Superoxide dismutase activity of Mycobacterium tuberculosis isolated from tuberculosis patients and the immunoreactivity of superoxide dismutase from M. tuberculosis H37Rv.
OBJECTIVE
To determine the superoxide dismutase (SOD) activity from clinical isolates of Mycobacterium tuberculosis and to study the seroreactivity of SOD from M. tuberculosis H37Rv.


METHODS
Crude cell extracts of 16 strains of M. tuberculosis isolated from tuberculosis (TB) patients were assayed for SOD activity. SOD from H37Rv was partially purified and characterized, and the seroreactivity was studied by ELISA using sera from 36 active pulmonary TB and 31 leprosy patients.


RESULTS
SOD activity was detected in all the 16 strains of M. tuberculosis and also in the medium of logarithmic and stationary cultures of H37Rv. SOD activity from H37Rv extract was not affected by 1 mM KCN or by 5 mM H2O2 and was only 20% inhibited by 10 mM NaN3, suggesting that it is a Mn-containing enzyme. SOD was partially purified from H37Rv extract by gel filtration chromatography as a tetramer of molecular weight (MW) of 80,000 and a subunit MW of approximately 23,000. A delayed type hypersensitivity was elicited by SOD in guinea pigs sensitized with H37Rv or M. leprae sonicate. ELISA using SOD as antigen indicated 100% positivity with TB sera, while 84% positivity was observed with leprosy sera. Western blotting with pooled TB and leprosy sera indicated the presence of antibodies to the 23 kD SOD protein.


CONCLUSIONS
Our data indicate that M. tuberculosis strains are rich in SOD, and the secretion of SOD may play a valuable role in the pathogenesis of M. tuberculosis.
Deshpande
R G
RG
Department of Microbiology and Immunology, Morehouse School of Medicine, Atlanta, Georgia 30310.
Khan
M B
MB
Bhat
D A
DA
Navalkar
R G
RG
D000907:Antibodies, Bacterial / Q000032:analysis; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000276:immunology; D007918:Leprosy / Q000201:enzymology; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000276:immunology; D013482:Superoxide Dismutase / Q000276:immunology / Q000378:metabolism*; D014397:Tuberculosis, Pulmonary / Q000201:enzymology*
D000907:Antibodies, Bacterial; D013482:Superoxide Dismutase