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.

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.

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.

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.

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.

Infection and transmission of ancestral SARS-CoV-2 and its alpha variant in pregnant white-tailed deer

ABSTRACTSARS-CoV-2 was first reported circulating in human populations in December 2019 and has since become a global pandemic. Recent history involving SARS-like coronavirus outbreaks have demonstrated the significant role of intermediate hosts in viral maintenance and transmission. Evidence of SARS-CoV-2 natural infection and experimental infections of a wide variety of animal species has been demonstrated, and in silico and in vitro studies have indicated that deer are susceptible to SARS-CoV-2 infection. White-tailed deer (WTD) are amongst the most abundant and geographically widespread wild ruminant species in the US. Recently, WTD fawns were shown to be susceptible to SARS-CoV-2. In the present study, we investigated the susceptibility and transmission of SARS-CoV-2 in adult WTD. In addition, we examined the competition of two SARS-CoV-2 isolates, representatives of the ancestral lineage A and the alpha variant of concern (VOC) B.1.1.7 through co-infection of WTD. Next-generation sequencing was used to determine the presence and transmission of each strain in the co-infected and contact sentinel animals. Our results demonstrate that adult WTD are highly susceptible to SARS-CoV-2 infection and can transmit the virus through direct contact as well as vertically from doe to fetus. Additionally, we determined that the alpha VOC B.1.1.7 isolate of SARS-CoV-2 outcompetes the ancestral lineage A isolate in WTD, as demonstrated by the genome of the virus shed from nasal and oral cavities from principal infected and contact animals, and from the genome of virus present in tissues of principal infected deer, fetuses and contact animals.

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.

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.

Novel adenovirus associated with necrotizing bronchiolitis in a captive reindeer (Rangifer tarandus)

Adenoviruses cause a range of major diseases across many diverse animal species including ruminants. They are classified into six genera in the family Adenoviridae. In deer species, two adenoviruses are currently recognized: deer adenovirus 1 in the Atadenovirus genus, and deer adenovirus 2 in the Mastadenovirus genus. Deer adenovirus 1 causes adenovirus haemorrhagic disease with high fatality in black-tailed and mule deer in North America. Conversely, deer adenovirus 2 was incidentally detected from a healthy white-tailed deer fawn, but experimentally it has been shown to cause pyrexia, cough and moderate to severe haemorrhage. Here, we detected a novel adenovirus, reindeer adenovirus 1, from lung lesions of a 5-year-old male reindeer (Rangifer tarandus). This animal presented with aspiration pneumonia and necrotizing bronchiolitis following a period of clinical weakness, nasal discharge and wasting. Histopathological examination of the lung revealed large intranuclear basophilic inclusions associated with the areas of necrotizing bronchiolitis. Next generation sequencing of the lung tissue identified a novel mastadenovirus with close similarity to deer adenovirus 2 and bovine adenovirus 3. To our knowledge, this is the first report of a deer mastadenovirus associated with necrotizing bronchiolitis in captive reindeer.

Determination of the Discriminating Concentration Towards Permethrin for Surveying Resistance in Amblyomma americanum

Amblyomma americanum Linnaeus (Ixodida: Ixodidae) is ubiquitously present throughout the southeastern United States and is capable of vectoring several pathogens. White-tailed deer are the main host for adult A. americanum. However, this tick species is a generalist that will feed on most vertebrates, including humans, deer, livestock, and pets. Management of this species can be challenging due to a lack of cost-effective strategies. Acaricides are often utilized, however, this may lead to pesticide resistance. The Food and Agriculture Organization of the United Nations (FAO) larval packet test (LPT) was performed on susceptible A. americanum to determine the lethal concentration (LC) and discriminating concentration (DC) values for permethrin. The FAO LPT was used at these pre-established values to compare levels of resistance in ticks collected from a captive deer farm and wild areas representing high and low permethrin exposure settings, respectively. Resistance ratios (RR) calculated from the LC values for the ticks collected from farmed and wild deer ranged between 1 and 2. A. americanum collected from farmed and wild deer were not found to be resistant, however, some samples had slightly elevated RRs as compared to the susceptible laboratory strain, which may suggest tolerance development. Although the A. americanum sampled in this study were not resistant to permethrin, the DC calculated in this study will allow for rapid evaluation of resistance in a permethrin resistance monitoring program such that alternate management strategies can be adopted if resistance is detected.

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

Prion diseases are incurable neurodegenerative disorders caused by proteinase K-resistant prion protein (PrP^Sc ) derived from normal prion protein (PrP^C ) 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 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 analyzed 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 non-synonymous SNPs) in sika deer. Among the non-synonymous SNPs, we found a strong association of the 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. This article is protected by copyright. All rights reserved.

