APPLICATION OF IS900 NESTED-PCR FOR DETECTION OF MYCOBACTERIUM AVIUM SUBSP. PARATUBERCULOSIS DIRECTLY FROM FAECAL SPECIMENS

摘要

Mycobacterium paratuberculosis (MAP) is known to cause a chronic inflammation of intestine in cattle, called Johne's disease. The symptoms are very similar to Crohn's disease in humans. The feasi- bility of coupling a nested-PCR was investigated as a mean to improve turnaround time and detect MAP in the presence of contaminants. The aim of this study was to use nested-PCR as an accurate and rapid method to detect MAP in bovine faeces. Faecal samples from 120 dairy cattle were collected and the extracted DNA was eva- luated by PCR test for the MAP-specific IS900 gene. Of the 120 specimens, 96 were identified posi- tive by direct microscopy, whereas 4 were positive by single PCR. Nested-PCR showed a detection rate of 70.8% (68 out of 96 samples) as compared to direct microscopy. Nested PCR also identified many positive samples that were not detected by either Ziehl Neelsen staining or single PCR. The results show that IS900 nested-PCR assay may be applied to detect M. paratuberculosis directly from faecal sample of dairy cows and therefore could be a valuable diagnostic or screening test for herds with Johne’s disease.