Effects of vaccination against paratuberculosis on tuberculosis in goats: diagnostic interferences and cross-protection.
BACKGROUND
Most countries carrying out campaigns of bovine tuberculosis (TB) eradication impose a ban on the use of mycobacterial vaccines in cattle. However, vaccination against paratuberculosis (PTB) in goats is often allowed even when its effect on TB diagnosis has not been fully evaluated. To address this issue, goat kids previously vaccinated against PTB were experimentally infected with TB.


RESULTS
Evaluation of interferon-γ (IFN-γ) secretion induced by avian and bovine tuberculins (PPD) showed a predominant avian PPD-biased response in the vaccinated group from week 4 post-vaccination onward. Although 60% of the animals were bovine reactors at week 14, avian PPD-biased responses returned at week 16. After challenge with M. caprae, the IFN-γ responses radically changed to show predominant bovine PPD-biased responses from week 18 onward. In addition, cross-reactions with bovine PPD that had been observed in the vaccinated group at week 14 were reduced when using the M. tuberculosis complex-specific antigens ESAT-6/CFP-10 and Rv3615c as new DIVA (differentiation of infected and vaccinated animals) reagents, which further maintained sensitivity post-challenge. Ninety percent of the animals reacted positively to the tuberculin cervical comparative intradermal test performed at 12 weeks post-infection. Furthermore, post-mortem analysis showed reductions in tuberculous lesions and bacterial burden in some vaccinated animals, particularly expressed in terms of the degree of extrapulmonary dissemination of TB infection.


CONCLUSIONS
Our results suggest a degree of interference of PTB vaccination with current TB diagnostics that can be fully mitigated when using new DIVA reagents. A partial protective effect associated with vaccination was also observed in some vaccinated animals.
Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, Edifici CReSA, 08193, Bellaterra, Catalonia, Spain. bernat.perez@cresa.uab.cat
Bernat
B
Pérez de Val
Miquel
M
Nofrarías
Sergio
S
López-Soria
Joseba M
JM
Garrido
H Martin
HM
Vordermeier
Bernardo
B
Villarreal-Ramos
Maite
M
Martín
Eugenia
E
Puentes
Ramón A
RA
Juste
Mariano
M
Domingo
D000818:Animals; D001426:Bacterial Proteins; D002417:Cattle; D002418:Cattle Diseases / Q000517:prevention & control; D056738:Cross Protection; D015511:Goat Diseases / Q000097:blood / Q000517:prevention & control*; D006041:Goats; D007371:Interferon-gamma / Q000097:blood; D010283:Paratuberculosis / Q000175:diagnosis / Q000517:prevention & control*; D013045:Species Specificity; D014373:Tuberculin / Q000276:immunology; D014376:Tuberculosis / Q000175:diagnosis / Q000517:prevention & control / Q000662:veterinary*
D001426:Bacterial Proteins; D014373:Tuberculin; D007371:Interferon-gamma