Using retrospective life tables to assess the effect of extreme climatic conditions on ungulate demography

In Mediterranean areas, severe drought events are expected to intensify in forthcoming years as a consequence of climate change. These events may increase physiological and reproductive stress of wild populations producing demographic changes and distribution shifts. We used retrospective life tables to understand demographic changes on a wild population after severe drought events. We studied the impact of two extreme events (2003 and 2005) on the population dynamics of our model species, the red deer (Cervus elaphus). During both years, population density was high (40 and 36 ind/100 ha, respectively). Thus, we reconstructed retrospectively the age structure of the female part of the population for the period 2000-2010 by using data of known-age individuals culled during the period 2000-2019 (n = 4176). Also, based on previous study results, we aimed to validate this methodology. Both extremely dry years, 2003 and 2005, produced marked and lasting cohort effects on population demography. Age pyramid the following years (2004 and 2006) revealed that the extreme drought caused the female fawn cohort to be similar or even smaller than the yearling cohort. Furthermore, these cohort effects were still perceptible 3 years after these severe events. Results agree with previous findings that showed a negative effect of severe drought events on female pregnancy rates and conception dates. Although simple, this study provides an empirical quantification of the demographic effects of severe drought events for a wild population which might be useful to understand future demographic changes under the context of climate change.

Artificial Reproductive Technology (ART) Applied to Female Cervids Adapted from Domestic Ruminants

There are about 150 Cervidae species on the IUCN Red List of Threatened Species. Only a small part is counted among farm animals, and most of them are free roaming. The universality and large numbers of representatives of cervids such as red deer (Cervus elaphus) and roe deer (Capreolus capreolus) may predispose these species to be used as models for research on reintroduction or assisted reproduction of deer at risk of extinction. We outlined the historical fluctuation of cervids in Europe and the process of domestication, which led to breeding management. Consequently, the reproductive techniques used in domestic ruminants were adapted for use in female deer which we reviewed based on our results and other available results. We focused on stress susceptibility in cervids depending on habitat and antropopression and proposed copeptin as a novel diagnostic parameter suitable for stress determination. Some reproductive biotechniques have been adopted for female cervids with satisfactory results, e.g., in vitro fertilization, while others still require methodological refinement, e.g., cryopreservation of oocytes and embryos.

Polymorphisms of the prion-related protein gene are strongly associated with cervids' susceptibility to chronic wasting disease

BACKGROUND

Chronic wasting disease (CWD) is a cervid prion disease that is caused by abnormal prion protein (PrP^Sc ). Recent studies have reported that prion family genes showed a strong association with the susceptibility of several types of prion diseases. To date, an association study of the prion-related protein gene (PRNT) has not been performed in any type of cervid prion disease.

METHODS

In the present study, we investigated PRNT polymorphisms in large deer, including 235 elk, 257 red deer and 150 sika deer. We compared genotype, allele and haplotype frequencies of PRNT polymorphisms between CWD-negative animals and CWD-positive animals to find an association of PRNT polymorphisms with the susceptibility of CWD.

RESULTS

We found a total of five novel single nucleotide polymorphisms (SNPs) in the cervid PRNT gene. Interestingly, we observed significantly different distributions of genotypes and allele frequencies of three PRNT SNPs, including c.108C>T, c.159+30C>T and c.159+32A>C, between CWD-negative and CWD-positive red deer. In addition, significant differences of two haplotype frequencies in red deer were found between the CWD-negative and CWD-positive groups. However, the association identified in the red deer was not found in elk and sika deer.

CONCLUSION

To the best of our knowledge, this report is the first to describe the strong association of PRNT SNPs with the susceptibility of CWD.

Androgen and oestrogen receptors in the growing antlers velvet of adult and yearling pampas deer (Ozotoceros bezoarticus) males

To determine the presence, quantity and distribution of androgen (AR) and oestrogen receptors (ER) in the antler velvet (AV), samples were collected from adult and yearling pampas deer males, as well as skin from the ventrolateral abdominal area (ASK). Samples were analysed with ligand-binding assays for AR and ER activity and processed for AR and ERβ immunohistochemistry. There was more content of AR in adults than in yearling males (p = 0.02), as well as a category and type of tissue interaction (p = 0.03). There was more ER content in adults than in yearling males (p = 0.005) and in the AV than in the skin (p = 0.0001). The AR-positive score (PS) was greater in AV than in ASK in the surface stroma (p = 0.0007). In the intermediate epidermis, the AR PS was greater in adults than in yearling males (p = 0.04) and in the ASK than in the AV (p < 0.0001). There was a male category and type of tissue interaction for AR PS in the sebaceous glands (p = 0.014). The ERβ PS in the surface stroma was greater in ASK than in AV (p = 0.004) and tended to be greater in yearling than in adult males (p = 0.093). The ERβ PS in the intermediate epithelium and the sebaceous glands was greater in adults than in yearlings (p = 0.004 and p = 0.007, respectively). In conclusion, we reported for the first time the presence of AR and ER in the velvet skin of growing antlers in pampas deer males. Therefore, the velvet skin is sensitive to both androgens and oestrogens. Furthermore, the greater content of oestrogen receptors in the velvet of adult males suggests that adults are more sensitive to this hormone than yearlings, and thus, oestrogens have greater importance in velvet activity regulation in adult males.

