Where we stand on chronic wasting disease: A systematic literature review of its prevalence patterns, impacts, and management interventions.

With high fatality and no cure, chronic wasting disease (CWD) has infected cervids in multiple regions, including the United States, Canada, Europe, and South Korea. Despite the rapid growth of literature on CWD, the full scope of its ecological, social, and economic impacts and the most effective and socially acceptable management strategies to mitigate the disease is unclear. Of 3008 initially identified published peer-reviewed papers, 134 were included in a final systematic literature review to synthesize the current knowledge on CWD transmission patterns, impacts, and the effectiveness of management interventions. The number of publications on CWD has increased steadily since 2000 with an average of six papers per year. Most papers were related to CWD prevalence (39 %), human behavior (33 %), CWD impacts (31 %), and management interventions (16 %). Environmental factors such as soil, water, and plants were identified as the most common transmission medium, with a higher prevalence rate among adult male cervids than females. Hunters showed a higher risk perception and were more likely to change hunting behavior due to CWD detection than non-hunters. Ecological impacts included the decreased survival rate accompanied by lower population growth, eventually leading to the decline of cervid populations. Culling was found to be an effective and widely implemented management strategy across countries, although it often was associated with public resistance. Despite potentially high negative economic impacts anticipated due to CWD, studies on this subject were limited. Sustained surveillance, ongoing research, and engagement of affected stakeholders will be essential for future disease control and management.

Molecular detection of Setaria tundra (Issaitshikoff & Rajewskaya, 1928) and Setaria cervi (Rudolphi, 1819) in red deer in Slovakia.

Filaroid nematodes Setaria tundra (Issaitshikoff & Rajewskaya, 1928) and Setaria cervi (Rudolphi, 1819) are internal parasites from family Onchocercidae with occurrence in the northern hemisphere. They have a considerably wide range of final host, including many species of family Cervidae. Intermediate hosts and vectors at the same time, are represented by the several mosquito species, mostly of genus Aedes. Infection of Setaria is relatively harmless and especially in wild cervids usually pass unnoticed. Although in some cases it can induce peritonitis which might be a life threatening condition.This study was determined to reveal the presence of helminths Setaria tundra and Setaria cervi in red deer (Cervus elaphus) in Slovakia. The parasites were identified morphologically and genetically, based on the sequences of a fragment of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. For this purpose we used partial results of our longer parasitological monitoring realized in one particular hunting area located in eastern Slovakia, near the city of Kosice. A total of 60 red deer individuals were tested, of which one was found to be infected with Setaria tundra (prevalence of 1.7%) and four were detected to be infected with Setaria cervi (prevalence 6.7%). The intensity of infection was very low, only one specimen of Setaria spp. in each positive animal.

Mycobacterium kansasii Infection in a Farmed White-Tailed Deer (Odocoileus virginianus) in Florida, USA.

A 7-year-old farmed white-tailed deer doe was transported to a Levy County, Florida property and began to decline in health, exhibiting weight loss and pelvic limb weakness. The doe prematurely delivered live twin fawns, both of which later died. The doe was treated with corticosteroids, antibiotics, gastric cytoprotectants, and B vitamins but showed no improvement. The doe was euthanized, and a post mortem examination was performed under the University of Florida's Cervidae Health Research Initiative. We collected lung tissue after the animal was euthanized and performed histological evaluation, using H&E and Ziehl-Neelsen (ZN) staining, and molecular evaluation, using conventional PCR, followed by Sanger sequencing. The microscopic observations of the H&E-stained lung showed multifocal granuloma, while the ZN-stained tissue revealed low numbers of beaded, magenta-staining rod bacteria inside the granuloma formation. Molecular analysis identified the presence of Mycobacterium kansasii. This isolation of a non-tuberculous Mycobacterium in a white-tailed deer emphasizes the importance of specific pathogen identification in cases of tuberculosis-like disease in farmed and free-ranging cervids. We report the first case of M. kansasii infection in a farmed white-tailed deer (Odocoileus virginianus) in Florida. Although M. kansasii cases are sporadic in white-tailed deer, it is important to maintain farm biosecurity and prevent farmed cervids from contacting wildlife to prevent disease transmission.

