Evaluation of Winter Ticks (Dermacentor albipictus) Collected from North American Elk (Cervus canadensis) in an Area of Chronic Wasting Disease
Research Article
04 August 2021
Evaluation of Winter Ticks (Dermacentor albipictus) Collected from North American Elk (Cervus canadensis) in an Area of Chronic Wasting Disease
Endemicity for Evidence of PrPCWD Amplification Using Real-Time Quaking-Induced Conversion Assay
Authors: N. J. Haley https://orcid.org/0000-0003-0502-7862 nicholas.j.haley@gmail.com, D. M. Henderson, K. Senior, M. Miller, and R. DonnerAUTHORS INFO & AFFILIATIONS
Volume 6, Number 4
31 August 2021
ABSTRACT
Chronic wasting disease (CWD) is a progressive and fatal spongiform encephalopathy of deer and elk species, caused by a misfolded variant of the normal prion protein. Horizontal transmission of the misfolded CWD prion between animals is thought to occur through shedding in saliva and other forms of excreta. The role of blood in CWD transmission is less clear, though infectivity has been demonstrated in various blood fractions. Blood-feeding insects, including ticks, are known vectors for a range of bacterial and viral infections in animals and humans, though to date, there has been no evidence for their involvement in prion disease transmission. In the present study, we evaluated winter ticks (Dermacentor albipictus) collected from 136 North American elk (Cervus canadensis) in an area where CWD is endemic for evidence of CWD prion amplification using the real-time quaking-induced conversion assay (RT-QuIC). Although 30 elk were found to be CWD positive (22%) postmortem, amplifiable prions were found in just a single tick collected from an elk in advanced stages of CWD infection, with some evidence for prions in ticks collected from elk in mid-stage infection. These findings suggest that further investigation of ticks as reservoirs for prion disease may be warranted.
IMPORTANCE This study reports the first finding of detectable levels of prions linked to chronic wasting disease in a tick collected from a clinically infected elk. Using the real-time quaking-induced conversion assay (RT-QuIC), “suspect” samples were also identified; these suspect ticks were more likely to have been collected from CWD-positive elk, though suspect amplification was also observed in ticks collected from CWD-negative elk. Observed levels were at the lower end of our detection limits, though our findings suggest that additional research evaluating ticks collected from animals in late-stage disease may be warranted to further evaluate the role of ticks as potential vectors of chronic wasting disease.
In summary, we report that RT-QuIC may serve as a useful tool for evaluating the role of ticks and other insects as reservoirs of PrPCWD. Amplifiable levels of PrPCWD in the present study were low, and likely limited to ticks collected from animals in later stages of disease. Additional studies focusing on insect vectors feeding on terminally infected cervids and the biological relevance of any detectable CWD prions in these vectors are warranted to more fully characterize the role of external parasites in prion transmission.
SATURDAY, DECEMBER 21, 2013
Parelaphostrongylus (Brainworm) Infection in Deer and Elk and the potential for CWD TSE prion consumption and spreading there from ?
I brought up a concern for a worm long ago, that gets in the brains of cervids, and then the worm gets excreted via feces, and then deer forage and eat that worm. if the host cervid of this worm has CWD, could this later transmit CWD?
I was concerned about this long ago, still am. I was curious what any else might think about this potential mode of transmission with cwd ?