Exploitative Competition between Mountain Hare and Moose-Qualitative Effects on Hare Winter Forage?

Simple Summary

Mountain hares in Scandinavia are classified as Near Threatened in the Norwegian and Swedish Redlists assessing the risk of species extinction. This is due to a possible population decline witnessed during the last decades in Scandinavia. Competition between large herbivores such as moose, red deer, roe deer on one hand and hares on the other, is one of several hypotheses that has been put forward to explain this decline. In a cafeteria trial (providing several types of forage to determine food preference) we investigate the effects of previous moose winter foraging on the food selection (i.e., amount consumed, bites per minute and bitediameter) of downy birch and goat willow by captive hares. We find that hares do not differentiate among levels of previous moose foraging on downy birch but have larger bite diameters of goat willow earlier eaten on by moose, compared to plants not fed on by moose. Thus, effects of moose on hare winter food quality seem to be limited. We highlight the need for studies focusing on (1) effects of previous moose foraging using wild hares in a natural experimental design, and (2) effects of moose foraging on available hare food at a landscape scale during winter.

Abstract

Mountain hares (Lepus timidus) in Scandinavia are classified as Near Threatened in the Norwegian and Swedish Redlists. This is due to a possible population decline witnessed during the last decades in Scandinavia. Competition between large herbivores and mountain hares is one of several hypotheses that has been put forward to explain this decline. In a cafeteria trial we investigate the effects of previous moose (Alces alces) winter browsing on the food selection (i.e., biomass consumed, bites per minute and bitediameter) of downy birch (Betula pubescens) and goat willow (Salix caprea) by captive mountain hares. We find that mountain hares do not differentiate among previous browsing levels of downy birch, but have larger bite diameters of goat willow earlier browsed by moose, compared to non-browsed plants. Thus, effects of moose on mountain hare winter food quality seem to be limited. We highlight the need for studies focusing on (1) qualitative effects of moose browsing using wild mountain hares in a natural experimental design, and (2) quantitative effects of moose browsing on available mountain hare forage at a landscape scale during winter.

Infection and transmission of SARS-CoV-2 and its alpha variant in pregnant white-tailed deer

SARS-CoV-2, a novel Betacoronavirus, was first reported circulating in human populations in December 2019 and has since become a global pandemic. Recent history involving SARS-like coronavirus outbreaks (SARS-CoV and MERS-CoV) have demonstrated the significant role of intermediate and reservoir hosts in viral maintenance and transmission cycles. Evidence of SARS-CoV-2 natural infection and experimental infections of a wide variety of animal species has been demonstrated, and in silico and in vitro studies have indicated that deer are susceptible to SARS-CoV-2 infection. White-tailed deer (Odocoileus virginianus) are amongst the most abundant, densely populated, and geographically widespread wild ruminant species in the United States. Human interaction with white-tailed deer has resulted in the occurrence of disease in human populations in the past. Recently, white-tailed deer fawns were shown to be susceptible to SARS-CoV-2. In the present study, we investigated the susceptibility and transmission of SARS-CoV-2 in adult white-tailed deer. In addition, we examined the competition of two SARS-CoV-2 isolates, representatives of the ancestral lineage A (SARS-CoV-2/human/USA/WA1/2020) and the alpha variant of concern (VOC) B.1.1.7 (SARS-CoV-2/human/USA/CA_CDC_5574/2020), through co-infection of white-tailed deer. Next-generation sequencing was used to determine the presence and transmission of each strain in the co-infected and contact sentinel animals. Our results demonstrate that adult white-tailed deer are highly susceptible to SARS-CoV-2 infection and can transmit the virus through direct contact as well as vertically from doe to fetus. Additionally, we determined that the alpha VOC B.1.1.7 isolate of SARS-CoV-2 outcompetes the ancestral lineage A isolate in white-tailed deer, as demonstrated by the genome of the virus shed from nasal and oral cavities from principal infected and contact animals, and from virus present in tissues of principal infected deer, fetuses and contact animals.

Chronic Wasting Disease Transmission Risk Assessment for Farmed Cervids in Minnesota and Wisconsin

CWD (chronic wasting disease) has emerged as one of the most important diseases of cervids and continues to adversely affect farmed and wild cervid populations, despite control and preventive measures. This study aims to use the current scientific understanding of CWD transmission and knowledge of farmed cervid operations to conduct a qualitative risk assessment for CWD transmission to cervid farms and, applying this risk assessment, systematically describe the CWD transmission risks experienced by CWD-positive farmed cervid operations in Minnesota and Wisconsin. A systematic review of literature related to CWD transmission informed our criteria to stratify CWD transmission risks to cervid operations into high-risk low uncertainty, moderate-risk high uncertainty, and negligible-risk low uncertainty categories. Case data from 34 CWD-positive farmed cervid operations in Minnesota and Wisconsin from 2002 to January 2019 were categorized by transmission risks exposure and evaluated for trends. The majority of case farms recorded high transmission risks (56%), which were likely sources of CWD, but many (44%) had only moderate or negligible transmission risks, including most of the herds (62%) detected since 2012. The presence of CWD-positive cervid farms with only moderate or low CWD transmission risks necessitates further investigation of these risks to inform effective control measures.

