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Cox N, De Swaef E, Corteel M, Van Den Broeck W, Bossier P, Nauwynck HJ, Dantas-Lima JJ. Experimental Infection Models and Their Usefulness for White Spot Syndrome Virus (WSSV) Research in Shrimp. Viruses 2024; 16:813. [PMID: 38793694 PMCID: PMC11125927 DOI: 10.3390/v16050813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 05/14/2024] [Accepted: 05/17/2024] [Indexed: 05/26/2024] Open
Abstract
White spot syndrome virus (WSSV) is marked as one of the most economically devastating pathogens in shrimp aquaculture worldwide. Infection of cultured shrimp can lead to mass mortality (up to 100%). Although progress has been made, our understanding of WSSV's infection process and the virus-host-environment interaction is far from complete. This in turn hinders the development of effective mitigation strategies against WSSV. Infection models occupy a crucial first step in the research flow that tries to elucidate the infectious disease process to develop new antiviral treatments. Moreover, since the establishment of continuous shrimp cell lines is a work in progress, the development and use of standardized in vivo infection models that reflect the host-pathogen interaction in shrimp is a necessity. This review critically examines key aspects of in vivo WSSV infection model development that are often overlooked, such as standardization, (post)larval quality, inoculum type and choice of inoculation procedure, housing conditions, and shrimp welfare considerations. Furthermore, the usefulness of experimental infection models for different lines of WSSV research will be discussed with the aim to aid researchers when choosing a suitable model for their research needs.
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Affiliation(s)
- Natasja Cox
- IMAQUA, 9080 Lochristi, Belgium; (E.D.S.); (M.C.); (J.J.D.-L.)
- Laboratory of Virology, Department of Translational Physiology, Infectiology and Public Health, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium;
| | | | - Mathias Corteel
- IMAQUA, 9080 Lochristi, Belgium; (E.D.S.); (M.C.); (J.J.D.-L.)
| | - Wim Van Den Broeck
- Department of Morphology, Medical Imaging, Orthopedics, Physiotherapy and Nutrition, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium;
| | - Peter Bossier
- Laboratory of Aquaculture & Artemia Reference Center, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, 9000 Ghent, Belgium;
| | - Hans J. Nauwynck
- Laboratory of Virology, Department of Translational Physiology, Infectiology and Public Health, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium;
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Cox N, De Swaef E, Corteel M, Van Den Broeck W, Bossier P, Dantas-Lima JJ, Nauwynck HJ. The Way of Water: Unravelling White Spot Syndrome Virus (WSSV) Transmission Dynamics in Litopenaeus vannamei Shrimp. Viruses 2023; 15:1824. [PMID: 37766231 PMCID: PMC10534367 DOI: 10.3390/v15091824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 08/23/2023] [Accepted: 08/27/2023] [Indexed: 09/29/2023] Open
Abstract
White spot disease (WSD) is a severe viral threat to the global shrimp aquaculture industry. However, little is known about white spot syndrome virus (WSSV) transmission dynamics. Our aim was to elucidate this in Litopenaeus vannamei using peroral in vivo WSSV challenge experiments. We demonstrated that WSD progression was rapid and irreversible, leading to death within 78 h. Viral DNA shedding was detected within 6 h of disease onset. This shedding intensified over time, reaching a peak within 12 h of the time of death. Isolating shrimp (clinically healthy and diseased) from infected populations at different time points post-inoculation showed that host-to-host WSSV transmission was occurring around the time of death. Exposing sentinels to environmental components (i.e., water, feces, molts) collected from tanks housing WSSV-infected shrimp resulted in a significantly (p-value < 0.05) increased infection risk after exposure to water (1.0) compared to the risk of infection after exposure to feces (0.2) or molts (0.0). Furthermore, ingestion of WSSV-infected tissues (cannibalism) did not cause a significantly higher number of WSD cases compared to immersion in water in which the same degree of cannibalism had taken place.
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Affiliation(s)
- Natasja Cox
- IMAQUA, 9080 Lochristi, Belgium; (E.D.S.); (M.C.); (J.J.D.-L.)
- Laboratory of Virology, Department of Translational Physiology, Infectiology and Public Health, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium;
| | | | - Mathias Corteel
- IMAQUA, 9080 Lochristi, Belgium; (E.D.S.); (M.C.); (J.J.D.-L.)
| | - Wim Van Den Broeck
- Department of Morphology, Medical Imaging, Orthopedics, Physiotherapy and Nutrition, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium;
| | - Peter Bossier
- Laboratory of Aquaculture & Artemia Reference Center, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, 9000 Ghent, Belgium;
| | | | - Hans J. Nauwynck
- Laboratory of Virology, Department of Translational Physiology, Infectiology and Public Health, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium;
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3
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Wssv susceptibility in the early life stages of penaeus vannamei shows relationship with bodyweight. J Invertebr Pathol 2023; 198:107912. [PMID: 36924987 DOI: 10.1016/j.jip.2023.107912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 03/03/2023] [Accepted: 03/09/2023] [Indexed: 03/16/2023]
Abstract
White Spot Syndrome Virus (WSSV) continues to cause considerable loss to shrimp farmers globally with frequent outbreaks even in specific pathogen free Peneaus vannamei. Our studies showed that the bodyweight (BW) of PL has a bearing on their susceptibility to the virus. To test this hypothesis, PL of the same age group and family were grouped according to BW (10-20, 30-40, and 50-60 mg) and challenged through immersion route with two viral doses (106 and 107 virus copies/L of water). It was observed that the PL became susceptible to WSSV at ≥50 mg BW. In the 50-60 mg PL group, the higher challenge dose shows a sharp mortality curve with 100% mortality at 10 days post immersion, while the lower dose shows a steady increase in cumulative mortality that reaches 100% on the 13th day post immersion. The study also brings out that an in vivo viral load of approximately 3.5 to 4.5×107WSSV copies/100 ng shrimp DNA results in mortality. This is the first report on the relationship between BW and WSSV susceptibility in shrimp PL. Also reported here is a quantitative assessment of WSSV infection in P. vannamei PL and an optimized challenge protocol.
