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Two regulatory region polymorphisms in the prion gene of cattle have been reported to have an association with resistance to classical bovine spongiform encephalopathy (BSE). However, it is not known if this association also applies to other transmissible spongiform encephalopathies (TSE) in cattle. In this report, we compare the relationship between these 2 polymorphisms and resistance in cattle affected with naturally occurring atypical BSE as well as in cattle experimentally inoculated with either scrapie, chronic wasting disease, or transmissible mink encephalopathy. Our analysis revealed no association between genotype and resistance to atypical BSE or experimentally inoculated TSE. This indicates the promoter polymorphism correlation is specific to classical BSE and that atypical BSE and experimentally inoculated TSE are bypassing the site of influence of the polymorphisms. This genetic discrepancy demonstrates that atypical BSE progresses differently in the host relative to classical BSE. These results are consistent with the notion that atypical BSE originates spontaneously in cattle. [ABSTRACT FROM AUTHOR]

Bovine spongiform encephalopathy (BSE) is a neurodegenerative disease of cattle caused by abnormally folded prion proteins. Two regulatory region polymorphisms in the bovine prion gene are associated with resistance to classical BSE disease: a 23-bp region in the promoter that contains a binding site for the repressor protein RP58, and a 12-bp region in intron 1 that has a binding site for the transcription factor SP1. The presence of these binding sites enhances BSE resistance in cattle, whereas cattle that lack these regions are more susceptible to the disease. The present study examined the allele, genotype, and haplotype frequencies for the 23-bp and 12-bp polymorphisms in Holstein cattle from 9 different US states, and these frequencies were compared with data previously established for Holstein cattle from the United Kingdom, Germany, and Japan. Additionally, the coding region of the prion gene was sequenced from the US samples. Finally, archival samples from US Holstein sires born between 1953 and 1957 were analyzed. We found that the resistant allele and genotype frequencies for the US Holstein cattle were as high, or higher, relative to that observed in other countries. Furthermore, the current US frequencies were comparable to those determined in the archival samples from the 1950s. Based on the frequencies of these regulatory region polymorphisms, the US Holstein population is not at a greater risk for BSE than Holsteins worldwide. [ABSTRACT FROM AUTHOR]