The disclosure relates to genetically modified swine wherein at least one allele of a SIGLEC1 gene has been inactivated and/or at least one allele of a CD163 gene has been inactivated. Genetically modified swine having both alleles of the SIGLEC1 gene and/or both alleles CD 163 gene inactivated are resistant to porcine reproductive and respiratory syndrome virus (PRRSV). Methods for producing such transgenic swine are also provided.