uk study raises doubts about the new generation vaccines being developed against tuberculosis (tb), a major killer in the developing world. Most of the research on tb vaccines is being done in Europe and the us where the immune response of the people is different from those living in the developing world. But this fact has not been factored in while developing the new vaccines, according to the study published in the August issue of Nature Reviews Immunology (Vol 5, No 8).

"The work done in the uk and usa relates to local conditions, and tends to ignore the problems of the developing world. bcg, for instance, protects rather well in the uk. Perhaps there should be much more research effort in India,' says Graham Rook of the Centre for Infectious Diseases and International Health, University College Medical School, London.

The disease is caused by a bacterium, Mycobacterium tuberculosis. The standard bcg vaccine works by stimulating production of t_H1 immune cells. New vaccines also take the same approach. But studies have shown that in developing countries, exposure to common pathogens such as helminthes (worms) stimulates the immune system to readily produce not only t_H1 but also t_H2 cells. However, the chemicals t_H2 cells produce suppress t_H1. The authors suggest vaccines testing models should incorporate such factors to be effective in developing countries. For example, helminth-infected lab animals, primed with environmental mycobacteria, should be used instead of immunologically na