Spatio-temporal analyses reveal infectious disease-driven selection in a free-ranging ungulate

Infectious diseases play an important role in wildlife population dynamics by altering individual fitness, but detecting disease-driven natural selection in free-ranging populations is difficult due to complex disease-host relationships. Chronic wasting disease (CWD) is a fatal infectious prion disease in cervids for which mutations in a single gene have been mechanistically linked to disease outcomes, providing a rare opportunity to study disease-driven selection in wildlife. In Wyoming, USA, CWD has gradually spread across mule deer (Odocoileus hemionus) populations, producing natural variation in disease history to evaluate selection pressure. We used spatial variation and a novel temporal comparison to investigate the relationship between CWD and a mutation at codon 225 of the mule deer prion protein gene that slows disease progression. We found that individuals with the 'slow' 225F allele were less likely to test positive for CWD, and the 225F allele was more common in herds exposed to CWD longer. We also found that in the past 2 decades, the 225F allele frequency increased more in herds with higher CWD prevalence. This study expanded on previous research by analysing spatio-temporal patterns of individual and herd-based disease data to present multiple lines of evidence for disease-driven selection in free-ranging wildlife.

PREVALENCE OF PARELAPHOSTRONGYLUS ANDERSONI IN WHITE-TAILED DEER, OTHER CERVIDS, AND BOVIDS IN NORTHERN FLORIDA

Parelaphostrongylus andersoni, the muscleworm, commonly infects white-tailed deer (Odocoileus virginianus) and also infects caribou (Rangifer tarandus [R.t.] groenlanicus, R.t. grantii, R.t. tarandus, and R.t. caribou). Heavy infection with P. andersoni leads to weakness in the hindquarters, abnormal gait, and pulmonary lesions. The geographical range and full host spectrum of this parasite are not fully known. This study aims to understand host specificity better, especially in nonnative cervids and bovids. This study involved the collection of 140 fecal samples from native and nonnative cervid and bovid species, and 34 snail specimens. With the use of real-time PCR, we found 4/47 (8.5%) O. virginianus fecal samples were positive for P. andersoni. No previously undocumented species of cervids or bovids were found to be infected. Further research is warranted to understand P. andersoni range, host distribution, and potential impact on host health.

Cervid Prion Protein Polymorphisms: Role in Chronic Wasting Disease Pathogenesis

Chronic wasting disease (CWD) is a prion disease found in both free-ranging and farmed cervids. Susceptibility of these animals to CWD is governed by various exogenous and endogenous factors. Past studies have demonstrated that polymorphisms within the prion protein (PrP) sequence itself affect an animal's susceptibility to CWD. PrP polymorphisms can modulate CWD pathogenesis in two ways: the ability of the endogenous prion protein (PrP^C) to convert into infectious prions (PrP^Sc) or it can give rise to novel prion strains. In vivo studies in susceptible cervids, complemented by studies in transgenic mice expressing the corresponding cervid PrP sequence, show that each polymorphism has distinct effects on both PrP^C and PrP^Sc. It is not entirely clear how these polymorphisms are responsible for these effects, but in vitro studies suggest they play a role in modifying PrP epitopes crucial for PrP^C to PrP^Sc conversion and determining PrP^C stability. PrP polymorphisms are unique to one or two cervid species and most confer a certain degree of reduced susceptibility to CWD. However, to date, there are no reports of polymorphic cervid PrP alleles providing absolute resistance to CWD. Studies on polymorphisms have focused on those found in CWD-endemic areas, with the hope that understanding the role of an animal's genetics in CWD can help to predict, contain, or prevent transmission of CWD.

Functional limb anatomy in a refugee species: The endangered Patagonian huemul deer (Hippocamelus bisulcus)

Early naturalists already considered huemul rare, refuged and a stocky, short-legged mountain deer, 163 years before declared endangered (1972). Anatomically, huemul do not overlap with rock-climbers previously considered analogous, as corroborated in this paper by including additional huemul cases. Assertions that population declines are caused principally via livestock infections remain unfounded. Instead, osteopathology in multiple populations across 1,000 km, affecting 57% among dead and 86% among live specimens, may relate to micronutrient deficiencies. Historically classified a mountain deer, widespread osteopathology, micronutrient deficiencies and lack of recovery qualify huemul as a refugee species. Recovery strategies thus must include repopulating historical distribution sites.

