Discrimination of sheep susceptible and resistant to transmissible spongiform encephalopathies by an haplotype specific monoclonal antibody

In the present report, the selective detection of sheep PrP haplotypes by monoclonal antibody 2A11 is described. It is showed that the substitution of glutamine by arginine but not by histidine at ovine PrP position 171 abolishes completely the recognition of either PrPc or PrPd by mAb 2A11, in such a way that the application of this antibody allows the unambiguous discrimination of R171 homozygotes. On the basis of the high resistance to classical scrapie and bovine spongiform encephalophaty (BSE) infection associated to the R171 PrP haplotype, animals bearing the ARR allele are currently selected within the scrapie national plan initiated in Great Britain. A 2A11-based immuno enzymatic test have been developed and evaluated using a panel of plasma and sera from sheep of different PrP genotypes and breeds. The test allows the efficient discrimination of R171 homozygotes, R171 heterozygotes and non-R171 carriers, therefore offering a rapid, cheap and easy to use alternative method to select sheep for their resistance to scrapie.