573. A major QTL affects resistance to viral nervous necrosis in farmed European seabass

Abstract

Viral nervous necrosis (VNN) presents a significant threat to the European seabass aquaculture industry, causing extensive losses due to mortality and impaired growth of infected fish. Selective breeding presents an opportunity to develop seabass strains with increased resistance, thus reducing the impact of the disease on the industry. Knowledge of the genetic architecture of the trait is important to inform selective breeding strategies, including use of genomic tools. In the current study the genetic basis of VNN resistance in European seabass was investigated through an extensive study based on nervous necrosis virus (NNV) challenge of juvenile seabass fish. The results highlighted moderate heritability (up to 0.39±0.05) of VNN resistance in farmed seabass. A major QTL was identified on LG12 or Chromosome 13 and impacted VNN resistance when defined as binary survival or as days to death. This QTL explains up to 37% of the genetic variation in VNN resistance, and therefore has a significant value for marker-assisted and genomic selection to improve resistance in sea bass breeding programmes. Together, our results provide insight into the genetic architecture of resistance to VNN that could further be utilized for enhancing genomic selection for more resistant fish.