Evaluation of the comparative accuracy of the complement fixation test, Western blot and five enzyme-linked immunosorbent assays for serodiagnosis of glanders.
Authors: Elschner Mandy Carolina, Laroucau Karine, Singha Harisankar, Tripathi Bhupendra Nath, Saqib Muhammad, Gardner Ian, Saini Sheetal, Kumar Subodh, El-Adawy Hosny, Melzer Falk, Khan Iahtasham, Malik Praveen, Sauter-Louis Carola, Neubauer Heinrich
Journal: PloS one
Summary
# Editorial Summary: Serodiagnostic Accuracy for Equine Glanders Glanders remains a significant concern for equine practitioners and international trade, yet the complement fixation test (CFT)—currently mandated by the OIE for regulatory purposes—has known limitations in both sensitivity and specificity. Elschner and colleagues evaluated six alternative serological methods against the CFT using sera from 254 infected and 3,000 uninfected equids, comparing two recombinant ELISA platforms (TssA, TssB, BimA, and Hcp1 antigens), a semi-purified antigen ELISA (IDVet), and Western blot using purified lipopolysaccharide-containing B. mallei antigen. The Western blot (96.8% sensitivity, 99.4% specificity), Hcp1-ELISA (95.3%, 99.6%), and IDVet-ELISA (92.5%, 99.5%) demonstrated comparable or superior performance to the CFT (98.0%, 96.4%), with the first two offering markedly better specificity and thus fewer false-positives in disease-free populations. For practitioners and regulatory bodies, these findings suggest viable alternatives to the CFT could reduce unnecessary quarantine or culling decisions whilst maintaining diagnostic reliability, though further validation and standardisation would be required before any shift in OIE protocols could be justified.
Read the full abstract on PubMed
Practical Takeaways
- •The CFT, currently required by OIE for international trade, performs comparably to Western blot and Hcp1-ELISA; these alternatives may offer improved specificity and reduce false positives in some populations
- •If implementing alternative tests to CFT, Hcp1-ELISA and IDVet-ELISA maintain sensitivity while offering better specificity; avoid TssA and TssB ELISAs due to lower sensitivity for affected horses
- •For herds where false positives create economic burden, Western blot or Hcp1-ELISA could be confirmatory tests, though CFT remains the OIE standard for trade purposes
Key Findings
- •Western blot and most ELISAs showed significantly higher specificity (96.4–99.6%) than the OIE-prescribed CFT (96.4%)
- •CFT, Hcp1-ELISA, IDVet-ELISA and Western blot demonstrated comparable sensitivities (92.5–98.0%), while TssA, TssB and BimA ELISAs had significantly lower sensitivity
- •Western blot achieved the highest specificity at 99.4% with 96.8% sensitivity
- •Study evaluated 3,000 glanders-free and 254 naturally infected equids using six different serological methods