Felis ISSN 2398-2950

Interferon gamma test (for Feline mycobacterial disease)

Synonym(s): Interferon gamma release assay IGRA, IFNG

Contributor(s): Paul Burr, Danielle Gunn-Moore

Overview

  • The test is an aid to the diagnosis of feline mycobacterial disease. In particular it provides guidance as to whether a suspected infection with acid fast bacteria is likely to be environmental, avian TB   Mycobacterium avium  , Mycobacterium microti,or Mycobacterium bovis  Mycobacterium bovis   or Mycobacterium tuberculosis    Mycobacterium tuberculosis      Feline tuberculosis  , the latter two having the highest zoonotic potential.

Sampling

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Tests

Methodologies

  • The test method prepares feline peripheral blood mononuclear cells (PBMCs) from the whole blood submitted. The PBMCs are cultivated for 72 hours in 5 separate reactions: with control materials (positive and  negative controls) and TB specific antigens (PPDA, PPDB and the ESAT6/CF10 peptide mix). The assay is run in duplicate. Following cultivation supernatant is collected from each well and tested for interferon gamma in an ELISA   Enzyme linked immunosorbent assay (ELISA)  .

Availability

Validity

Sensitivity

  • 70-100% depending on precise criteria applied by the laboratory to each case.

Specificity

  • 95-100% depending on precise criteria applied by the laboratory to each case.

Predictive value

  • Predictive value depends on the prevalence of disease in the population under test. This is directly affected by the skill of the clinician in selecting cases appropriate for testing. The test is intended to assist classitification of the type of mycobacterial infection and is most appropriate where acid fast bacteria are present or where mycobacterial diseases is strongly suspected due to history and clinical presentation.

Technique (intrinsic) limitations

  • The test supports a diagnosis of feline mycobacterial disease and provides an indication of the class of mycobacteria involved. The test should be used to support diagnosis in the context of other supportive clinical and laboratory findings.

Result Data

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Further Reading

Publications

Refereed papers

  • Recent references fromVetMed ResourceandPubMed.
  • Gunn-Moore D A, McFarland S E, Schock A, Brewer J I, Crawshaw T R, Clifton-Hadley R S, Shaw D J (2011)Mycobacterial disease in a population of 339 cats in Great Britain: II. Histopathology of 225 cases, and treatment and outcome of 184 cases. J Feline Med Surg13, 945-952PubMed.
  • Rhodes S G, Gunn-Mooore D, Boschiroli M L, Schiller I, Esfandiari J, Greenwald R, Lyashchenko K P (2011)Comparative study of IFNG and antibody tests for feline tuberculosis. Vet Immunol Immunopathol144, 129-134 PubMed.

Other sources of information

  • www.biobest.co.uk
  • Further information on mycobacterial disease in the dog and cat can be found in Greene C E (2011),Infectious Disease of the Dog and Cat. 4th edn, Saunders.

Organization(s)

  • Test is available from Biobest Laboratories Ltd who provide full support on how to use the test and interpretation of results.


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