결핵군 55 kDa 항원의 면역학적 분석 = Immunologic Characterization of the 55 kDa Antigen of Mycobacterium tuberculosis

다국어 초록 (Multilingual Abstract)

Identification and characterization of mycobacterial antigens are critical for evaluation of their role in diagnosis, vaccination, and pathogenesis of mycobacterial diseases. An attempt has been made to immunologic characterize the 55 kDa protein antigen of Mycobacterium tuberculosis H37Rv which attracted our interest because it is present in high concentration in 50-80% ammonium sulfate fraction of the culture filtrate. Two monoclonal antibodies (MAbs) directed to 55 kDa antigen were produced. MAbs MT55-1 and MT55-2 reacted with a single 55 kDa protein band. On examination of degree for cross-reactivity with other mycobacterial species by enzymelinked immunosorbent assay (ELISA) and immunoblotting, these antibodies reacted strongly with M. tuberculosis and M. bovis BCG, and reacted weakly with M. marinum and M. smegmatis.
To investigated the subcellular distribution of MAbs defined epitopes in the 55 kDa antigen within the mycobacterium, we isolated three major subcellular factions of M. tuberculosis, namely, cell wall, cytoplasmic membrane, and cytosol, by a simple fractionation procedure. MAb MT55-1 reactive cpitope was found in the cytosol when tested by immunoblotting.
A sandwich ELISA was initially developed for detecting 55 kDa antigen using MT55-1 MAb in mycobacterial culture filtrate before detecting it in clincal specimens. The minimal detectable concentration was 1.0 ㎍/m1 for M. tuberculosis culture filtrate and 100 ㎍/ml for sonic extracts of M. bovis BCG and M. marinum, respectively. But the 55 kDa antigen was not detected in sonic extracts of other mycobacterial species examined.
Although further evaluations are required, this study suggests that the 55 kDa antigen may be of interest as potential diagnostic reagent.