Potential Pronghorn ( Antilocapra americana ) Susceptibility to Chronic Wasting Disease Through PRNP Sequencing

For years, Chronic Wasting Disease (CWD) has posed significant concerns for wildlife managers, public health officials, and hunters. Given the complexity of prion transmission and emergence of novel prion diseases, interfamilial transmission represents a potential challenge to CWD management. Pronghorn ( Antilocapra americana ) use similar habitats and are geographically sympatric with some CWD-susceptible cervids. However, little research has specifically focused upon pronghorn susceptibility to prion diseases, namely CWD, as their membership in a non-cervid ungulate family provides the conceptual framework to assume resistance. Yet, pronghorn are sympatric with free-ranging white-tailed deer ( Odocoileus virginianus ), elk ( Cervus canadensis ), and mule deer ( O. hemionus ) throughout their geographic range. We sequenced PRNP exon 3 in pronghorn from Texas ( n = 47) and New Mexico ( n = 28) to compare amino acid sequences of known susceptible cervids and assess if pronghorn could be susceptible to prion diseases. Pronghorn possess one additional octapeptide repeat relative to the five repeats observed in cervids, and while whole-gene phylogenetic analyses place pronghorn outside Cervidae. Pronghorn share amino acids with cervids at loci 95, 96, 116, 132, 225 and 226 – the positions most strongly associated with CWD susceptibility. At locus 173, pronghorn share the bovid residue (serine) rather than the cervid residue (asparagine), further illustrating that pronghorn occupy a genuinely intermediate molecular position between these lineages. Although no CWD-positive pronghorn detections have been reported in the literature, the assumption of resistance based on taxonomic placement is not supported by site-specific sequence data, and this study provides a molecular basis for reassessing that assumption.