BOVIGAM: an in vitro cellular diagnostic test for bovine tuberculosis

Area of Science:

• Veterinary Immunology
• Infectious Disease Diagnostics
• Animal Health

Background:

• Tuberculosis (TB) remains a significant concern in animal populations worldwide.
• Accurate and early detection of TB is crucial for effective disease control and eradication programs.
• Existing diagnostic methods, such as skin tests, have limitations in sensitivity and early detection.

Purpose of the Study:

• To evaluate the BOVIGAM assay, a gamma interferon (IFN-γ) based test, for the detection of TB infection in animals.
• To assess the diagnostic performance (sensitivity and specificity) of BOVIGAM compared to culture-confirmed TB.
• To explore the utility of BOVIGAM in specific scenarios, such as detecting infection in skin-test negative animals or serial testing.

Main Methods:

• The BOVIGAM assay involves incubating whole animal blood with specific antigens (bovine PPD, avian PPD) or a control.
• Gamma interferon (IFN-γ) levels in plasma supernatant are measured using an enzyme immunoassay (EIA).
• A predominant IFN-γ response to bovine PPD indicates potential TB infection.

Main Results:

• BOVIGAM demonstrated high sensitivity (81.8%–100%) and specificity (94%–100%) across extensive trials in over 200,000 animals.
• The IFN-γ assay detects M. bovis infection earlier than traditional skin tests.
• BOVIGAM results are reliable, unaffected by poor nutrition, and only mildly affected by dexamethasone treatment or parturition.

Conclusions:

• BOVIGAM is a rapid and reliable laboratory assay for detecting cell-mediated immune responses to TB infection in animals.
• The assay is effective in identifying M. bovis infection earlier than skin tests and is used routinely in several countries for cattle, buffalo, and goats.