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Test performance data demonstrates utility of a cattle DIVA skin test reagent (DST-F) compatible with BCG vaccination
Gareth J Jones1, Timm Konold2, Shellene Hurley2
1TB Immunology and Vaccinology, Department of Bacteriology, Animal and Plant Health Agency, New Haw, Addlestone, KT15 3NB, Surrey, UK. Gareth.Jones@apha.gov.uk.
Insights
A new diagnostic skin test using a single fusion protein (DST-F) effectively identifies bovine tuberculosis in BCG-vaccinated cattle. This test maintains specificity in vaccinated animals and detects infection even when vaccination fails.
Area of Science:
- Veterinary Immunology
- Infectious Disease Diagnostics
- Mycobacterial Research
Background:
- Bacillus Calmette-Guérin (BCG) vaccination is crucial for controlling bovine tuberculosis (TB) in cattle.
- BCG vaccination interferes with traditional tuberculin skin tests, hindering TB surveillance.
- There is a need for diagnostic tests that are unaffected by BCG vaccination.
Purpose of the Study:
- To evaluate a novel diagnostic skin test using a single fusion protein (DST-F) for bovine TB detection in BCG-vaccinated cattle.
- To assess the specificity and sensitivity of the DST-F test in BCG-vaccinated animals exposed to Mycobacterium bovis (M. bovis).
- To develop a reliable diagnostic tool that overcomes the limitations of current TB surveillance methods.
Main Methods:
- Development of a 'ready to use' reagent using a single fusion protein (DST-F) containing ESAT-6, CFP-10, and Rv3615c antigens.
- Performance evaluation of the DST-F diagnostic skin test in BCG-vaccinated cattle experimentally exposed to M. bovis.
- Comparison of DST-F test specificity and sensitivity against traditional tuberculin reagents.
Main Results:
- The DST-F diagnostic skin test demonstrated high specificity in BCG-vaccinated cattle, unlike tuberculin reagents.
- The DST-F test showed high relative sensitivity in detecting M. bovis infection in vaccinated animals.
- The test successfully identified infected animals where BCG vaccination did not prevent TB pathology.
Conclusions:
- The DST-F skin test is a promising diagnostic tool for bovine TB surveillance in BCG-vaccinated cattle.
- This novel test overcomes the specificity issues associated with BCG vaccination and tuberculin testing.
- Further field trials are underway to support the licensure and commercialization of the DST-F test.
Abstract:
Bacillus Calmette-Guérin (BCG), an attenuated strain of Mycobacterium bovis (M. bovis), is the lead candidate vaccine for control of bovine tuberculosis (TB) in cattle. However, BCG vaccination sensitises cattle to bovine tuberculin, thus compromising the use of the current bovine TB surveillance tests. To address this, we have developed a diagnostic skin test that is not compromised by BCG vaccination and is able to detect BCG vaccinated animals that subsequently develop bovine TB following exposure to M. bovis. Building on previous work using 'in house' formulated protein cocktail reagents, we herein present test performance data for a single fusion protein (DST-F) containing the mycobacterial antigens ESAT-6, CFP-10 and Rv3615c formulated as a 'ready to use' reagent by a commercial manufacturer. Our results demonstrate that, unlike tuberculin reagents, a diagnostic skin test using DST-F maintained high specificity in BCG vaccinated animals. Furthermore, the DST-F skin test demonstrated a high relative sensitivity in identifying M. bovis infected animals, including those where BCG vaccination failed to prevent bovine TB pathology following experimental exposure to M. bovis. The DST-F is currently undergoing field trials in Great Britain to support its licensure and commercialisation.