there is much cwd risk factor now with soil, and now the potential exists via plants, so I was just pondering out loud here, is it possible that some cwd is being spread, by the Parelaphostrongylus (Brainworm), after sucking up on a CWD infected cervids brain, and then being discarding via feces by that same CWD infected cervid, soaking up the prions via the feces, laying in wait, for a CWD free cervid to come scoop up and eat that Parelaphostrongylus (Brainworm), that has been extremely exposed to the TSE prion ? kind regards, terry
Research Project: Pathobiology, Genetics, and Detection of Transmissible Spongiform Encephalopathies Location: Virus and Prion Research
Title: Successful transmission of the chronic wasting disease (CWD) agent to white-tailed deer by intravenous blood transfusion
Author item MAMMADOVA, NAJIBA - Orise Fellow item CASSMAN, ERIC - Orise Fellow item Greenlee, Justin Submitted to: Research in Veterinary Science Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/14/2020 Publication Date: N/A Citation: N/A Interpretive Summary: Chronic wasting disease (CWD) is a fatal disease of cervids that causes damaging changes in the brain. The infectious agent is an abnormal protein called a prion that has misfolded from its normal state. Chronic wasting disease may be transmitted from ingestion of prions shed in bodily fluids (e.g. feces, urine, saliva, placenta tissue) of infected animals. Few studies have also reported detection of infectious prions in blood. To determine if CWD-infected blood can transmit prion disease, recipient deer were inoculated intravenously (IV) with blood derived from a CWD-infected white-tailed deer. We found that two out of three animals developed disease. This study complements and supports an earlier finding that CWD can be transmitted to deer by intravenous blood transfusion from white-tailed deer with CWD. This information is useful to wildlife and agricultural officials that are involved in efforts to control the spread of chronic wasting disease.
Technical Abstract: Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSEs) that affects free-ranging and captive cervid species. The infectious agent of CWD may be transmitted from ingestion of prions shed in bodily fluids (e.g. feces, urine, saliva, placenta tissue) of infected animals, contaminated pastures, and/or decomposing carcasses from dead animals. Studies have also demonstrated prion infectivity in whole blood or blood fractions of CWD infected animals. To determine if CWD-infected blood contained sufficient levels of prion infectivity to cause disease, recipient deer were inoculated intravenously (IV) with blood derived from a CWD-infected white-tailed deer. We found that the CWD agent can be successfully transmitted to white-tailed deer by a single intravenous blood transfusion with a mean incubation period of approximately 35 months and an attack rate of 100%. This study complements and supports an earlier finding that CWD can be transmitted to deer by intravenous blood transfusion from white-tailed deer with CWD.
Successful transmission of the chronic wasting disease (CWD) agent to white-tailed deer by intravenous blood transfusion
Najiba Mammadovaa,b, Eric Cassmanna,b, Justin J. Greenleea,* aVirus and Prion Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, 1920 Dayton Avenue, Ames, IA 50010, USA bOak Ridge Institute for Science and Education (ORISE), USA A
RTICLE INFO Keywords: Blood transfusion Cervid CWD Prion disease Prions in blood White-tailed deer
ABSTRACT
Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSEs) that affects free-ranging and captive cervid species. The infectious agent of CWD may be transmitted from ingestion of prions shed in bodily fluids (e.g. feces, urine, saliva, placenta tissue) of infected animals, contaminated pastures, and/or decomposing carcasses from dead animals. Studies have also demonstrated prion infectivity in whole blood or blood fractions of CWD infected animals. To determine if CWD-infected blood contained sufficient levels of prion infectivity to cause disease, recipient deer were inoculated intravenously (IV) with blood derived from a CWD- infected white-tailed deer. We found that the CWD agent can be successfully transmitted to white-tailed deer by a single intravenous blood transfusion. The incubation period was associated with recipient prion protein genotype at codon 96 with the GG96 recipient incubating for 25.6 months and the GS96 recipient incubating for 43.6 months. This study complements and supports an earlier finding that CWD can be transmitted to deer by intravenous blood transfusion from white-tailed deer with CWD.
