Caprine tuberculosis in Spain is mainly caused by Mycobacterium caprae although the progression of the disease and lesion severity is similar to that caused by Mycobacterium bovis. In this study, the sensitivity of the gamma-interferon (IFN-γ) assay using an antigen cocktail containing early secretory antigenic target-6. kDa (ESAT-6) and culture filtrate protein 10 (CFP-10) peptides for stimulation was determined and compared with those obtained in single intradermal tuberculin (SIT) and single intradermal cervical comparative tuberculin (SICCT) tests and IFN-γ assay using purified protein derivative (PPD) in three different flocks infected with M. caprae under different epidemiological conditions. Correlation between specific IFN-γ production and severity of lesions was also evaluated. Sensitivities of the diagnostic tests varied greatly in the three flocks studied, with higher values in those where higher lesion scores were observed. The results show that IFN-γ assay applied in goats using PPD or the ESAT-6/CFP-10 peptides cocktail for stimulation yielded similar sensitivity values. A significant yet weak positive correlation between specific IFN-γ production and lesion scores was detected after the stimulation with PPDs (p= 0.004) whereas when the blood samples were stimulated with ESAT-6/CFP-10 peptides, the correlation was not significant (p> 0.05). Therefore, specific-IFN-γ production after the stimulation with PPDs or ESAT-6/CFP-10 was not an accurate indicator of lesion severity in naturally tuberculosis infected goats with M. caprae.
Bibliographical noteFunding Information:
This research was funded by Project AGL2006-06206 of the Spanish Ministry of Science and Technology and the Ministry of Environment and Rural and Marine Affairs and the European Project FP7-KBBE-2007-1 “Strategies for the eradication of bovine tuberculosis (TB-STEP)”. J. Bezos was the recipient of a research contract assigned by the Spanish Ministry of Science and Innovation and the European Social Fund. Antigen cocktail and PPDs were kindly provided by the Veterinary Laboratories Agency (VLA) and CZ Veterinaria, respectively.
- IFN-γ assay
- Lesion score