Effective vaccination of mice against Mycobacterium tuberculosis infection with a soluble mixture of secreted mycobacterial proteins.
An experimental vaccine that was based on secreted proteins of Mycobacterium tuberculosis was investigated in a mouse model of tuberculosis. I used a short-term culture filtrate (ST-CF) containing proteins secreted from actively replicating bacteria grown under defined culture conditions. The immunogenicity of the ST-CF was investigated in combination with different adjuvants, and peak proliferative responses were observed when ST-CF was administered with the surface-active agent dimethyldioctadecylammonium chloride. The immunity induced by this vaccine was dose dependent, and, in the optimal concentration, the vaccine induced a potent T-helper 1 response which efficiently protected the animals against a subsequent challenge with virulent M. tuberculosis. Antigenic targets for the T cells generated were mapped by employing narrow-molecular-weight fractions of ST-CF. The experimental vaccine primed a broadly defined T-cell repertoire directed to multiple secreted antigens present in ST-CF. A vaccination with viable Mycobacterium bovis bacillus Calmette-Guérin (BCG), in contrast, induced a restricted T-cell reactivity directed to two secreted protein fractions with molecular masses of 5 to 12 and 25 to 35 kDa. The protective efficacy of the ST-CF vaccine was compared with that of a BCG standard vaccine, and both induced a highly significant protection of equal magnitude. The vaccination with ST-CF gave rise to a population of long-lived CD4 cells which could be isolated 22 weeks after the vaccination and could adoptively transfer acquired resistance to T-cell-deficient recipients. My results confirm the hypothesis that M. tuberculosis cells release protective antigens during growth. The high efficacy of a subunit vaccine observed in the present study is discussed as a possible alternative to a live recombinant vaccine carrier.
Andersen
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Bacterial Vaccine Department, Statens Seruminstitut, Copenhagen, Denmark.
D000818:Animals; D001500:BCG Vaccine / Q000276:immunology; D001426:Bacterial Proteins / Q000276:immunology*; D001428:Bacterial Vaccines / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D014376:Tuberculosis / Q000276:immunology; D014611:Vaccination
D001500:BCG Vaccine; D001426:Bacterial Proteins; D001428:Bacterial Vaccines