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From: TSS ()
Subject: SEAC Draft open minutes of the 97th meeting held on 10th May 2007
Date: July 14, 2007 at 9:13 am PST

Draft open minutes of the 97th meeting held on 10th May 2007


2. The SEAC Secretary explained that open meetings allow the public
an opportunity to observe the committee at work and provide an
insight into how an advisory committee provides independent
scientific advice to Government. Government officials with
responsibility for Transmissible Spongiform Encephalopathy (TSE)
policy may be invited to contribute to discussions. The committee
will hold a reserved business session in the afternoon to allow
discussion of unpublished studies on unusual cases of BSE and
ongoing research on possible transmission of variant CJD (vCJD)
via dentistry. This is in accordance with the SEAC Code of
Practice. Short summaries of the open and reserved business
discussions would be published on the SEAC website.


7. SEAC was informed about the following issues, both of which were
discussed later in the agenda:
• United Kingdom Chief Dental Officers recently issued
guidance to dentists to limit certain dental instruments to
single use as a precautionary measure to reduce the potential
risk of variant Creutzfeldt-Jakob Disease (CJD) transmission1.
• The first unusual case of Bovine Spongiform Encephalopathy
(BSE) in the UK.


24. Question one related to changes in the prevalence of atypical
scrapie. Members considered that changes in prevalence would
be most significant if concomitant changes occurred in the
prevalence of new types of CJD cases. However, it was
acknowledged that, because of the long incubation periods of prion
diseases, such changes may take years or even decades to
emerge. Surveillance should continue so that any changes in
prevalence of CJD types can be detected.
25. Question two related to the implications of finding atypical scrapie
in countries previously thought to be free from classical and
atypical scrapie. Members noted that in the absence of any data
which suggests a link between types of CJD and atypical scrapie
such a scenario would not change the assessment of risk.
26. Question three related to the perception of risk should atypical
scrapie be found to have a similar epidemiology to classical
scrapie. Members responded that if historic data show the disease
had been around for many years this may suggest the risk was
low, however the long incubation period of human prion diseases
© SEAC 2006
made it impossible to draw firm conclusions at this time. It was
noted that the earliest atypical scrapie case identified was from
1989 highlighting that this is not a very new disease. Members
considered it important to continue to assess the prevalence of
atypical scrapie and that historic sheep samples be analysed for
the presence of atypical scrapie. Dr Matthews noted that atypical
scrapie had now been found in the United States of America.
27. Question four asked what significance should be attached to
analysis of historic samples if results show similar biochemical
profiles to recent cases. Members considered that this was
dependent on whether surveillance suggested that atypical scrapie
was associated with CJD. Question five asked whether the 1989
case of atypical scrapie in the UK heightens concern that this was
a newly emerged disease that had spread and whether humans
may be incubating the disease without having developed clinical
disease. Members considered that this was possible but, perhaps
28. Questions six to 10 considered the interpretation of results from
transmission experiments of atypical scrapie, BSE and classical
scrapie in mice. Members responded that although transmissions
would be suggestive of a risk, especially in experiments using
humanised mice, the level of risk would be difficult to determine
without comparative studies with other TSEs using the same
model. Strong evidence of a risk would only be obtained if similar
results from comparative studies were obtained in more than one
model were obtained, this would provide strong evidence of a risk.
Members also considered it important that transmission studies be
conducted in ovinised mice of all sheep prion protein genotypes to
assess transmissibility between sheep. If secondary but not
primary passage of atypical scrapie lead to transmissions in
humanised mice, members agreed it would be important to
conduct further subpassages and compare the behaviour of
atypical scrapie with other TSEs in these studies.
29. Questions 11 and 12 related to the interpretation of transmission of
atypical scrapie in non-human primates. Members noted that nonhuman
primate models are all methionine homozygous at codon
129 of the prion protein gene and therefore, unlike humanised
mice, gave data relating only to one genotype. However, unlike
mice, the immune and lymphoreticular system of non-human
primates were closely related to those of humans. Thus, data from
non-human primates and humanised mice would provide
complementary data and together provide a better assessment of
the risk than data from one type of model. However, the route of
© SEAC 2006
administration was critical and experiments using the oral route are
the most relevant to human exposure.


