[3. Methods and protocols U.K.
3.1. Laboratory testing for the presence of BSE in bovine animals U.K.
(a) Suspect cases U.K.
Samples from bovine animals sent for laboratory testing pursuant to the provisions of Article 12(2) shall immediately be subjected to confirmatory examinations using at least one of the following methods and protocols laid down in the latest edition of the Manual:
(i)
the immunohistochemical (IHC) method;
(iii)
the demonstration of characteristic fibrils by electron microscopy;
(iv)
histopathological examination;
(v)
the combination of rapid tests as laid down in the third subparagraph.
If the histopathological examination is inconclusive or negative, the tissues shall be submitted to a further examination by one of the other confirmatory methods and protocols.
Rapid tests may be used for both primary screening of suspect cases and, if inconclusive or positive, for subsequent confirmation, according to the guidelines from the EU reference laboratory — ‘ OIE rules for the official confirmation of BSE in bovines (based on an initial reactive result in an approved rapid test) by using a second rapid test ’ , and provided that:
(i)
the confirmation is carried out in a national reference laboratory for TSEs; and
(ii)
one of the two rapid tests is a Western blot; and
(iii)
the second rapid test used:
includes a negative tissue control and a bovine BSE sample as positive tissue control,
is of a different type than the test used for the primary screening; and
(iv)
if a rapid Western blot is used as the first test, the result of that test must be documented and the blot image submitted to the national reference laboratory for TSEs; and
(v)
where the result of the primary screening is not confirmed by the subsequent rapid test, the sample must be subjected to an examination by one of the other confirmatory methods; where the histopathological examination is used for that purpose, but proves to be inconclusive or negative, the tissues must be submitted to a further examination by one of the other confirmatory methods and protocols.
If the result of one of the confirmatory examinations referred to in points (i) to (v) of the first subparagraph is positive, the animal shall be regarded as a positive BSE case.
(b) BSE monitoring U.K.
Samples from bovine animals sent for laboratory testing pursuant to the provisions of Annex III, Chapter A, Part I shall be examined by a rapid test.
When the result of the rapid test is inconclusive or positive, the sample shall immediately be subjected to confirmatory examinations using at least one of the following methods and protocols laid down in the latest edition of the Manual:
(i)
the immunohistochemical (IHC) method;
(iii)
the demonstration of characteristic fibrils by electron microscopy;
(iv)
histopathological examination;
(v)
the combination of rapid tests as laid down in the fourth subparagraph.
Where the histopathological examination is inconclusive or negative, the tissues shall be submitted to a further examination by one of the other confirmatory methods and protocols.
Rapid tests may be used for both primary screening and, if inconclusive or positive, for subsequent confirmation, according to the guidelines from the EU reference laboratory — ‘ OIE rules for the official confirmation of BSE in bovines (based on an initial reactive result in an approved rapid test) by using a second rapid test, and provided that ’ :
(i)
the confirmation is carried out in a national reference laboratory for TSEs; and
(ii)
one of the two rapid tests is a Western blot; and
(iii)
the second rapid test used:
includes a negative tissue control and a bovine BSE sample as positive tissue control,
is of a different type than the test used for the primary screening; and
(iv)
if a rapid Western blot is used as the first test, the result of that test must be documented and the blot image submitted to the national reference laboratory for TSEs; and
(v)
where the result of the primary screening is not confirmed by the subsequent rapid test, the sample must be subjected to an examination by one of the other confirmatory methods; where the histopathological examination is used for that purpose, but proves to be inconclusive or negative, the tissues must be submitted to a further examination by one of the other confirmatory methods and protocols.
An animal shall be regarded a positive BSE case if the result of the rapid test is inconclusive or positive, and at least one of the confirmatory examinations referred to in points (i) to (v) of the second subparagraph is positive.
(c) Further examination of positive BSE cases U.K.
Samples from all positive BSE cases shall be forwarded to a laboratory, appointed by the competent authority, which has participated successfully in the latest proficiency testing organised by the EU reference laboratory for discriminatory testing of confirmed BSE cases, where they shall be further tested in accordance with the methods and protocols laid down in the EU reference laboratory's method for the classification of bovine TSE isolates (a two-blot method for the provisional classification of bovine TSE isolates).
3.2. Laboratory testing for the presence of TSE in ovine and caprine animals U.K.
(a) Suspect cases U.K.
Samples from ovine and caprine animals sent for laboratory testing pursuant to the provisions of Article 12(2) shall immediately be subjected to confirmatory examinations using at least one of the following methods and protocols laid down in the latest edition of the Manual:
(i)
the immunohistochemical (IHC) method;
(iii)
the demonstration of characteristic fibrils by electron microscopy;
(iv)
histopathological examination.
