The Comparison of Bovine Fecal and Buffy Coat Samples for Diagnosis of Johne's Disease Based on PCR

Paratuberculosis, or Johne's disease, is caused by Mycobacterium avium subsp paratuberculosis (MAP) and affects the domestic and wild ruminants worldwide. Fecal culture as well as serological and molecular methods have been used for detection of MAP.
The aim of this study was to compare bovine fecal and buffy coat samples for diagnosis of Johne’s disease based on PCR and to find out which one was more suitable for detection of MAP.
Feces and blood samples were collected from 100 suspected cows with clinical signs of Johne’s disease. DNA extraction was performed from fecal and blood samples by CTAB and proteinase K method. Polymerase chain reaction (PCR) was used to detect the presence of MAP.
In this study, 4 cases were positive in buffy coat PCR test and 9 cases were positive in feces PCR test for the detection of MAP. Although fecal culture has been used as a standard method to detect MAP, this method can’t detect all positive cases.
Despite the fact that DNA extraction from blood samples is easier than that of fecal samples, replacement of fecal PCR with buffy coat PCR was recommended for the diagnosis of MAP. In addition, using fecal samples based on PCR for diagnosis of Johne’s disease is considered more efficient.