PRNP and variant Creutzfeldt-Jakob disease: Mice that express the PrP allele with M (tg35 and tg45 lines) or V (valine; tg152 line) at codon-129 at supra-physiological levels, while exhibiting a greatly enhanced susceptibility to sCJD compared to wild-type mice, produced a complex pattern of transmission upon BSE or vCJD challenge.