A preliminary study of possible genetic influences on the susceptibility of sheep to Johne's disease.
OBJECTIVE
To investigate possible genetic influences on susceptibility or resistance of sheep to Johne's disease.


METHODS
A field and laboratory study of two fine-wool Merino flocks with a high prevalence of disease due to Mycobacterium avium subsp paratuberculosis infection.


METHODS
Adult sheep were phenotypically classified as having severe, mild or no disease on the basis of clinical, pathological and cultural tests for paratuberculosis, and as positive or negative in tests for humoral immunity (agar gel immunodiffusion test) or cell mediated immunity (skin test for delayed type hypersensitivity). Correlations with phenotype were sought for polymorphisms at loci within selected immune function genes (NRAMP, MHC complex, IFN-gamma, lysozyme, leukaemia inhibiting factor).


RESULTS
Possible associations of particular NRAMP and MHC alleles with susceptibility or resistance to Johne's disease were detected.


CONCLUSIONS
If the results of this preliminary study are confirmed in further work, then the use of rams with "resistant" genotypes may assist in the control of Johne's disease in infected flocks.
Reddacliff
L A
LA
New South Wales Department of Primary Industries, PMB 8, Camden, New South Wales.
Beh
K
K
McGregor
H
H
Whittington
R J
RJ
D000818:Animals; D000917:Antibody Formation / Q000235:genetics; D017931:DNA Primers; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D007111:Immunity, Cellular / Q000235:genetics; D009517:New South Wales / Q000453:epidemiology; D010283:Paratuberculosis / Q000453:epidemiology / Q000235:genetics*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012756:Sheep; D012757:Sheep Diseases / Q000453:epidemiology / Q000235:genetics*
D017931:DNA Primers