Molecular definition of unique species status of Mycobacterium w; a candidate leprosy vaccine strain.

Mycobacterium w, a candidate leprosy vaccine strain, is an atypical cultivable mycobacterium. Based on its growth and metabolic properties, M. w was listed in Runyon Group IV, along with other rapid growers such as M. fortuitum, M. smegmatis, M. chelonae and M. vaccae. However, M. w was not fully identical to any one of these. In the present study, a molecular biology approach was used to define the species identity of M. w in a manner that allows reliable comparison to be made with over 30 known mycobacterial species. A 383-bp region, present at the amino terminus of the conserved mycobacterial 65-kDa gene, has been polymerase chain reaction (PCR) amplified in M. w and DNA sequence was determined. A comparison of the M. w DNA sequence with those of M. tuberculosis, M. avium, M. paratuberculosis and M. fortuitum revealed a species-specific polymorphism, i.e., the presence of nucleotide substitutions unique to M. w. In an alternate approach, a 441-bp region, also a part of the 65-kDa gene, has been PCR amplified in M. w and a Hae III restriction pattern was generated.(ABSTRACT TRUNCATED AT 250 WORDS)