40. Professor Noel Gill (Health Protection Agency [HPA]) explained
that the National Anonymous Tonsil Archive was on track to report
to the SEAC Epidemiology Subgroup in June 2007 the analysis of
tonsils collected to date from the age group likely to be at most risk
of BSE infection. The report from the Post Mortem Tissue Archive
Working Group investigating the feasibility of a large scale archive
of tissues collected from coroners’ autopsies would be published in
the near future. The recommendations would be considered by the
Department of Health (DH). The HPA had received four tenders
from manufacturers of prototype blood tests for the analysis of a
large number of anonymised blood samples. These tenders would
be considered by the HPA’s Tissue Testing Advisory Group at the
end of May 2007 and the study would be taken forward on the
advice of this group.
41. Members asked whether there were sufficient blood samples from
vCJD cases to include as controls in a survey of anonymised blood
samples. Professor Gill noted that such material was in very short
supply and access was considered by an advisory group convened
by the National Institute of Biological Standards and Control
(NIBSC). A member noted that blood from vCJD cases held at the
NCJDSU had been sent to NIBSC and that other institutes had
agreed to provide the samples that they hold to NIBSC. A
suggestion had been made that the current protocol for collection
of blood from vCJD cases be altered so that future blood samples
can be sent directly to NIBSC.
42. Dr Peter Bennett (DH) explained that, although there was some
consensus about the risk of vCJD transmission from transfusion of
blood components, there was little consensus about the risks from
transfusion of plasma products. Although, since 1999, plasma
products were produced from plasma imported from countries
considered to be free of BSE, a risk of infection existed for
individuals transfused with plasma products prior to this time.
Thus, there is a need to quantify the effect of the production
process prior to 1999 on the levels of infectivity in plasma products
produced from contaminated plasma. Studies to examine the
effect of the production process had mostly used plasma spiked
© SEAC 2006
with TSE agents. As SEAC had considered spiking studies to be
of uncertain reliability in the past, these data had been ignored.
However, more recently SEAC had considered spiking studies
useful in assessing the efficacy of prion reduction filters, provided
confirmatory experiments were conducted using endogenous
infectivity. Given this, a reassessment of the data on the effect of
plasma product production may be informative. In addition, SEAC
consideration of the time window for possible infections arising
from use of plasma products prior to 1999 would also be helpful.
43. The Chair agreed that SEAC should consider these issues at
SEAC 98. Members noted that it is unlikely that new compelling
data would be available to inform such a reassessment. An
assessment is complicated by the variability in the likely distribution
of infectivity in plasma components and in the effect of processing
steps. It was suggested that some new data may be available
from the Haemophilia Doctors Association and that a
representative should be invited for the discussion. It was also
suggested that a representative from Bio Products Laboratory, the
main centre for plasma fractionation in the UK, be invited.
44. The Chair closed the meeting, thanking all those that had
presented information to the committee and all those that attended
the meeting.

Published online before print October 20, 2005

Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0502296102
Medical Sciences

A newly identified type of scrapie agent can naturally infect sheep with
resistant PrP genotypes

( sheep prion | transgenic mice )

