If health authorities in the developing world were asked to list their priorities for medical funding, there can be little doubt that decoding the human genome would not be at the top.

Higher would be education in hygiene and safe sex, the provision of adequate clean water and the use of genetic modification and other techniques to increase the food supply.

Indeed, the genome of greatest interest to poor tropical countries is not the human version, but those of the parasites, bacteria and viruses which plague their people, as well as those of their staple crops.

The deciphering of bacterial and viral genomes provides new targets for drugs, as well as the basis for new vaccines.

Select and protect

However, one area where more knowledge of the human genome can benefit the developing world is in understanding why some individuals and populations are more or less susceptible to particular infectious diseases and more or less well protected by vaccines.

For example, research has shown that the existing vaccine widely used to protect against tuberculosis (TB), the so-called BCG vaccine, is generally effective in the UK but is ineffective in Malawi.

This differential effectiveness almost certainly results from genetic differences between populations.

A team lead by Professor Paul Fine of the London School of Hygiene and Tropical Medicine, with colleagues in Malawi, is investigating this and related questions such as why does BCG vaccination protect against leprosy but not TB in Malawi. And why does the HIV virus have a greater effect in reducing immunity to leprosy than TB?

Pinpointing the genetic differences responsible will be invaluable in revealing the detailed mechanism of the immune response and that is likely to be very valuable in designing new vaccines.

These may be able to stimulate the human immune system in the complex ways required to provide protection against tropical parasitic diseases in particular. Hopefully, it will also ensure that such vaccines protect all populations adequately.

Long-term benefit

In the long term, the deeper understanding of human health and disease resulting from human genome data will certainly benefit people everywhere on Earth. It will probably be in ways that are unforeseeable today, as the history of research has often shown.

But in the shorter term, there is a danger that the promise that genetic research holds for attacking the diseases of the poorer countries will be neglected.

And if rich countries focus on using the human genome to produce prohibitively expensive drugs designed to meet western ailments then the existing health gap between rich and poor will widen.

By John Newell