A rapid and simple method for identifying Mycobacterium tuberculosis W-Beijing strains based on detection of a unique mutation in Rv0927c by PCR-SSCP

Recently we have found that W-Beijing Mycobacterium tuberculosis strains have a unique in-frame trinucleotide (AGC) deletion at position 421 of Rv0927c and a -127G → A mutation in Rv0927c-pstS3 intergenic region. Based on detecting the 421 trinucleotide deletion of these two mutations which can alter the ssDNA conformation more extensively than the other, we developed a PCR-SSCP method for rapid identification of W-Beijing strains among non-Beijing strains. Altogether, 104 clinical isolates were analyzed, including 68 W-Beijing strains and 36 non-Beijing strains. We found that PCR-SSCP successfully differentiated all the W-Beijing strains from the non-Beijing strains. In addition, we unexpectedly discovered that SDS-PAGE protein gels had better resolving power than conventional TBE polyacrylamide gel in detecting the AGC deletion mutation in the SSCP analysis.