Tilapia lake virus: The story so far

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.

Infection of Tilapia tilapinevirus in Mozambique Tilapia (Oreochromis mossambicus), a Globally Vulnerable Fish Species

“…Tilapia tilapinevirus, aka tilapia lake virus (TiLV), was first described in farmed and wild tilapia in Israel [4] and later reported in sixteen additional countries [2,48,49]. Although the potency of TiLV has been demonstrated in various species of tilapia including Nile tilapia (Oreochromis niloticus), blue tilapia (O. aureus), and its hybrid species [4,5,15,42,50,51], there have been no reports of TiLV infection in Mozambique tilapia, which is genetically close to the Nile tilapia, a susceptible host to TiLV infection.…”

“…Tilapia Lake Virus Disease (TiLVD) is a new disease caused by Tilapia tilapinevirus, or tilapia lake virus (TiLV), which is a linear, negative-sense single-strand RNA virus containing ten segments; it has a total genome size of 10,323 kb [1,2]. Since 2014, TiLV has been reported on four continents, North America, South America, Asia, and Africa [2][3][4]. All stages of tilapia, from fry to adult and broodstock, are susceptible to TiLV, with mortality ranging from 5% to 100% [2,[4][5][6][7][8][9].…”

“…Since 2014, TiLV has been reported on four continents, North America, South America, Asia, and Africa [2][3][4]. All stages of tilapia, from fry to adult and broodstock, are susceptible to TiLV, with mortality ranging from 5% to 100% [2,[4][5][6][7][8][9]. TiLVD has been most extensively reported and studied in several species of tilapia, including Nile tilapia (Oreochromis niloticus) [5,8,[10][11][12][13][14], hybrid tilapia (Oreochromis niloticus × O. aureus) [4], gray tilapia (O. niloticus × O. aureus) [15], and red hybrid tilapia (Oreochromis sp.)…”

First report of tilapia lake virus emergence in fish farms in the department of Córdoba, Colombia

“…In the present study, it was observed that the variation of nucleotides at position 412 of the Colombian sequences showed a change at position 130 of the amino acid sequence of the protein. These changes in both nucleotides and amino acids of the TiLV strains detected within the same country were described for segments 1, 5, and 9 in the TiLV strains detected in Thailand [ 9 , 30 ].…”

“…This study demonstrated morbidity rates of 50-100% and mortality rates of 30-87% in each fish farm. The prevalence of TiLV infection is low and increases when massive mortalities are observed [ 14 , 15 , 30 ]. Results of the present study revealed 27.27% (18/66) prevalence of TiLV, indicating a more significant prevalence than that reported in Peru [ 21 ] at 14.8% (4/27) but lower than that reported in Ecuador [ 11 ], which was 63% (17/27).…”