Diagnostic performance of antigen cocktails in the interferon-gamma release assay for bovine tuberculosis diagnosis

Abstract Background As a zoonosis of worldwide concern, bovine tuberculosis (bTB) is predominantly attributed to infection with Mycobacterium tuberculosis complex (MTBC). Currently, the intradermal tuberculin skin test and the interferon-gamma (IFN-γ) release assay (IGRA) are the principal tests used worldwide for bovine tuberculosis, both of which employ purified protein derivatives (PPD) as conventional reagents. Nevertheless, several shortcomings of PPD have been recognized, including inter-batch variability, incomplete compositional definition and standardization, and cross-reactivity with antigens from non-pathogenic environmental mycobacteria. To overcome this issue, specific antigens of the Mycobacterium tuberculosis complex that elicit strong T-cell responses, such as CFP10 and ESAT6, have been employed. To potentially broaden the antigenic repertoire and enhance diagnostic sensitivity, we assessed the biological potency of ten immunodominant recombinant protein. Results In this study, several antigen cocktails contain Rv0394c, EspC and HspX were developed and used as stimuli in IGRA, all of which showed superior diagnostic performance over the CE fusion protein. Compared to the PPD based IGRA, the positive agreement rate and negative agreement rate of the CE+EspC+HspX antigen cocktail -based IGRA were higher than 89% and 96%, respectively, which stand out as the best-performing diagnostic antigen cocktail among those tested. Conclusion Taken together, our investigation suggests that these antigen cocktails can enhance diagnosis by increasing the sensitivity of previously described differential diagnostic tests based on CFP10 and ESAT6, which has the potential to replace PPDA and PPDB-based IGRA for the diagnosis of bTB.