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A pilot study of three potential vaccines for leprosy in Bombay
R Ganapati1, C R Revankar, D N Lockwood
1Bombay Leprosy Project, Bombay, Maharashtra, India.
Insights
This study compared three vaccines in children. Vaccine B, combining BCG Glaxo with killed Mycobacterium vaccae, significantly enhanced skin-test positivity to leprosin A, suggesting it may be a superior leprosy vaccine.
Area of Science:
- Immunology
- Vaccinology
- Infectious Diseases
Background:
- Bacille Calmette-Guérin (BCG) is a primary vaccine for tuberculosis.
- Leprosy, a chronic infectious disease, requires effective vaccination strategies.
- Previous research suggested combining BCG with killed Mycobacterium vaccae may improve leprosy prevention.
Purpose of the Study:
- To evaluate the immunogenicity of three distinct vaccine formulations in children.
- To compare the efficacy of BCG alone versus combination vaccines in eliciting skin-test responses.
- To determine if BCG combined with killed Mycobacterium vaccae or Mycobacterium leprae enhances immune responses relevant to leprosy.
Main Methods:
- Three groups of children received different vaccines: BCG Glaxo alone (A), BCG Glaxo plus killed M. vaccae (B), or BCG Glaxo plus killed M. leprae (C).
- Quadruple skin testing was performed 1-3 years post-vaccination to assess immune responses.
- Statistical analysis was used to compare the significance of observed differences in skin-test positivity.
Main Results:
- All three vaccines significantly increased tuberculin skin-test positivity (p < 0.00001).
- Vaccine B (BCG + M. vaccae) uniquely and significantly enhanced skin-test positivity to leprosin A (p < 0.002).
- No significant enhancement of leprosin A positivity was observed with vaccine C (BCG + M. leprae).
Conclusions:
- The combination of BCG with killed Mycobacterium vaccae (Vaccine B) demonstrates superior immunogenicity compared to BCG alone or BCG with M. leprae.
- Findings support the hypothesis that BCG combined with M. vaccae is a potentially more effective vaccine for leprosy prevention.
- Further research into BCG-M. vaccae combination vaccines for leprosy is warranted based on these results.
Abstract:
Three vaccines, BCG Glaxo alone (vaccine A), BCG Glaxo plus 10(7) killed Mycobacterium vaccae (vaccine B), and BCG Glaxo plus 10(7) killed M. leprae (vaccine C), were given to groups of selected children. The effects of these vaccines on subsequent quadruple skin testing 1-3 years after vaccination were compared. All three vaccines equally and significantly (p less than 0.00001) increased positivity to tuberculin, but only vaccine B was found to significantly enhance development of skin-test positivity to leprosin A (p less than 0.002). The data support the evidence previously obtained in rural Iran that the combination of BCG with killed M. vaccae is likely to be a better vaccine for leprosy than is BCG alone.