No replies
Offline
Joined: 01/01/2006
Posts: 230
species barriers for cwd by in vitro conversion of PrP

Subject: Species barriers for chronic wasting disease by in vitro conversion
of prion protein
Date: November 3, 2007 at 10:57 am PST

Species barriers for chronic wasting disease by in vitro conversion of prion
protein

Li Li a, Michael B. Coulthart b, Aru Balachandran c, Avi Chakrabartty d,
Neil R. Cashman a,*
a Brain Research Centre, Division of Neurology, Department of Medicine,
University of British Columbia and Vancouver Coastal Health,
UBC Hospital, 2211 Wesbrook Mall, Vancouver, BC, Canada V6T 2B5
b Prion Diseases Program, National Microbiology Laboratory, Public Health
Agency of Canada, Winnipeg, Man., Canada R3E 3R2 Q1
c National Reference Laboratory for Scrapie and CWD, Animal Diseases
Research Institute, Canadian Food Inspection Agency,
3851 Fallowfield Road, Nepean, Ont., Canada K2H 8P9
d University Health Network, Department of Medical Biophysics, University of
Toronto, Toronto, Ont., Canada M5G 1L7
Received 6 October 2007

Abstract

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy
that can affect North American cervids (deer, elk, and
moose). Using a novel in vitro conversion system based on incubation of
prions with normal brain homogenates, we now report that
PrPCWD of elk can readily induce the conversion of normal cervid PrP (PrPC)
molecules to a protease-resistant form, but is less efficient
in converting the PrPC of other species, such as human, bovine, hamster, and
mouse. However, when substrate brain homogenates are
partially denatured by acidic conditions (pH 3.5), PrPCWD-induced conversion
can be greatly enhanced in all species. Our results dem-
onstrate that PrPC from cervids (including moose) can be efficiently
converted to a protease-resistant form by incubation with elk CWD
prions, presumably due to sequence and structural similarities between these
species. Moreover, partial denaturation of substrate PrPC
can apparently overcome the structural barriers between more distant
species.

snip...

Although Syrian hamsters were initially deemed resistant to CWD [19], a
recent publication demonstrates that CWD can be transmitted
and adapted to hamster [20].

snip...

Substrate denaturation and human health

We confirm with multiple species that acid/GdnHCl-
treated brain PrPC is a superior substrate for in vitro con-
version than untreated PrPC, possibly by overcoming con-
formational barriers in partial denaturation of substrate
PrPC. PrP conversion in scrapie-infected neuroblastoma
cells is believed to occur in endosomes, a low-pH and
reducing environment [26]. The non-ruminant stomach
possesses a low pH lumen, and PrPC is expressed in this
organ [27]. Such acidic (denaturing) organ or cellular
organellar environments might also promote CWD trans-
mission to non-cervid species, including humans.

Acknowledgments

This work was supported by the Canadian Institutes of
Health Research (Institute of Infection and Immunity, Safe
Food and Water program) and PrioNet Canada.

[20] G.J. Raymond, L.D. Raymond, K.D. Meade-White, A.G. Hughson,
C. Favara, D. Gardner, E.S. Williams, M.W. Miller, R.E. Race, B.
Caughey, Transmission and adaptation of chronic wasting disease to
hamsters and transgenic mice: evidence for strains, J. Virol. 81 (2007)
4305–4314.

http://jvi.asm.org/cgi/content/abstract/81/8/4305

2007 Elsevier Inc. All rights reserved.

Please cite this article in press as: L. Li et al., Species barriers for
chronic wasting disease by in vitro...,
Biochem. Biophys. Res. Commun. (2007), doi:10.1016/j.bbrc.2007.10.087

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WBK-4R04PFW-3...

Transmission and adaptation of chronic wasting disease to hamsters and
transgenic mice: evidence for strains

Gregory J. Raymond1, Lynne D. Raymond1, Kimberly D. Meade-White1, Andrew G.
Hughson1, Cynthia Favara1, Donald Gardner2, Elizabeth S. Williams3§, Michael
W.
Miller4, Richard E. Race1*, and Byron Caughey1*

Running title: CWD transmission to rodent species

Laboratory of Persistent Viral Diseases1, and Rocky Mountain Veterinary
Branch2, NIAID, NIH, Rocky Mountain Laboratories, Hamilton, MT 59840;
Department of Veterinary Sciences, University of Wyoming, Laramie, WY
820703; Colorado Division of Wildlife, Wildlife Research Center, Fort
Collins, CO
80526-20974.
§deceased
*corresponding authors:
Byron Caughey, Rocky Mountain Labs, 903 S. 4th St, Hamilton, MT 59840, USA;
bcaughey@nih.gov; Tel: (406) 363-9264; FAX: (406) 363-9286
Richard Race, Rocky Mountain Labs, 903 S. 4th St, Hamilton, MT 59840, USA;
rrace@nih.gov; Tel: (406) 363-9358; FAX: (406) 363-9286

