Prion Can plants serve as a vector for prions ...

7 downloads 0 Views 883KB Size Report
Rasmussen J, Gilroyed BH, Reuter T, Badea A, Eudes. F, Graf R, Laroche A, Kav NNV, ... Silveira JR, Raymond GJ, Hughson AG, Race RE,. Sim VL, Hayes SF, ...
This article was downloaded by: [University of Guelph] On: 27 May 2015, At: 06:22 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK

Prion Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/kprn20

Can plants serve as a vector for prions causing chronic wasting disease? ab

c

d

e

f

Jay Rasmussen , Brandon H Gilroyed , Tim Reuter , Sandor Dudas , Norman F Neumann , g

a

e

e

b

Aru Balachandran , Nat NV Kav , Catherine Graham , Stefanie Czub & Tim A McAllister a

Department of Agricultural, Food and Nutritional Sciences; University of Alberta; Edmonton, AB Canada b

Agriculture and Agri-Food Canada; Lethbridge Research Centre; Lethbridge, AB Canada

c

School of Environmental Sciences; University of Guelph Ridgetown Campus; Ridgetown, ON Canada d

Alberta Agriculture and Rural Development; Agriculture Centre; Lethbridge, AB Canada

e

Click for updates

National and OIE Reference Laboratories for BSE; National Centres for Animal Disease Lethbridge Laboratory; Canadian Food Inspection Agency; Lethbridge, AB Canada f

School of Public Health; University of Alberta; Edmonton, AB Canada

g

National and OIE Reference Laboratory for scrapie and CWD; CFIA; Ottawa, ON Canada Published online: 07 Feb 2014.

To cite this article: Jay Rasmussen, Brandon H Gilroyed, Tim Reuter, Sandor Dudas, Norman F Neumann, Aru Balachandran, Nat NV Kav, Catherine Graham, Stefanie Czub & Tim A McAllister (2014) Can plants serve as a vector for prions causing chronic wasting disease?, Prion, 8:1, 136-142, DOI: 10.4161/pri.27963 To link to this article: http://dx.doi.org/10.4161/pri.27963

PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions

Research Paper Research Paper

Prion 8:1, 136–142; January/February 2014; © 2014 Landes Bioscience

Can plants serve as a vector for prions causing chronic wasting disease? 1 Department of Agricultural, Food and Nutritional Sciences; University of Alberta; Edmonton, AB Canada; 2Agriculture and Agri-Food Canada; Lethbridge Research Centre; Lethbridge, AB Canada; 3School of Environmental Sciences; University of Guelph Ridgetown Campus; Ridgetown, ON Canada; 4Alberta Agriculture and Rural Development; Agriculture Centre; Lethbridge, AB Canada; 5National and OIE Reference Laboratories for BSE; National Centres for Animal Disease Lethbridge Laboratory; Canadian Food Inspection Agency; Lethbridge, AB Canada; 6School of Public Health; University of Alberta; Edmonton, AB Canada; 7National and OIE Reference Laboratory for scrapie and CWD; CFIA; Ottawa, ON Canada

Downloaded by [University of Guelph] at 06:22 27 May 2015

Keywords: prion, wheat, transmission, chronic wasting disease, risk assessment, cervid, food safety Abbreviations: CWD, chronic wasting disease; PrPTSE, infectious prion protein; PrPC, cellular prion protein; TSE, transmissible spongiform encephalopathy; TME, transmissible mink encephalopathy; N, nitrogen; MS, murashige and skoog media; PK, proteinase K; BH, brain homogenate; PBS, phosphate-buffered saline; SDS, sodium dodecyl sulphate; TME HY, hyper strain TME

Prions, the causative agent of chronic wasting disease (CWD) enter the environment through shedding of bodily fluids and carcass decay, posing a disease risk as a result of their environmental persistence. Plants have the ability to take up large organic particles, including whole proteins, and microbes. This study used wheat (Triticum aestivum L.) to investigate the uptake of infectious CWD prions into roots and their transport into aerial tissues. The roots of intact wheat plants were exposed to infectious prions (PrPTSE) for 24 h in three replicate studies with PrPTSE in protein extracts being detected by western blot, IDEXX and Bio-Rad diagnostic tests. Recombinant prion protein (PrPC) bound to roots, but was not detected in the stem or leaves. Protease-digested CWD prions (PrPTSE) in elk brain homogenate interacted with root tissue, but were not detected in the stem. This suggests wheat was unable to transport sufficient PrPTSE from the roots to the stem to be detectable by the methods employed. Undigested PrPTSE did not associate with roots. The present study suggests that if prions are transported from the roots to the stems it is at levels that are below those that are detectable by western blot, IDEXX or Bio-Rad diagnostic kits.