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Parrilla-Taylor DP, Vibanco-Pérez N, Durán-Avelar MDJ, Gomez-Gil B, Llera-Herrera R, Vázquez-Juárez R. Molecular variability and genetic structure of white spot syndrome virus strains from northwest Mexico based on the analysis of genomes. FEMS Microbiol Lett 2019; 365:5090402. [PMID: 30184198 DOI: 10.1093/femsle/fny216] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 09/02/2018] [Indexed: 12/14/2022] Open
Abstract
White spot syndrome virus (WSSV) has a ∼300 kb double-stranded DNA genome. It originated in China, spread rapidly through shrimp farms in Asia, and subsequently to America. This study determined complete genome sequences for nine historic WSSV strains isolated from Pacific white shrimp (Litopenaeus vannamei) captured in farm ponds in northwest Mexico (Sinaloa and Nayarit). Genomic DNA was captured by an amplification method using overlapping long-range PCR and sequencing by Ion Torrent-PGM. Complete genome sequences were assembled (length range 255-290 kb) and comparative genome analysis with WSSV strains revealed substantial deletions (3 and 10 kb in two regions) in seven strains, with two strains differing from the rest. Phylogenetic analysis identified that the WSSV strains from the northern area of the state of Sinaloa clustered with strains from China (LC1, LC10, DVI) and Korea (ACF2, ACF4), while those from the southern region of the state of Nayarit (AC1 and JP) differed from both of those and from strains found in Taiwan and Thailand. Our data offer insights into the diversity of the WSSV genome in one country and their divergent origin, suggest that it entered Mexico via multiple routes and that specific genome regions can accommodate substantial deletions without compromising viability.
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Affiliation(s)
- Delia Patricia Parrilla-Taylor
- Centro de Investigaciones Biológicas del Noroeste, Av. Instituto Politécnico Nacional 195, Col. Playa Palo de Santa Rita Sur, La Paz, B.C.S. 23096. México
| | - Norberto Vibanco-Pérez
- Universidad Autónoma de Nayarit. Unidad Académica de Ciencias Químico Biológicas y Farmacéuticas, Tepic, Nayarit. 63000. México
| | - Maria de Jesús Durán-Avelar
- Universidad Autónoma de Nayarit. Unidad Académica de Ciencias Químico Biológicas y Farmacéuticas, Tepic, Nayarit. 63000. México
| | - Bruno Gomez-Gil
- CIAD, A.C. Mazatlán Unit for Aquaculture, Sinaloa. 82000. México
| | - Raúl Llera-Herrera
- Instituto de Ciencias del Mar y Limnología - Unidad Académica Mazatlán, Universidad Nacional Autónoma de México. Joel Montes Camarena s/n, P.O.Box 811. Mazatlán, Sinaloa, Mexico. 82000
| | - Ricardo Vázquez-Juárez
- Centro de Investigaciones Biológicas del Noroeste, Av. Instituto Politécnico Nacional 195, Col. Playa Palo de Santa Rita Sur, La Paz, B.C.S. 23096. México
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Pereira JMP, de Souza ENV, Candido JRB, Dantas MDA, Nunes ARD, Ribeiro K, Teixeira DIA, Lanza DCF. Alternative PCR primers for genotyping of Brazilian WSSV isolates. J Invertebr Pathol 2019; 162:55-63. [PMID: 30738030 DOI: 10.1016/j.jip.2019.02.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 02/04/2019] [Accepted: 02/06/2019] [Indexed: 10/27/2022]
Abstract
White spot syndrome virus (WSSV) is one of the major challenges faced by global shrimp farming in recent decades. The characterization of WSSV genetic variability has been used to determine viral dispersion and is a promising method to determine the association between genotype and virulence. The major variable regions that have been used as markers to differentiate the WSSV genomes include the VNTR loci inside ORF94, ORF75, ORF125, and insertions/deletions interspersing ORF14/15 and ORF23/24. The primers used to amplify these regions were described at least 10 years ago, but some of them do not work efficiently to identify new WSSV variants. The objective of this work was to develop improved PCR primers for WSSV genotyping based on sequence alignments that include new sequences described in recent years. We validated these new primers in a pilot study to verify the genetic variability of the WSSV in Rio Grande do Norte state (northeast Brazil), and efficiency was compared to that of other previously described primers. We confirmed that the primers we developed were more efficient for genotype Brazilian WSSV isolates, enabling us to genotype a larger number of samples. In addition, our results also introduce new data about the genetic characterization of the WSSV isolates that occur in the northeastern region of Brazil.
