Abstract
The interferon gamma (IFN-γ) test measuring specific cell-mediated immune responses in whole blood can be used for diagnosis at an early stage of Mycobacterium avium subsp. paratuberculosis (MAP) infection. A major obstacle for the practical use of IFN-γ testing is the recommended maximum 8 hour time interval from blood sampling to culture.
The objective of the study was to assess options for use of day-old blood samples for early-stage diagnosis of MAP infections.
Bovine interleukin 12 (IL-12) can induce, and IL-10 reduce, IFN-γ production. Therefore, addition of IL-12 and anti-IL-10 could result in production of IFN-γ in samples previously exposed to MAP antigens.
Whole blood samples were collected from heifers in a Danish dairy herd known to be infected with MAP. The samples were collected on three sample dates, and on each date the blood samples were stimulated with PPDj and recombinant antigens as fresh samples, as day-old samples potentiated with bovine IL-12, and as day-old samples treated with anti-bovine IL-10 antibody. Day-old samples were stored overnight at -4ºC. The correlations between IFN-γ responses in the three types of samples and on different sampling dates were then investigated.
The highest correlations were seen between fresh samples and day-old samples potentiated with IL-12, but there was little difference between addition of IL-12 and antibodies to IL-10. However, between-sample day variation was high for both types of day-old samples, irrespective of treatment type. This aspect needs to be further investigated. Optimisation of the IFN-γ test on day-old samples for diagnosing MAP infected herds would facilitate the large scale use of this diagnostic test.
Original language | English |
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Publication date | 2009 |
Publication status | Published - 2009 |
Event | 10th International Colloquium on Paratuberculosis - Minneapolis, MN, United States Duration: 9 Aug 2009 → 13 Aug 2009 Conference number: 10 |
Conference
Conference | 10th International Colloquium on Paratuberculosis |
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Number | 10 |
Country/Territory | United States |
City | Minneapolis, MN |
Period | 09/08/2009 → 13/08/2009 |