LAUSR

Significance Amino acid substitutions within the cervid prion protein (PrP) can decrease susceptibility to chronic wasting disease, generally with more prominent effects in homozygous animals. Using novel gene-targeted mouse models expressing S138N reindeer/caribou PrP, we demonstrate subclinical infection with prion seeding activity in spleen and fecal prion shedding in heterozygous 138SN and homozygous 138NN mice. A lower percentage of heterozygous 138SN-PrP than homozygous 138NN-PrP expressing mice harbored seeding-efficient prions in tissues. This is caused by dominant-negative interference of the PrP variants occurring only if they are coexpressed. Our findings are relevant to inform conservation efforts for caribou, an endangered species in North America. Furthermore, our study provides new mechanistic insights into genetic resistance and dominant-negative interference of conversion-competent PrP variants.