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Affiliation(s)
- Jéssica M P Pereira
- Laboratório de Biologia Molecular Aplicada - LAPLIC, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil; Programa de Pós-Graduação em Bioquímica, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil
| | - Emília N V de Souza
- Laboratório de Biologia Molecular Aplicada - LAPLIC, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil; Escola Agrícola de Jundiaí, Universidade Federal do Rio Grande do Norte, Macaíba, RN, Brazil
| | - Jéssica R B Candido
- Laboratório de Biologia Molecular Aplicada - LAPLIC, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil; Escola Agrícola de Jundiaí, Universidade Federal do Rio Grande do Norte, Macaíba, RN, Brazil
| | - Márcia D A Dantas
- Laboratório de Biologia Molecular Aplicada - LAPLIC, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil; Programa de Pós-Graduação em Bioquímica, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil
| | - Allan R D Nunes
- Laboratório de Biologia Molecular Aplicada - LAPLIC, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil; Programa de Pós-Graduação em Bioquímica, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil
| | - Karina Ribeiro
- Escola Agrícola de Jundiaí, Universidade Federal do Rio Grande do Norte, Macaíba, RN, Brazil
| | - Dárlio I A Teixeira
- Escola Agrícola de Jundiaí, Universidade Federal do Rio Grande do Norte, Macaíba, RN, Brazil
| | - Daniel C F Lanza
- Laboratório de Biologia Molecular Aplicada - LAPLIC, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil; Programa de Pós-Graduação em Bioquímica, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil.
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Ngo TTN, Senior AM, Culina A, Santos ESA, Vlak JM, Zwart MP. Quantitative analysis of the dose-response of white spot syndrome virus in shrimp. JOURNAL OF FISH DISEASES 2018; 41:1733-1744. [PMID: 30117593 DOI: 10.1111/jfd.12877] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 07/11/2018] [Accepted: 07/12/2018] [Indexed: 06/08/2023]
Abstract
White spot syndrome virus (WSSV) is an important cause of mortality and economic losses in shrimp farming. Although WSSV-induced mortality is virus dose dependent and WSSV infection does not necessarily lead to mortality, the relationships between virus-particle dose, infection and mortality have not been analysed quantitatively. Here, we explored WSSV dose-response by a combination of experiments, modelling and meta-analysis. We performed dose-response experiments in Penaeus vannamei postlarvae, recorded host mortality and detected WSSV infection. When we fitted infection models to these data, two models-differing in whether they incorporated heterogeneous host susceptibility to the virus or not-were supported for two independent experiments. To determine the generality of these results, we reanalysed published data sets and then performed a meta-analysis. We found that WSSV dose-response kinetics is indeed variable over experiments. We could not clearly identify which specific infection model has the most support by meta-analysis, but we argue that these results also are most concordant with a model incorporating varying levels of heterogeneous host susceptibility to WSSV. We have identified suitable models for analysing WSSV dose-response, which can elucidate the most basic virus-host interactions and help to avoid underestimating WSSV infection at low virus doses.
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Affiliation(s)
- Thuy T N Ngo
- Quantitative Veterinary Epidemiology Group, Wageningen University and Research, Wageningen, The Netherlands
- Laboratory of Virology, Wageningen University, Wageningen, The Netherlands
- Research Institute for Aquaculture No. 2, The Ministry of Agriculture and Rural Development, Ho Chi Minh City, Vietnam
| | - Alistair M Senior
- Charles Perkins Centre, and School of Mathematics and Statistics, University of Sydney, Sydney, New South Wales, Australia
| | - Antica Culina
- Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | - Eduardo S A Santos
- BECO do Departamento de Zoologia, Universidade de São Paulo, São Paulo, Brazil
| | - Just M Vlak
- Laboratory of Virology, Wageningen University, Wageningen, The Netherlands
| | - Mark P Zwart
- Quantitative Veterinary Epidemiology Group, Wageningen University and Research, Wageningen, The Netherlands
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-UPV, València, Spain
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
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Sivakumar S, Vimal S, Abdul Majeed S, Santhosh Kumar S, Taju G, Madan N, Rajkumar T, Thamizhvanan S, Shamsudheen KV, Scaria V, Sivasubbu S, Sahul Hameed AS. A new strain of white spot syndrome virus affecting Litopenaeus vannamei in Indian shrimp farms. JOURNAL OF FISH DISEASES 2018; 41:1129-1146. [PMID: 29745450 DOI: 10.1111/jfd.12811] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 03/01/2018] [Indexed: 06/08/2023]
Abstract
White spot syndrome virus (WSSV)-infected shrimp samples collected from grow-out ponds located at Nellore, Andhra Pradesh, India, showed WSSV negative and positive by PCR using primer sets specific to ORF119 and VP28 gene of WSSV, respectively. This indicated the deletion of genetic fragments in the genome of WSSV. The WSSV isolate along with lab strain of WSSV was subjected to next-generation sequencing. The sequence analysis revealed a deletion of 13,170 bp at five positions in the genome of WSSV-NS (new strain) relative to WSSV-TH and WSSV-LS (lab strain). The PCR analysis using the ORF's specific primer sets revealed the complete deletion of 10 ORFs in the genome of WSSV-NS strain. The primer set was designed based on sequence covering ORF161/162/163 to amplify a product of 2,748 bp for WSSV-LS and 402 bp for WSSV-NS. Our surveillance programme carried out since 2002 revealed the replacement of WSSV-LS by WSSV-NS in Indian shrimp culture system.