Prion forensics: a multidisciplinary approach to investigate CWD at an illegal deer carcass disposal site.

Infectious prions are resistant to degradation and remain infectious in the environment for several years. Chronic wasting disease (CWD) has been detected in cervids inhabiting North America, the Nordic countries, and South Korea. CWD-prion spread is partially attributed to carcass transport and disposal. We employed a forensic approach to investigate an illegal carcass dump site connected with a CWD-positive herd. We integrated anatomic, genetic, and prion amplification methods to discover CWD-positive remains from six white-tailed deer (Odocoileus virginianus) and, using microsatellite markers, confirmed a portion originated from the CWD-infected herd. This approach provides a foundation for future studies of carcass prion transmission risk.

Drivers of geophagy by red brocket deer (Mazama americana) at Amazonian interior forest mineral licks.

Mineral licks are key ecological components of the Amazon rainforest, providing critical dietary functions for herbivorous and frugivorous mammals and birds, which help maintain the structure and function of the forest itself through seed and nutrient dispersal. One of the most frequent visitors of interior forest mineral licks in the Amazon is the red brocket deer (Mazama americana), a large-bodied ruminant frugivore and seed predator. While several hypotheses for the drivers of geophagy exist, including mineral supplementation, toxin adsorption, and habitat selection, robust data on geophagy for the red brocket deer for large numbers of mineral licks is nonexistent. We used soil data from 83 mineral licks in conjunction with camera trap data from 52 of those mineral licks and a mixed-effects modeling approach to test the three proposed hypotheses of geophagy for the red brocket deer. We found that consumed soils at mineral licks had elevated concentrations of almost all major and minor biologically active minerals measured, including Ca, Na, Mg, K, Cu, Zn, and Mn. Model results suggest that all three hypotheses hold true to some extent for the red brocket deer, with the greatest support for the mineral supplementation hypothesis, in particular with respect to Mg, Ca, Na, Cu, and Zn. This study provides critical information on the feeding ecology of the red brocket deer in the wild, and the first robust analysis of geophagy of an Amazonian mammal involving a large sample size of interior forest mineral licks.

Experimental SARS-CoV-2 Infection of Elk and Mule Deer.

To assess the susceptibility of elk (Cervus canadensis) and mule deer (Odocoileus hemionus) to SARS-CoV-2, we performed experimental infections in both species. Elk did not shed infectious virus but mounted low-level serologic responses. Mule deer shed and transmitted virus and mounted pronounced serologic responses and thus could play a role in SARS-CoV-2 epidemiology.

Toxoplasma gondii seroprevalence in reindeer (Rangifer tarandus tarandus L.) in northern Sweden: a cross-sectional study from 2014.

BACKGROUND: Toxoplasma gondii is a parasitic protozoan that can infect a wide range of warm-blooded animals, including humans. The infection with T. gondii, is of particular concern due to its potential impact on human and animal health. In Sweden, semi-domesticated reindeer (Rangifer tarandus tarandus L.) is an important species both economically and culturally, but susceptibility to Toxoplasma infection and seroprevalence in reindeer herds remain relatively understudied. RESULTS: A total of 528 reindeer, sampled at two slaughterhouses in Sweden in 2014, were investigated for antibodies to T. gondii. Specific antibodies to T. gondii were found in 5 of 209 (2.3%) tested adult reindeer and in 6 of 308 (1.9%) tested calves, giving an apparent total prevalence of 2.1% (95% confidence interval 1.1-3.8%). None of four putative risk factors studied (sex, age, type of grazing area, county) were statistically associated with T. gondii seroprevalence. CONCLUSIONS: Swedish semi-domesticated reindeer are exposed to T. gondii and may harbour infectious tissue cysts. To mitigate the risk of T. gondii infection in consumers, reindeer meat should be frozen or cooked thoroughly before consumption. The global climate change may influence the seroprevalence and possible associated risk factors for T. gondii in reindeer. To be able to manage the risk and get better advice to the consumers there is a need for further investigations covering the whole spectra of herding conditions for reindeer.

