2003/859/EC: Commission Decision of 5 December 2003 amending Decision 2002/106/EC as regards the establishment of a classical swine fever discriminatory test (Text with EEA relevance) (notified under document number C(2003) 4522)
Date: 2003-12-05
Institutions: European Commission
Subjects: animal plague, balance of payments assistance, research body, swine, testing

11.12.2003

EN

Official Journal of the European Union

L 324/55

COMMISSION DECISION

of 5 December 2003

amending Decision 2002/106/EC as regards the establishment of a classical swine fever
discriminatory test

(notified under document number C(2003) 4522)

(Text with EEA relevance)

(2003/859/EC)

THE COMMISSION OF THE EUROPEAN COMMUNITIES,

(5)

Having regard to the Treaty establishing the European
Community,

Having regard to Council Directive 2001/89/EC of 23 October
2001 on Community measures for the control of classical
swine fever (1), and in particular Article 17(5) thereof,

Whereas:

The new discriminatory test to distinguish vaccinated
pigs from pigs naturally infected with classical swine
fever virus should therefore be established in accordance
with Directive 2001/89/EC by laying down guidelines
on its use. Those rules should ensure that the use of
marker vaccines in conjunction with this test does not
pose unacceptable risks in relation to the movements or
trade of the vaccinated pigs,
their offspring or their
products.

(1)

(2)

(3)

(4)

Rules on the use of classical swine fever vaccines and
related discriminatory tests are laid down in Directive
2001/89/EC and in Commission Decision 2002/106/EC
of 1 February 2002 approving a Diagnostic Manual
establishing diagnostic procedures, sampling methods
and criteria for evaluation of the laboratory tests for the
confirmation of classical swine fever (2).

The use of marker vaccines has been hampered by the
lack of a reliable discriminatory test able to distinguish
between vaccinated pigs and pigs naturally infected with
classical swine fever virus. For that reason no classical
swine fever discriminatory test was established by
Decision 2002/106/EC.

In 2003 the Community reference laboratory for clas-
sical swine fever in cooperation with the national clas-
sical swine fever laboratories evaluated a newly devel-
oped discriminatory test in the context of Commission
Decision 2003/265/EC of 10 April 2003 on financial
assistance to the Community reference laboratory for
classical swine fever for the evaluation of a new classical
swine fever discriminatory test (3).

The results of that evaluation show that the sensitivity
and specificity of the new discriminatory test are suffi-
cient to allow its use in the context of an emergency
vaccination with a marker vaccine.

(6)

(7)

Commission Decision 2002/106/EC should therefore be
amended accordingly.

The measures provided for in this Decision are in
accordance with the opinion of the Standing Committee
on the Food Chain and Animal Health,

HAS ADOPTED THIS DECISION:

Article 1

Chapter VIII of
amended in accordance with the Annex to this Decision.

the Annex to Decision 2002/106/EC is

Article 2

This Decision is addressed to the Member States.

Done at Brussels, 5 December 2003.

For the Commission

David BYRNE

Member of the Commission

(1) OJ L 316, 1.12.2001, p. 5.
(2) OJ L 39, 9.2.2002, p. 71.
(3) OJ L 97, 15.4.2003, p. 81.

L 324/56

EN

Official Journal of the European Union

11.12.2003

Chapter VIII of the Annex to Decision 2002/106/EC is replaced by the following:

ANNEX

‘CHAPTER VIII

Discriminatory test in case of emergency vaccination

A. Basic principles

1. A discriminatory serological ELISA test (discriminatory test) is available to successfully distinguish pigs which have
been vaccinated with marker vaccines, that induce antibodies only against the E2 glycoprotein of classical swine
fever virus, from pigs which have been infected with the wild type of classical swine fever virus. This test is
designed to detect antibodies against the glycoprotein Erns of classical swine fever virus. It is based on the principle
that non-infected animals vaccinated with marker vaccines only produce antibodies against the glycoprotein E2 of
classical swine fever virus, whilst animals infected with field virus react and produce antibodies against other virus
antigens, too.

This discriminatory test is sensitive and specific (1). However, also pigs which have become infected with Pesti-
viruses other than classical swine fever virus, such as BVD virus and BD virus, will also react Erns-positive. Further-
more, the sensitivity of the test is not ideal, as some marker-vaccinated and then infected animals may not react
Erns-positive.

The data currently available suggest that the discriminatory test cannot be reliably used to test serum samples
from feral pigs.

2. The discriminatory test is a liquid phase blocking enzyme-linked immunoassay. The samples to be tested are incu-
bated onto microtitre plates precoated with monoclonal anti-Erns antibodies together with a defined amount of Erns
antigen. Any antibody specific for Erns binds to the defined amount of Erns antigen in the solution and an antigen/
antibody complex is formed, which does not react with the anti-Erns antibodies on the microtitre plate. After
washing of the plates to remove unbound material a peroxidase labelled anti-Erns conjugate is added which binds
to the Erns antigen complexed with the antibody coated on the surface of the microtitre plate. Unbound conjugate
is removed by washing and chromogen-containing substrate is added. The degree of colour, which develops, is
reversely proportional to the amount of antibody specific for Erns present in the sample. If the sample does not
contain antibodies (negative sample) much of the defined amount of Erns antigen that was added can bind to the
anti-Erns antibodies on the plate surface and a strong colour reaction is observed.

A result is obtained by comparing the optical density (OD) in wells containing test samples with those of wells
containing the negative and positive controls.

B. Guidelines for the use of the discriminatory test in the context of an emergency vaccination with a marker

vaccine in pig holdings in the framework of Article 19 of Directive 2001/89/EC

The discriminatory test is designed to verify the presence or absence of classical swine fever virus circulation on a
pig population vaccinated with a marker vaccine. The available data suggest that it can be successfully used for that
purpose on herd bases, but it cannot reliably exclude that individual pigs are infected with classical swine fever virus.
In particular, the specificity of the discriminatory test might not be sufficient to reliably discriminate marker vacci-
nated pigs from infected pigs in case of vaccination of adult pigs. In case of doubtful results, however, the pigs in
question must be slaughtered or killed in a humane way in accordance with Directive 93/119/EC and their organs
tested for classical swine fever virus. Virus isolation and the PCR are the most suitable tests for that purpose.

These aspects have to be taken into full account when designing an emergency marker-vaccination strategy and then
interpreting the results of a classical swine fever virus survey onto the marker-vaccinated population.

The procedure for sampling and testing the vaccinated pig population before lifting the restrictions to be applied in
the vaccinated area in accordance with Article 19 of Directive 2001/89/EC, should depend on the age of the vacci-
nated pigs, the category of pigs (fattening/slaughter, breeding) and the desired level of safety as regards the absence
of virus circulation in the population.

Details on the procedure for sampling and testing shall therefore be laid down in the emergency vaccination plan to
be submitted to the Commission pursuant to Article 19(3) of Directive 2001/89/EC.’

(1) In accordance with the results of a study carried out by the Community reference laboratory for classical swine fever and the national

classical swine fever laboratories, the sensitivity of the discriminatory test is about 94 % and the specificity is about 98 %.