Challenges of BTV-Group Specific Serology Testing: No One Test Fits All

Area of Science:

• Veterinary Virology
• Immunodiagnostics
• Animal Health

Background:

• Bluetongue virus (BTV) poses a significant threat to livestock globally.
• Accurate and sensitive diagnostic tools are essential for BTV surveillance and control.
• Existing diagnostic methods for BTV antibodies may have limitations in sensitivity and specificity.

Purpose of the Study:

• To develop and validate a novel sandwich ELISA (sELISA) for detecting antibodies against bluetongue virus (BTV) in bovine and ovine sera and plasma.
• To evaluate the diagnostic sensitivity (DSe) and diagnostic specificity (DSp) of the new sELISA.
• To compare the performance of the sELISA with existing competition ELISAs (cELISAs) and assess its inclusivity and exclusivity against related orbiviruses.

Main Methods:

• Development and validation of a sandwich ELISA (sELISA) for BTV antibody detection.
• Testing of 949 negative and 752 positive bovine and ovine sera/plasma samples.
• Validation using virus neutralization test (VNT) and/or PCR, and comparison with four cELISAs, including assessments for cross-reactivity with epizootic hemorrhagic disease virus (EHDV) and other orbiviruses.

Main Results:

• The sELISA demonstrated high diagnostic performance: DSe of 99.70% and DSp of 99.20% for bovine sera, and DSe of 97.80% and DSp of 99.50% for ovine sera.
• The sELISA showed comparable or superior sensitivity to cELISAs, particularly for BTV-15 positive sera.
• The sELISA exhibited the least cross-reactivity with EHDV and other non-BTV orbivirus antibodies compared to tested cELISAs.

Conclusions:

• The newly developed sELISA is a highly sensitive and specific diagnostic tool for detecting BTV antibodies in cattle and sheep.
• This assay provides an improved method for early BTV detection, crucial for managing endemic and emerging serotypes.
• The sELISA offers better specificity against related orbiviruses, enhancing its utility in BTV surveillance programs.