Genetic modulation of CWD prion propagation in cervid PrP Drosophila.

Chronic wasting disease is a fatal prion condition of cervids such as deer, elk, moose and reindeer. Secretion and excretion of prion infectivity from North American cervids with this condition causes environmental contamination and subsequent efficient lateral transmission in free-ranging and farmed cervids. Variants of cervid PrP exist that affect host susceptibility to chronic wasting disease. Cervid breeding programmes aimed at increasing the frequency of PrP variants associated with resistance to chronic wasting disease may reduce the burden of this condition in animals and lower the risk of zoonotic disease. This strategy requires a relatively rapid and economically viable model system to characterise and support selection of prion disease-modifying cervid PrP variants. Here, we generated cervid PrP transgenic Drosophila to fulfil this purpose. We have generated Drosophila transgenic for S138 wild type cervid PrP, or the N138 variant associated with resistance to chronic wasting disease. We show that cervid PrP Drosophila accumulate bona fide prion infectivity after exposure to cervid prions. Furthermore, S138 and N138 PrP fly lines are susceptible to cervid prion isolates from either North America or Europe when assessed phenotypically by accelerated loss of locomotor ability or survival, or biochemically by accumulation of prion seeding activity. However, after exposure to European reindeer prions, N138 PrP Drosophila accumulated prion seeding activity with slower kinetics than the S138 fly line. These novel data show that prion susceptibility characteristics of cervid PrP variants are maintained when expressed in Drosophila, which highlights this novel invertebrate host in modelling chronic wasting disease.

Oral vaccination as a potential strategy to manage chronic wasting disease in wild cervid populations.

Prion diseases are a novel class of infectious disease based in the misfolding of the cellular prion protein (PrPC) into a pathological, self-propagating isoform (PrPSc). These fatal, untreatable neurodegenerative disorders affect a variety of species causing scrapie in sheep and goats, bovine spongiform encephalopathy (BSE) in cattle, chronic wasting disease (CWD) in cervids, and Creutzfeldt-Jacob disease (CJD) in humans. Of the animal prion diseases, CWD is currently regarded as the most significant threat due its ongoing geographical spread, environmental persistence, uptake into plants, unpredictable evolution, and emerging evidence of zoonotic potential. The extensive efforts to manage CWD have been largely ineffective, highlighting the need for new disease management tools, including vaccines. Development of an effective CWD vaccine is challenged by the unique biology of these diseases, including the necessity, and associated dangers, of overcoming immune tolerance, as well the logistical challenges of vaccinating wild animals. Despite these obstacles, there has been encouraging progress towards the identification of safe, protective antigens as well as effective strategies of formulation and delivery that would enable oral delivery to wild cervids. In this review we highlight recent strategies for antigen selection and optimization, as well as considerations of various platforms for oral delivery, that will enable researchers to accelerate the rate at which candidate CWD vaccines are developed and evaluated.

The first report of Setaria tundra (Issaitshikoff & Rajewskaya, 1928) in Slovakia by using of molecular methods.

Setaria tundra is a filarioid parasite occurring in the northern hemisphere. Adult forms of helminths are located free in the peritoneal cavity of its definitive host - cervids, while microfilariae are presented in the host's bloodstream. Intermediate hosts are represented by several mosquito species, mainly of the genus Aedes.Nematode S. tundra is well adapted to roe deer (Capreolus capreolus) and therefore is the infection usually asymptomatic. In this study we present the first report of S. tundra in Slovakia. During a period 2022 a total of 6 roe deer coming from eastern Slovakia (Trebisov district) were examined. Nematodes were found during the evisceration process in the abdominal cavity of 3 specimens Intensity of infection was in range from 5 to 38 helminths per host. Mean intensity of infection reached 18.3 parasites per host. The helminths were identified as S. tundra by morphological examination and molecular typing of the COI gene. This study is the first report of S. tundra in Slovakia.

