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Surachetpong W, Roy SRK, Nicholson P. Tilapia lake virus: The story so far. JOURNAL OF FISH DISEASES 2020; 43:1115-1132. [PMID: 32829488 DOI: 10.1111/jfd.13237] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/16/2020] [Accepted: 07/17/2020] [Indexed: 05/08/2023]
Abstract
Tilapia lake virus (TiLV) is a highly contagious pathogen that has detrimental effects on tilapia farming. This virus was discovered in 2014 and has received tremendous global attention from the aquaculture sector due to its association with high fish mortalities and its strong economic impact on the tilapia aquaculture industry. Currently, TiLV has been reported in 16 countries, and this number is continuing to rise due to improved diagnostic assays and surveillance activities around the world. In this review, we summarize the up-to-date knowledge of TiLV with regard to TiLV host species, the clinical signs of a TiLV infection, the affected tissues, pathogenesis and potential disease risk factors. We also describe the reported information concerning the virus itself: its morphology, genetic make-up and transmission pathways. We review the current methods for virus detection and potential control measures. We close the review of the TiLV story so far, by offering a commentary on the major TiLV research gaps, why these are delaying future TiLV research and why the TiLV field needs to come together and proceed as a more collaborative scientific community if there is any hope limiting the impact of this serious virus.
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Affiliation(s)
- Win Surachetpong
- Department of Veterinary Microbiology and Immunology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand
| | - Sri Rajiv Kumar Roy
- Department of Veterinary Microbiology and Immunology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand
| | - Pamela Nicholson
- Next Generation Sequencing Platform, Institute of Genetics, Vetsuisse, University of Bern, Bern, Switzerland
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
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Chaput DL, Bass D, Alam MM, Al Hasan N, Stentiford GD, van Aerle R, Moore K, Bignell JP, Haque MM, Tyler CR. The Segment Matters: Probable Reassortment of Tilapia Lake Virus (TiLV) Complicates Phylogenetic Analysis and Inference of Geographical Origin of New Isolate from Bangladesh. Viruses 2020; 12:v12030258. [PMID: 32120863 PMCID: PMC7150994 DOI: 10.3390/v12030258] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 02/25/2020] [Accepted: 02/26/2020] [Indexed: 12/26/2022] Open
Abstract
Tilapia lake virus (TiLV), a negative sense RNA virus with a 10 segment genome, is an emerging threat to tilapia aquaculture worldwide, with outbreaks causing over 90% mortality reported on several continents since 2014. Following a severe tilapia mortality event in July 2017, we confirmed the presence of TiLV in Bangladesh and obtained the near-complete genome of this isolate, BD-2017. Phylogenetic analysis of the concatenated 10 segment coding regions placed BD-2017 in a clade with the two isolates from Thailand, separate from the Israeli and South American isolates. However, phylogenetic analysis of individual segments gave conflicting results, sometimes clustering BD-2017 with one of the Israeli isolates, and splitting pairs of isolates from the same region. By comparing patterns of topological difference among segments of quartets of isolates, we showed that TiLV likely has a history of reassortment. Segments 5 and 6, in particular, appear to have undergone a relatively recent reassortment event involving Ecuador isolate EC-2012 and Israel isolate Til-4-2011. The phylogeny of TiLV isolates therefore depends on the segment sequenced. Our findings illustrate the need to exercise caution when using phylogenetic analysis to infer geographic origin and track the movement of TiLV, and we recommend using whole genomes wherever possible.
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Affiliation(s)
- Dominique L. Chaput
- Biosciences, Geoffrey Pope Building, University of Exeter, Exeter, Devon EX4 4QD, UK
- Correspondence: (D.L.C.); (C.R.T.); Tel.: +44-(0)-1392-724450 (C.R.T.)
| | - David Bass
- Centre for Sustainable Aquaculture Futures, University of Exeter, Exeter, Devon EX4 4QD, UK; (D.B.); (G.D.S.); (R.v.A.)
- International Centre of Excellence for Aquatic Animal Health, Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, Weymouth, Dorset DT4 8UB, UK;
| | - Md. Mehedi Alam
- Department of Aquaculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh; (M.M.A.); (N.A.H.); (M.M.H.)
| | - Neaz Al Hasan
- Department of Aquaculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh; (M.M.A.); (N.A.H.); (M.M.H.)
| | - Grant D. Stentiford
- Centre for Sustainable Aquaculture Futures, University of Exeter, Exeter, Devon EX4 4QD, UK; (D.B.); (G.D.S.); (R.v.A.)
- International Centre of Excellence for Aquatic Animal Health, Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, Weymouth, Dorset DT4 8UB, UK;
| | - Ronny van Aerle
- Centre for Sustainable Aquaculture Futures, University of Exeter, Exeter, Devon EX4 4QD, UK; (D.B.); (G.D.S.); (R.v.A.)
- International Centre of Excellence for Aquatic Animal Health, Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, Weymouth, Dorset DT4 8UB, UK;
| | - Karen Moore
- Exeter Sequencing Service, Geoffrey Pope Building, University of Exeter, Exeter, Devon EX4 4QD, UK;
| | - John P. Bignell
- International Centre of Excellence for Aquatic Animal Health, Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, Weymouth, Dorset DT4 8UB, UK;
| | - Mohammad Mahfujul Haque
- Department of Aquaculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh; (M.M.A.); (N.A.H.); (M.M.H.)
| | - Charles R. Tyler
- Biosciences, Geoffrey Pope Building, University of Exeter, Exeter, Devon EX4 4QD, UK
- Centre for Sustainable Aquaculture Futures, University of Exeter, Exeter, Devon EX4 4QD, UK; (D.B.); (G.D.S.); (R.v.A.)
- Correspondence: (D.L.C.); (C.R.T.); Tel.: +44-(0)-1392-724450 (C.R.T.)
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