Factors influencing the performance of an interferon-γ assay for the diagnosis of tuberculosis in goats

J. Bezos, J. Álvarez, L. de Juan, B. Romero, S. Rodríguez, E. Castellanos, J. L. Saéz-Llorente, A. Mateos, L. Domínguez, A. Aranaz

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

The interferon-gamma (IFN-γ) assay is an effective tool for the diagnosis of tuberculosis (Tb) in goats. The objectives of this study were to evaluate factors that might affect assay performance: (1) the phenol concentration of the purified protein derivative (PPD, tuberculin) used; (2) dialysis of PPD; and (3) delaying antigenic stimulation of blood samples for 8, 16 and 24. h after collection. The assay was performed in duplicate with two cut-off points. Dialysis of PPD reduced test sensitivity, whereas the concentration of phenol did not significantly affect test outcome. Delaying antigenic stimulation of samples >8. h resulted in a reduction in test sensitivity, compromising the capacity of the assay to detect infected animals. Performing the assay in duplicate was unnecessary, which has implications for reducing assay costs. These findings will facilitate the effective application of the IFN-γ assay as an ancillary test in Tb eradication programmes in goats.

Original languageEnglish (US)
Pages (from-to)131-135
Number of pages5
JournalVeterinary Journal
Volume190
Issue number1
DOIs
StatePublished - Oct 2011
Externally publishedYes

Bibliographical note

Funding Information:
This research was funded by The Spanish Ministry of Science and Technology and The Ministry of Environment and Rural and Marine Affairs (Project AGL2006-06206). J. Bezos is funded by The Spanish Ministry of Science and Innovation and the European Social Fund. We wish to thank The National and Regional Animal Health Authorities, in particular J. Carpintero and R. Díaz, for their continuous encouragement and CZ Veterinaria S.A for kindly providing the PPD. We are also grateful to F. Lozano, N. Moya and S. González for technical assistance. We thank Devin J. Morey for help in revising the manuscript.

Keywords

  • Goat
  • Interferon-γ assay
  • Purified protein derivative
  • Tuberculin
  • Tuberculosis

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