Antigen cocktails boost interferon-gamma release assay for cattle tuberculosis

Bovine tuberculosis, a zoonotic disease of worldwide concern caused predominantly by members of the Mycobacterium tuberculosis complex (MTBC), is currently diagnosed mainly with the intradermal tuberculin skin test and the interferon-gamma (IFN-γ) release assay (IGRA). Both tests rely on purified protein derivatives (PPD) as their conventional reagents, but PPD has well-recognized shortcomings: batch-to-batch variability, an incompletely defined and poorly standardized composition, and cross-reactivity with antigens from non-pathogenic environmental mycobacteria that can confound results.

To address these limitations, researchers have turned to specific MTBC antigens that elicit strong T-cell responses, such as CFP10 and ESAT6. In the new study, published in BMC Veterinary Research, the team sought to broaden the antigenic repertoire and potentially enhance diagnostic sensitivity by assessing the biological potency of ten immunodominant recombinant proteins as stimuli for the interferon-gamma release assay.

From this work, several antigen cocktails containing the proteins Rv0394c, EspC and HspX were developed and used as stimulating reagents in the IGRA. All of these cocktails showed superior diagnostic performance over the CE fusion protein, a previously described reagent combining CFP10 and ESAT6.

The standout performer was the CE+EspC+HspX cocktail. When compared with the PPD-based IGRA, the positive agreement rate of the cocktail-based assay exceeded 89 percent and its negative agreement rate exceeded 96 percent, making it the best-performing diagnostic antigen cocktail among those tested in the study.

According to the authors, these findings suggest that the antigen cocktails can enhance diagnosis by increasing the sensitivity of previously described differential diagnostic tests based on CFP10 and ESAT6. They conclude that such cocktails have the potential to replace PPDA- and PPDB-based IGRA for the diagnosis of bovine tuberculosis, offering a defined, recombinant alternative to PPD reagents whose variability and cross-reactivity have long constrained the assay.

Subject of Research: Diagnostic performance of recombinant antigen cocktails in the interferon-gamma release assay for bovine tuberculosis

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

Article References: Xu, Z., Pan, F., Gao, Y., Fan, C., Wu, G., Meng, C., Zheng, C., Chen, X., & Jiao, X.-A. (2026). Diagnostic performance of antigen cocktails in the interferon-gamma release assay for bovine tuberculosis diagnosis. BMC Veterinary Research. https://doi.org/10.1186/s12917-026-06061-y

Image Credits: AI Generated

DOI: 10.1186/s12917-026-06061-y

Keywords: bovine tuberculosis, interferon-gamma release assay, IGRA, antigen cocktails, Rv0394c, EspC, HspX, CFP10, ESAT6, purified protein derivative, Mycobacterium tuberculosis complex, veterinary diagnostics