The management and containment of infectious diseases represent one of the main challenges for sustainable aquaculture development. Lactococcosis, characterised by high mortality rates, has a significant economic impact on both freshwater and more recently marine aquaculture production.
In the context of the European project SUPERTROUT selective breeding was proposed as control strategy for lactococcosis. Two different approaches were employed: a candidate gene approach based on the MHC class II gene, examining its involvement in resistance to lactococcosis, and a genomic approach aiming to investigate the involvement of different regions of interest across the genome.
This was made possible by selecting a farm with a high prevalence of lactococcosis, monitoring the progression of natural infection, and comparing the genetic and genomic profiles of dead and surviving individuals. Different MHC gene variants were found to be protective against lactococcosis in Italy, but only some of them have been confirmed as significant in other Countries partner of SUPERTROUT.
The study of 57,000 SNPs distributed throughout the trout genome, using commercially available systems, first revealed that the analysed populations (Italy, Turkey, Greece, and Spain) exhibited genetic differences among them; notably, the Turkish population was divided into two distinct groups, with deceased and surviving individuals separated within each group. However, the genomic association study did not identify markers significantly associated with disease resistance.