Abstract :
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.