Estimating sequence diversity of prion protein gene (PRNP) in Portuguese populations of two cervid species: red deer and fallow deer.

Among the transmissible spongiform encephalopathies (TSEs), chronic wasting disease (CWD) in cervids is now a rising concern in wildlife within Europe, after the detection of the first case in Norway in 2016, in a wild reindeer and until June 2022 a total of 34 cases were described in Norway, Sweden and Finland. The definite diagnosis is post-mortem, performed in target areas of the brain and lymph nodes. Samples are first screened using a rapid test and, if positive, confirmed by immunohistochemistry and Western immunoblotting. The study of the genetics of the prion protein gene, PRNP, has been proved to be a valuable tool for determining the relative susceptibility to TSEs. In the present study, the exon 3 of PRNP gene of 143 samples from red deer (Cervus elaphus) and fallow deer (Dama dama) of Portugal was analysed. Three single nucleotide polymorphisms (SNPs) were found in red deer - codon A136A, codon T98A, codon Q226E - and no sequence variation was detected in fallow deer. The low genetic diversity found in our samples is compatible with previous studies in Europe. The comparison with results from North America suggests that the free-ranging deer from our study may present susceptibility to CWD, although lack of experimental data and the necessity of continuous survey are necessary to evaluate these populations.

Effects of immunocastration and supplementary feeding level on the performance and blood biochemical markers of farmed yearling fallow deer (Dama dama).

In cervids, blood biochemical markers may reflect changes in various physiological and environmental factors, especially in response to changes in metabolism following nutrient supplementation or the manipulation of hormone production. Decreasing androgen production through immunocastration (IC) to ease the husbandry of male animals is currently a more ethically acceptable method than physical castration, but its commercial use is unexplored in fallow deer. Forty yearlings male fallow deer were grouped into four treatment combinations: IC on high (200 g commercial pellets + 600 g concentrate mixture of 90% oats and 10% wheat grains) or low (100 g commercial pellets + 300 g concentrate mixture of 90% oats and 10% wheat grains) level of feed supplementation, or noncastrated bucks on a high or low level of feed supplementation. Immunocastrated animals were vaccinated at the start of the study (Week 1) and again during Week 3 of the study. Diet affected all body growth parameters (slaughter weight, daily gain, carcass weight, dressing percentage and body condition score). Fallow deer from all treatments showed increasing concentrations of fat and energy blood biochemical markers over the study period, including plasma glucose (GLU) and triglyceride (TRIG), and decreased cholesterol (CHOL) and lipase (LIPA) concentrations. The higher level of supplementary feeding decreased plasma albumin (ALB) and creatinine (CREA), and increased globulin (GLOB) concentrations. On the other hand, IC and lower-level supplementation reduced growth performance. Overall, IC may be an interesting tool for welfare management of yearling stags for slaughter; however, the advantage appears to only be in well-fed animals, as low-level of feeding can further reduce growth performance in immunocastrated animals. Further studies should evaluate the carcass performance of animals under similar treatment conditions to ascertain the effects on muscle and fat yields.

Characterization of Classical Sheep Scrapie in White-tailed Deer after Experimental Oronasal Exposure.

