Effect of polymorphisms in the GBP1, Mx1 and CD163 genes on host responses to PRRSV infection in pigs

Porcine reproductive and respiratory syndrome (PRRS) is the most economically important disease to the swine industry, and effective prevention strategy for this disease is still required. Guanylate-binding protein 1 (GBP1) and myxovirus resistance protein 1 (Mx1) are two important proteins belonging to the GTPase superfamily that have been previously described to show antiviral effects. CD163 is considered the most important receptor for PRRSV attachment and internalization. Therefore, the aim of the present study was to evaluate the effects of these genes on host resistance against PRRSV infection in conjunction with the host immune response following PRRSV challenge. The results showed that pigs with AG genotype for the GBP1 exon2 exhibited a significantly higher average daily weight gain (ADWG) and lower average viremia than AA or GG genotype. Furthermore, pigs harbouring the AG genotype for the GBP1 gene presented greater CD4(+)CD25(+) and CD8(+)CD25(+) T cell populations at 4 and 18 days post challenge (dpc), respectively, as compared with other genotypes whereas pigs with CC genotype for the CD163 gene displayed significantly higher nucleocapsid-specific antibody titers at 11dpc. However, pigs with a single 11-bp deletion or insertion in the Mx1 gene did not show significant differences in either weight gain or viremia. Based on these results, we concluded that GBP1 is most significantly associated with resistance against PRRSV infection and efficient T cell activation in pigs.