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Charoenwai O, Senapin S, Dong HT, Sonthi M. Detection of scale drop disease virus from non-destructive samples and ectoparasites of Asian sea bass, Lates calcarifer. J Fish Dis 2021; 44:461-467. [PMID: 33118189 DOI: 10.1111/jfd.13290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 10/06/2020] [Accepted: 10/07/2020] [Indexed: 06/11/2023]
Abstract
Non-destructive sampling methods offer practical advantages to detection and monitoring of viral pathogens in economically important farmed fish and broodstock. Here, we investigated whether blood, mucus and fin can be used as non-lethal sample sources for detection of scale drop disease virus (SDDV) in farmed Asian sea bass, Lates calcarifer. Detection of SDDV was performed in parallel from three non-destructive and seven destructive sample types, collected from both clinically sick fish and subclinical fish obtained from an affected farm. The results showed that SDDV was detectable in all 10 sample types with the percentage ranging from 20% to 100%. Blood was the best non-destructive sample source exhibited by the fact that it yielded 100% SDDV-positive tests from both sick (n = 12, 95% CI: 69.9-99.2) and clinically healthy fish (n = 4, 95% CI: 39.6%-97.4%) and is considered a "sterile" sample. This study also revealed concurrent infection of SDDV and two ectoparasites Lernanthropus sp. and Diplectanum sp., in all affected fish (n = 8, 95% CI: 46.7-99.3) during the disease outbreak. These ectoparasites also tested positive for SDDV by PCR, indicating that they were potential sample sources for PCR-based detection of SDDV and possibly other viruses infecting Asian sea bass.
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Affiliation(s)
- Onanong Charoenwai
- Faculty of Marine Technology, Burapha University Chanthaburi Campus, Chanthaburi, Thailand
- Aquatic Animal Disease Diagnostics and Immunology Research Unit, Burapha University Chanthaburi Campus, Chanthaburi, Thailand
| | - Saengchan Senapin
- Fish Health Platform, Faculty of Science, Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp), Mahidol University, Bangkok, Thailand
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, Thailand
| | - Ha Thanh Dong
- Faculty of Science and Technology, Suan Sunandha Rajabhat University, Bangkok, Thailand
| | - Molruedee Sonthi
- Faculty of Marine Technology, Burapha University Chanthaburi Campus, Chanthaburi, Thailand
- Aquatic Animal Disease Diagnostics and Immunology Research Unit, Burapha University Chanthaburi Campus, Chanthaburi, Thailand
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Sriisan S, Boonchird C, Thitamadee S, Sonthi M, Thanh Dong H, Senapin S. A sensitive and specific SYBR Green-based qPCR assay for detecting scale drop disease virus ( SDDV) in Asian sea bass. Dis Aquat Organ 2020; 139:131-137. [PMID: 32406868 DOI: 10.3354/dao03484] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Scale drop disease virus (SDDV) is a megalocytivirus known to cause disease in Asian sea bass in Southeast Asia. To support SDDV diagnosis and surveillance, we report on a sensitive and specific SYBR Green qPCR assay. The qPCR primers were designed to target a 135 bp fragment of the SDDV ATPase gene. The optimized SDDV qPCR assay reliably detected 2 copies of a plasmid dsDNA control and did not cross-amplify DNA to any of 12 viral or bacterial pathogens commonly found in aquatic animals. When assessed with 86 field samples, the assay detected SDDV in DNA extracted from each of 34 scale drop disease-affected fish collected from 5 affected farms. The qPCR also detected SDDV in DNA from 30 of 52 overtly healthy fish collected from 9 farms where SDDV had not been detected previously, using a semi-nested conventional PCR. The higher sensitivity of our SDDV qPCR assay can thus be useful in detecting fish with subclinical/chronic infections. However, the qPCR showed that SDDV DNA loads varied from 8.0 × 102 to 6.8 × 104 viral DNA copies per 200 ng DNA template among the 8 organ tissue types sampled from 3 diseased fish. In circumstances requiring SDDV to be detected unequivocally in subclinical carriers with lower-level infection, qPCR testing of more than one type of tissue is advisable.