Granulomatous Inflammation of the Muzzle in White-Tailed Deer (Odocoileus virginianus) and Mule Deer (Odocoileus hemionus) Associated With Mannheimia granulomatis

Since 2002, reports of deer with swollen muzzles from throughout the United States have resulted in significant interest by wildlife biologists and wildlife enthusiasts. The condition was identified in 25 white-tailed deer (Odocoileus virginianus) and 2 mule deer (O. hemionus). Microscopic lesions consisted of severe, granulomatous or pyogranulomatous inflammation of the muzzle, nasal planum, and upper lip, as well as similar but less severe inflammation of the hard palate. Lymphadenitis of regional lymph nodes was common and granulomatous pneumonia was present in one individual. Splendore-Hoeppli material was typical in the center of inflammatory foci. Other than the single instance of pneumonia, systemic disease was not evident. Various bacterial species were isolated in culture, most of which were not morphologically consistent with the colonies of small, gram-negative bacteria observed in the center of the granulomas. Amplification and sequencing of the bacterial 16S rRNA gene from tissues of affected deer resulted in the identification of Mannheimia granulomatis. Laser capture microdissection was used to confirm that the colonies in the inflammatory foci were M. granulomatis. The cases described here are reminiscent of a bovine disease in Brazil and Argentina, locally called lechiguana. Although the inflammation of lechiguana is mostly truncal, the microscopic lesions are very similar and are also attributed to M. granulomatis. It is unclear if this is an emerging infectious disease of deer, or if it is a sporadic, uncommon condition that has only recently been recognized.

Adult and yearling pampas deer stags (Ozotoceros bezoarticus) display mild reproductive seasonal patterns with maximum values in autumn

The pampas deer is an endangered species, from which reproductive biology little is known. We aimed to describe and compare the reproductive seasonal patterns of adult and yearling pampas deer stags throughout the year, including morphological traits, testosterone concentration, sperm morphology and cryoresistance pattern changes. Six adult (AS) and five yearling (YS) stags were captured with anesthetic darts once in winter, spring, summer and autumn to study morphological variables, serum testosterone and semen. Adult males were heavier, their neck girth tended to be greater and their testosterone concentration was higher than in YS. Animals were heavier in summer and autumn. Neck girth and testosterone concentration were greater in autumn. Scrotal circumference, testicular volume and gonado-somatic index varied with seasons, decreasing from winter to spring, increasing in summer and remaining in greater values in autumn. Sperm quality had maximum values from summer to winter. However, the cryoresistance ratio of motility score was greater in spring. In conclusion, in the captivity conditions, pampas deer stags seems to present a light seasonal reproductive pattern, with maximum testis size, testosterone secretion and fresh semen quality in autumn. Nevertheless, sperm cryoresistance ratio seemed to remain stable along the year. Although YS were still growing, they achieved similar semen quality than AS.

An Agouti-Signaling-Protein Mutation is Strongly Associated with Melanism in European Roe Deer (Capreolus capreolus)

Although the European roe deer (Capreolus capreolus) population of North-West Germany has a remarkable number of melanistic specimens between 10% and 25%, the underlying genetic mutation-causing melanism is still unknown. We used a gene targeting approach focusing on MC1R and ASIP as important genes of coat coloration. Overall, 1384 bp of MC1R and 2039 bp of ASIP were sequenced in 24 specimens and several SNPs were detected. But only the ASIP-SNP c.33G>T completely segregated both phenotypes leading to the amino acid substitution p.Leu11Phe. The SNP was further evaluated in additional 471 samples. Generally, all black specimens (n = 33) were homozygous TT, whereas chestnut individuals were either homozygote GG (n = 436) or heterozygote GT (n = 26). Considering the fact that all melanistic animals shared two mutated alleles of the strongly associated SNP, we concluded that melanism is inherited in a recessive mode in European roe deer.

Aggressive interactions among female, semi-captive pampas deer (Ozotoceros bezoarticus) increase within the hierarchy and after short-term removal of the male

Two trials were carried out to determine: (a) if there is a positive relation between the frequency of aggressive interactions among female pampas deer and their position within the hierarchy (HI), (b) if short-term removal of the male triggers an increase in the frequency of aggression, and (c) if the magnitude of this increase is related to the individual rank position of the female. Each of 19 breeding groups comprised one adult male and from four to six adult females. The HI was determined for each female and all aggressive interactions were recorded. These were recorded while the male was present (i.e., all of Trial 1 and the "with male" period in Trial 2) and after removal of the male (i.e., the "without male" period in Trial 2). The individual percentage change in the frequency of aggressive interactions after male removal was calculated. In Trial 1 the HI, the frequency of different types of aggressive interaction and the total of aggressive interactions were positively related (all: p < .001; General Linear Mixed Model [GLMM]). In Trial 2, the frequency of total aggressive interactions increased after male removal (F(1, 27) = 3.5; p < .001; GLMM). The individual percentage changes in aggressive interaction between periods were positively related to HI (F(6, 24) = 2.56; p = .05; GLMM). For female pampas deer maintained in breeding groups, we conclude that the frequency of aggressive interactions increases within the hierarchy. Aggression also increases after the short-term removal of the male, mainly among females of higher social status.

