Extraction Of Lipoarabinomannan From Mycobacterium Tuberculosis And Detection Of LAM-IgG In Serum For The Diagnosis Of Tuberculosis

Objective: Extract lipoarabinomanan(LAM)from Mycobacterium tuberculosis(MTB) and investigate its serological diagnosis value for tuberculosis.Methods : MTB was delipidated with CHCl3:CH3OH, disrupted by probe sonication. Ethanol was added and the mixture refluxed for 1h.The protein, nucleic acid and lipids in the ethanol extracts were removed, and crude lipopolysaccharides(LPS) were prepared.After the LPS were purified with Sephacryl-100 gel filtration, LAM was obtained.Methods of enzyme-linked-immunosorbent-assay(ELISA) and dot-immunogold-filtration-as-say(DIGFA) were established with the LAM to detect corresponding antiboies in TB patient serum and control patient serum.Results:From 1.89 g dry weight cell preparation ,6mg LAM was obtained.The relative molecular weight of the LAM was approximately 37kD by SDS-PAGE, consistent with the reference.The methods of ELISA and DIGFA were established.117 cases with pulmonary tuberculosis (including smear-positive and smear-negative),92 cases of non-tuberculosis lung disease patients and 188 healthy individuals were detected by ELISA,the sensitivity and specificity were 71.3% and 93.9%; Moreover,the sensitivity and specificity were 91.7% and 87.8 by DIGFA (192 cases of smear positive tuberculosis patients,46 cases of non-tuberculosis lung disease patients, 68 healthy individuals).Conclusions: LAM was successfully extracted and purified from MTB,This antigen can be used as coating antigen for the serodiagnosis of tuberculosis by ELISA and DIGFA.