the Cellular and Molecular Research Center; Shaheed Beheshti University of Medical Sciences, Tehran, I.R.Iran. , F_ doustdar@yahoo.com
Abstract: (5581 Views)
Tuberculosis remains as an important socioeconomical and medical problem
throughout the world and especially in Iran. Early and timely diagnosis of
pulmonary and extrapulmonary tuberculosis is vital to initiate prompt treatment.
Current diagnostic methods are either slow or lack enough sensitivity or specificity.
Several mycobacterial antigens are involved in the complex interaction with
the immune system of the host. Their identification is important for both diagnosis
and protection against mycobacteria. Antigen 60 (A60) is a thermostable antigen
found in the cytosol of M. bovis and M. tuberculosis. An ELISA test using
A60 is designed for diagnosis of tuberculosis with satisfactory results. In previous
studies, A60 has also showed a protective effect against experimental infections
and useful immunotherapeutic effects in promotion of cancer development.
In the present work we tried to purify A60 from the cytoplasm of BCG. A60
was purified by exclusion gel chromatography using sepharose 4B. A60 was
recognized by bidimensional immunoelectrophoresis with anti-BCG and anti-A60
antiserum, where it appears as the less mobile component. In agarose electrophoresis,
A60 showed only one band but in immunodiffusion it showed two
immunoprecipitinogen lines with anti-BCG anti-serum. In analyzing with dot blotting,
both cytoplasm and cell wall of BCG showed positive reaction with antiA60
anti-serum. When A60 was fractionated by SDS-PAGE and analyzed by:
western blot using anti-A60 antibody, 65,46, 40, 38 and 35 KDa protein fractions'
were identified.
It is concluded that A60 is a macromolecular antigen of BCG with a molecular
weight of 106_107 Da and is a lipoprotein-polysaccharide complex which contains
several proteins. A60 is present in both cytoplasm and cell wall of BCG and
can easily be purified from BCG vaccine using exclusion chromatography by
sepharose 4B, to be used for designing diagnostic tests for TB.