There has been an increased interest in using genetic information to select pigs with health traits, such as a strong immune system. The innate immune response has receptors encoded in the germline, but the functional immune response requires expression of germline encoded regulatory genes. The result is a complicated genetic make-up for the immune response, but Genome-Wide Association Studies should help to determine the genetic pathways and genes involved. A QTL database already contains many locations for health-related QTLs, and studies have begun to test the application of this knowledge. Genetic components for pathogen resistance or vaccine response remain complicated and are likely polygenic. Of specific interest is a resistance to PRRSv, and it has been determined that macrophage response and cytokine levels could contribute. PRRSv subverts innate immunity, and vaccines are ineffective because it is an RNA virus which constantly mutates. The PRRS Host Genomic Consortium is working to identify genes associated with PRRSv resistance, and so far has found the genes involved to have some heritability. This suggests selective breeding might be used to increase PRRSv resistance, and studies are ongoing including ones for the commercial application. Genetic sequencing and other genetic techniques are allowing the genes associated with certain traits to be identified. Health-related genes are one of the current focuses, and studies are ongoing on pathogen resistance and vaccine response, especially PRRSv resistance.