Infectious spleen and kidney necrosis disease (ISKND) outbreaks in farmed barramundi (Lates calcarifer) in Vietnam

Dong, Ha Thanh; Jitrakorn, Sarocha; Kayansamruaj, Pattanapon; Pirarat, Nopadon; Rodkhum, Channarong; Rattanarojpong, Triwit; Senapin, Saengchan; Saksmerprome, Vanvimon

doi:10.1016/j.fsi.2017.06.054

Cited by 59 publications

(47 citation statements)

References 26 publications

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“…These include infectious spleen and kidney necrosis virus (ISKNV), red seabream iridovirus (RSIV) and turbot reddish body iridovirus (TBIV) (Dong, Jitrakorn et al, 2017;Huang et al, 2011;Kurita & Nakajima, 2012;Song et al, 2008;Wu, Kai, & Chi, 2013;Zainathan et al, 2017). A commercial vaccine against RSIV (Aquavac IridoV, MSD) showed only partial protection against ISKNV infection when tested by sea bass farmers (Dong, Jitrakorn et al, 2017) and showed no cross-protection against SDDV in a laboratory test (De Groof et al, 2015). Therefore, a polyvalent vaccine against multiple Megalocytivirus infections should be considered a worthy research goal for disease prevention in sea bass aquaculture.…”

Section: Discussionmentioning

confidence: 99%

“…Asian sea bass, Lates calcarifer (also known as barramundi), is an economically important finfish species of marine aquaculture in Asia (FAO ). Although production is rising, infectious diseases are considered major threats to production (Dong, Jitrakorn et al., ; Ransangan & Manin, ; Sharma, Rathore, Verma, Sadhu, & Philipose, ; Tendencia, ; Toranzo, Magariños, & Romalde, ). One emerging disease in farmed L. calcarifer in Southeast Asia is scale drop disease (SDD) caused by a novel Megalocytivirus (SDDV) (De Groof et al., ; Gibson‐Kueh et al., ).…”

Section: Introductionmentioning

confidence: 99%

“…Another is scale drop and muscle necrosis (SDMN) disease associated with a pathogenic Vibrio harveyi isolate (Dong, Taengphu et al., ; Kayansamruaj et al., ). Yet another is infectious spleen and kidney necrosis disease (ISKND) caused by the virus called ISKNV genotype II (Dong, Jitrakorn et al., ).…”

Section: Introductionmentioning

confidence: 99%

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Mortality from scale drop disease in farmed Lates calcarifer in Southeast Asia

Senapin

Dong

Meemetta

et al. 2018

Journal of Fish Diseases

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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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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mortality from scale drop disease in farmed Lates calcarifer in Southeast Asia

Senapin

Dong

Meemetta

et al. 2018

Journal of Fish Diseases

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“…Current evidence indicates that we must consider the three genotypes of ISKNV (i.e., RSIV, ISKNV and TRBIV) as potentially globally distributed pathogens, each able to infect fish in a variety of environments (Fusianto, Hick, & Becker, ). For example, ISKNV has been reported as the cause of significant mortality at marine farms holding barramundi ( Lates calcarifer ; Dong et al, ) whilst the geographic range is expanded with detections in ornamental fish in Brazil (de Lucca Maganha et al, ), Germany (Jung‐Schroers et al, ) and the USA (Subramaniam et al, ). TRBIV was recently reported in a marine food fish (starry flounder, Platichthys stellatus ) in Korea (Jin et al, ; Woong et al, ) and from archived clinical cases of freshwater ornamental fish from the late 1980s and early 1990s in the USA (Koda et al, ), Canada and Australia (Go et al, ).…”

Section: Discussionmentioning

confidence: 99%

The impact of pooling samples on surveillance sensitivity for the megalocytivirus Infectious spleen and kidney necrosis virus

