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Development of improved methods for the diagnosis of foot-and-mouth disease

Contract nr: FAIR-CT98-4032
Project nr: 4032
Project type: CA
Starting date: 01/01/1999
Duration: 36 months
Total cost: 278,300 EUR
EC Contribution: 278,300 EUR
Scientific Officer: Isabel MINGUEZ-TUDELA
Research topic: Animal health
Acronym: FMD DIAGNOSIS

Background:
FMD is an extremely contagious viral disease of cloven-hoofed animals which results in considerable economic losses. Especially in areas of high animal density the epidemiology of the disease could take a catastrophic course, leading to a situation where the usefulness of established diagnostic tests would be limited. As an antibody to structural proteins is produced following either infection or vaccination, its detection does not distinguish between animals which have merely been vaccinated and those which have been infected. Emergency 'ring' vaccination may be needed as an adjunct to stamping out to control the spread of infection.

Cattle, including vaccinated cattle, can carry FMDV in their oropharynx for up to 2 years. Therefore, if ring vaccination is performed, it will be necessary to identify animals in which viral replication has taken place in order to prevent the establishment of virus carriers. As long as there are no diagnostic means available for swift and broad-scale screening of vaccinated populations, the economic value of vaccinated animal populations could collapse due to the trade restrictions imposed in order to prevent further spread of the disease.

Objectives:
The objectives of the Concerted Action (CA) are to accelerate and coordinate the development and validation of new methods for the diagnosis of Foot-and-Mouth disease (FMD), especially those which offer a chance to identify both infected contact holdings before they become the source for a further spread of the disease, as well as methods that could limit the economic consequences of FMD for affected areas after emergency vaccination. The research efforts of seven European FMD laboratories will be coordinated during the next 3 years and 4 workshops will be organised.

Description:
The European Commission sponsored a CA (1994-1997) to coordinate the research into the potential use of assays measuring antibody to the non-structural (NS) proteins of FMD virus, to differentiate infected from vaccinated animals. In animals seropositive for the antibody to structural proteins, the detection of the antibody to the polyprotein 3ABC was found to be the most reliable single indicator of infection. On a herd or group basis, measurement of antibody to the NS proteins can be used to detect previous infection in a vaccinated population.

Preliminary results justify further research. However, absolute differentiation of infection from vaccination is not possible by serological means alone. For this reason, serology has to be complemented by other assays. Currently, the established test to ensure freedom from infective FMD virus in individual animals of a vaccinated population is the probang test. This test, or a variant using nasal swabs, is used to diagnose FMD where epithelial tissue is not available, e.g. where infection is suspected in the absence of clinical signs. This also applies to prodromal stages of disease, when considerable amounts of virus can already be excreted, as well as to subclinical cases, especially in small ruminants. Since the probang test is laborious and time-consuming, broad scale screening of ruminants, whether in contact holdings after a primary outbreak or in a vaccinated area, is not feasible or would take too much time to be useful. Principally, nucleic acid recognition methods are an alternative to virus isolation. The polymerase chain reaction (PCR) can be used to amplify genome fragments of FMD virus in diagnostic material.

However, in order to at least match the sensitivity of virus isolation, a nested PCR has to be performed. This method is laborious and prone to give false positive results, so PCRs cannot currently be employed for broad-scale screening campaigns or pre-movement testing of large numbers of animals. Advanced PCR protocols ('PCR-ELISA'), that could at least partially overcome these problems have been described, but have to be optimised and validated for the diagnosis of FMD. Another diagnostic approach that should be evaluated is the isotype-specific detection of antibodies to FMD in oesophageal-pharyngeal fluid.


Coordinator
Bernd HAAS
Federal Research Centre for Virus Diseases of Animals
Paul-Ehrlich-Straße 28
D-72078 Tübingen
Tel.: +49 707 196 72 52
Fax: +49 707 196 73 05
E-mail: bernd.haas@tue.bfav.de


Partners

  • Kris DE CLERCQ
    Centrum voor Onderzoek in Diergeneeskunde en Agrochemie
    Afdeling epizootische ziekten
    Groeselenberg 99
    B-1180 Brussels
    Tel.: +32 2 375 44 55
    Fax: +32 2 375 09 79

  • Karl-Johan SORENSEN
    Danish Veterinary Institute for Virus Research
    Lindholm
    DK-4771 Kalvehalve
    Tel.: +45 55 86 02 31
    Fax: +45 55 86 03 00

  • Emiliana BROCCHI
    Instituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna
    National FMD Laboratory
    Via A Bianchi N7
    I-25125 Brescia
    Tel.: +39 030 22 90 310
    Fax: +39 030 22 90 310 or +39 030 22 56 13

  • Remco SCHRIJVER
    Institute for Animal Science and Health (ID-Lelystad)
    Houtribweg 39
    P.O. Box 65
    NL-8200 AB Lelystad
    Tel.: +31 320 23 86 10
    Fax: +31 320 23 86 68

  • Francisco SOBRINO
    Instituto Nacional de Investicacion y Tecnologia Agraria y Alimentaria
    Centro de Investigacion en Sanidad Animal CISA-INIA
    E-28130 Valdeolmos
    Tel.: +34 916 20 23 00
    Fax: +34 916 20 22 47

  • Paul KITCHING
    Institute for Animal Health
    Pirbright Laboratory
    Ash Road
    UK-GU24 ONF Pirbright Woking
    Tel.: +44 1483 23 24 41
    Fax: +44 1483 23 26 21 or +44 1483 23 24 48

 
 
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