Genetic control of disease resistance and immunoresponsiveness

Ample evidence points to substantial genetic control over aspects of the im mune response. In essence, all immune systems are not created equally. Sing le genes with large effects on clinical disease have been documented, yet a great majority of disease resistance traits are likely to be influenced by the aggregate of many genes, each with a relatively small effect. Heritabi lity estimates of immunoresponsiveness traits such as antibody response and neutrophil function have typically ranged from 0.10 to 0.30. Animal improv ement programs aimed at enhanced disease resistance in North America will l ikely use immunoresponsiveness traits as indirect markers for clinical dise ase resistance.