Thursday, August 21, 2014

New vaccine against tuberculosis and leprosy

A new vaccine offers protection against tuberculosis and leprosy :
Aug 20, 2014 : In a breakthrough, US researchers have found that an improved tuberculosis vaccine can offer strong protection against leprosy. In lab experiments over mice, researchers found that rBCG30, a recombinant variant of BCG that over expresses a highly abundant 30 kDa protein of the tuberculosis bacterium known as Antigen 85B, is superior to BCG in protecting against tuberculosis in animal models, and also cross protects against leprosy.
In addition, they found that boosting rBCG30 with the antigen 85B protein also expressed by the leprosy bacillus provides considerably stronger protection against leprosy.

 The original article published in : Infection and Immunity 
rBCG30-Induced Immunity and Cross-Protection against Mycobacterium leprae Challenge Are Enhanced by Boosting with the Mycobacterium tuberculosis 30-Kilodalton Antigen 85B
Thomas P. Gillisa, Michael V. Tulliusb and Marcus A. Horwitzb
J. L. Flynn, Editor

Leprosy remains a major global health problem and typically occurs in regions in which tuberculosis is endemic. Vaccines are needed that protect against both infections and do so better than the suboptimal Mycobacterium bovis BCG vaccine. Here, we evaluated rBCG30, a vaccine previously demonstrated to induce protection superior to that of BCG against Mycobacterium tuberculosis and Mycobacterium bovis challenge in animal models, for efficacy against Mycobacterium leprae challenge in a murine model of leprosy. rBCG30 overexpresses the M. tuberculosis 30-kDa major secretory protein antigen 85B, which is 85% homologous with the M. leprae homolog (r30ML). Mice were sham immunized or immunized intradermally with BCG or rBCG30 and challenged 2.5 months later by injection of viable M. leprae into each hind footpad. After 7 months, vaccine efficacy was assessed by enumerating the M. leprae bacteria per footpad. Both BCG and rBCG30 induced significant protection against M. leprae challenge. In the one experiment in which a comparison between BCG and rBCG30 was feasible, rBCG30 induced significantly greater protection than did BCG. Immunization of mice with purified M. tuberculosis or M. leprae antigen 85B also induced protection against M. leprae challenge but less so than BCG or rBCG30. Notably, boosting rBCG30 with M. tuberculosis antigen 85B significantly enhanced r30ML-specific immune responses, substantially more so than boosting BCG, and significantly augmented protection against M. leprae challenge. Thus, rBCG30, a vaccine that induces improved protection against M. tuberculosis, induces cross-protection against M. leprae that is comparable or potentially superior to that induced by BCG, and boosting rBCG30 with antigen 85B further enhances immune responses and protective efficacy.

The next step is to test the rBCG30 vaccine for efficacy in humans against TB. If it is effective against TB, then the next step would be to test its effectiveness in humans against leprosy.

(Reproduced from  :
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