##################### Bovine Spongiform Encephalopathy #####################
Subject: Infectious Prions in the Saliva and Blood of Deer with Chronic Wasting Disease
Date: October 5, 2006 at 1:45 pm PST
Infectious Prions in the Saliva
and Blood of Deer with Chronic
Wasting Disease
Candace K. Mathiason,1 Jenny G. Powers,3 Sallie J. Dahmes,4 David A. Osborn,5 Karl V. Miller,5
Robert J. Warren,5 Gary L. Mason,1 Sheila A. Hays,1 Jeanette Hayes-Klug,1 Davis M. Seelig,1
Margaret A. Wild,3 Lisa L. Wolfe,6 Terry R. Spraker,1,2 Michael W. Miller,6 Christina J. Sigurdson,1
Glenn C. Telling,7 Edward A. Hoover1*
A critical concern in the transmission of prion diseases, including chronic wasting disease (CWD)
of cervids, is the potential presence of prions in body fluids. To address this issue directly, we
exposed cohorts of CWD-nai¨ve deer to saliva, blood, or urine and feces from CWD-positive deer.
We found infectious prions capable of transmitting CWD in saliva (by the oral route) and in blood
(by transfusion). The results help to explain the facile transmission of CWD among cervids and
prompt caution concerning contact with body fluids in prion infections.
SNIP...
Deer cohorts 1 (blood), 2 (saliva), and 3
(urine and feces) were electively euthanized at
18 months pi to permit whole-body examination
for PrPCWD. The greatest scrutiny was directed
toward those tissues previously established
to have highest frequency of PrPCWD deposition
in infected deer and generally regarded
as the most sensitive indicators of infection—
medulla oblongata and other brainstem regions,
tonsil, and retropharyngeal lymph node. We
found unequivocal evidence of PrPCWD in brain
and lymphoid tissue of all six tonsil biopsy–
positive deer in cohorts 1 (blood) and 2 (saliva),
whereas all deer in cohorts 3 and 5 were negative
for PrPCWD in all tissues (Table 2 and
Figs. 1 and 2).
The transmission of CWD by a single blood
transfusion from two symptomatic and one
asymptomatic CWDþ donor is important in at
least three contexts: (i) It reinforces that no tissue
from CWD-infected cervids can be considered
free of prion infectivity; (ii) it poses the
possibility of hematogenous spread of CWD,
such as through insects; and (iii) it provides a
basis for seeking in vitro assays sufficiently
sensitive to demonstrate PrPCWD or alternate
prion protein conformers in blood—one of the
grails of prion biology and epidemiology.
The identification of blood-borne prion
transmission has been sought before with mixed
results (9–11). Bovine spongiform encephalopathy
and scrapie have been transmitted to naBve
sheep through the transfer of 500 ml of blood
or buffy coat white blood cells from infected
sheep (12, 13). In addition, limited but compelling
evidence argues for the transmission of variant
Creutzfeldt-Jakob disease (vCJD) through blood
from asymptomatic donors (14–16). Even in
sporadic CJD, PrPres has been found in periph-
eral organs of some patients (17). The present
work helps establish that prion diseases can be
transmitted through blood.
The presence of infectious CWD prions in
saliva may explain the facile transmission of
CWD. Cervid-to-cervid interactions (SOM text),
especially in high density and captive situations,
would be expected to facilitate salivary crosscontact
(11, 18, 19). Salivary dissemination of
prions may not be limited to CWD. Proteaseresistant
prion protein has been demonstrated in
the oral mucosa, taste buds, lingual epithelium,
vomeronasal organ, and olfactory mucosa of
hamsters infected with transmissible mink
encephalopathy (19) and ferrets infected with
CWD (20). Although no instance of CWD
transmission to humans has been detected, the
present results emphasize the prudence of using
impervious gloves during contact with saliva or
blood of cervids that may be CWD-infected.
Environmental contamination by excreta
from infected cervids has traditionally seemed
the most plausible explanation for the dissemination
of CWD (21). However, we could not
detect PrPCWD in cohort 3 deer inoculated repeatedly
with urine and feces from CWDþ deer and examined up to 18 months pi (Table 2).
