campus, Nagpur-440 033, India.
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Graham RI, Tyne WI, Possee RD, Sait SM, Hails RS. Genetically variable nucleopolyhedroviruses isolated from spatially separate populations of the winter moth Operophtera brumata (Lepidoptera: Geometridae) in Orkney. J Invertebr Pathol 2004; 87:29-38. [PMID: 15491596 DOI: 10.1016/j.jip.2004.06.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2004] [Accepted: 06/12/2004] [Indexed: 10/26/2022]
Abstract
Here we report a lepidopteran system in which a pathogen is both abundant and genotypically variable. Geographically separate populations of winter moth (Operophtera brumata L.) were sampled in heather habitats on the Orkney Isles to investigate the prevalence of a pathogen, O. brumata Nucleopolyhedrovirus (OpbuNPV), within the natural system. Virus was recorded in 11 of the 13 winter moth populations sampled, with two populations suffering mortality due to virus at levels of 50%. The virus genome from 200 single insect isolations was investigated for variation using restriction endonuclease digests. Twenty-six variants of OpbuNPV were detected using SalI. The polyhedrin gene of the virus was partially sequenced, allowing the relationship between the 26 variants to be portrayed as a cladogram. The phylogenetic relationship between OpbuNPV and other known baculovirus polyhedrin gene sequences was also established. The discovery of virus at such high prevalence is discussed with reference to occurrence and genetic variation of pathogens in other lepidopteran host populations. This study shows encouraging results for further studies into the role of pathogens in the regulation of host insect populations.
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Affiliation(s)
- Robert I Graham
- NERC Centre for Ecology and Hydrology, Mansfield Rd, Oxford, OX1 3SR, UK
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Boots M, Greenman J, Ross D, Norman R, Hails R, Sait S. The population dynamical implications of covert infections in host-microparasite interactions. J Anim Ecol 2003. [DOI: 10.1046/j.1365-2656.2003.00777.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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47
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Cory JS, Myers JH. The Ecology and Evolution of Insect Baculoviruses. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2003. [DOI: 10.1146/annurev.ecolsys.34.011802.132402] [Citation(s) in RCA: 228] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Jenny S. Cory
- Molecular Ecology and Biocontrol Group, NERC Center for Ecology and Hydrology, Mansfield Road, Oxford, United Kingdom, OX1 3SR;
- Center for Biodiversity Research, Departments of Zoology and Agricultural Science, University of British Columbia, Vancouver, Canada, V6T 1Z4;
| | - Judith H. Myers
- Molecular Ecology and Biocontrol Group, NERC Center for Ecology and Hydrology, Mansfield Road, Oxford, United Kingdom, OX1 3SR;
- Center for Biodiversity Research, Departments of Zoology and Agricultural Science, University of British Columbia, Vancouver, Canada, V6T 1Z4;
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Burden JP, Nixon CP, Hodgkinson AE, Possee RD, Sait SM, King LA, Hails RS. Covert infections as a mechanism for long-term persistence of baculoviruses. Ecol Lett 2003. [DOI: 10.1046/j.1461-0248.2003.00459.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Cooper D, Cory JS, Myers JH. Hierarchical spatial structure of genetically variable nucleopolyhedroviruses infecting cyclic populations of western tent caterpillars. Mol Ecol 2003; 12:881-90. [PMID: 12753209 DOI: 10.1046/j.1365-294x.2003.01785.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The cyclic population dynamics of western tent caterpillars, Malacosoma californicum pluviale, are associated with epizootics of a nucleopolyhedrovirus, McplNPV. Given the dynamic fluctuations in host abundance and levels of viral infection, host resistance and virus virulence might be expected to change during different phases of the cycle. As a first step in determining if McplNPV virulence and population structure change with host density, we used restriction fragment length polymorphism (RFLP) analysis to examine the genetic diversity of McplNPV infecting western tent caterpillar populations at different spatial scales. Thirteen dominant genetic variants were identified in 39 virus isolates (individual larvae) collected from field populations during one year of low host density, and another distinct variant was discovered among nine additional isolates in two subsequent years of declining host density. The distribution of these genetic variants was not random and indicated that the McplNPV population was structured at several spatial levels. A high proportion of the variation could be explained by family grouping, which suggested that isolates collected within a family were more likely to be the same than isolates compared among populations. Additionally, virus variants from within populations (sites) were more likely to be the same than isolates collected from tent caterpillar populations on different islands. This may indicate that there is limited mixing of virus among tent caterpillar families and populations when host population density is low. Thus there is potential for the virus to become locally adapted to western tent caterpillar populations in different sites. However, no dominant genotype was observed at any site. Whether and how selection acts on the genetically diverse nucleopolyhedrovirus populations as host density changes will be investigated over the next cycle of tent caterpillar populations.
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Affiliation(s)
- Dawn Cooper
- Centre for Biodiversity Research, Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, B.C., Canada
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Burden JP, Griffiths CM, Cory JS, Smith P, Sait SM. Vertical transmission of sublethal granulovirus infection in the Indian meal moth, Plodia interpunctella. Mol Ecol 2002; 11:547-55. [PMID: 11918789 DOI: 10.1046/j.0962-1083.2001.01439.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Knowledge of the mechanisms of pathogen persistence in relation to fluctuations in host density is crucial to our understanding of disease dynamics. In the case of insect baculoviruses, which are typically transmitted horizontally via a lifestage that can persist outside the host, a key issue that remains to be elucidated is whether the virus can also be transmitted vertically as a sublethal infection. We show that RNA transcripts for the Plodia interpunctella GV granulin gene are present in a high proportion of P. interpunctella insects that survive virus challenge. Granulin is a late-expressed gene that is only transcribed after viral genome replication, its presence thus strongly indicates that viral genome replication has occurred. Almost all insects surviving the virus challenge tested positive for viral RNA in the larval and pupal stage. However, this proportion declined in the emerging adults. Granulin mRNA was also detected in both the ovaries and testes, which may represent a putative mechanism by which reduced fecundity in sublethally affected hosts might be manifested. RNA transcripts were also detected in 60-80% of second-generation larvae that were derived from mating surviving adults, but there was no difference between the sexes, with both males and females capable of transmitting a sublethal infection to their offspring. The data indicate that low-level persistent infection, with at least limited gene expression, can occur in P. interpunctella following survival of a granulovirus challenge. We believe that this is the first demonstration of a persistent, sublethal infection by a baculovirus to be initiated by a sublethal virus dose. We hypothesize that the 'latent' baculovirus infections frequently referred to in the literature may also be low level persistent, sublethal infections resulting from survival from initial baculovirus exposure.
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Affiliation(s)
- J P Burden
- NERC Centre for Ecology and Hydrology - Oxford, Mansfield Road, Oxford OX1 3SR, UK
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