Partnering with Taxidermists for Improved Chronic Wasting Disease Surveillance

Simple Summary

Chronic wasting disease (CWD) is a contagious neurological disease affecting deer, moose, elk, and reindeer. CWD is predominantly found in North America and has a higher prevalence in older male deer. To increase the submission of samples from older male deer, the Taxidermy Partnership Program (TPP) was implemented in New York State (NYS). This program partners with taxidermists to obtain valuable samples that would otherwise be lost and helps raise awareness about CWD. Since its start, the TPP has been successful in increasing the number of older male deer submitted for CWD testing.

Abstract

Chronic wasting disease (CWD) is a neurodegenerative disease of cervids caused by a misfolded protein called a prion. This disease affects captive and free-ranging deer, moose, elk, and reindeer, and has been detected in 26 states. Cervids infected with CWD may be asymptomatic for months or years. In most areas, older male deer have higher prevalence rates. Prior to 2013, CWD surveillance in New York State focused on testing samples of convenience, by collecting deer heads from meat processors. However, this sampling was biased because many of the heads from older male deer were taken to taxidermists to be mounted. In 2013, the Taxidermy Partnership Program (TPP) was created to train taxidermists to collect CWD samples, and to increase the proportion of older male deer submitted for CWD testing. Added benefits include improved communication with taxidermists and increased awareness about CWD. Trained taxidermists were able to successfully collect and submit tissue samples with few errors. Participating taxidermists were paid for viable samples. Currently, there is a stable number of taxidermists that participate each year. This program has proven to be a valuable resource for obtaining high-value CWD samples for the wildlife agency, requiring a minimal amount of funding and time.

Novel Type of Chronic Wasting Disease Detected in Moose (Alces alces), Norway

Chronic wasting disease (CWD) persists in cervid populations of North America and in 2016 was detected for the first time in Europe in a wild reindeer in Norway. We report the detection of CWD in 3 moose (Alces alces) in Norway, identified through a large scale surveillance program. The cases occurred in 13-14-year-old female moose, and we detected an abnormal form of prion protein (PrP^Sc) in the brain but not in lymphoid tissues. Immunohistochemistry revealed that the moose shared the same neuropathologic phenotype, characterized by mostly intraneuronal deposition of PrP^Sc. This pattern differed from that observed in reindeer and has not been previously reported in CWD-infected cervids. Moreover, Western blot revealed a PrP^Sc type distinguishable from previous CWD cases and from known ruminant prion diseases in Europe, with the possible exception of sheep CH1641. These findings suggest that these cases in moose represent a novel type of CWD.

Whole Genome Sequencing of Mycobacterium bovis Isolated From Livestock in the United States, 1989-2018

The United States official bovine tuberculosis (bTB) eradication program has utilized genotyping for Mycobacterium bovis isolates since 2000 and whole genome sequencing was implemented in 2013. The program has been highly successful, yet as bTB prevalence has reached historic lows, a small number of new bTB-affected cattle herds occur annually. Therefore, understanding the epidemiology of bTB transmission is critically important, in order to target limited resources for surveillance and achieve eradication. This evaluation described the diversity and epidemiology of M. bovis isolates identified in the USA livestock. Isolates from animals within the bTB endemic area of Michigan were excluded. Broad diversity was found among 1,248 isolates, collected from affected cattle and farmed cervids herds and fed cattle during 1989–2018. Nearly 70% of isolates from 109 herds/cases during 1999–2018 were European clonal complex 1 and 30% were European clonal complex 2. The sources of infection based on the herd investigation were known for 41% of herds/cases and 59% were not epidemiologically linked to another USA origin herd. Whole genome sequencing results were consistent with the investigation findings and previously unrecognized links between herds and cases were disclosed. For herds/cases with an unknown source of infection, WGS results suggested several possible sources, including undocumented cattle movement, imported cattle and humans. The use of WGS in new cases has reduced the time and costs associated with epidemiological investigations. Within herd SNP diversity was evaluated by examining 18 herds with 10 or more isolates sequenced. Forty percent of isolates had not diverged or accumulated any SNPs, and 86% of the isolates had accumulated 3 or fewer SNPs. The results of WGS does not support a bTB reservoir in USA cattle. The bTB eradication program appears to be highly effective as the majority of herds/cases in the USA are unique strains with limited herd to herd transmission.

Spatial correlations between browsing on balsam fir by white-tailed deer and the nutritional value of neighboring winter forage

Associational effects, that is, the influence of neighboring plants on herbivory suffered by a plant, are an outcome of forage selection. Although forage selection is a hierarchical process, few studies have investigated associational effects at multiple spatial scales. Because the nutritional quality of plants can be spatially structured, it might differently influence associational effects across multiple scales. Our objective was to determine the radius of influence of neighbor density and nutritional quality on balsam fir (Abies balsamea) herbivory by white-tailed deer (Odocoileus virginianus) in winter. We quantified browsing rates on fir and the density and quality of neighboring trees in a series of 10-year-old cutovers on Anticosti Island (Canada). We used cross-correlations to investigate relationships between browsing rates and the density and nutritional quality of neighboring trees at distances up to 1,000 m. Balsam fir and white spruce (Picea glauca) fiber content and dry matter in vitro true digestibility were correlated with fir browsing rate at the finest extra-patch scale (across distance of up to 50 m) and between cutover areas (300-400 m). These correlations suggest associational effects, that is, low nutritional quality of neighbors reduces the likelihood of fir herbivory (associational defense). Our results may indicate associational effects mediated by intraspecific variation in plant quality and suggest that these effects could occur at scales from tens to hundreds of meters. Understanding associational effects could inform strategies for restoration or conservation; for example, planting of fir among existing natural regeneration could be concentrated in areas of low nutritional quality.