BACKGROUND: Classic scrapie is a prion disease of sheep and goats that is associated with accumulation of abnormal prion protein (PrPSc) in the central nervous and lymphoid tissues. Chronic wasting disease (CWD) is the prion disease of cervids. This study was conducted to determine the susceptibility of white-tailed deer (WTD) to the classic scrapie agent. METHODS: We inoculated WTD (n = 5) by means of a concurrent oral/intranasal exposure with the classic scrapie agent from sheep or oronasally with the classic scrapie agent from goats (n = 6). RESULTS: All deer exposed to the agent of classic scrapie from sheep accumulated PrPSc. PrPSc was detected in lymphoid tissues at preclinical time points, and necropsies in deer 28 months after inoculation showed clinical signs, spongiform lesions, and widespread PrPSc in neural and lymphoid tissues. Western blots on samples from the brainstem, cerebellum, and lymph nodes of scrapie-infected WTD have a molecular profile similar to CWD and distinct from samples from the cerebral cortex, retina, or the original classic scrapie inoculum. There was no evidence of PrPSc in any of the WTD inoculated with classic scrapie prions from goats. CONCLUSIONS: WTD are susceptible to the agent of classic scrapie from sheep, and differentiation from CWD may be difficult.

Effects of Immunocastration and Amino Acid Supplementation on Yearling Fallow Deer (Dama dama) Testes Development.

Forty-four fallow deer bucks (10 months old; 22.9 ± 2.4 kg) were utilized to investigate the effects of immunocastration and amino acid supplementation on testes development. Immunocastrated bucks were administered Improvac® at weeks 1, 8, and 20 of this study (control group: intact males). Starting at week 8, half of each sex received rumen-protected lysine and methionine (3:1) supplementation. At slaughter (week 37/39), body size, internal fat deposits, antler size parameters, testes weight, testes surface color, cauda epididymal sperm viability and morphology, and seminiferous tubule circumference and epithelium thickness were determined. Animals with larger body sizes, greater forequarter development, and antler growth also had greater testes development. Whilst the result of immunocastration on testes size is unexpected, testes tissue showed impaired development (atrophied seminiferous tubules), decreased sperm viability, and normal morphology. Testes tissue from immunocastrated deer was less red, possibly indicating reduced blood supply. Conversely, amino acid supplementation increased testes' redness and sperm viability, and intact males fed amino acids showed the greatest seminiferous tubule development. Thus, immunocastration may be a welfare-friendly alternative for venison production. Whilst the results support findings from the literature that testes size is not a reliable indicator of immunocastration success, this warrants further investigation in deer over different physiological development stages.

Wild Red Deer (Cervus elaphus) Do Not Play a Role as Vectors or Reservoirs of SARS-CoV-2 in North-Eastern Poland.

Several studies reported a high prevalence of SARS-CoV-2 among white-tailed deer in North America. Monitoring cervids in all regions to better understand SARS-CoV-2 infection and circulation in other deer populations has been urged. To evaluate deer exposure and/or infection to/by SARS-CoV-2 in Poland, we sampled 90 red deer shot by hunters in five hunting districts in north-eastern Poland. Serum and nasopharyngeal swabs were collected, and then an immunofluorescent assay (IFA) to detect anti-SARS-CoV-2 antibodies was performed as well as real-time PCR with reverse transcription for direct virus detection. No positive samples were detected. There is no evidence of spillover of SARS-CoV-2 from the human to deer population in Poland.

Agricultural land use shapes dispersal in white-tailed deer (Odocoileus virginianus).

BACKGROUND: Dispersal is a fundamental process to animal population dynamics and gene flow. In white-tailed deer (WTD; Odocoileus virginianus), dispersal also presents an increasingly relevant risk for the spread of infectious diseases. Across their wide range, WTD dispersal is believed to be driven by a suite of landscape and host behavioral factors, but these can vary by region, season, and sex. Our objectives were to (1) identify dispersal events in Wisconsin WTD and determine drivers of dispersal rates and distances, and (2) determine how landscape features (e.g., rivers, roads) structure deer dispersal paths. METHODS: We developed an algorithmic approach to detect dispersal events from GPS collar data for 590 juvenile, yearling, and adult WTD. We used statistical models to identify host and landscape drivers of dispersal rates and distances, including the role of agricultural land use, the traversability of the landscape, and potential interactions between deer. We then performed a step selection analysis to determine how landscape features such as agricultural land use, elevation, rivers, and roads affected deer dispersal paths. RESULTS: Dispersal predominantly occurred in juvenile males, of which 64.2% dispersed, with dispersal events uncommon in other sex and age classes. Juvenile male dispersal probability was positively associated with the proportion of the natal range that was classified as agricultural land use, but only during the spring. Dispersal distances were typically short (median 5.77 km, range: 1.3-68.3 km), especially in the fall. Further, dispersal distances were positively associated with agricultural land use in potential dispersal paths but negatively associated with the number of proximate deer in the natal range. Lastly, we found that, during dispersal, juvenile males typically avoided agricultural land use but selected for areas near rivers and streams. CONCLUSION: Land use-particularly agricultural-was a key driver of dispersal rates, distances, and paths in Wisconsin WTD. In addition, our results support the importance of deer social environments in shaping dispersal behavior. Our findings reinforce knowledge of dispersal ecology in WTD and how landscape factors-including major rivers, roads, and land-use patterns-structure host gene flow and potential pathogen transmission.