Chronic wasting disease (CWD) is a naturally occurring transmissible spongiform encephalopathy (TSEs) of cervids. Other TSEs include scrapie in sheep and goats, bovine spongiform encephalopathy (BSE), and sporadic and familial Creutzfeldt-Jakob disease (CJD) in humans. The CWD agent has a wide host range among various species of free- ranging and captive cervids, including mule deer (Odocoileus hemi-onus) (Williams & Young, 1980; Spraker et al., 1997; Miller & Wild, 2004), white-tailed deer (Odocoileus virginianus) (Spraker et al., 1997; Miller & Wild, 2004), Rocky Mountain elk (Cervus elaphus nelsoni) (Williams & Young, 1982), moose (Alces alces shirasi) (Baeten et al., 2007; Kreeger et al., 2006), and reindeer (Rangifer tarandus tarandus) (Benestad et al., 2016; Moore et al., 2016). The infectious agent of CWD may be transmitted from ingestion of prions shed in bodily fluids (e.g. feces, urine, saliva) or placenta tissue of infected animals, contaminated pastures, and/or decomposing carcasses from dead animals (Haley et al., 2011; Haley et al., 2009; Mathiason et al., 2010; Mathiason et al., 2006). A limited number of reports have demonstrated prion infectivity in whole blood or blood fractions of CWD infected animals (Mathiason et al., 2010; Mathiason et al., 2006; Kramm et al., 2017). To determine if CWD-infected blood contained sufficient levels of prion infectivity to cause disease, recipient deer consisting of three female deer of approximately 2 years of age were inoculated intravenously (IV) with 100 mL of blood immediately after collection from a CWD-infected white-tailed deer (animal ID: 936). Deer 936 was a 21.8-month-old male white-tailed deer that was intracranially (IC) inoculated with 1 mL of a 10% (wt./vol) brain homogenate (derived from a pool of white- tailed deer brainstem material from Wisconsin) at 3 months of age. The procedure for IC inoculation of fawns has been described previously (Greenlee et al., 2011). Donor deer 936 presented with clinical signs of neurologic disease approximately ~17.8 months post inoculation at which time blood was collected by jugular venipuncture into 50 mL syringes containing 7 mL of citrate phosphate dextrose adenine solution anticoagulant (CPDA-1) that were immediately pooled and used as inoculum. Deer 936 was determined CWD positive based on accumu-lation of abnormal prion protein (PrPSc) by immunohistochemistry (IHC) in the brainstem at the level of the obex, the palatine tonsil, and the retropharyngeal lymph node (RLN). Recipient deer were initially housed in separate biosafety level 2 facilities following exposure to CWD. Non-inoculated control deer (n =3) were kept with the CWD-free herd on pasture at the National Animal Disease Center. All white-tailed deer (including donor animals) were genotyped and determined to be homozygous QQ at codons 95 and 226, but there were polymorphisms at codon 96. The donor deer (936) and two recipient deer (940, 942) were homozygous G at codon 96, and a single recipient deer (941) was het-erozygous GS at codon 96.
The animals were fed pelleted growth and maintenance rations that contained no ruminant protein, and clean water was available ad libi-tum. Deer were observed daily for the development of clinical signs of CWD (e.g., behavioral abnormalities, excess salivation, and emaciation) and were euthanized at the onset of unequivocal clinical signs of disease, or at the end of the observation period. At necropsy, duplicate tissue samples were collected and either frozen or stored in 10% buffered neutral formalin. For detection of PrPSc, slides were stained by an automated immunohistochemistry (IHC) method using primary anti-body F99/F96.7.1, described previously (Greenlee et al., 2012; Greenlee et al., 2006).
At the completion of the study, two of the three IV inoculated deer were determined CWD positive. The two positive deer presented with clinical signs and were euthanized at 25.6- and 43.6-months post inoc-ulation. These deer had detectable pathogenic prion protein (PrPSc) in the CNS and various non-CNS tissues (lymphoid tissues comprised of retropharyngeal lymph node (RPLN), tonsils (palatine and pharyngeal), spleen, recto-anal mucosa-associated lymphoid tissue (RAMALT), gut- associated lymphoid tissue (GALT) of the small intestines, and the enteric nervous system (Table 1). Deer #942 was euthanized 2.9 months post inoculation due to intercurrent disease, and no PrPSc was detectable by IHC, although it’s probable that this deer would have developed CWD given a longer duration of incubation.
This study complements and reinforces earlier findings that CWD can be transmitted to deer by intravenous blood transfusion from white- tailed deer with CWD (Mathiason et al., 2010; Mathiason et al., 2006). In a previous study, a group of eight, 6-month-old fawns were IV inoc-ulated with ~250 mL of whole blood derived from experimentally IC inoculated CWD positive white-tailed deer (Mathiason et al., 2010). In this study, all eight deer were determined to be CWD positive by IHC of all relevant tissues, and began to show clinical signs of TSE between 15 and 26 months post inoculation (Mathiason et al., 2010). While similar results were obtained in our study, we determined that only 100 mL of CWD-infected blood contained sufficient levels of prion infectivity to cause disease compared to the 250 mL of whole blood used by Mathiason et al. (Mathiason et al., 2010). In an earlier study, a cohort of three 6-month-old white-tailed deer fawns were exposed to the agent of CWD via either a single intraperitoneal (IP) inoculation (n =2) or an IV transfusion (n =1) of blood derived from a naturally infected CWD positive mule deer (Mathiason et al., 2006). Similar to our findings, the fawn that received blood via IV transfusion had detectable PrPSc in the CNS (medulla at the level of the obex), tonsil, and retropharyngeal lymph nodes (Mathiason et al., 2006); however, it did not present with clinical signs and was euthanized 18 months post inoculation (Mathia-son et al., 2006).
