Diagnosis of paratuberculosis in fresh and paraffin embedded samples by histopathology, PCR and immunohistochemistry techniques

Abstract

Mycobacterium avium subsp. paratuberculosis (Map) is the causative agent of paratuberculosis, also called Johne’s disease. Affected ruminants show emaciation, decreased milk production, oedema, anaemia and infertility. The objective of the present study was to compare histopathology, immuno-histochemistry (IHC) and IS900-based PCR techniques for diagnosis of ovine paratuberculosis in archival fresh and paraffin-embedded tissues. A total of 24 samples (11 fresh and 13 older than 1 year paraffin-embedded intestines) grossly suspected to ovine paratuberculosis were used. By histopathology, Ziehl-Neelsen, and IHC methods, 9/11 fresh and 5/13 paraffin-embedded tissues were posi-tive for paratuberculosis. PCR detected 413 bp amplicons in all histopathologically positive fresh and none of paraffin-embedded samples. In the present study, it seems that using PCR assay on the old paraffin-embedded tissues in comparison with the fresh samples cannot be useful although a higher number of samples is necessary to make a reliable conclusion.

Keywords

• Mycobacterium avium subspecies paratuberculosis
• paraffin-embedded tissue sample
• paratuberculosis
• PCR