Genetic Markers Associated with Field PRRSV-Induced Abortion Rates

In gilts and sows, the more severe clinical manifestation of porcine reproductive and respiratory syndrome virus (PRRSV) occurs in late gestation and can result in up to a 40% abortion incidence. Despite the known genetic component in resilience to PRRSV, there is scarce information regarding the abortive outcome of this disease. We tested the relationship between eight molecular markers (six from published studies and two identified in the present study in the HDAC6 gene) and the probability of abortion during a PRRSV outbreak, using data from two commercial Landrace x Large White sow farms with an incidence of abortion of 35% and 17%. From the markers tested, USP18_-1533G>A did not segregate in these populations, and CD163_c.3534C>T and HDAC6_g.2360C>T did not affect the abortion rate. In contrast, the minor allele of two markers in SSC4 (WUR1000125 in GBP1 and rs340943904 in GBP5), which lower viremia in growing pigs, and the major alleles of CD163_rs1107556229 and HDAC6_rs325981825 were associated with a lower probability of abortion during PRRSV outbreaks. The more striking result was for the MX1 gene, where the odds ratio of aborting versus not aborting was nine times lower in the sows homozygous for a 275-bp insertion than in the other genotypes. Interactions between markers were not relevant. All together, we bring here the first evidence that mutations in the host genome can predispose or protect from complete reproductive failure in sows infected with PRRSV.