Johnson

Hick

Robinson

et al. 2019

Transbound Emerg Dis

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Movements of large volumes and species varieties make the ornamental fish industry a high‐risk pathway for the transfer of aquatic pathogens to new geographical regions and naïve hosts, potentially resulting in emergency disease events. Infectious spleen and kidney necrosis virus (genus Megalocytivirus) is considered exotic to Australia despite documented incursions since 2003. There are current import controls requiring freedom from infection for entry to Australia. The objective was to evaluate the effect of tissue pooling strategies for qPCR testing using a SYBR® assay for freedom from ISKNV at 2% expected prevalence with 95% confidence. Tissue homogenates from apparently healthy imported ornamental fish were tested as individuals and in pools of 5 and 10. Analytical sensitivity of the qPCR assay was reduced by two orders of magnitude when the nucleic acid extraction process was accounted for by spiking the plasmid in fish tissues and compared with molecular grade water. Diagnostic sensitivity of the assay was substantially reduced when testing tissues in pools compared with individual testing. For Population 1 (66% positive for ISKNV with moderate viral loads), surveillance sensitivity was only achieved using individual testing. For Population 2 (100% positive ISKNV with high viral loads), surveillance sensitivity was achieved using 260 fish in pools of 10 for a total of 26 tests or 200 fish in pools of 5 for 40 tests. Surveillance sensitivity could be maximized even when there was a reduction in pooled diagnostic sensitivity compared with diagnostic sensitivity for individual fish by increasing the sample size. Pooled sensitivity was influenced by the prevalence and variable virus load among fish with subclinical infections. Pooled testing is highly effective when the prevalence is >10% which should be informed by prior knowledge or pooling can be used for a screening test to rapidly identify populations with high prevalence.

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“…Barramundi ( Lates calcarifer ) or Asian sea bass is one of the economically important finfish species in Asia-Pacific which has been farmed in a wide range of salinity in either open cage systems or earthen ponds (Jerry et al, 2014). Barramundi, like other intensively farmed fish, is susceptible to various infectious pathogens and often subject to serious outbreaks and economic losses (Dong et al, 2017a, b; Jerry et al, 2014; Ransangan et al, 2010; Toranzo et al, 2005). In recent years, three newly emerging viruses have been reported in farmed barramundi in Asia-Pacific, including scale drop disease virus (SDDV) (Gibson-Kueh et al, 2012; de Groof et al, 2015), Lates calcarifer herpes virus (LCHV) (Chang et al, 2017) and Lates calcarifer birnavirus (LCBV) (Chen et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Development of a SYBR Green quantitative PCR assay for detection ofLates calcarifer herpesvirus(LCHV) in farmed barramundi

Meemetta

Domingos

Dong

et al. 2020

Preprint

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Lates calcarifer herpes virus (LCHV) is a new virus of farmed barramundi in Southeast Asia. However, a rapid detection method is yet to be available for LCHV. This study, therefore, aimed to develop a rapid quantitative PCR (qPCR) detection method for LCHV and made it timely available to public for disease diagnostics and surveillance in barramundi farming countries. A newly designed primer set targeting a 93-bp fragment of the LCHV putative major envelope protein encoding gene (MEP) was used for developing and optimizing a SYBR Green based qPCR assay. The established protocol could detect as low as 10 viral copies per µl of DNA template in a reaction containing spiked host DNA. No cross-amplification with genomic DNA extracted from host as well as common aquatic pathogens (12 bacteria and 3 viruses) were observed. Validation test of the method with clinical samples revealed that the virus was detected in multiple organs of the clinically sick fish but not in the healthy fish. We thus recommend that barramundi farming countries should promptly initiate active surveillance for LCHV in order to understand their circulation for preventing possibly negative impact to the industry.HighlightsThis study reported a new SYBR Green qPCR method for detection of LCHVThe qPCR method had detection limit of 10 copies per µl plasmid DNA template when spiked with genomic DNA from the hostThe aforementioned method is highly specific to LCHVValidation with clinical samples revealed that LCHV could be detected from multiple organs with fin and brain the best organs for qPCR detection

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Infectious spleen and kidney necrosis disease (ISKND) outbreaks in farmed barramundi (Lates calcarifer) in Vietnam

Cited by 59 publications

References 26 publications

Mortality from scale drop disease in farmed Lates calcarifer in Southeast Asia

Mortality from scale drop disease in farmed Lates calcarifer in Southeast Asia

The impact of pooling samples on surveillance sensitivity for the megalocytivirus Infectious spleen and kidney necrosis virus

Development of a SYBR Green quantitative PCR assay for detection ofLates calcarifer herpesvirus(LCHV) in farmed barramundi

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