RESUMEN
Bovine spongiform encephalopathy [BSE] is a fatal infectious neurodegenerative disease in cattle, characterized by the accumulation of an abnormal, proteaseresistant prion protein [PrPSc] in the brain. BSE is similar to scrapie in sheep and goats and Creuzfeldt-Jakob disease in humans. Susceptibility in cattle has been shown to be under the influence of two polymorphic locations, which are a 23 bp in/del polymorphism and a 12 bp indel within intron 1 of the prion protein gene [PRNP]. DNA was extracted from blood samples of three Iranian cattle populations including Sistani [Bos indicus] [n=60], Golpayegani [Bos indicus] [n=62] and Iranian Holstein [Bos taurus] [n=50], In order to identify the putative polymorphisms of the PRNP gene of those breeds. Allele, genotype and haplotype frequencies of the polymorphisms were determined for the three populations. Susceptibility analysis was considered as per literature, upon which, it was suggested that the two Bos indicus native populations are more resistant to BSE than the Iranian Holstein [Bos taurus], due to higher gene frequency for insertion allele of the intron 1 of the PRNP gene polymorphism