Differential effects of divalent cations on elk prion protein fibril formation and stability

Misfolding of the normally folded prion protein of mammals (PrP^C) into infectious fibrils causes a variety of diseases, from scrapie in sheep to chronic wasting disease (CWD) in cervids. The misfolded form of PrP^C, termed PrP^Sc, or in this case PrP^CWD, interacts with PrP^C to create more PrP^CWD. This process is not clearly defined but is affected by the presence and interactions of biotic and abiotic cofactors. These include nucleic acids, lipids, glycosylation, pH, and ionic character. PrP^C has been shown to act as a copper-binding protein in vivo, though it also binds to other divalents as well. The significance of this action has not been conclusively elucidated. Previous reports have shown that metal binding sites occur throughout the N-terminal region of PrP^C. Other cations like manganese have also been shown to affect PrP^C abundance in a transcript-independent fashion. Here, we examined the ability of different divalent cations to influence the stability and in vitro conversion of two variants of PrP from elk (L/M132, 26-234). We find that copper and zinc de-stabilize PrP. We also find that PrP M132 exhibits a greater degree of divalent cation induced destabilization than L132. This supports findings that leucine at position 132 confers resistance to CWD, while M132 is susceptible. However, in vitro conversion of PrP is equally suppressed by either copper or zinc, in both L132 and M132 backgrounds. This report demonstrates the complex importance of ionic character on the PrP^C folding pathway selection on the route to PrP^Sc formation.

Horizontal Transmission of Chronic Wasting Disease in Reindeer

We challenged reindeer by the intracranial route with the agent of chronic wasting disease sourced from white-tailed deer, mule deer, or elk and tested for horizontal transmission to naive reindeer. Reindeer were susceptible to chronic wasting disease regardless of source species. Horizontal transmission occurred through direct contact or indirectly through the environment.

EPIDEMIOLOGY OF SCHMALLENBERG VIRUS IN EUROPEAN BISON ( BISON BONASUS) IN POLAND

Schmallenberg virus (SBV), an emerging arbovirus in Europe, is an important pathogen in domestic ruminants; however, its impact on free-ranging wild ruminants is not well studied. Three hundred and forty-seven serum samples collected between 2011 and 2016 from 302 European bison ( Bison bonasus) from 12 different sites in Poland were tested for the presence of SBV antibodies. In addition, 86 sera were collected between 2013 and 2016 from three species of cervids for testing for SBV antibodies. After the first detection of the virus in Poland in October 2012, the proportion of SBV-seropositive European bison reached 81% (95% confidence interval [CI]: 77.1-85.8%), whereas in cervids seroprevalence was 34% (95% CI: 23.5-43.9%). There was an increase in seroprevalence in European bison from 2012 to 2014. Biting midges ( Culicoides spp.), the primary vectors of SBV, were monitored entomologically for the identification of the biting midge populations and virologically for SBV infections in the Białowieża Forest region, which contains the world's largest European bison population. We detected SBV by PCR in 3% of Culicoides pools from 2015. In addition, seven fetal brain samples from European bison or cervids were tested and were negative for SBV RNA. Our results indicate a high seroprevalence with reduced transmission of SBV in subsequent years in the European bison populations and lower seroprevalence in cervids.

Current evidence on the transmissibility of chronic wasting disease prions to humans-A systematic review

A number of prion diseases affect humans, including Creutzfeldt-Jakob disease; most of these are due to genetic mutations in the affected individual and occur sporadically, but some result from transmission of prion proteins from external sources. Of the known animal prion diseases, only bovine spongiform encephalopathy prions have been shown to be transmissible from animals to humans under non-experimental conditions. Chronic wasting disease (CWD) is a prion disease that affects cervids (e.g., deer and elk) in North America and isolated populations in Korea and Europe. Systematic review methodology was used to identify, select, critically appraise and analyse data from relevant research. Studies were evaluated for adherence to good conduct based on their study design following the Cochrane collaboration's approach to grading the quality of evidence and the strength of recommendations (GRADE). Twenty-three studies were included after screening 800 citations from the literature search and evaluating 78 full papers. Studies examined the transmissibility of CWD prions to humans using epidemiological study design, in vitro and in vivo experiments. Five epidemiological studies, two studies on macaques and seven studies on humanized transgenic mice provided no evidence to support the possibility of transmission of CWD prions to humans. Ongoing surveillance in the United States and Canada has not documented CWD transmission to humans. However, two studies on squirrel monkeys provided evidence that transmission of CWD prions resulting in prion disease is possible in these monkeys under experimental conditions and seven in vitro experiments provided evidence that CWD prions can convert human prion protein to a misfolded state. Therefore, future discovery of CWD transmission to humans cannot be entirely ruled out on the basis of current studies, particularly in the light of possible decades-long incubation periods for CWD prions in humans. It would be prudent to continue CWD research and epidemiologic surveillance, exercise caution when handling potentially contaminated material and explore CWD management opportunities.

