Oral and Poster Abstracts

In Belgium, an increasing amount of catastrophic botulism outbreaks in
cattle herds have recently been reported to the Belgian Federal Agency for
the Safety of the Food Chain (FASFC). The latter confirms that at least in
Belgium botulism is becoming an emerging disease in cattle resulting in
large economical loss for the farmers. This presentation describes 4 major
outbreaks in the Flemish part of Belgium occurring between July 2005
and February 2007. The average mortality on all farms varied from 27 to
96 %. The first case involved a mixed dairy-poultry farm that encountered
a morbidity of 33 % and mortality of 27 %. Two possible causes of
intoxication have been proposed. One being a severe rainfall spreading
the toxins from the poultry litter to the dairy stable and maize silage, the
other is an infected grass silage after fertilization with poultry litter. C.
botulinum intoxication was diagnosed by identification of C. botulinum
type C and D toxins in the faeces and the liver of the affected animals and
in samples of the maize silage. The second dairy farm reported a
morbidity and mortality of respectively 51 % and 49 %. Here, the
diagnosis was confirmed by identification of the C. botulinum type D
toxin in liver and mixed-forage samples. A chicken cock housing a nearby
water well that provided the drinking water for the cows was found
positive for the same type of toxin, and was hence seen as the main
contributor to the catastrophe. On the third farm, a mixed swine-dairy
herd, the highest morbidity and mortality was seen, being respectively 100
% and 96 %. The farm had one ensilaged grass pack in which possibly a
wild animal was encaptured while moving. A sample of this grass silage
was positive for the C. botulinum type D toxin. The fourth poultry-dairy
mixed farm previously piled up poultry litter on the place where actually
the wet brewer grains fed to the dairy cows were stored. On a total of 85
cows, 67 died leading to a mortality of 79 %. Neurotoxin type D was
isolated in a wet brewer grain sample leading to the C. botulinum
diagnosis. The presented outbreaks here encouraged Belgian farmers,
veterinarians, the Flemish Animal Health Service (DGZ-Vlaanderen) and
the FASFC on describing risk factors for botulism more profoundly and
elaborated a strategy leading to a quicker diagnosis and a better approach
of a C. botulinum outbreak in cattle. These will be discussed in detail.
Key words: Clostridium botulinum outbreak, cattle, poultry
48 Molecular Mechanism of Action of Pentosan Polysulfate on the
Cellular Prion Protein
V. Stadnyk, C. Mayor,V. Vlizlo
Institute of Animal Biology UAAS, Scientific Center for Prion
Infections Study, Lviv, Ukraine
Objectives of study: It was shown by our previous researches, that
pentosan polysulfat has the ability to inhibit the expression of cellular
prion protein (PrP C ) in the prion-replicative organs of laboratory animals,
that it can be used for the prophylaxis of prion infections, in particular
BSE. But the molecular mechanism of action of this preparation on PrP C
until now is not clear. The aim of our work was to find out the molecular
mechanisms of pentosan polysulfate influencing on PrP C .
Materials and Methods: for the research of co-operation of pentosan
polysulfate and PrP C were used the ELISA method, mapping of amino
acid residues of PrP C , which co-operate with pentosan polisulfate were
carried out by bioinformatical methods and UV-spectroscopy.
Results: It is set that PrP C and pentosan polysulfate specifically cooperate
in vitro. Except this, it is shown that for this co-operation the
sulfate groups of pentosan are responsible and aminogroups of Arg148
and Arg151.
Conclusions: it is set that inhibiting influence of pentosan polysulfate
on PrP C is predefined, probably, by the direct co-operation of these
molecules.
