Use of antigen-specific interleukin-2 to differentiate between cattle vaccinated with mycobacterium bovis BCG and cattle infected with M. bovis

Shelley G. Rhodes*, Lucy C. McKinna, Sabine Steinbach, Gilly S. Dean, Bernardo Villarreal-Ramos, Adam O. Whelan, C. Pirson, Gareth J. Jones, Derek Clifford, H. Martin Vordermeier

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (SciVal)

Abstract

We describe here the application of a novel bovine interleukin-2 (IL-2) enzyme-linked immunosorbent assay (ELISA) for the measurement of antigen-specific IL-2 in cattle naturally infected with Mycobacterium bovis and in cattle vaccinated with Mycobacterium bovis BCG and then experimentally challenged with pathogenic M. bovis. Supernatants from whole-blood cultures stimulated with mycobacterial antigen (bovine purified protein derivative [PPDB] or the peptide cocktail ESAT6-CFP10) were assessed using a sandwich ELISA consisting of a new recombinant monoclonal fragment capture antibody and a commercially available polyclonal anti-bovine-IL-2. The production of IL-2 was compared to the production of gamma interferon (IFN-7) in the same antigen-stimulated whole-blood supernatants. The data show that cattle infected with M. bovis produced quantifiable levels of antigen-specific IL-2, while IL-2 levels in cattle vaccinated with M. bovis BCG did not. Furthermore, cattle vaccinated with M. bovis BCG and then challenged with pathogenic M. bovis displayed a more rapid induction of IL-2 but ultimately had lower levels of infection-induced IL-2 than did unvaccinated challenge control cattle. These data suggest that IL-2 responses are not detectable post-BCG vaccination and that these responses may require infection with virulent M. bovis to develop. This may be useful to differentiate infected cattle from uninfected or BCG-vaccinated cattle, although the overall sensitivity is relatively low, particularly in single intradermal comparative cervical tuberculin (SICCT)-negative infected animals. Furthermore, the strength of the IL-2 response may correlate with pathology, which poses interesting questions on the immunobiology of bovine tuberculosis in contrast to human tuberculosis, which is discussed.

Original languageEnglish
Pages (from-to)39-45
Number of pages7
JournalClinical and Vaccine Immunology
Volume21
Issue number1
Early online date31 Dec 2013
DOIs
Publication statusPublished - 01 Jan 2014

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