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Affiliation(s)
- S Sivakumar
- OIE Reference Laboratory for WTD, C. Abdul Hakeem College, Melvisharam, India
| | - S Vimal
- OIE Reference Laboratory for WTD, C. Abdul Hakeem College, Melvisharam, India
| | - S Abdul Majeed
- OIE Reference Laboratory for WTD, C. Abdul Hakeem College, Melvisharam, India
| | - S Santhosh Kumar
- OIE Reference Laboratory for WTD, C. Abdul Hakeem College, Melvisharam, India
| | - G Taju
- OIE Reference Laboratory for WTD, C. Abdul Hakeem College, Melvisharam, India
| | - N Madan
- OIE Reference Laboratory for WTD, C. Abdul Hakeem College, Melvisharam, India
| | - T Rajkumar
- OIE Reference Laboratory for WTD, C. Abdul Hakeem College, Melvisharam, India
| | - S Thamizhvanan
- OIE Reference Laboratory for WTD, C. Abdul Hakeem College, Melvisharam, India
| | - K V Shamsudheen
- CSIR-Institute of Genomics and Integrative Biology, Delhi, India
- Academy of Scientific and Innovative Research, Delhi, India
| | - V Scaria
- CSIR-Institute of Genomics and Integrative Biology, Delhi, India
- Academy of Scientific and Innovative Research, Delhi, India
| | - S Sivasubbu
- CSIR-Institute of Genomics and Integrative Biology, Delhi, India
- Academy of Scientific and Innovative Research, Delhi, India
| | - A S Sahul Hameed
- OIE Reference Laboratory for WTD, C. Abdul Hakeem College, Melvisharam, India
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Direct sequencing of the white spot syndrome virus from Brazil: Genome assembly and new insights on phylogeny. Virus Res 2018; 245:52-61. [DOI: 10.1016/j.virusres.2017.12.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 12/04/2017] [Accepted: 12/11/2017] [Indexed: 11/19/2022]
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Ramos-Paredes J, Grijalva-Chon JM, Ibarra-Gámez JC. Virulence and genotypes of white spot syndrome virus infecting Pacific white shrimp Litopenaeus vannamei in north-western Mexico. JOURNAL OF FISH DISEASES 2017; 40:425-435. [PMID: 28105747 DOI: 10.1111/jfd.12598] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 11/15/2016] [Accepted: 11/16/2016] [Indexed: 06/06/2023]
Abstract
White spot syndrome virus (WSSV) has caused substantial global economic impact on aquaculture, and it has been determined that strains can vary in virulence. In this study, the effect of viral load was evaluated by infecting Litopenaeus vannamei with 10-fold serial dilution of tissue infected with strain WSSV Mx-H, and the virulence of four WSSV strains from north-western Mexico was assessed along with their variable number of tandem repeat (VNTR) genotypes in ORF75, ORF94 and ORF125. The LD50 of the Mx-H strain was a dilution dose of 10-7.5 ; the mortality titre was 109.2 LD50 per gram. In shrimp injected with 102.5 to 106.5 LD50 , no significant virulence differences were evident. Using mortality data, the four WSSV strains grouped into three virulence levels. The Mx-F strain (intermediate virulence) and the Mx-C strain (high virulence) showed more genetic differences than those observed between the Mx-G (low-virulence) and Mx-H (high-virulence) strains, in ORF94 and ORF125. The application of high-viral-load inocula proved useful in determining the different virulence phenotypes of the WSSV strains from the Eastern Pacific.
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Affiliation(s)
- J Ramos-Paredes
- Laboratorio de Análisis de Sanidad Acuícola, Departamento de Ciencias Agronómicas y Veterinarias, Instituto Tecnológico de Sonora, Ciudad Obregón, Sonora, México
| | - J M Grijalva-Chon
- Laboratorio de Ecología Molecular, Departamento de Investigaciones Científicas y Tecnológicas, Universidad de Sonora, Hermosillo, Sonora, México
| | - J C Ibarra-Gámez
- Laboratorio de Análisis de Sanidad Acuícola, Departamento de Ciencias Agronómicas y Veterinarias, Instituto Tecnológico de Sonora, Ciudad Obregón, Sonora, México
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Li F, Gao M, Xu L, Yang F. Comparative genomic analysis of three white spot syndrome virus isolates of different virulence. Virus Genes 2016; 53:249-258. [DOI: 10.1007/s11262-016-1421-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 12/08/2016] [Indexed: 10/20/2022]
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Liu F, Wu X, Li L, Zou Y, Liu S, Wang Z. Evolutionary characteristics of morbilliviruses during serial passages in vitro: Gradual attenuation of virus virulence. Comp Immunol Microbiol Infect Dis 2016; 47:7-18. [DOI: 10.1016/j.cimid.2016.05.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 05/22/2016] [Accepted: 05/24/2016] [Indexed: 02/05/2023]
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Pace BT, Hawke JP, Subramanian R, Green CC. Experimental inoculation of Louisiana red swamp crayfish Procambarus clarkii with white spot syndrome virus (WSSV). DISEASES OF AQUATIC ORGANISMS 2016; 120:143-150. [PMID: 27409237 DOI: 10.3354/dao03018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The red swamp crayfish Procambarus clarkii represents an important aquaculture species responsible for over half of all commercial aquaculture profits in Louisiana, USA. White spot syndrome virus (WSSV) is highly pathogenic in crustacean species and induces mass mortality in aquaculture operations worldwide. Natural outbreaks of WSSV occur yearly in cultured populations of crayfish in Louisiana. The goal of this study was to better understand the infectivity of WSSV in P. clarkii, by determining the minimum lethal dose necessary to initiate infection and to measure the resulting cumulative mortality following infection with different doses. A real time quantitative PCR (qPCR) method was used to detect WSSV in DNA extracted from gill tissue to ensure P. clarkii study populations were WSSV-free before the start of trials. Viable viral particles were isolated from naturally infected P. clarkii gill tissue and quantified using a novel digital PCR approach. Three infectivity trials were performed, and WSSV inocula were created by serial dilution, generating 5 treatments per trial. Five crayfish (weighing ~25 g) per dilution per trial received viral inoculations. Mortality was monitored daily for the duration of the trial in order to construct a median lethal dose (LD50) curve, and probit regression analysis was used to determine LD50 concentrations of viral particles. Knowledge of the infectivity of WSSV in native crayfish populations is of critical importance to the management of the commercial crayfish aquaculture industry in Louisiana. This is the first study to investigate the infectivity and to determine the LD50 of the Louisiana strain of WSSV in native crayfish.
