Prion protein (PrP) gene polymorphism in Red Maasai and Black Head Persian sheep breeds in Tanzania: Consistent profile regardless of locations

The status of scrapie in Africa is largely unknown. The susceptibility to scrapie and its pathology is determined by amino acid polymorphisms at positions 136 (A/V), 154 (R/H) and 171 (Q/R/H) of the ovine PrP gene (PrP genotype) of the animals. Despite the widely studied PrP gene polymorphisms worldwide, limited data is available on PrP genotypes of sheep from the African continent. Previously, we have reported six PrP genotypes derived from four different alleles in Red Maasai and Black Herd Persian (BHP), the ARQ/ARQ genotype being more frequent in the Red Maasai than in the BHP sheep. The highly susceptible VRQ allele was not found in any of the sheep breeds; the ARR allele was absent in the Red Maasai or occurred at a low frequency in the BHP. The lack of the highly susceptible VRQ alleles among Tanzanian sheep examined, necessitated further examinations on genetic susceptibility in sheep of the same breeds, but originating from an entirely different part of Tanzania. Consistently, ARQ/ARQ genotype was observed in 88% of Red Maasai and 64% of BHP sheep, ARQ/AHQ genotype was present in 12% in Red Maasai and 36% in BHP. Neither the highly resistant (ARR/ARR), nor the highly susceptible (VRQ/VRQ) genotypes were found. The ARQ and AHQ were the only alleles observed. The ARQ allele constituted 94%, 82% and 67% in the Red Maasai, BHP and cross-bred sheep, respectively. The AHQ constituted 6%, 18% and 33%, respectively. Data reported here, provide additional information on genetic susceptibility of the Red Maasai, BHP and their crosses; they may be helpful in policy formulation for future prevention of scrapie.