The consequences of vaccination with the Johne's disease vaccine, Gudair, on diagnosis of bovine tuberculosis
- 1Department of Bovine Tuberculosis, Animal Health and Veterinary Laboratories Agency, New Haw, Addlestone, Surrey KT15 3NB, UK
- 2Animal Sciences Unit, AHVLA, New Haw, Addlestone, Surrey KT15 3NB, UK
- E-mail for correspondence:
The single intradermal comparative cervical tuberculin skin-test (SICCT) remains the primary surveillance tool to diagnose bovine tuberculosis (BTB) in the UK. Therefore, understanding the potential confounding influences on this test is important. This study investigated the effects of vaccination against Johne's disease (JD) on the immunodiagnosis of BTB using a Mycobacterium bovis BCG vaccination model as a surrogate of M bovis infection. Calves were vaccinated with either BCG (an attenuated live vaccine) or the JD vaccine, Gudair (a heat-inactivated suspension of Mycobacterium avium subspecies paratuberculosis), or a combination of both, and SICCT responses were measured approximately six and 12 weeks postvaccination. Animals vaccinated with Gudair only were negative to the SICCT test, thus supporting the specificity of the SICCT test following Gudair vaccination. However, while animals vaccinated with BCG-only demonstrated a bovine tuberculin-biased response as expected, covaccination with Gudair resulted in a bias towards avian tuberculin in the SICCT test. Therefore, our model demonstrates the potential of the Gudair vaccine to reduce the sensitivity of the SICCT. In addition, while we also demonstrate that Gudair vaccination can compromise the specificity of serological tests to detect JD, the specificity of defined M bovis antigens in serological or interferon gamma-based blood assays was not compromised by the vaccine.
- Accepted November 23, 2012.
- Published Online First 21 December 2012
- British Veterinary Association