Rumen microbiota for wild boreal cervids living in the same habitat

Knowledge about the factors shaping the rumen microbiota in wild animals is limited. Therefore, the aim of this study was to compare the microbiota from the three cervid species moose (Alces alces, n = 5), red deer (Cervus elaphus, n = 4) and roe deer (Capreolus capreolus, n = 12), sharing the same habitat. Using deep 16S rRNA gene sequencing, we found that the largest species moose had the highest number of unique operational taxonomic units. Furthermore, red deer and moose shared more of the microbiota, compared with the smallest species, roe deer, with Firmicutes and Euryarchaeota being significantly overrepresented for the shared microbiota. These differences could not be explained by diet or range. The animals largely shared the same range, and there are no systematic differences in diet. We therefore believe rumen physiology can be one of the main contributing factors to the observed distribution of the rumen microbiota in cervid species.

Beyond mice and men: environmental change, immunity and infections in wild ungulates

In the face of rapid environmental change, anticipating shifts in microparasite and macroparasite dynamics, including emergence events, is an enormous challenge. We argue that immunological studies in natural populations are pivotal to meeting this challenge: many components of environmental change--shifts in biotic assemblages, altered climate patterns and reduced environmental predictability--may affect host immunity. We suggest that wild ungulates can serve as model systems aiding the discovery of immunological mechanisms that link environmental change with parasite transmission dynamics. Our review of eco-immunological studies in wild ungulates reveals progress in understanding how co-infections affect immunity and parasite transmission and how environmental and genetic factors interact to shape immunity. Changes in bioavailability of micronutrients have been linked to immunity and health in wild ungulates. Although physiological stress in response to environmental change has been assessed, downstream effects on immunity have not been studied. Moreover, the taxonomic range of ungulates studied is limited to bovids (bighorn sheep, Soay sheep, chamois, musk oxen, bison, African buffalo) and a few cervids (red deer, black-tailed deer). We discuss areas where future studies in ungulates could lead to significant contributions in understanding the patterns of immunity and infection in natural populations and across species.

Environmental sources of prion transmission in mule deer

Whether transmission of the chronic wasting disease (CWD) prion among cervids requires direct interaction with infected animals has been unclear. We report that CWD can be transmitted to susceptible animals indirectly, from environments contaminated by excreta or decomposed carcasses. Under experimental conditions, mule deer (Odocoileus hemionus) became infected in two of three paddocks containing naturally infected deer, in two of three paddocks where infected deer carcasses had decomposed in situ =1.8 years earlier, and in one of three paddocks where infected deer had last resided 2.2 years earlier. Indirect transmission and environmental persistence of infectious prions will complicate efforts to control CWD and perhaps other animal prion diseases.

Functional anatomy of the omasum in high Arctic Svalbard reindeer (Rangifer tarandus platyrhynchus) and Norwegian reindeer (Rangifer tarandus tarandus)

The structure and fill of the omasum was investigated in summer and in winter in adult female reindeer living on the polar desert and tundra of the high Arctic archipelago of Svalbard and in sub-Arctic mountain habitats in northern Norway. The mean total mass of the omasum in non-lactating adult female Svalbard reindeer was 467 g (0.65 g per 100 g live body mass (BM)) in September and 477 g (1.03 g per 100 g BM) in April. By contrast, the mean mass of the omasum in non-lactating adult reindeer in northern Norway was 534 g (0.83 g per 100 g BM) in September but only 205 g (0.35 g per 100 g BM p < 0.05) in late March, owing to a decrease in both tissue mass and the wet mass of the contents of the organ. The mean absorptive surface of the omasum in Svalbard reindeer was 2300 cm2 in September and 2023 cm2 in April. In Norwegian reindeer, by contrast, the absorptive surface area decreased from 2201 cm2 in September to 1181 cm2 (p < 0.05) in late March. The marked seasonal decline of omasal tissue and contents in Norwegian reindeer probably results from intake of highly digestible forage plants, including lichens, in winter. Svalbard reindeer, a non-migratory sub-species, survive eating poor quality fibrous vascular plants in winter. The absence of any marked seasonal change in the mass, total absorptive surface area or filling of the omasum in Svalbard reindeer in winter despite a substantial decline in body mass presumably reflects their need to maintain maximum absorption of nutrients, including volatile fatty acids, when feeding on such poorly fermentable forage.