Interventions for Tuberculosis Control and Elimination 2002

Appendix 3
Current vaccine development strategies
The incomplete protection that BCG provides against tuberculosis and its
dismally disappointing effects in some areas have challenged researchers to
develop a vaccine with better and more consistent performance. It is uncertain
whether a much better vaccine can be developed in the near future, as
the development of vaccines against bacteria that do not exert their pathogenicity
through toxins has been fraught with difficulties. Vaccine development
strategies currently being pursued include: 1185-1188
• Immunotherapy;
• Vaccination with saprophytic (environmental) mycobacteria;
• Auxotrophs;
• DNA vaccines;
• Recombinants;
• Subunits.
Immunotherapy with M. vaccae
M. vaccae is an environmental mycobacterium not known to cause disease
in humans. A killed suspension of M. vaccae has been proposed, not to
vaccinate against future tuberculosis, but to increase therapeutic response
in the treatment of clinically manifest tuberculosis. 1189
Numerous anecdotes have been published to illustrate its putative
effects, but a clinical trial utilizing rigorous scientific standards has not
shown any beneficial effect in addition to chemotherapy alone. 1190 Another
controlled clinical trial indicates that immunotherapy with M. vaccae may
be effective. In that trial, sputum culture conversion at one month (but
not at two months) was significantly higher among persons receiving M. vaccae
compared to controls. In addition, radiographic improvement was
swifter. 1191 In yet another trial, no relevant differences during treatment
and a four-year follow-up were found. 1192
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