Resilience Effects of SGK1 and TAP1 DNA Markers during PRRSV Outbreaks in Reproductive Sows

SIMPLE SUMMARY: The genetics of pig resilience is a key issue to select animals with more stable performance when facing unexpected challenges. In pigs, a major stressor is the porcine reproductive and respiratory syndrome virus (PRRSV), which causes serious health problems and productivity drops in farms. In this study, we investigated the role of variants in the SGK1 and TAP1 genes using a large dataset of reproductive parameters collected in a farm of Landrace × Large White sows in stable conditions and during a PRRSV outbreak. We showed that all variants affected the reproductive performance in the outbreak, but not during the endemic phase. That is to say, sows carrying certain SGK1 and TAP1 genotypes were able to keep up their reproductive performance in spite of the viral outbreak. The number of piglets born alive, stillborn, and mummified piglets were the three parameters more influenced by the genotype of the SGK1 and TAP1 markers. Pending validation in other genetic types and farm conditions, these results can have practical applications when planning pig selection and crossbreeding schemes in order to improve resilience to PRRSV. ABSTRACT: The porcine reproductive and respiratory syndrome virus (PRRSV) is a major infectious stressor that causes serious health problems and productivity drops. Based on previous genome-wide analyses, we selected SGK1 and TAP1 as candidate genes for resilience, and genotyped three mutations, including a 3′UTR variant SGK1_rs338508371 and two synonymous variants TAP1_rs1109026889 and TAP1_rs80928141 in 305 Landrace × Large White sows. All polymorphisms affected the reproductive performance in the outbreak, but not during the endemic phase, thereby indicating a potential use of these markers for resilience. Moreover, some genotypes were associated with a stable performance across PRRSV phases. Thus, in the outbreak, the SGK1_rs338508371 AA sows had less piglets born alive (p < 0.0001) and more stillborns (p < 0.05) while other sows were able to keep their productivity. During the outbreak, TAP1_rs80928141 GG sows had less piglets born alive (p < 0.05) and both TAP1 polymorphisms influenced the number of mummies in an additive manner (p < 0.05). Remarkably, TAP1_rs80928141 AA sows had around one mummy more than GG sows (p < 0.01). Resilience to PRRSV could be improved by including the SGK1 and TAP1 markers in crossbreeding and/or selection schemes, as they contribute to maintaining a stable number of piglets born alive and lost, particularly mummies, despite the outbreak.