Multiple mutations in the rpoB gene of Mycobacterium leprae strains from leprosy patients in Thailand.

A new finding is reported of multiple mutations in the rpoB gene of 9 Mycobacterium leprae strains from leprosy patients in Thailand, who did not respond to therapy even when rifampicin, the main drug in multi-drug therapy was used. By means of sequence analysis of 9 Thai M. leprae strains, various mutations in 289 bps of the rpoB gene revealed forms of mutation never before described, such as multiple mutations (ie, mutation at two, three, six, seven, eight and nine positions in the rpoB gene), most of which were point-mutation substitutions (a few of which were silent), and some insertions. This investigation demonstrates that mutation in the rpoB gene of M. leprae strains from Thailand involves more variety than previously reported for rpoB mutation patterns in rifampicin resistance M. leprae strains.

Comparison of the protective efficacy on mekongi schistosomiasis in mice induced by antigens derived from cercariae, schistosomulae and adult worms.

Protective efficacy of the extracts of cercariae, schistosomulae and adult worms of S. mekongi was studied in mice receiving immunizations with these extracts emulsified with Freund's complete adjuvant initially and incomplete adjuvant subsequently, and compared with mice receiving physiological saline with or without adjuvants as controls. After challenge with cercariae, the animals were sacrificed and the larvae or adult worms harvested by lung recovery and perfusion techniques on day 5 and weeks 6-8, respectively. Worm reduction rates were significantly higher in mice receiving extracts of schistosomula (59%) and adult worms (51%) than in those receiving the cercarial extracts (31%). Similar findings were obtained with the perfusion technique showing worm reduction rates of 57%, 53% and 30% in mice receiving extracts of schistosomulae, adult worms and cercariae, respectively. ELISA antibody titers were correspondingly increased in mice receiving extracts of schistosomulae and adult worms, but not in those receiving cercariae. This apparent association may be inadequate to suggest that the increase in ELISA titer be used as an indicator for resistance in mekongi schistosomiasis.