Relation between pathologic findings and cellular immune responses in sheep with naturally acquired paratuberculosis.

Abstract

OBJECTIVE:

To investigate the relation between lesions and cellular immune response-based tests in sheep with naturally acquired paratuberculosis and to evaluate efficacy of an interferon-gamma (IFN-gamma) assay and the intradermal skin test.

ANIMALS:

110 and 88 adult sheep were used to evaluate the IFN-gamma assay and skin test, respectively.

PROCEDURE:

Before euthanasia, heparinized blood was collected and incubated with avian purified protein derivative (PPD). Interferon-y production was assessed, using a commercial enzyme immunoassay. Skin testing in the caudal fold also was performed, using avian PPD. Sensitivity and specificity of these techniques were evaluated, using histopathologic findings as reference.

RESULTS:

Of the sheep examined, 61 (55.4%) had lesions that were classified in 5 categories, according to location, extension, cellular types, and presence of acid-fast bacilli. Regarding cellular immunity test results, 55.4% of sheep with and 6.1 % without pathologic changes had positive results of the IFN-gamma assay. Skin test sensitivity (55.6%) and specificity (100%) were slightly greater.

CONCLUSION:

Close association between pathologic findings and cellular immune response was apparent. Most sheep with focal (tuberculoid) and some with diffuse lesions (borderline tuberculoid), all with scant or no acid-fast bacilli in the intestine, had positive results of the IFN-gamma assay and skin test. Most sheep with diffuse lesions and high numbers of bacilli (borderline lepromatous) were test negative.

CLINICAL RELEVANCE:

Cellular immune response-based and serologic tests are useful tools for seeking evidence of paratuberculosis. Each technique detects different types of immune-reacting sheep, and their simultaneous use may detect most infected animals.

• Authors: V Pérez, J Tellechea, J M Corpa, M Gutiérrez, J F García Marín
• Journal: American journal of veterinary research (Am J Vet Res) Vol. 60 Issue 1 Pg. 123-7 (Jan 1999) ISSN: 0002-9645 [Print] United States
• PMID: 9918160 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Interferon-gamma

Topics

• Animals
• Hypersensitivity, Delayed (immunology, pathology, veterinary)
• Immunity, Cellular
• Immunoenzyme Techniques (veterinary)
• Interferon-gamma (blood)
• Mycobacterium avium subsp. paratuberculosis (immunology)
• Paratuberculosis (immunology, pathology)
• Sensitivity and Specificity
• Sheep
• Sheep Diseases (immunology, pathology)
• Skin Tests (veterinary)