Assessment of the virucidal effect of a commercial biocide against two different strains of nervous necrosis virus, betanodavirus

Viral nervous necrosis (VNN) is the most threatening infectious disease in Mediterranean aquaculture. VNN is caused by the nervous necrosis virus (NNV) a small naked ssRNA+ virus, highly resistant in the aquatic environment. Four genotypes of NNV have been so far described: RGNNV, SJNNV, BFNNV, TPNNV among which the RGNNV is the most spread in the Mediterranean Sea. European sea bass (Dicentrarchus labrax) is one of the species most affected by VNN, however the emergence of a reassortant strain RGNNV/SJNNV caused high mortality outbreaks also in gilthead sea bream (Sparus aurata) larvae (Volpe et al., 2020). So far, no therapy is available for VNN control and vaccination is applied limited to ongrowing facilities, therefore the control in hatchery is strongly based on direct prophylaxis aimed to prevent the entering and the spreading of the virus in the farms. In this respect the setup of effective hygiene standard procedures can greatly contribute to the reduction of the VNN impact.

The aim of this study was to assess the in vitro virucidal activity of a commercial compound (Virkon® S) towards the two NNV variants most spread in the Mediterranean Sea.