Verification of chromosomal regions affecting the innate immunity in pigs using linkage mapping

Understanding the genetic control of innate immunity in pigswould offerthe opportunity to utilize natural variation and improve selective breeding programmes. As part of our porcine genome scan to identify quantitative trait loci (QTL) we examined immune response traits in a Duroc x Berlin miniature pig resource family (DUMI). Complement activity via classical (CH50) and alternative (AH50) pathways, antibody response to Mycoplasma hyopneumoniae (Mh), tetanus toxoid (TET) and PRRS virus (PRRSV), the complement component (C3c), and Haptoglobin serum concentration (HP) were used as phenotypes for linkage mapping. A total of 220 backcross animals were used for the QTL analysis. Blood was collected six times from each animal prior to and after vaccinations against Mycoplasma hyopneumoniae, tetanus toxoid and PRRS, respectively. Seventy-four microsatellites from 18 autosomes were used for QTL mapping. The analyses were performed treating the measurements of phenotypes at different time points as single traits. Forty-two significant and 24 highly significant QTL were detected, using the program QTL Express, for all immune traits using the single traits. Most QTL were detected on SSC3, SSC16, and SSC18. No significant F-value corresponded to data for SSC12 and SSC13.