Tuberculin Skin Testing Boosts Interferon Gamma Responses to DIVA Reagents in Mycobacterium bovis-Infected Cattle
Clinical and Vaccine Immunology publish this investigation article
May 5th, 2017
BCG vaccination sensitises cattle to bovine tuberculin which compromises the use of the current bovine TB surveillance tests. Although the performance of a blood test (that utilises antigens expressed by Mycobacterium bovis but not by BCG) capable of discriminating infected from vaccinated animals (DIVA interferon-gamma test, DIT) has been evaluated in naturally infected TB field reactors, there is a need to perform similar analysis in a BCG vaccinated/M. bovis infected population. Furthermore, we explored different scenarios under which a DIT may be implemented alongside BCG vaccination: (i) serial testing to resolve potential false positive skin test results; or (ii) standalone test to replace the single intradermal comparative cervical tuberculin skin test (SICCT). Our results demonstrated significantly better relative test sensitivity when the DIT was evaluated in a serial test scenario. Direct comparison of pre and post skin test blood samples revealed that the SICCT test induced significant boosting of the interferon-gamma response in M. bovis-infected animals to both the ESAT-6/CFP-10 and Rv3615c peptide cocktails that comprise the DIT, which persisted for the ESAT-6/CFP-10 reagent for at least 14 days. Importantly, no similar boosting effects were observed in non-infected BCG vaccinates, suggesting that DIVA blood testing after a recent skin test would have minimal impact on test specificity
Jones GJ., Coad M., Khatri B., Bezos J., Parlane NA., Buddle BM., Villareal-Ramos B., Hewinson RG. and Vordermeier M.
 | TB Immunology and Vaccinology. Department of Bacteriology. Animal and Plant Health Agency (APHA). |
 | MAEVA SERVET, S.L.. |
 | Servicio de Micobacterias (MYC). Centro de Vigilancia Sanitaria Veterinaria (VISAVET). Universidad Complutense (UCM). |
| Hopkirk Research Institute. AgResearch. National Centre for Biosecurity and Infectious Disease (NCBID). | |
