are very peculiar “infectious agents” composed of only one protein genome free.
Prions are aggregates of a “normal” prion protein (PrP,) mainly and normally
present on the surface of the neuron’s membrane. Aggregation occurs when the
normal cellular PrP (PrPc) meets a PrP scrapie (PrPsc) that is a PrPc with a
consistent modified conformation (the “seed”) able to induce transformation and
aggregation of PrPc.
The PrPc could be:
Prions cause transmissible
spongiform encephalopathy (TSE), a degenerative disease of the central nervous
system with a very long incubation period lastingly many years. Typical disease
in humans is Creutzfeldt-Jakob (CJD), while in animals scrapie in ovine and BSE
in bovine. All TSEs are lethal with a relatively short clinical period, with
signs typical for each disease.
Starting from 2001, IZSLER
examined well over 2 million adult bovines as requested by the European
surveillance plan for TSE, finalized to definitively establish the incidence of
BSE in all the European countries. In over 10 years of activity the IZSLER
laboratories found around one hundredBSE positive cases, most of which in the
first three years of control. As expected, cases of BSE rapidly disappeared and
the disease could be now considered eradicated in Italy.
The situation for scrapie of
goat and sheep is different. The disease is endemic in Italy, although at low
levels, and few case each year are still detected.
The IBVR at IZSLER includes
part of the original samples resulted BSE or Scrapie positive. They consist in
few grams of the brainstem left after the tests (rapid test and confirmatory
test carried out at the National Reference Center for TSE at IZS of Torino) and
stored at – 72°C.
People interested must know
that working with prions (class 3 risk material) requires special safety and
dedicated areas, specific equipment and well trained people. In addition,
considering the high epidemiological risk and danger represented by BSE prion,
the permission to transport and export prion samples must follow a particular
procedure that has to directly involve the Health Authorities of all the
Samples originated directly
from the field (mainly slaughterhouses) and therefore they are carrier of a
generic microbiological contamination.
All the samples resulted
positive towards UE validated rapid tests. They changed over the time according
to the outcomes of a specific national tender and were: Prionics western
blotting, LIA Prionics, Priostrip Prionics, ELISA Ideex. All the samples were then
confirmed as positive at CEA Torino (histology, immunohistochemistry and
Quality management system
IZSLER laboratories, that
supply biological resources to IBVR, use testing methods performed according to
UNI EN ISO/IEC 17025 Quality System.
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