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Affiliation(s)
- Sukhontip Sriisan
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
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Charoenwai O, Meemetta W, Sonthi M, Dong HT, Senapin S. A validated semi-nested PCR for rapid detection of scale drop disease virus ( SDDV) in Asian sea bass (Lates calcarifer). J Virol Methods 2019; 268:37-41. [PMID: 30898576 DOI: 10.1016/j.jviromet.2019.03.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 01/28/2019] [Accepted: 03/15/2019] [Indexed: 11/18/2022]
Abstract
Scale drop diseases virus (SDDV), a newly characterized virus of farmed Asian sea bass (Lates calcarifer), has been reported in several countries in Southeast Asia. However, no fully validated detection method is publicly available for disease diagnosis and surveillance. Here, we described a newly developed semi-nested PCR (snPCR) method for detection of the virus from field samples. The designed primers targeting a gene encoding ATPase generated amplicons of 738 bp and 412 bp in the first and second step PCR, respectively. The established protocol could detect down to 100 viral copies/μL template and was 100-fold more sensitive than single step PCR. A Specificity test against extracted DNA from ten bacterial pathogens, tissues from viral infected specimens and fish host revealed no cross amplification. The SDDV snPCR method could detect the virus from all clinical samples showing symptoms of scale drop disease (n = 25) and all samples from outbreaks of an unknown disease (n = 6) whereas all clinically healthy fish sea bass (n = 161) and grouper (n = 45) collected from different provinces tested negative. The newly established protocol might be useful for Asian sea bass farming countries to initiate disease diagnosis and surveillance.
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Affiliation(s)
- Onanong Charoenwai
- Faculty of Marine Technology, Burapha University Chanthaburi Campus, Chanthaburi, Thailand
| | - Watcharachai Meemetta
- Fish Health Platform, Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Molrudee Sonthi
- Faculty of Marine Technology, Burapha University Chanthaburi Campus, Chanthaburi, Thailand
| | - Ha Thanh Dong
- Faculty of Science and Technology, Suan Sunandha Rajabhat University, Bangkok, Thailand.
| | - Saengchan Senapin
- Fish Health Platform, Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp), Faculty of Science, Mahidol University, Bangkok, Thailand; National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani, Thailand.
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Senapin S, Dong HT, Meemetta W, Gangnonngiw W, Sangsuriya P, Vanichviriyakit R, Sonthi M, Nuangsaeng B. Mortality from scale drop disease in farmed Lates calcarifer in Southeast Asia. J Fish Dis 2019; 42:119-127. [PMID: 30397913 DOI: 10.1111/jfd.12915] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 09/27/2018] [Accepted: 09/28/2018] [Indexed: 06/08/2023]
Abstract
In Southeast Asia, a new disease called scale drop disease (SDD) caused by a novel Megalocytivirus (SDDV) has emerged in farmed Asian sea bass (Lates calcarifer) in Singapore, Malaysia and Indonesia. We received samples from an Eastern Thai province that also showed gross signs of SDD (loss of scales). Clinical samples of 0.2-1.1 kg L. calcarifer collected between 2016 and 2018 were examined for evidence of SDDV infection. Histopathology was similar to that in the first report of SDDV from Singapore including necrosis, inflammation and nuclear pyknosis and karyorrhexis in the multiple organs. Intracytoplasmic inclusion bodies were also observed in the muscle tissue. In a density-gradient fraction from muscle extracts, TEM revealed enveloped, hexagonal megalocytiviral-like particles (~100-180 nm). By PCR using primers derived from the Singaporean SDDV genome sequence, four different genes were amplified and sequenced from the Thai isolate revealing 98.7%-99.9% identity between the two isolates. Since viral inclusions were rarely observed, clinical signs and histopathology could not be used to easily distinguish between SDD caused by bacteria or SDDV. We therefore recommend that PCR screening be used to monitor broodstock, fry and grow-out fish to estimate the current impact of SDDV in Southeast Asia and to prevent its spread.
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Affiliation(s)
- Saengchan Senapin
- Faculty of Science, Fish Health Platform, Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp), Mahidol University, Bangkok, Thailand
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani, Thailand
| | - Ha Thanh Dong
- Faculty of Science, Fish Health Platform, Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp), Mahidol University, Bangkok, Thailand
- Faculty of Science and Technology, Suan Sunandha Rajabhat University, Bangkok, Thailand
| | - Watcharachai Meemetta
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani, Thailand
| | - Warachin Gangnonngiw
- Faculty of Science, Fish Health Platform, Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp), Mahidol University, Bangkok, Thailand
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani, Thailand
| | - Pakakul Sangsuriya
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani, Thailand
- Aquatic Molecular Genetics and Biotechnology Laboratory, National Science and Technology Development Agency, Pathumthani, Thailand
| | - Rapeepun Vanichviriyakit
- Faculty of Science, Fish Health Platform, Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp), Mahidol University, Bangkok, Thailand
- Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Molruedee Sonthi
- Faculty of Marine Technology, Burapha University Chanthaburi Campus, Chanthaburi, Thailand
| | - Bunlung Nuangsaeng
- Faculty of Marine Technology, Burapha University Chanthaburi Campus, Chanthaburi, Thailand
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