In case the histopathological examination is inconclusive or negative, the tissues shall be submitted to a further examination by one of the other confirmatory methods and protocols.
Rapid tests may be used for primary screening of suspect cases. Such tests may not be used for subsequent confirmation.
Where the result of the rapid test used for primary screening of suspect cases is positive or inconclusive, the sample shall be subjected to an examination by one of the confirmatory examinations referred to in points (i) to (iv) of the first subparagraph. Where the histopathological examination is used for that purpose, but proves to be inconclusive or negative, the tissues shall be submitted to a further examination by one of the other confirmatory methods and protocols.
If the result of one of the confirmatory examinations referred to in points (i) to (iv) of the first subparagraph is positive, the animal shall be regarded as a positive TSE case and further examination as referred to in point (c) shall be performed.
(b) TSE monitoring U.K.
Samples from ovine and caprine animals sent for laboratory testing pursuant to the provisions of Annex III, Chapter A, Part II (Monitoring in ovine and caprine animals) shall be examined by a rapid test, in order to ensure the detection of all known strains of TSE.
When the result of the rapid test is inconclusive or positive, the sampled tissues shall immediately be sent to an official laboratory for confirmatory examinations by histopathology, immunohistochemistry, Western blotting or demonstration of characteristic fibrils by electron microscopy, as referred to in point (a). If the result of the confirmatory examination is negative or inconclusive, the tissues shall be submitted to a further examination by immunohistochemistry or Western blotting.
If the result of one of the confirmatory examinations is positive, the animal shall be regarded as a positive TSE case and further examination as referred to in point (c) shall be performed.
(c) Further examination of positive TSE cases U.K.
(i) Primary molecular testing with a discriminatory Western blotting method U.K.
Samples from clinical suspect cases and from animals tested in accordance with Annex III, Chapter A, Part II, points 2 and 3 which are regarded as positive TSE cases but which are not atypical scrapie cases following the examinations referred to in points (a) or (b), or which display characteristics which are deemed by the testing laboratory to merit investigation, shall be examined using a discriminatory Western blotting method listed in the guidelines of the EU reference laboratory by an official diagnostic laboratory designated by the competent authority, which has participated successfully in the latest proficiency testing organised by the EU reference laboratory for the use of such a method.
(ii) Secondary molecular testing with additional molecular testing methods U.K.
TSE cases in which the presence of BSE cannot be excluded according to the guidelines issued by the EU reference laboratory by the primary molecular testing referred to in point (i), shall be referred immediately to the EU reference laboratory, with all the relevant information available. The samples shall be submitted to further investigation and confirmation by at least one alternative method, differing immunochemically from the original primary molecular method, depending on the volume and nature of the referred material, as described in the guidelines of the EU reference laboratory. These additional tests will be carried out in the following laboratories approved for the relevant method:
Agence Nationale de Sécurité Sanitaire de l'alimentation, de l'environnement et du travail
31, avenue Tony Garnier
BP 7033
F-69342 Lyon Cedex
Commissariat à l'Energie Atomique
18, route du Panorama
BP 6
F-92265 Fontenay-aux-Roses Cedex
Animal Health and Veterinary Laboratories Agency
Woodham Lane
New Haw
Addlestone
Surrey KT15 3NB
United Kingdom
The results shall be interpreted by the EU reference laboratory assisted by a panel of experts referred to as the Strain Typing Expert Group (STEG), including a representative of the relevant national reference laboratory. The Commission shall be informed immediately about the outcome of that interpretation.
(iii) Mouse bioassay U.K.
Samples indicative of BSE or inconclusive for BSE, following secondary molecular testing, shall be further analysed by mouse bioassay for final confirmation. The nature or quantity of available material may influence the bioassay design, which will be approved by the EU reference laboratory assisted by the STEG on a case by case basis. Bioassays will be performed by the EU reference laboratory, or by laboratories designated by the EU reference laboratory.
The results shall be interpreted by the EU reference laboratory assisted by the STEG. The Commission shall be informed immediately about the outcome of that interpretation.
3.3. Laboratory testing for the presence of TSEs in species other than those referred to in points 3.1 and 3.2 U.K.
Where methods and protocols are established for tests carried out to confirm the suspected presence of a TSE in a species other than bovine, ovine and caprine, they shall include at least a histopathological examination of brain tissue. The competent authority may also require laboratory tests such as immunohistochemistry, Western blotting, demonstration of characteristic fibrils by electron microscopy or other methods designed to detect the disease associated form of the prion protein. In any case at least one other laboratory examination shall be carried out if the initial histopathological examination is negative or inconclusive. At least three different examinations with positive results shall be carried out in the event of the first appearance of the disease.
In particular, where BSE is suspected in a species other than bovine animals, the cases shall be referred to the EU reference laboratory assisted by the STEG for further characterisation.]