Genetic resistance to bacterial diseases of animals.

Despite traditional disease control measures, losses attributable to infectious diseases continue to impede the livestock industries. An alternative approach to this problem is genetic disease resistance involving both immune and non-immune mechanisms, which is the inherent capacity of a previously unexposed animal to resist disease when challenged by pathogens. Although the nurturing environment influences variability in disease expression, natural resistance has been found to be inheritable and is transmitted from parent to offspring. Thus, an alternative approach to enhancing animal health management systems is to increase the overall level of genetic resistance at herd and population levels by using selective breeding programmes. The purpose of this review is to bring veterinarians, regulatory officials, industry representatives and animal technicians up to date with the principles and applications of genetic resistance as an adjunct to traditional interventions to control bacterial diseases of livestock. Although genetic resistance to bacterial diseases is often regulated by multiple genes controlling different processes of the host-pathogen interaction, the genetics of natural resistance is being unravelled increasingly by identification and characterisation of candidate genes, microsatellite markers and comparative gene mapping, to develop more practical methods of application.