Immunogenicity assay of KatG protein from Mycobacterium tuberculosis in mice: preliminary screening of TB vaccine

摘要

The tuberculosis (TB) disease is still widely found even though BCG vaccine given to many people. Ineffectiveness of the BCG vaccine is one of causes that make the difficulties in preventing TB transmission. Objective of the research was to determine the immunogenicity of KatG protein of M. tuberculosis clinical isolate L19 in mice. The KatG protein as antigen was prepared by expression of the katG gene of M. tuberculosis clinical isolate L19 in Escherichia coli BL21 using pColdII-DNA vector. After purification by affinity chromatography, the KatG was vaccinated to mice to detect its immunogenicity. The expression of katG in E. coli BL21 could result in KatG protein with molecular weight 80 kDa in sodium dodecyl sulfate gel electrophoresis (SDS-PAGE). The pure KatG protein could significantly stimulate the immune response of mice by triggering the antibodies production of IgG1, IgG2a, IgG2b, IgG2c, IgG3, and IgM. The highest antibody level was obtained when the mice were vaccinated by KatG L19 with the dose of 45 μg/ml. Of the antibodies, the IgG2c isotype was dominantly produced in the blood serum. The KatG protein exhibited a high immunogenicity in mice, so it is possible to develop as a vaccine candidate for TB. A clinical test should be performed in a future to ensure its safety as a therapeutic protein.