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Affiliation(s)
- Barcley T Pace
- Louisiana State University Agricultural Center, Aquaculture Research Station, Baton Rouge, Louisiana 70820, USA
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Thammasorn T, Sangsuriya P, Meemetta W, Senapin S, Jitrakorn S, Rattanarojpong T, Saksmerprome V. Large-scale production and antiviral efficacy of multi-target double-stranded RNA for the prevention of white spot syndrome virus (WSSV) in shrimp. BMC Biotechnol 2015; 15:110. [PMID: 26626024 PMCID: PMC4667486 DOI: 10.1186/s12896-015-0226-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 11/27/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND RNA interference (RNAi) is a specific and effective approach for inhibiting viral replication by introducing double-stranded (ds)RNA targeting the viral gene. In this study, we employed a combinatorial approach to interfere multiple gene functions of white spot syndrome virus (WSSV), the most lethal shrimp virus, using a single-batch of dsRNA, so-called "multi-WSSV dsRNA." A co-cultivation of RNase-deficient E. coli was developed to produce dsRNA targeting a major structural protein (VP28) and a hub protein (WSSV051) with high number of interacting protein partners. RESULTS For a co-cultivation of transformed E. coli, use of Terrific broth (TB) medium was shown to improve the growth of the E. coli and multi-WSSV dsRNA yields as compared to the use of Luria Bertani (LB) broth. Co-culture expression was conducted under glycerol feeding fed-batch fermentation. Estimated yield of multi-WSSV dsRNA (μg/mL culture) from the fed-batch process was 30 times higher than that obtained under a lab-scale culture with LB broth. Oral delivery of the resulting multi-WSSV dsRNA reduced % cumulative mortality and delayed average time to death compared to the non-treated group after WSSV challenge. CONCLUSION The present study suggests a co-cultivation technique for production of antiviral dsRNA with multiple viral targets. The optimal multi-WSSV dsRNA production was achieved by the use of glycerol feeding fed-batch cultivation with controlled pH and dissolved oxygen. The cultivation technique developed herein should be feasible for industrial-scale RNAi applications in shrimp aquaculture. Interference of multiple viral protein functions by a single-batch dsRNA should also be an ideal approach for RNAi-mediated fighting against viruses, especially the large and complicated WSSV.
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Affiliation(s)
- Thitiporn Thammasorn
- Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.
| | - Pakkakul Sangsuriya
- Department of Biochemistry, Center of Excellence for Molecular Biology and Genomics of Shrimp, Faculty of Science, Chulalongkorn University, Bangkok, Thailand. .,National Center of Genetic Engineering and Biotechnology, (BIOTEC), Thailand Science Park, Pathum Thani, 12120, Thailand.
| | - Watcharachai Meemetta
- Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.
| | - Saengchan Senapin
- Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand. .,National Center of Genetic Engineering and Biotechnology, (BIOTEC), Thailand Science Park, Pathum Thani, 12120, Thailand.
| | - Sarocha Jitrakorn
- Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand. .,National Center of Genetic Engineering and Biotechnology, (BIOTEC), Thailand Science Park, Pathum Thani, 12120, Thailand.
| | - Triwit Rattanarojpong
- Department of Microbiology, Faculty of Science, King Mongkut's University of Technology Thonburi, Bangkok, 10140, Thailand.
| | - Vanvimon Saksmerprome
- Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand. .,National Center of Genetic Engineering and Biotechnology, (BIOTEC), Thailand Science Park, Pathum Thani, 12120, Thailand.
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de Jesús Durán-Avelar M, Pérez-Enríquez R, Zambrano-Zaragoza JF, Montoya-Rodríguez L, Vázquez-Juárez R, Vibanco-Pérez N. Genotyping WSSV isolates from northwestern Mexican shrimp farms affected by white spot disease outbreaks in 2010-2012. DISEASES OF AQUATIC ORGANISMS 2015; 114:11-20. [PMID: 25958803 DOI: 10.3354/dao02844] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
White spot disease (WSD) causes high mortality in cultured shrimp throughout the world. Its etiologic agent is the white spot syndrome virus (WSSV). The genomic repeat regions ORF 75, ORF 94, and ORF 125 have been used to classify WSSV isolates in epidemiological studies using PCR with specific primers and sequencing. The present study investigated the variation in nucleotide sequences from 107, 150, and 143 isolates of WSSV collected from Litopenaeus vannamei shrimp ponds with WSD outbreaks in northwestern Mexico during the period 2010-2012, in the genomic repeat regions ORFs 75, 94, and 125, respectively. The haplotypic nomenclature for each isolate was based on the number of repeat units and the position of single nucleotide polymorphisms on each ORF. We report finding 17, 43, and 66 haplotypes of ORFs 75, 94, and 125, respectively. The study found high haplotypic diversity in WSSV using the complete sequences of ORFs 94 and 125 as independent variables, but low haplotypic diversity for ORF 75. Different haplotypes of WSSV were found from region-to-region and year-to-year, though some individual haplotypes were found in different places and in more than one growing cycle. While these results suggest a high rate of mutation of the viral genome at these loci, or perhaps the introduction of new viral strains into the area, they are useful as a tool for epidemiological surveys. Two haplotypes from some of the ORFs in the same shrimp were encountered, suggesting the possibility of multiple infections.
