TABLE 1.
Summary of the relevant QTL studies pointing toward the implication of adaptive mechanisms in disease resistance.
| Fish species | Disease | Challenge type | Experimental design (genotyped fish in the analysis) | Genetic molecular markers | Resistance traits | Number of detected QTL | Size of detected QTL | % of variance explained by QTL | Publication |
| Atlantic salmon (S. salar) | CMS | Injection (ip) and natural outbreak | 571 and 4312 and 901 (FS and HF in three populations) | 55,735 SNPs | BS and lesion score | 2 QTL | 0.2–31 Mb | 8–31% of Vg | Boison et al., 2019a |
| Atlantic salmon (S. salar) | CMS | Injection (ip) | 1144 fish (60 FS) | 48K SNPs | Lesion score and viral load | 2 QTL | 320 kb (Ssa12) and 19 Mb (Ssa27) | Up to 57% of Vg (Ssa27) | Hillestad and Moghadam, 2019 |
| Atlantic salmon (S. salar) | Sea lice | Immersion | 94 fish (3 FS) | SSR markers located within 3′ of MHC I (in two chromosomes) | Parasite count | 2 QTL | 28 cM | 13% of Vp | Gharbi et al., 2009 |
| Atlantic salmon (S. salar) | ISA | Injection (ip) | 1031 fish (25 FS) | 17 polymorphic repeats located within 3′ of MHC I and MHC II | BS | 5 MHC I and II alleles | Grimholt et al., 2003 | ||
| Atlantic salmon (S. salar) | Furunculosis | Cohabitation | 1182 fish (33 FS) | 17 polymorphic repeats located within 3′ of MHC I and MHC II | BS | 7 MHC I and II alleles | Grimholt et al., 2003 | ||
| Rainbow trout (O. mykiss) | IPN | Immersion | 199 fish (BC and F1) | 226 markers (microsatellites AFPLs, MHC I and II genes) | BS | 9 QTL | 8–15% of Vp | Ozaki et al., 2007 | |
| Turbot (S. maximus) | Scuticociliatosis | Injection (ic) | 758 fish (4 FS) | 211 microsatellites | BS and TTD | 5–10 QTL | 7–30 cM | 7–22% of Vp | Rodríguez-Ramilo et al., 2013 |
| Red sea bream (P. major) | RSI disease | Injection | 120 and 400 fish (2 F1) | 458 microsatellites | BS | 1 QTL | 12–31% of Vp | Sawayama et al., 2017 |
QTL, quantitative trait loci; CMS, cardiomyopathy syndrome; ISA, infectious salmon anemia; IPN, infectious pancreatic necrosis; RSI, red seabream iridovirus; ip, intraperitoneal; ic, intracelomical; BS, binary survival that takes into account the outcomes of the challenge as dead or alive; TTD, time to death, measured as the time (in days or hours) between the infection and the day of death of a fish; Vp, phenotypic variance of the resistance trait; Vg, genetic or genomic variance of the resistance trait; FS; full-sib; HS, half-Sib; BC, back-cross; SNP, single-nucleotide polymorphism; MHC, major histocompatibility complex; cM, centi-Morgan. Size of detected QTL corresponds to either confidence intervals when calculated or cumulated windows with significant SNPs.