Identification of QTL Responsible for the Immune Response to Porcine Reproductive and Respiratory Syndrome (PRRS) Virus Infection

Porcine reproductive and respiratory syndrome virus (PRRSV) is the most important infectious disease threatening pig production worldwide. The PRRS Host Genetics Consortium (PHGC) was established to probe the role of host genetics in resistance to PRRSV infection and related growth effects. The PHGC uses a commercial nursery pigs have been infected with PRRSV (NVSL 97-7985) and followed for 42 days post infection (dpi). Genomic DNA was genotyped with the PorcineSNP60 chip from the ear tissue. Serum blood samples were collected to quantify the viral load at 0, 4, 7, 11, 14, 28, 35 and 42 dpi and body weight were measured at 0, 7, 14, 28, 35 and 42 dpi. The objective of current study was to identify QTL that are associated with immune response to PRRSV infection. Based on viremia level in the declining phase, animals were classified into two groups to elucidate genetic role in immune response to PRRSV infection. We conducted a genome wide association study (GWAS) with two different groups of animals. The pruning procedure was performed using PLINK and over 44,000 SNPs were used in this study. This genome scan will facilitate the understanding of genetic role involved in the immune response, especially at later time points after PRRSV infection.