We demonstrate here that the CWD agent can be successfully transmitted to white-tailed deer by a single intravenous blood trans-fusion from CWD-infected white-tailed deer. The incubation period appeared to be associated with recipient genotype with the GG96 deer (940) incubating for 25.6 months, while the GS96 deer (941) incubated for 43.6 months; however, we take into consideration the limitation of the small sample size in this study. While a previous and larger study showed similar results, we determined that only 100 mL of CWD- infected blood (~2.5 times less than previously shown in (Mathiason et al., 2010)) contained sufficient levels of prion infectivity to cause disease. The identification of blood-borne transmission of the CWD agent is important in reinforcing the risk of exposure to CWD via blood as well as the possibility of hematogenous transmission of the CWD agent through insect vector. Finally, these results further highlight the importance of developing a sensitive and reproducible blood-based test to detect pre-clinical CWD, and warrant the continued advancement and evaluation of sensitive antemortem diagnostic tests for the detection of PrPSc in blood of asymptomatic cervids early in the incubation period.
Funding This research was supported in part by an appointment to the Agri-cultural Research Service (ARS) Research Participation Program administered by the Oak Ridge Institute for Science and Education (ORISE) through an interagency agreement between the U.S. Depart-ment of Energy (DOE) and the U.S. Department of Agriculture (USDA). ORISE is managed by ORAU under DOE contract number DE- SC0014664. All opinions expressed in this paper are the author’s and do not necessarily reflect the policies and views of USDA, ARS, DOE, or ORAU/ORISE. This research was funded in its entirety by congressio-nally appropriated funds to the United States Department of Agriculture, Agricultural Research Service. The funders of the work did not influence study design, data collection and analysis, decision to publish, or the preparation of the manuscript.
* Corresponding author. E-mail address: justin.greenlee@usda.gov (J.J. Greenlee). Contents lists available at ScienceDirect Research in Veterinary Science journal homepage: www.elsevier.com/locate/rvsc https://doi.org/10.1016/j.rvsc.2020.10.009 Received 7 May 2020; Received in revised form 9 October 2020; Accepted 14 October 2020
''We found that the CWD agent can be successfully transmitted to white-tailed deer by a single intravenous blood transfusion with a mean incubation period of approximately 35 months and an attack rate of 100%.''
terrible news, price of tse prion poker goes up...terry
***> Antler velvet is rich in blood and nervous supply and may represent a source of infectious material as the velvet is shed every year.
***> These findings demonstrate prion infectivity accumulates in antler velvet and may have impact on marketing of this product.
SUNDAY, JULY 24, 2016
Chronic Wasting Disease Prions in Elk Antler Velvet and Marketing of this Product in Nutritional Supplements for Humans?
Antler velvet is rich in blood and nervous supply and may represent a source of infectious material as the velvet is shed every year.
Control of Chronic Wasting Disease OMB Control Number: 0579-0189 APHIS-2021-0004 Singeltary Submission
Docket No. APHIS-2018-0011 Chronic Wasting Disease Herd Certification
Thursday, July 29, 2021
TSE PRION OCCUPATIONAL EXPOSURE VIA ANIMAL OR HUMAN, iatrogenic transmission, nvCJD or sCJD, what if?
Wednesday, July 28, 2021
France issues moratorium on prion research after fatal brain disease strikes two lab workers
TUESDAY, AUGUST 03, 2021
USA Tables of Cases Examined National Prion Disease Pathology Surveillance Center Cases Examined July 9th, 2021
Terry S. Singeltary Sr.
posted by Terry S. Singeltary Sr. at
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