White-tailed deer consumption of emergent macrophytes mediates aquatic-to-terrestrial nutrient flows.

Trophic interactions between mobile animals and their food sources often vector resource flows across ecosystem boundaries. However, the quality and quantity of such ecological subsidies may be altered by indirect interactions between seemingly unconnected taxa. We studied whether emergent macrophytes growing at the aquatic-terrestrial interface facilitate multi-step aquatic-to-terrestrial resource flows between streams and terrestrial herbivores. We also explored whether aquatic animal aggregations indirectly promote such resource flows by creating biogeochemical hotspots of nutrient cycling and availability.We tested whether white-tailed deer (Odocoileus virginianus) in eastern North America vector nutrient fluxes from streams to terrestrial ecosystems by consuming emergent macrophytes (Justicia americana) using isotope and nutrient analyses of fecal samples and motion-sensing cameras. We also tested whether mussel-generated biogeochemical hotspots might promote such fluxes by surveying the density and nutrient stoichiometry of J. americana beds growing in association with variable densities of freshwater mussels (Bivalvia: Unionoida).Fecal samples from riparian deer had 3% lower C:N and 20% lower C:P ratios than those in upland habitats. C and N isotopes suggested riparian deer ate both terrestrial and aquatic (J. americana) vegetation, whereas upland deer ate more terrestrial foods. Motion-sensing cameras showed deer eating J. americana more than twice as frequently at mussel-generated hotspots than non-mussel sites. However, mussels were not associated with variation in J. americana growth or N and P content-although N isotopes in J. americana leaves did suggest assimilation of animal-derived nutrients.Our findings suggest that white-tailed deer may conduct significant transfers of aquatic-derived nutrients into terrestrial habitats when they feed on macrophytes and defecate on land. Whether aquatic animal aggregations promote such resource flows by creating biogeochemical hotspots remains unresolved, but the nearly global distributions of the deer family (Cervidae) and of macrophytes suggest that cervid-driven aquatic-to-terrestrial nutrient flows may be widespread and ecologically important.

Wintertime pharmacokinetics of intravenously and orally administered meloxicam in semi-domesticated reindeer (Rangifer tarandus tarandus).

OBJECTIVE: To investigate the pharmacokinetics of orally and intravenously (IV) administered meloxicam in semi-domesticated reindeer (Rangifer tarandus tarandus). STUDY DESIGN: A crossover design with an 11 day washout period. ANIMALS: A total of eight young male reindeer, aged 1.5-2.5 years and weighing 74.3 ± 6.3 kg, mean ± standard deviation. METHODS: The reindeer were administered meloxicam (0.5 mg kg-1 IV or orally). Blood samples were repeatedly collected from the jugular vein for up to 72 hours post administration. Plasma samples were analysed for meloxicam concentrations with ultraperformance liquid chromatography combined with triple quadrupole mass spectrometry. Noncompartmental analysis for determination of pharmacokinetic variables was performed. RESULTS: The pharmacokinetic values, median (range), were determined. Elimination half-life (t½) with the IV route (n = 4) was 15.2 (13.2-16.8) hours, the volume of distribution at steady state was 133 (113-151) mL kg-1 and clearance was 3.98 (2.63-5.29) mL hour-1 kg-1. After oral administration (n = 7), the peak plasma concentration (Cmax) was detected at 6 hours, t½ was 19.3 (16.7-20.5) hours, Cmax 1.82 (1.17-2.78) µg mL-1 and bioavailability (n = 3) 49 (46-73)%. No evident adverse effects were detected after either administration route. CONCLUSIONS AND CLINICAL RELEVANCE: A single dose of meloxicam (0.5 mg kg-1 IV or orally) has the potential to maintain the therapeutic concentration determined in other species for up to 3 days in reindeer plasma.