In vitro screening using the cell-free prion protein conversion system
indicated
that certain rodents may be susceptible to chronic wasting disease (CWD).
Therefore,
CWD isolates from mule deer, white-tailed deer and elk were inoculated
intracerebrally
into various rodent species to assess their susceptibility and to develop
new rodent
models of CWD. The species inoculated were Syrian golden, Djungarian,
Chinese,
Siberian, and Armenian hamsters; transgenic mice expressing the Syrian
golden
hamster prion protein; and, RML Swiss and C57 BL10 wild-type mice. The
transgenic
mice and the Syrian golden, Chinese, Siberian and Armenian hamsters had
limited
susceptibility to certain of the CWD inocula as evidenced by incomplete
attack rates and
long incubation periods. With serial passages of CWD isolates in Syrian
golden
hamsters, incubation periods rapidly stabilized as isolates with either
short (85-89 days)
or long (408-544 days) mean incubation periods and distinct
neuropathological patterns.
In contrast, wild-type mouse strains and Djungarian hamsters were not
susceptible to
CWD. These results show that CWD can be transmitted and adapted to some
species
of rodents and suggest that the cervid-derived CWD inocula may have
contained, or
diverged into, at least two distinct transmissible spongiform encephalopathy
strains.

snip...

Differences in PrP-res glycoform patterns analyzed from several CWD-
affected deer and elk have also suggested that CWD in mule deer may be more
heterogeneous than in elk (19). Curiously, however, this apparent strain
difference was not manifested when the identical mule deer CWD inoculum was
serially passaged through only one recipient species. Serial passage in Sg
hamsters yielded only the fast isolate (Table 1 and Figure 3), while passage
first
through the Tg (haPrP) mice then into Sg hamsters yielded only the slow
isolate
(Table 2 and Figure 3). With this in mind, it is important to consider other
possible explanations for these results. One possibility is that CWD might
be
able to undergo a stochastic change into a more rapid and aggressive strain
in
Sg hamsters, and that this happened to occur after the mule deer CWD
inoculations. A similar emergence of both fast and slow strains has been
observed upon inoculation of TME into Sg hamsters (5). These strains
developed even when a clonal isolate of the TME inoculum was used,
suggesting
that they arose in the recipient Sg hamsters rather than in the mink source
(1).
Finally, although extensive precautions were taken, we cannot formally
prove that inadvertent contamination of the mule deer CWD inoculum with
hamster-derived 263K strain did not occur which potentially could yield
short-
incubation-period passages in Sg hamsters (Table 1). However, the incubation
period observed with the CWD passages (85-89 d) were significantly longer
than
263K incubation periods observed in our lab (70-75 d) and no mock-infected

controls became sick during their lifespan. Also, we saw no 263K-like
infectivity
develop in the highly susceptible Tg (haPrP) mice even though we used the
identical primary inoculum for both recipient species. Interestingly, the
similarity
of the Sg hamster-adapted CWD fast isolate and 263K might be due to a
common origin since there is circumstantial evidence that CWD arose from
cervid exposure to sheep scrapie, which was also the origin of the 263K
strain in
hamsters (14). Furthermore, the Hyper strain derived from TME inoculations
has
263K-like strain characteristics in Sg hamsters (5). Thus, it would appear
that
both CWD and TME transmissions into Sg hamsters can result in divergent fast
and slow strains.

end...

http://jvi.asm.org/cgi/reprint/JVI.02474-06v1

http://jvi.asm.org/cgi/content/abstract/JVI.02474-06v1

Transmissible Mink Encephalopathy TME

http://transmissible-mink-encephalopathy.blogspot.com/

TME hyper/drowsy, INTER-SPECIES TRANSMISSION CWD and strain
properties

https://www.blogger.com/comment.g?blogID=37955408&postID=116577315153980667

Monitoring the occurrence of emerging forms of Creutzfeldt-Jakob disease in
the United States

http://cjdusa.blogspot.com/

i am reminded of a few things deep throat (high ranking official at usda)
told me years ago;

==========================================

The most frightening thing I have read all day is the
report of Gambetti's finding of a new strain of
sporadic cjd in young people.........Dear God,

https://www.blogger.com/comment.g?blogID=7842737484277562285&postID=5759...

BSE BASE MAD COW TESTING TEXAS, USA, AND CANADA, A REVIEW OF SORTS

http://madcowtesting.blogspot.com/

MADCOW USDA the untold story

http://madcowusda.blogspot.com/

MADCOW USDA the untold story continued

https://www.blogger.com/comment.g?blogID=6472149427883113751&postID=4829...

USA NOR-98 SCRAPIE UPDATE AUGUST 31, 2007 RISES TO 5 DOCUMENTED CASES

http://nor-98.blogspot.com/

Government Accountability Project

https://www.blogger.com/comment.g?blogID=3995372399492420922&postID=2957...

PLEASE NOTE IN USA CJD UPDATE AS AT JUNE 2007, please note steady increase
in ''TYPE UNKNOWN''. ...TSS

1 Acquired in the United Kingdom; 2 Acquired in Saudi Arabia; 3 Includes 17
inconclusive and 9 pending (1 from 2006, 8
from 2007); 4 Includes 17 non-vCJD type unknown (2 from 1996, 2 from 1997, 1
from 2001, 1 from 2003, 4 from 2004, 3
from 2005, 4 from 2006) and 36 type pending (2 from 2005, 8 from 2006,

*** 26 from 2007)

http://www.cjdsurveillance.com/pdf/case-table.pdf

TSS