Fecal material from cattle which was confirmed to be infected with Johne’s disease by clinical and pathological symptoms, was decontaminated with 4% NaOH and inoculated into the Lowenstein-Jensen media supplemented with 1% of heat-killed Mycobacterium bovis. After 2-4 week-incubation at 37℃, typical acid-fast mycobacteria was isolated. With the results of staining properties, morphological characteristics, the requirement of mycobactin for growth and the other biochemical properties, isolated mycobacteria was identified as Mycobacterium paratuberculosis.
Female guinea pigs were sensitized with the isolates, and skin test was done with purified protein derivatives (PPDs) of M. avium, M. bovis and M. paratuverculosis 4 weeks after sensitization. Animals showed the largest reaction to the PPDs of M. avium and M. paratuverculosis.
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