There are several reasons to view this negative
finding cautiously, including small sample size,
elective preclinical termination, and potential
variation in individual susceptibility that may
be associated with the 96 G/S polymorphism in
the PRNP gene (7, 22). Although no genotype
of white-tailed deer is resistant to CWD infection,
PRNP genotypes S/S or G/S at codon 96
appear to have reduced susceptibility manifest
by longer survival (7). Both deer in cohort 3
(urine and feces) were subsequently shown to
be of the PRNP 96 G/S genotype. Thus, it is
possible, although we think unlikely, that these
deer had a prolonged incubation period (918
months pi) before the amplification of PrPCWD
became detectable in tissues. Recent studies
have shown that PrPres is poorly preserved
after incubation with intestinal or fecal content
(23, 24). Further research using cervid and surrogate
cervid PrP transgenic mice (25) are indicated
to continue to address the presence of
infectious CWD prions in excreta of CWDþ deer and to provide a more substantial basis for
reconsideration of the assumption that excreta
are the chief vehicle for CWDdissemination and
transmission.
The results reported here provide a plausible
basis for the efficient transmission of CWD in
nature. We demonstrate that blood and saliva in
particular are able to transmit CWD to naBve deer
and produce incubation periods consistent with
those observed in naturally acquired infections
(3, 26). The time from exposure to first detection
of PrPCWD by tonsil biopsy was variable—as
short as 3 months but as long as 18 months (likely
underestimates due to sampling frequency).
The results also reinforce a cautious view of the
exposure risk presented by body fluids, excreta,
and all tissues from CWDþ cervids. ...
SNIP...END
http://www.sciencemag.org/
CWD AND ENVIRONMENTAL FACTORS i.e. saliva, fecal shedding and fecal-oral transmission is likely
http://p079.ezboard.com/fwolftracksproductionsfrm2.showMessage?topicID=592.topic
TSS
#################### https://lists.aegee.org/bse-l.html ####################
Subject: Infectious Prions in the Saliva and Blood of Deer with Chronic Wasting Disease
Date: October 5, 2006 at 1:45 pm PST
Infectious Prions in the Saliva
and Blood of Deer with Chronic
Wasting Disease
Candace K. Mathiason,1 Jenny G. Powers,3 Sallie J. Dahmes,4 David A. Osborn,5 Karl V. Miller,5
Robert J. Warren,5 Gary L. Mason,1 Sheila A. Hays,1 Jeanette Hayes-Klug,1 Davis M. Seelig,1
Margaret A. Wild,3 Lisa L. Wolfe,6 Terry R. Spraker,1,2 Michael W. Miller,6 Christina J. Sigurdson,1
Glenn C. Telling,7 Edward A. Hoover1*
A critical concern in the transmission of prion diseases, including chronic wasting disease (CWD)
of cervids, is the potential presence of prions in body fluids. To address this issue directly, we
exposed cohorts of CWD-nai¨ve deer to saliva, blood, or urine and feces from CWD-positive deer.
We found infectious prions capable of transmitting CWD in saliva (by the oral route) and in blood
(by transfusion). The results help to explain the facile transmission of CWD among cervids and
prompt caution concerning contact with body fluids in prion infections.
SNIP...
Deer cohorts 1 (blood), 2 (saliva), and 3
(urine and feces) were electively euthanized at
18 months pi to permit whole-body examination
for PrPCWD. The greatest scrutiny was directed
toward those tissues previously established
to have highest frequency of PrPCWD deposition
in infected deer and generally regarded
as the most sensitive indicators of infection—
medulla oblongata and other brainstem regions,
tonsil, and retropharyngeal lymph node. We
found unequivocal evidence of PrPCWD in brain
and lymphoid tissue of all six tonsil biopsy–
positive deer in cohorts 1 (blood) and 2 (saliva),
whereas all deer in cohorts 3 and 5 were negative
for PrPCWD in all tissues (Table 2 and
Figs. 1 and 2).