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Affiliation(s)
- Ma de Jesús Durán-Avelar
- Universidad Autónoma de Nayarit, Unidad Académica de Ciencias Químico Biológicas y Farmacéuticas, Tepic 63000, Nayarit, Mexico
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15
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Adesiji YO, Deekshit VK, Karunasagar I. Antimicrobial-resistant genes associated with Salmonella spp. isolated from human, poultry, and seafood sources. Food Sci Nutr 2014; 2:436-42. [PMID: 25473501 PMCID: PMC4221842 DOI: 10.1002/fsn3.119] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 03/31/2014] [Accepted: 04/06/2014] [Indexed: 12/13/2022] Open
Abstract
Antimicrobial-resistant salmonellosis is a significant public health concern globally. A study was conducted to screen for Salmonella species from a total of 120 samples, of which 50 were retail meat samples purchased from five randomly selected sales outlets in the city of Mangalore, India. Twenty poultry fecal materials freshly voided before slaughter were obtained with sterile spatula and placed in sterile sealable polythene envelopes, and 20 clams were purchased from the estuaries of Nethravathi and Kankarnady market. In addition, 30 clinical isolates from Nigeria suspected to be Salmonella by only cultural characterization were also included in the study. In all, 30 samples-6 poultry, 8 seafood, and 16 Salmonella isolates from clinical samples-were confirmed positive by PCR and used in this study. The disk-diffusion test was performed to determine the zone of inhibition, and detection of resistance genes was tested by PCR targeting various antimicrobial genes. Resistance to tetracycline (TET), cotrimoxazole, nalidixic acid, nitrofurantion, and piperacillin/tazobactin was found in 66.7%, 60%, 53.3%, 50% and 50% of the isolates, respectively. About 60-100% of MDR isolates possessed antibiotic-resistant genes, of the tetracyclines resistant isolates, 20 (100%) 6 (30%), 7 (35%), and 10 (50%) carried tetA, tetB, tetC, and tetG genes, respectively. Of 18 cotrimoxazole-resistant strains, 18 (100%), 14 (77.7%), and 4 (22.2%) had sul1, sul2, and sul3 genes, respectively. Of the 14 multidrug-resistant isolates tested, 8 (61%) and 9 (69%) were positive for cmlA and cmlB genes, respectively, 10 (1.4%) tested positive for aph(3)11a genes, 8 (57%) tested positive for aac(3)lla, while none was positive for the aac6 gene. The results show the presence of antibiotic-resistant Salmonella spp. in food samples from India and in human samples from Nigeria.
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Affiliation(s)
- Yemisi O Adesiji
- Department of Fisheries Microbiology, Karnataka Veterinary Animal and Fisheries Sciences University, College of Fisheries Mangalore, 575002, India
| | - Vijaya Kumar Deekshit
- Department of Fisheries Microbiology, Karnataka Veterinary Animal and Fisheries Sciences University, College of Fisheries Mangalore, 575002, India
| | - Indrani Karunasagar
- Department of Fisheries Microbiology, Karnataka Veterinary Animal and Fisheries Sciences University, College of Fisheries Mangalore, 575002, India
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16
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Gao M, Li F, Xu L, Zhu X. White spot syndrome virus strains of different virulence induce distinct immune response in Cherax quadricarinatus. FISH & SHELLFISH IMMUNOLOGY 2014; 39:17-23. [PMID: 24795080 DOI: 10.1016/j.fsi.2014.04.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 03/21/2014] [Accepted: 04/18/2014] [Indexed: 06/03/2023]
Abstract
In this study, we identified three white spot syndrome virus (WSSV) strains (WSSV-CN01, WSSV-CN02 and WSSV-CN03) with significant differences in virulence. Among them, WSSV-CN01 caused significant higher and earlier mortality in redclaw crayfish Cherax quadricarinatus, thus was determined as high-virulent, while WSSV-CN02 and WSSV-CN03 were moderate-virulent and low-virulent. By investigating the total number of the circulating haemocytes and the activity of immune relative enzymes, we demonstrated that the different virulent WSSV strains induced distinct immune response in the host. Notably, a dramatic reduction of circulating haemocytes was observed in the crayfish infected with WSSV-CN01 and WSSV-CN02 but not WSSV-CN03. Further analysis revealed that cell death induced by WSSV-CN01 and WSSV-CN02 might be responsible for the decrease of circulating haemocytes.
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Affiliation(s)
- Meiling Gao
- College of Ocean and Earth Science, Xiamen University, Xiamen 361005, PR China; State Key Laboratory Breeding Base of Marine Genetic Resources, Key Laboratory of Marine Genetic Resources of State Oceanic Administration & Fujian, Third Institute of Oceanography, Xiamen 361005, PR China
| | - Fang Li
- State Key Laboratory Breeding Base of Marine Genetic Resources, Key Laboratory of Marine Genetic Resources of State Oceanic Administration & Fujian, Third Institute of Oceanography, Xiamen 361005, PR China.
| | - Limei Xu
- State Key Laboratory Breeding Base of Marine Genetic Resources, Key Laboratory of Marine Genetic Resources of State Oceanic Administration & Fujian, Third Institute of Oceanography, Xiamen 361005, PR China
| | - Xiaoming Zhu
- College of the Environment & Ecology, Xiamen University, Xiamen 361005, PR China.