Introduction Chronic Wasting Disease (CWD) is a fatal neurodegenerative prion disease affecting wild and farmed cervids. Specifically, CWD has been found in deer (mule and white-tail), elk and moose.1 Experimental transmission has also been demonstrated in reindeer.2 Prion diseases, also termed Transmissible Spongiform Encephalopathies (TSE), are caused by misfolding of the cellular prion protein, PrPC, into the disease-causing conformation designated PrP TSE. Misfolded PrPTSE is broadly accepted as the disease causing agent responsible for misfolding of PrPC into PrPTSE.3,4 Prevalence of CWD is high in endemic areas like Wyoming (USA) where, in a number of herds, 50% of wild mule deer are CWD positive.1 Indirect transmission of CWD has been confirmed in studies where deer became infected following exposure to areas which previously held CWD-positive deer.5,6 CWD PrPTSE remains infectious for more than two years ex vivo in the environment representing a long-term hazard for transmission.5

Infected cervids have been reported to shed PrP TSE in bodily fluids, disseminating infectious prions in urine, feces, blood and saliva.7-10 PrPTSE binds to whole soil and interaction with some soil minerals has been shown to increase the infectivity of PrPTSE.11,12 Although PrPTSE binds to soil, it requires 60 d for CWD PrPTSE to become fully bound in sandy soil as compared with 30 d for prions associated with transmissible mink encephalopathy (TME).13 In seawater, scrapie PrPTSE remains stable with a one log reduction only observed after 30 d, suggesting unbound PrP TSE may persist and flow with surface or ground water.14 Taken together, these factors suggest PrP TSE may remain unbound within the soil environment for substantial periods. Plants acquire nutrients from the surrounding soil environment. Nitrogen (N) is one of the main macronutrients vital for plant growth and reproduction. There are multiple forms of N in the soil environment and the importance of organic N, including amino acids and peptides, to plant health is well documented.15,16

*Correspondence to: Tim McAllister; Email: [email protected] Submitted: 11/28/2013; Revised: 01/10/2014; Accepted: 01/22/2014; Published Online: 02/07/2014 http://dx.doi.org/10.4161/pri.27963 136 Prion

Volume 8 Issue 1

© 2014 Landes Bioscience. Do not distribute.

Jay Rasmussen1,2, Brandon H Gilroyed3, Tim Reuter4, Sandor Dudas5, Norman F Neumann6, Aru Balachandran7, Nat NV Kav1, Catherine Graham5, Stefanie Czub5, and Tim A McAllister2,*

The nutritional value of protein N to plants is contentious but, the potential for uptake has been demonstrated.17-19 Uptake of green fluorescent protein into roots has been shown for Arabidopsis thaliana and Hakea actites.19 Earlier work suggested ovalbumin is not only taken up by roots, but is subsequently transported to upper regions of tomato plants when roots are damaged.18 The ability of plants to take up larger organic particles raises the possibility that PrPTSE may enter plants through roots. This study used wheat as a model to investigate the potential uptake of CWD PrP TSE into roots and its subsequent transport to the stem. If such a phenomenon was confirmed it would suggest the potential for plants to act as a vector for the transmission of CWD in cervids.

Results PrPC exposures. Wheat plants with roots exposed to recombinant mouse PrPC contained a prion band in the root protein extract as identified by western blotting (Fig. 1, lane 3). The prion band in the root extract had a slightly smaller molecular weight than PrPC in the solution roots were exposed to (Fig. 1, lane 5). When the outer surface of roots was exposed to 10 µg/mL proteinase K (PK) for 5 min at room temperature, no prion signal in the root protein extract was observed (Fig. 1, lane 4). No prion signal was seen in stem or leaf protein extracts (data not shown). PrPTSE exposures. In wheat plants exposed to PrPTSE, the root extract had three prion reactive bands