Antibodies against BCG and M. tuberculosis H37Ra do not Consistently Recognize Pathogenic M. tuberculosis whole Cells but Recognize their Cytoplasmic Constituents. Implications for the Variability and Protective Efficacy of the Vaccine

Abstract

The production of antibodies by mycobacterial pathogens and BCG vaccine is still poorly understood. This study showed that antibodies raised against cells of TB strain H37Ra and against whole sonicates of BCG do not react consistently with whole cells of TB pathogenic strains and very poorly with whole BCG cells. These antibodies react with the internal components of the BCG cell, i.e. A60 and cytoplasmic constituents. It is concluded that the failure of antibodies raised against BCG to recognize some pathogenic strains permits the unrestricted entrance of these pathogenic bacteria in a vaccinated host and may explain the variable efficacy of this vaccine. The reactivity of these antibodies with internal components of the mycobacteria may impede the progress of the infection toward disease. These protective antibodies are not consistently produced in BCG vaccinees and may explain the excess TB and leprosy cases sometimes observed after vaccination.