New RT-qPCR assay for viral nervous necrosis virus detection in sea bass, Dicentrarchus labrax (L.): application and limits for hatcheries sanitary control

A sensitive and quantitative one step RT-qPCR method was developed to study Viral Nervous Necrosis (VNN) virus loads in sea bass Dicentrarchus labrax (L.) in hatcheries. After determining the limits of this new method, fin tissues were identified as an interesting new simple non-invasive sample source, which might be useful for screening D. labrax (L.) in hatcheries. We observed VNN virus strain V26 associated to D. labrax (L.) eggs and it’s release in tank water during spawning suggesting both vertical transmission to the eggs and the possibility of horizontal transmission by contamination of tank water. VNN is widespread in water bodies and has the ability to infect a large number of fish species, with this in mind, this PCR technique may be used for the surveillance of various fish farms.