Nervous necrosis virus viability modulation by water salinity and temperature

Nervous necrosis virus (NNV) is a hazardous aquatic pathogen, distributed worldwide and in a wide range of temperatures. Viral persistence in water has been demonstrated to be affected by different factors, such as temperature, UV, or biological load. In this study, we have investigated the viability of NNV strains in low- and high-salinity seawater (LS and HS, respectively) both in laboratory and aquarium conditions, at different storage temperatures, and for comparative purposes, in culture medium. Our results showed the highest NNV viability in seawater at 15°C and as temperature increased, a drop in viral persistence was observed. Additionally, survival at 15 and 30°C was strongly affected by increasing salt content, while no differences were observed between LS and HS groups at 20 and 25°C. The results of the incubation under aquarium conditions indicated that the effect of UV light and oxygen exposure accelerate the inactivation of infective particles. According to previous studies, NNV persistence in cell culture medium was higher than in seawater, and as observed in the latter, increasing incubation temperatures led to a decrease in viral survival.