Cellular prion protein distribution in the vomeronasal organ, parotid, and scent glands of white-tailed deer and mule deer.

Chronic wasting disease (CWD) is a contagious and fatal transmissible spongiform encephalopathy affecting species of the cervidae family. CWD has an expanding geographic range and complex, poorly understood transmission mechanics. CWD is disproportionately prevalent in wild male mule deer and male white-tailed deer. Sex and species influences on CWD prevalence have been hypothesized to be related to animal behaviours that involve deer facial and body exocrine glands. Understanding CWD transmission potential requires a foundational knowledge of the cellular prion protein (PrPC) in glands associated with cervid behaviours. In this study, we characterized the presence and distribution of PrPC in six integumentary and two non-integumentary tissues of hunter-harvested mule deer (Odocoileus hemionus) and white-tailed deer (O. virginianus). We report that white-tailed deer expressed significantly more PrPC than their mule deer in the parotid, metatarsal, and interdigital glands. Females expressed more PrPC than males in the forehead and preorbital glands. The distribution of PrPC within the integumentary exocrine glands of the face and legs were localized to glandular cells, hair follicles, epidermis, and immune cell infiltrates. All tissues examined expressed sufficient quantities of PrPC to serve as possible sites of prion initial infection, propagation, and shedding.

First report of a strong association between genetic polymorphisms of the prion protein gene (PRNP) and susceptibility to chronic wasting disease in sika deer (Cervus nippon).

Prion diseases are incurable neurodegenerative disorders caused by proteinase K-resistant prion protein (PrPSc ) derived from normal prion protein (PrPC ) encoded by the prion protein gene (PRNP). Although the cervid PRNP gene plays a pivotal role in the pathological mechanism of chronic wasting disease (CWD), there is no existing association analysis between susceptibility to CWD and genetic polymorphisms of the PRNP gene in sika deer. We investigated genetic polymorphisms of the PRNP gene using amplicon sequencing in sika deer. In addition, to identify a genetic susceptibility factor, we compared the genotype, allele and haplotype frequencies of the PRNP gene between CWD-positive and CWD-negative sika deer. Furthermore, to assess the effect of the genetic polymorphisms on sika deer prion protein (PrP), we performed in silico analysis using PolyPhen-2, PROVEAN and AMYCO. Finally, we analysed the tertiary structure and electrostatic potential of sika deer PrP based on single nucleotide polymorphisms (SNPs) using the SWISS-MODEL and Swiss-PdbViewer programs. We found a total of 24 SNPs of the PRNP gene, including 22 novel SNPs (10 synonymous SNPs and 12 nonsynonymous SNPs), in sika deer. Among the nonsynonymous SNPs, we found a strong association of susceptibility to CWD with c.56G > A (Ser19Asn). In addition, we found that c.56G > A (Ser19Asn), c.296A > T (His99Leu) and c.560T > A (Val187Asp) were predicted to have damaging effects on sika deer PrP. Furthermore, we observed significant alterations in the electrostatic potential of sika deer PrP by genetic polymorphisms of the 187Asp allele. To the best of our knowledge, this was the first association study between genetic polymorphisms of the PRNP gene and susceptibility to CWD in sika deer.