Effect of a recent intradermal test on the specificity of P22 ELISA for the diagnosis of caprine tuberculosis

Author contributions CV: Writing – review & editing, Formal analysis, Writing – original draft. JO: Formal analysis, Writing – original draft, Writing – review & editing. JR: Data curation, Writing – review & editing. BR: Writing – review & editing, Resources, Data curation. LJ: Writing – review & editing, Investigation, Supervision. LD: Writing – review & editing, Conceptualization, Resources. MD: Writing – review & editing. JÁ: Writing – review & editing. JB: Writing – review & editing, Formal analysis, Data curation.
Caprine tuberculosis (TB) is a zoonotic disease caused by members of the Mycobacterium tuberculosis complex. TB eradication programs in goats are based on the single and comparative intradermal tuberculin tests (SITT and CITT, respectively). Antibody-based diagnostic techniques have emerged as potential diagnostic tools for TB. P22 ELISA has been previously evaluated using samples collected after the intradermal tuberculin tests to maximize the sensitivity, a phenomenon known as booster effect. However, there is no information available on whether the use of this diagnostic strategy could lead to a decrease of its specificity (Sp). The aim of the present study was to elucidate the interference effect of a recent CITT on the Sp of the P22 ELISA in serum and milk samples collected at different times after the CITT from a TB-free herd (n = 113). The number of reactors to P22 ELISA was significantly higher (p < 0.01) on serum samples collected 15 days post-CITT compared to day 0, showing a decrease in Sp from 99.1% (95% CI; 95.2–99.8%) to 88.5% (95% CI; 81.3–93.2%). The number of reactors and the quantitative values of P22 ELISA were significantly higher (p < 0.01) in serum samples compared to milk. No significant (p > 0.05) changes in the Sp of the P22 ELISA were observed throughout the different time samplings using milk No significant (p > 0.05) changes were observed on days 30 and 60 post-CITT. In conclusion, the booster effect strategy may significantly decrease the Sp of P22 ELISA in TB-free herds when serum samples are used but not when milk is tested.
European Union
ICRAD
Ministerio de Agricultura, Pesca y Alimentación (ref. 21.06.412D.640.08)
Ministerio de Ciencia, Innovación y Universidades (PCI2023-143368; FPU18/05197)
Depto. de Sanidad Animal
Centro de Vigilancia Sanitaria Veterinaria (VISAVET)
Fac. de Veterinaria
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