Annick Le Dur *, Vincent Béringue *, Olivier Andréoletti , Fabienne Reine *,
Thanh Lan Laï *, Thierry Baron , Bjørn Bratberg ¶, Jean-Luc Vilotte ||,
Pierre Sarradin **, Sylvie L. Benestad ¶, and Hubert Laude *
*Virologie Immunologie Moléculaires and ||Génétique Biochimique et
Cytogénétique, Institut National de la Recherche Agronomique, 78350
Jouy-en-Josas, France; Unité Mixte de Recherche, Institut National de la
Recherche Agronomique-Ecole Nationale Vétérinaire de Toulouse, Interactions
Hôte Agent Pathogène, 31066 Toulouse, France; Agence Française de Sécurité
Sanitaire des Aliments, Unité Agents Transmissibles Non Conventionnels,
69364 Lyon, France; **Pathologie Infectieuse et Immunologie, Institut
National de la Recherche Agronomique, 37380 Nouzilly, France; and
¶Department of Pathology, National Veterinary Institute, 0033 Oslo, Norway

Edited by Stanley B. Prusiner, University of California, San Francisco, CA,
and approved September 12, 2005 (received for review March 21, 2005)

Scrapie in small ruminants belongs to transmissible spongiform
encephalopathies (TSEs), or prion diseases, a family of fatal
neurodegenerative disorders that affect humans and animals and can transmit
within and between species by ingestion or inoculation. Conversion of the
host-encoded prion protein (PrP), normal cellular PrP (PrPc), into a
misfolded form, abnormal PrP (PrPSc), plays a key role in TSE transmission
and pathogenesis. The intensified surveillance of scrapie in the European
Union, together with the improvement of PrPSc detection techniques, has led
to the discovery of a growing number of so-called atypical scrapie cases.
These include clinical Nor98 cases first identified in Norwegian sheep on
the basis of unusual pathological and PrPSc molecular features and "cases"
that produced discordant responses in the rapid tests currently applied to
the large-scale random screening of slaughtered or fallen animals.
Worryingly, a substantial proportion of such cases involved sheep with PrP
genotypes known until now to confer natural resistance to conventional
scrapie. Here we report that both Nor98 and discordant cases, including
three sheep homozygous for the resistant PrPARR allele (A136R154R171),
efficiently transmitted the disease to transgenic mice expressing ovine PrP,
and that they shared unique biological and biochemical features upon
propagation in mice. These observations support the view that a truly
infectious TSE agent, unrecognized until recently, infects sheep and goat
flocks and may have important implications in terms of scrapie control and
public health.


Author contributions: H.L. designed research; A.L.D., V.B., O.A., F.R.,
T.L.L., J.-L.V., and H.L. performed research; T.B., B.B., P.S., and S.L.B.
contributed new reagents/analytic tools; V.B., O.A., and H.L. analyzed data;
and H.L. wrote the paper.

A.L.D. and V.B. contributed equally to this work.

To whom correspondence should be addressed.

Hubert Laude, E-mail:

Then follow up with PNAS studies from which
new scientist article written from;

Published online before print March 20, 2001
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.041490898

Adaptation of the bovine spongiform encephalopathy agent to primates and
comparison with Creutzfeldt- Jakob disease: Implications for human health
Corinne Ida Lasmézas*, [dagger] , Jean-Guy Fournier*, Virginie Nouvel*,
Hermann Boe*, Domíníque Marcé*, François Lamoury*, Nicolas Kopp [Dagger
] , Jean-Jacques Hauw§, James Ironside¶, Moira Bruce [||] , Dominique
Dormont*, and Jean-Philippe Deslys*

Edited by D. Carleton Gajdusek, Centre National de la Recherche
Scientifique, Gif-sur-Yvette, France, and approved December 7, 2000
(received for review October 16, 2000)


There is substantial scientific evidence to support the notion that
bovine spongiform encephalopathy (BSE) has contaminated human beings,
causing variant Creutzfeldt-Jakob disease (vCJD). This disease has
raised concerns about the possibility of an iatrogenic secondary
transmission to humans, because the biological properties of the
primate-adapted BSE agent are unknown. We show that (i) BSE can be
transmitted from primate to primate by intravenous route in 25 months,
and (ii) an iatrogenic transmission of vCJD to humans could be readily
recognized pathologically, whether it occurs by the central or
peripheral route. Strain typing in mice demonstrates that the BSE agent
adapts to macaques in the same way as it does to humans and confirms
that the BSE agent is responsible for vCJD not only in the United
Kingdom but also in France. The agent responsible for French iatrogenic
growth hormone-linked CJD taken as a control is very different from vCJD
but is similar to that found in one case of sporadic CJD and one sheep
scrapie isolate. .........SNIP