Key words: prion protein, pentosan polysulphate
49 Distribution of Abnormal Prion Protein in the Brain of Goats
E. Bouzalas 1 , C. Dovas 1 , S. Kritas 1 , M. Papanastasopoulou 1 ,
D. Papakostaki 2 , E. Chatzinasiou 1 , G. Koptopoulos 1
1
Aristotle University of Thessaloniki, School of Veterinary Medicine,
Department of Microbiology and Infectious Diseases, Thessaloniki,
Greece
2
Veterinary Institute of Infectious and Parasitic Diseases,
Thessaloniki, Greece
The objective of this study was to assess the distribution of PrP Sc in the
brain of goats raised in a flock with high incidence of scrapie. Scrapie
is a progressive fatal neurodegenerative disease affecting both sheep
and goats. Its diagnosis is mainly based on the detection of the
76 XXV. Jubilee World Buiatrics Congress 2008
abnormal prion protein (PrP Sc ) in the medulla oblongata at the level of
the obex. The study was undertaken in a semi-extensive flock of goats
comprised of 250 animals, 105 of which were older than 12 months. All
animals were euthanized and samples from medulla oblongata were
taken from 86 out of the 105 goats. Additional samples were collected
from pons, cerebellum, midbrain at the level of superior colliculus,
diencephalon at the level of optic chiasm and frontal lobe of cerebrum
to study the distribution of PrP Sc in these animals. The samples were
examined by a rapid ELISA (Enzyme-Linked-Immunosorbent-Assay)
test (EC No 999/2001) and an immunochromatography assay and
positive samples were additionally confirmed with Western blot (WB)
and/or immunohistochemistry (IHC). Examination of the obex with the
rapid ELISA test revealed the presence of PrP Sc in 12 goats (14%). Five
of them had shown also clinical signs such as disorientation, ataxia,
apathy and sometimes aggressiveness. In 10 out of those 12 animals,
PrP Sc was detected by both methods in other parts of the brain besides
obex. Interestingly, in 3 goats other than the obex positive ones, PrP Sc
was found in other parts of the brain and mainly in the hypothalamus
(diencephalon). It was concluded that these findings might question the
use of obex as the exclusive sampling site for detecting the presence of
PrP Sc in goats.
Key words: scrapie, PrP Sc , distribution, brain, goats
50 Dynamics and Distribution of Prion Infectivity in Sheep Blood
C. Lacroux 1 , N. Morel 2 , S. Simon 2 , H. Cassard 1 , F. Corbiere 1 ,
J. Mathey 1 , F. Schelcher 1 , F. Lantier 3 , J. Grassi 2 , O. Andréoletti 1
1
INRA ENVT UMR 1225, Interactions hôtes-agents pathogénes,
Toulouse, France
2
CEA, SPI, Saclay, France
3
INRA, IASP, tours, France
In sheep prion transmission has been observed by transfusion of whole
blood sampled at the end of the first half of the incubation phase.
However, in this species, dynamics and distribution of the infectivity
presence in blood remained poorly documented. We first characterized
infectivity dynamics and distribution in blood from sheep experimentally
challenged by the oral route with a “rapid” strain. In this model clinical
onset is observed as soon as 160 days post challenge. Inoculated animals
were sampled every month and blood was fractionated into buffy-coat,
Ficoll cells and plasma. Moreover T CD4 and CD8 lymphocytes, B
lymphocytes (CD45r), Mono-nucleated phagocytes (CD14) and Negative
fraction (containing CD4-, CD8-, CD45r- and CD14- cells) were sorted
from Ficoll preparations. Each fraction was immunoprecipitated before
concentration under small volume and IC inoculation to Tg338 mice
(transgenic ovine PrP gene). Bioassay revealed that, infectivity (i) can be
detected in this model as early as D60 post challenge (ii) is mainly linked
to CD14 positive cells. Moreover this experiment provided elements
indicating that infectivity presence in blood is correlated to PrPsc presence
in secondary lymphoid tissue. In a second experiment, we investigated
sheep naturally infected with scrapie (Langlade model). In this model,
blood transfusion allowed to transmit disease as early as 3 months of age
and infectivity presence in blood persisted all along the incubation phase.
Moreover we demonstrated that animals contracting scrapie through
transfusion were contaminant (through blood) 3 months post transfusion.
In this model first results of bioassay in Tg338 mice confirmed that most
infectious blood fractions are the mononucleated cells and more
particularly CD14. Finally, the efficiency of contamination by blood
transfusion was established by comparison to IV inoculation using a
titrated (in Tg338 mice) inoculum. Results revealed that a 200 ml whole
blood transfusion was as efficient as an IV inoculation with 510 5 DL50, in
contrast with the low infectivity level observed by direct blood bioassay in
mice. This element could suggest that infectivity in whole blood is
supported by a highly efficient mechanism. Both dynamics and nature of
the infectivity positive fractions are of interest with regards to (i) the
development and evaluation of diagnostic tests on live animals and (ii)
human blood sanitary policy.
Key words : prion, scrapie, sheep, blood, infectivity
51 Retrospective Study of BSE Surveillance in Canada from 1992
to 2005
J. Kellar 1 , J. Paré 2 , L. Myers 3
1
Canadian Food Inspection Agency, Animal Products Directorate,
Ottawa, Canada
2
Canadian Food Inspection Agency, Epidemiology and Surveillance
Section, Saint-Hyacinthe, Canada