Genetic determination of tuberculin hypersensitivity in chicken inbred lines

A dominant inheritance of the ability of CB line chickens to react to tuberculin over the inability of the WB line to develop this type of immune reaction was observed. The tuberculin reactivity in this line seems to be determined by one locus and is associated with the B locus. The involvement of the B locus in the regulation of tuberculin reactivity in other inbred lines of chickens is supported by the reactivity of the CA. IB (N6F2) birds in which the B allele of the IB line was introduced into the CA genotype. The CA. IB (N6F2) chickens manifest strong tuberculin sensitivity, corresponding to the type of reaction of the IB line, not to the weaker type of response of the CA line. The intensity of the tuberculin reaction of the CA and CC lines resembles that of the CB line, but the proportion of nonreactive birds is higher in these two lines than in CB chickens.