Objective: To analyze and compare polypeptide antigens of 13 Mycobacterium strains and try to find out tuberculosis associated antigens.
Method: Polypeptide antigens were analyzed by using SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblots techniques. Specific antibodies in serum or CSF samples obtained from 575 tuberculosis patients, 450 healthy individuals and 250 non-tuberculosis patients were detected by using immunoblots technique with purified specific antigen.
Results: The results showed that polypeptide of H37Rv, H37Ra, BCG, Bovis strains had the similar polypeptide bands and the similar immunogenicity in major polypeptide antigens. Molecular weight of major polypeptide antigens were 76,000, 65,000, 34,000-40,000, 28,000 and 25,000. The 76,000, 65,000 and 25,000 polypeptides were found in all the 13 Mycobacterium strains and they were common antigens probably. Purified specific antigen was used in serodiagnosis of tuberculosis and the sensitivity was 89.7%, while specificity was 95.7%.
Conclusion: Polypeptide bands of Mycobacterium were found different and Mycobacterium strains could be identified by SDS-PAGE technique. The results suggested that specific antigen of H37Rv strain for antibody detection was a useful supplementary tool for diagnosis of extrapulmonary tuberculosis and bacteria-negative pulmonary tuberculosis.