[Biotechnology for the improvement of disease resistance]

Although satisfactory results in regard to genetic resistance may be obtained by classical breeding methods (selection and cross-breeding), there are considerable drawbacks to these techniques because of the number of generations of selection and the cost of challenge tests. Using the present knowledge of the immunology and pathology of Marek's disease, the genetic basis and the association with the B locus (the Major Histocompatibility Complex in chicken), it is possible to improve genetic resistance to Marek's by biotechnological methods today. The hybridisation technique and DNA studies will be helpful in rapidly tracing resistant birds. Resistant genes may be isolated by DNA studies and transferred to birds in which these genes are absent. The birds which came into possession of these genes have the advantage that other, undesirable genetic material was not transmitted by cross-breeding. The example provided by the use of biotechnological techniques in Marek's disease may also serve for other forms of disease and other farm animals.