Furthermore, we showed that
the strain responsible for iCJD is closely related to that of one
patient with sCJD, and, more unexpectedly, that these agents were
similar to the French scrapie strain studied (but different from the
U.S. scrapie strain). This finding requires a cautious interpretation
for several reasons, not least because of the inevitably limited number
of TSE strains that can be studied by such a cumbersome method as strain
typing. Nonetheless, it also prompts reconsideration of the possibility
that, in some instances, sheep and human TSEs can share a common origin.


Oral transmission of kuru, Creutzfeldt-Jakob disease, and scrapie to
nonhuman primates.

Gibbs CJ Jr, Amyx HL, Bacote A, Masters CL, Gajdusek DC.

Kuru and Creutzfeldt-Jakob disease of humans and scrapie disease of sheep
and goats were transmitted to squirrel monkeys (Saimiri sciureus) that were
exposed to the infectious agents only by their nonforced consumption of
known infectious tissues. The asymptomatic incubation period in the one
monkey exposed to the virus of kuru was 36 months; that in the two monkeys
exposed to the virus of Creutzfeldt-Jakob disease was 23 and 27 months,
respectively; and that in the two monkeys exposed to the virus of scrapie
was 25 and 32 months, respectively. Careful physical examination of the
buccal cavities of all of the monkeys failed to reveal signs or oral
lesions. One additional monkey similarly exposed to kuru has remained
asymptomatic during the 39 months that it has been under observation.

PMID: 6997404


This is provided by the statistically significant increase in the incidence
of sheep scrape from 1985, as determined from analyses of the submissions
made to VI Centres, and from individual case and flock incident studies.

AS implied in the Inset 25 we must not _ASSUME_ that
transmission of BSE to other species will invariably
present pathology typical of a scrapie-like disease.


18 January 2007 - Draft minutes of the SEAC 95 meeting (426 KB) held on 7
December 2006 are now available.


64. A member noted that at the recent Neuroprion meeting, a study was
presented showing that in transgenic mice BSE passaged in sheep may be more
virulent and infectious to a wider range of species than bovine derived BSE.

Other work presented suggested that BSE and bovine amyloidotic spongiform
encephalopathy (BASE) MAY BE RELATED. A mutation had been identified in the


3:30 Transmission of the Italian Atypical BSE (BASE) in Humanized Mouse

Models Qingzhong Kong, Ph.D., Assistant Professor, Pathology, Case Western Reserve

Bovine Amyloid Spongiform Encephalopathy (BASE) is an atypical BSE strain
discovered recently in Italy, and similar or different atypical BSE cases
were also reported in other countries. The infectivity and phenotypes of
these atypical BSE strains in humans are unknown. In collaboration with
Pierluigi Gambetti, as well as Maria Caramelli and her co-workers, we have
inoculated transgenic mice expressing human prion protein with brain
homogenates from BASE or BSE infected cattle. Our data shows that about half
of the BASE-inoculated mice became infected with an average incubation time
of about 19 months; in contrast, none of the BSE-inoculated mice appear to
be infected after more than 2 years.

***These results indicate that BASE is transmissible to humans and suggest that BASE is more virulent than
classical BSE in humans.***

6:30 Close of Day One

1997 TO 2006. SPORADIC CJD CASES TRIPLED, with phenotype
of 'UNKNOWN' strain growing. ...

There is a growing number of human CJD cases, and they were presented last
week in San Francisco by Luigi Gambatti(?) from his CJD surveillance

He estimates that it may be up to 14 or 15 persons which display selectively
SPRPSC and practically no detected RPRPSC proteins.


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