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Wargo AR, Kurath G. Viral fitness: definitions, measurement, and current insights. Curr Opin Virol 2012; 2:538-45. [PMID: 22986085 PMCID: PMC7102723 DOI: 10.1016/j.coviro.2012.07.007] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 07/24/2012] [Indexed: 11/03/2022]
Abstract
Viral fitness is an active area of research, with recent work involving an expanded number of human, non-human vertebrate, invertebrate, plant, and bacterial viruses. Many publications deal with RNA viruses associated with major disease emergence events, such as HIV-1, influenza virus, and Dengue virus. Study topics include drug resistance, immune escape, viral emergence, host jumps, mutation effects, quasispecies diversity, and mathematical models of viral fitness. Important recent trends include increasing use of in vivo systems to assess vertebrate virus fitness, and a broadening of research beyond replicative fitness to also investigate transmission fitness and epidemiologic fitness. This is essential for a more integrated understanding of overall viral fitness, with implications for disease management in the future.
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Affiliation(s)
- Andrew R Wargo
- US Geological Survey, Western Fisheries Research Center, 6505 NE 65th Street, Seattle, WA 98115, USA
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Pradeep B, Rai P, Mohan SA, Shekhar MS, Karunasagar I. Biology, Host Range, Pathogenesis and Diagnosis of White spot syndrome virus. INDIAN JOURNAL OF VIROLOGY : AN OFFICIAL ORGAN OF INDIAN VIROLOGICAL SOCIETY 2012; 23:161-74. [PMID: 23997440 PMCID: PMC3550756 DOI: 10.1007/s13337-012-0079-y] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 06/26/2012] [Indexed: 01/31/2023]
Abstract
White spot syndrome virus (WSSV) is the most serious viral pathogen of cultured shrimp. It is a highly virulent virus that can spread quickly and can cause up to 100 % mortality in 3-10 days. WSSV is a large enveloped double stranded DNA virus belonging to genus Whispovirus of the virus family Nimaviridae. It has a wide host range among crustaceans and mainly affects commercially cultivated marine shrimp species. The virus infects all age groups causing large scale mortalities and the foci of infection are tissues of ectodermal and mesodermal origin, such as gills, lymphoid organ and cuticular epithelium. The whole genome sequencing of WSSV from China, Thailand and Taiwan have revealed minor genetic differences among different strains. There are varying reports regarding the factors responsible for WSSV virulence which include the differences in variable number of tandem repeats, the genome size and presence or absence of different proteins. Aim of this review is to give current information on the status, host range, pathogenesis and diagnosis of WSSV infection.
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Affiliation(s)
- Balakrishnan Pradeep
- />Krishi Vigyan Kendra, Indian Institute of Spices Research, Peruvannamuzhi, Kozhikode, 673528 Kerala India
| | - Praveen Rai
- />Department of Fishery Microbiology, College of Fisheries, Karnataka Veterinary, Animal and Fisheries Sciences University, Mangalore, 575 002 India
| | - Seethappa A. Mohan
- />Department of Fishery Microbiology, College of Fisheries, Karnataka Veterinary, Animal and Fisheries Sciences University, Mangalore, 575 002 India
| | - Mudagandur S. Shekhar
- />Genetics and Biotechnology Unit, Central Institute of Brackishwater Aquaculture, Chennai, India
| | - Indrani Karunasagar
- />Department of Fishery Microbiology, College of Fisheries, Karnataka Veterinary, Animal and Fisheries Sciences University, Mangalore, 575 002 India
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White spot syndrome virus: Genotypes, Epidemiology and Evolutionary Studies. INDIAN JOURNAL OF VIROLOGY : AN OFFICIAL ORGAN OF INDIAN VIROLOGICAL SOCIETY 2012; 23:175-83. [PMID: 23997441 DOI: 10.1007/s13337-012-0078-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 06/26/2012] [Indexed: 10/28/2022]
Abstract
White spot syndrome virus (WSSV) is a pathogen that has emerged globally affecting shrimp populations. Comparison of WSSV genome have shown the virus to share a high genetic similarity except for a few variable genomic loci that has been employed as markers in molecular epidemiology studies for determining the origin, evolution and spread in different geographical regions. Molecular genotyping of WSSV are based on genomic deletions associated with ORF23/24 and ORF14/15 variable regions and the three variable number of tandem repeat regions, ORF75, ORF94 and ORF125. Studies show the prevalence of several genotypes for WSSV with particular genotypes being more prevalent than others in a given geographical area. Deletions associated with ORF23/24 and ORF14/15 variable regions have proven to be of evolutionary significance. Fitness and virulence studies on different genotypes of WSSV suggest that all the strains of WSSV are equally virulent, but the one with smaller genomic size is the fittest. Studies also have shown that mixed genotype infection of WSSV correlates with lower disease outbreaks. This review focuses on the genotyping studies that were undertaken in elucidating WSSV evolution and epidemiology.
