Abstract
Tilapia lake virus (TiLV; genus: Tilapinevirus, family: Amnoonviridae) is a recently characterised enveloped virus with a linear, negative-sense single-stranded RNA genome, which causes high mortality in tilapia species. In the present study, we demonstrated that zebrafish (Danio rerio) larvae are susceptible to TiLV infection upon systemic injection. TiLV replicated in zebrafish larvae and caused their high mortality (of about 70%). Histopathological examination revealed that TiLV infection caused pathological abnormalities in zebrafish larvae that were well visible within the brain. Moreover, gene expression analysis revealed that TiLV infection induced up-regulation of the expression of the immune-related genes encoding pathogen recognition receptors involved in sensing of viral dsRNA (rig-I (ddx58), tlr3, tlr22), transcription factors (irf3, irf7), type I interferon (infϕ1), antiviral protein (mxa), and pro-inflammatory cytokine (il-1β). We also demonstrated the protective role of the recombinant zebrafish IFNϕ1 on the survival of zebrafish larvae during TiLV infection. Our results show the importance of type I IFN response during TiLV infection in zebrafish larvae and demonstrate that zebrafish is a good model organism to study interactions between TiLV - a newly emerging in aquaculture virus, and fish host.
Highlights
Tilapia lake virus (TiLV) is a recently characterised enveloped virus of fish
Mortality of zebrafish larvae infected with TiLV to the duct of Cuvier was associated with strong viral replication, with a >3.106-fold increase in viral copy number between 1 and 48 h post-infection (Fig. 1D)
We demonstrated that zebrafish larvae are susceptible to tilapia lake virus and systemic injection of TiLV in duces their high mortality at 4–5 dpi
Summary
Tilapia lake virus (TiLV) is a recently characterised enveloped virus of fish. Its linear, negative-sense single-stranded RNA genome consists of 10 segments and is approximately 10.323 kb in total length. TiLV was initially described as Orthomyxo-like virus (Bacharach et al, 2016; Eyngor et al, 2014) and taxonomically updated as Tilapia tilapinevirus species, and classified into genus Tilapinevirus, family Amnoonviridae (ICTV Taxonomy, 2018). The biology of this virus is still poorly understood compared to most viruses important in aquaculture. As tilapia are one of the most important farmed fresh-water fish worldwide providing inexpensive sources of dietary proteins, TiLV is a real threat for global aquaculture (Dong et al, 2017; Eyngor et al, 2014; Jansen et al, 2019)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
