Surveillance and prevalence of potential disease in pronghorn (Antilocapra americana) and mule deer (Odocoileus hemionus) in the Texas Panhandle
Prion diseases such as Chronic Wasting Disease (CWD) are a concern to wildlife managers, public health officials, and the public. Given the complexity of prion transmission, and history of spontaneous generation of novel prion diseases, the possibility of interfamilial transmission has become a concern. Pronghorn (Antilocapra americana) utilize similar habitat as susceptible Cervids and occur within the endemic CWD area of Colorado and Wyoming. However, to date, there has been no research on pronghorn susceptibility to prion diseases including CWD, as they have been assumed to be resistant. In Texas, pronghorn occur in portions of both the Texas Panhandle and the Trans-Pecos regions, which both contain Texas Parks and Wildlife Department CWD surveillance zones. Our goal was to sequence the prion protein gene, PRNP, exon 3 in pronghorn from Texas and New Mexico to compare to amino acid sequences of known susceptible Cervids and assess if pronghorn could be susceptible to prion diseases. We also aimed to gain a better understanding of the evolution of PRNP in pronghorn. We amplified and sequenced PRNP from 45 individuals from Texas (including intra-state translocated individuals) and 28 individuals from New Mexico using standard PCR techniques. Phylogenetic analyses, including dated trees, were utilized to assess the evolution of PRNP in pronghorn. Our research identified that pronghorn have one additional octapeptide repeat, for a total of 6, rather than the 5 peptide repeats present in Cervids. Additionally, pronghorn share similarities to Cervid genotypes characterized by codons 95, 96, 116, 132, 225 and 226, indicating that pronghorn possess all the amino acids correlated with greater susceptibility to prion diseases in Cervids. Dated divergence analysis indicated that pronghorn PRNP diverged from taxa with known prion diseases (sheep, deer, and cattle) approximately 1.78 mya. Bovine viral diarrheal viruses are enveloped, single-stranded RNA virus and are members of the family Flaviviridae, genus Pestivirus. Known to have severe economic impacts on the cattle industry through respiratory disease and reproductive losses while also being known to also cause digestive disease., bovine viral diarrhea virus (BVDV) has been documented in many western states to spill over into various wildlife species. These species include bighorn sheep (Ovis canadensis), mountain goat (Oreamnos americanus), mule deer (Odocoileus hemionus), elk (Cervus elaphus), moose (Alces alces), bison (Bison bison), caribou (Rangifer tarandus), and pronghorn (Antilocapra americana). As such, the impacts of this virus on wildlife are largely unknown. Introduction of BVDV to free-ranging ruminant populations likely seems to stem from contact with cattle and various studies have demonstrated that BVDV is likely endemic in some North American wildlife populations. The Texas Panhandle is known to produce nearly 50% of finished beef in the U.S., with approximately 2.35 million head of cattle across 26 counties. Pronghorn and mule deer are known to be sympatric, free-ranging ungulate species which utilize agricultural fields during winter and times of low forage availability. During these times, pronghorn and mule deer are at increased proximity and increased risk of contact with cattle, and therefore at increased risk for transmission of zoonoses among cattle, pronghorn, and mule deer. The study herein aims to attempt to detect BVDV in serum samples collected from free-ranging pronghorn and mule deer in the Texas Panhandle utilizing the RT-PCR and Antigen-Capture ELISA techniques in cooperation with the Texas Veterinary Medical Diagnostic Laboratory. While BVDV was not detected in any sample, the importance of screening wildlife species for potential diseases which may have spilled over from cattle in areas of high cattle density remains an important objective of further study in the Texas Panhandle.