The transmission of CWD by a single blood
transfusion from two symptomatic and one
asymptomatic CWDþ donor is important in at
least three contexts: (i) It reinforces that no tissue
from CWD-infected cervids can be considered
free of prion infectivity; (ii) it poses the
possibility of hematogenous spread of CWD,
such as through insects; and (iii) it provides a
basis for seeking in vitro assays sufficiently
sensitive to demonstrate PrPCWD or alternate
prion protein conformers in blood—one of the
grails of prion biology and epidemiology.
The identification of blood-borne prion
transmission has been sought before with mixed
results (9–11). Bovine spongiform encephalopathy
and scrapie have been transmitted to naBve
sheep through the transfer of 500 ml of blood
or buffy coat white blood cells from infected
sheep (12, 13). In addition, limited but compelling
evidence argues for the transmission of variant
Creutzfeldt-Jakob disease (vCJD) through blood
from asymptomatic donors (14–16). Even in
sporadic CJD, PrPres has been found in periph-
eral organs of some patients (17). The present
work helps establish that prion diseases can be
transmitted through blood.
The presence of infectious CWD prions in
saliva may explain the facile transmission of
CWD. Cervid-to-cervid interactions (SOM text),
especially in high density and captive situations,
would be expected to facilitate salivary crosscontact
(11, 18, 19). Salivary dissemination of
prions may not be limited to CWD. Proteaseresistant
prion protein has been demonstrated in
the oral mucosa, taste buds, lingual epithelium,
vomeronasal organ, and olfactory mucosa of
hamsters infected with transmissible mink
encephalopathy (19) and ferrets infected with
CWD (20). Although no instance of CWD
transmission to humans has been detected, the
present results emphasize the prudence of using
impervious gloves during contact with saliva or
blood of cervids that may be CWD-infected.
Environmental contamination by excreta
from infected cervids has traditionally seemed
the most plausible explanation for the dissemination
of CWD (21). However, we could not
detect PrPCWD in cohort 3 deer inoculated repeatedly
with urine and feces from CWDþ deer and examined up to 18 months pi (Table 2).
There are several reasons to view this negative
finding cautiously, including small sample size,
elective preclinical termination, and potential
variation in individual susceptibility that may
be associated with the 96 G/S polymorphism in
the PRNP gene (7, 22). Although no genotype
of white-tailed deer is resistant to CWD infection,
PRNP genotypes S/S or G/S at codon 96
appear to have reduced susceptibility manifest
by longer survival (7). Both deer in cohort 3
(urine and feces) were subsequently shown to
be of the PRNP 96 G/S genotype. Thus, it is
possible, although we think unlikely, that these
deer had a prolonged incubation period (918
months pi) before the amplification of PrPCWD
became detectable in tissues. Recent studies
have shown that PrPres is poorly preserved
after incubation with intestinal or fecal content
(23, 24). Further research using cervid and surrogate
cervid PrP transgenic mice (25) are indicated
to continue to address the presence of
infectious CWD prions in excreta of CWDþ deer and to provide a more substantial basis for
reconsideration of the assumption that excreta
are the chief vehicle for CWDdissemination and
transmission.
The results reported here provide a plausible
basis for the efficient transmission of CWD in
nature. We demonstrate that blood and saliva in
particular are able to transmit CWD to naBve deer
and produce incubation periods consistent with
those observed in naturally acquired infections
(3, 26). The time from exposure to first detection
of PrPCWD by tonsil biopsy was variable—as
short as 3 months but as long as 18 months (likely
underestimates due to sampling frequency).
The results also reinforce a cautious view of the
exposure risk presented by body fluids, excreta,
and all tissues from CWDþ cervids. ...
SNIP...END
http://www.sciencemag.org/
CWD AND ENVIRONMENTAL FACTORS i.e. saliva, fecal shedding and fecal-oral transmission is likely
http://p079.ezboard.com/fwolftracksproductionsfrm2.showMessage?topicID=592.topic
TSS
#################### https://lists.aegee.org/bse-l.html ####################