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Hoa TTT, Zwart MP, Phuong NT, Oanh DTH, de Jong MCM, Vlak JM. Indel-II region deletion sizes in the white spot syndrome virus genome correlate with shrimp disease outbreaks in southern Vietnam. DISEASES OF AQUATIC ORGANISMS 2012; 99:153-162. [PMID: 22691984 DOI: 10.3354/dao02463] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Sequence comparisons of the genomes of white spot syndrome virus (WSSV) strains have identified regions containing variable-length insertions/deletions (i.e. indels). Indel-I and Indel-II, positioned between open reading frames (ORFs) 14/15 and 23/24, respectively, are the largest and the most variable. Here we examined the nature of these 2 indel regions in 313 WSSV-infected Penaeus monodon shrimp collected between 2006 and 2009 from 76 aquaculture ponds in the Mekong Delta region of Vietnam. In the Indel-I region, 2 WSSV genotypes with deletions of either 5950 or 6031 bp in length compared with that of a reference strain from Thailand (WSSV-TH-96-II) were detected. In the Indel-II region, 4 WSSV genotypes with deletions of 8539, 10970, 11049 or 11866 bp in length compared with that of a reference strain from Taiwan (WSSV-TW) were detected, and the 8539 and 10970 bp genotypes predominated. Indel-II variants with longer deletions were found to correlate statistically with WSSV-diseased shrimp originating from more intensive farming systems. Like Indel-I lengths, Indel-II lengths also varied based on the Mekong Delta province from which farmed shrimp were collected.
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Affiliation(s)
- Tran Thi Tuyet Hoa
- Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, PB Wageningen, The Netherlands
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Devivaraprasad Reddy A, Jeyasekaran G, Jeya Shakila R. Effect of processing treatments on the white spot syndrome virus DNA in farmed shrimps (Penaeus monodon). Lett Appl Microbiol 2011; 52:393-8. [DOI: 10.1111/j.1472-765x.2011.03026.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hoa TTT, Zwart MP, Phuong NT, Oanh DTH, de Jong MCM, Vlak JM. Mixed-genotype white spot syndrome virus infections of shrimp are inversely correlated with disease outbreaks in ponds. J Gen Virol 2010; 92:675-80. [DOI: 10.1099/vir.0.026351-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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Zwart MP, Dieu BTM, Hemerik L, Vlak JM. Evolutionary trajectory of white spot syndrome virus (WSSV) genome shrinkage during spread in Asia. PLoS One 2010; 5:e13400. [PMID: 20976239 PMCID: PMC2954812 DOI: 10.1371/journal.pone.0013400] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Accepted: 09/19/2010] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND White spot syndrome virus (WSSV) is the sole member of the novel Nimaviridae family, and the source of major economic problems in shrimp aquaculture. WSSV appears to have rapidly spread worldwide after the first reported outbreak in the early 1990s. Genomic deletions of various sizes occur at two loci in the WSSV genome, the ORF14/15 and ORF23/24 variable regions, and these have been used as molecular markers to study patterns of viral spread over space and time. We describe the dynamics underlying the process of WSSV genome shrinkage using empirical data and a simple mathematical model. METHODOLOGY/PRINCIPAL FINDINGS We genotyped new WSSV isolates from five Asian countries, and analyzed this information together with published data. Genome size appears to stabilize over time, and deletion size in the ORF23/24 variable region was significantly related to the time of the first WSSV outbreak in a particular country. Parameter estimates derived from fitting a simple mathematical model of genome shrinkage to the data support a geometric progression (k<1) of the genomic deletions, with k = 0.371 ± 0.150. CONCLUSIONS/SIGNIFICANCE The data suggest that the rate of genome shrinkage decreases over time before attenuating. Bioassay data provided support for a link between genome size and WSSV fitness in an aquaculture setting. Differences in genomic deletions between geographic WSSV isolates suggest that WSSV spread did not follow a smooth pattern of geographic radiation, suggesting spread of WSSV over long distances by commercial activities. We discuss two hypotheses for genome shrinkage, an adaptive and a neutral one. We argue in favor of the adaptive hypothesis, given that there is support for a link between WSSV genome size and fitness.
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Affiliation(s)
- Mark P Zwart
- Laboratory of Virology, Wageningen University, Wageningen, The Netherlands.
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Dieu BTM, Marks H, Zwart MP, Vlak JM. Evaluation of white spot syndrome virus variable DNA loci as molecular markers of virus spread at intermediate spatiotemporal scales. J Gen Virol 2010; 91:1164-72. [PMID: 20089797 DOI: 10.1099/vir.0.018028-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Variable genomic loci have been employed in a number of molecular epidemiology studies of white spot syndrome virus (WSSV), but it is unknown which loci are suitable molecular markers for determining WSSV spread on different spatiotemporal scales. Although previous work suggests that multiple introductions of WSSV occurred in central Vietnam, it is largely uncertain how WSSV was introduced and subsequently spread. Here, we evaluate five variable WSSV DNA loci as markers of virus spread on an intermediate (i.e. regional) scale, and develop a detailed and statistically supported model for the spread of WSSV. The genotypes of 17 WSSV isolates from along the coast of Vietnam--nine of which were newly characterized in this study--were analysed to obtain sufficient samples on an intermediate scale and to allow statistical analysis. Only the ORF23/24 variable region is an appropriate marker on this scale, as geographically proximate isolates show similar deletion sizes. The ORF14/15 variable region and variable-number tandem repeat (VNTR) loci are not useful as markers on this scale. ORF14/15 may be suitable for studying larger spatiotemporal scales, whereas VNTR loci are probably suitable for smaller scales. For ORF23/24, there is a clear pattern in the spatial distribution of WSSV: the smallest genomic deletions are found in central Vietnam, and larger deletions are found in the south and the north. WSSV genomic deletions tend to increase over time with virus spread in cultured shrimp, and our data are therefore congruent with the hypothesis that WSSV was introduced in central Vietnam and then radiated out.
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Affiliation(s)
- Bui Thi Minh Dieu
- Laboratory of Virology, Wageningen University, Radix building (#107), Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
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