POLYMORPHISM OF THE PRION PROTEIN GENE IN BELGIAN CATTLE

The prion protein gene seems to play a key role in the pathogenesis of spongiform encephalopathies. Indeed, polymorphisms of the prion prote in gene were associated to the susceptibility to natural infection in human and sheep or to different survival times after experimental inoc ulation with infectious material in sheep, mouse and hamster. Polymorp hisms of the bovine prion protein gene were investigated in the presen t study. No variation was found using hybridization of bovine genomic PrP DNA nor murine PrP cDNA on bovine BamH I, Bgl II, EcoR I, Hae III, Hind III, Hinf I, Msp I, Psf I, Pvu II and Tag I Southern blots. Afte r PCR amplification of a variable region of the bovine PrP gene, two a lleles of different molecular weights were detected in different breed s of the belgian cattle population, including Belgian White Blue. The frequency of the A allele (of highest M.W.) was greater than or equal to 0.95 in all groups, whereas the B allele frequency was so low that only one BB homozygote was found among the 135 tested animals. Direct sequencing of the PCR product showed the same insertion/deletion of a 24 bp GC-rich sequence within a stretch of 5 to 6 repeated elements in the PrP coding exon as previously described (Goldmann et al., 1991b). Our data provide the first records of the bovine PrP variability in b elgian cattle.