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Tuesday November 6 1:22 PM ET

Tuberculosis Vaccine Trials Set to Begin in Britain

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LONDON (Reuters Health) - Trials are about to begin in Britain on the first vaccine against tuberculosis since BCG was developed 80 years ago, the Wellcome Trust funding charity has announced.

In its latest newsletter, the trust said human volunteers would take part in a phase l study of a new ``prime-boost'' vaccine being developed to protect adults against the disease.

Although BCG vaccine works extremely well at protecting children from tuberculosis (TB), the report says there is a crucial shortcoming--after about 10 years resistance wanes and the body is again vulnerable to attack.

``With one third of the world's population thought to be latently infected with M. tuberculosis, about 2 million dying from tuberculosis every year, and resistance to available drugs on the increase in many parts of the world, the need for a new vaccine that helps adults is pressing,'' the trust said.

Oxford University researcher Dr. Helen McShane, who has been awarded a Wellcome Trust fellowship to pursue the research, added: ``The HIV (news - web sites) epidemic is making the problem worse. If you are infected with HIV you are more likely to get TB. There is a dangerous synergy between the two.''

The prime boost vaccine strategy developed for use against TB by McShane involves using two different vaccines, each of which includes the same antigen. The existing BCG vaccine will be given as the prime while the new vaccine will act as the booster.

The report explains that the new vaccine is based on MVA--shorthand for modified vaccinia virus--which has been tweaked to make it harmless to humans. Inserted into MVA is a gene that produces a protein antigen from M. tuberculosis.

``We chose antigen 85A for the new vaccine,'' McShane told the newsletter. ``It's a highly conserved protein common to all mycobacterial species, is an enzyme involved in building the cell wall and is actively secreted.''

The report states that in mice the new strategy works extremely well at boosting levels of T helper and T killer cells. To see whether the same happens in humans, the trial will look at the immune responses to BCG or MVA alone, and to BCG followed by MVA.

The phase l study is likely to take 2 to 3 years, optimising the dose and the intervals. If the vaccine works, it will then be tested in further phase l studies in countries where TB is endemic, the report adds.

ALL INFORMATION, DATA, AND MATERIAL CONTAINED, PRESENTED, OR PROVIDED HERE IS FOR GENERAL INFORMATION PURPOSES ONLY AND IS NOT TO BE CONSTRUED AS REFLECTING THE KNOWLEDGE OR OPINIONS OF THE PUBLISHER, AND IS NOT TO BE CONSTRUED OR INTENDED AS PROVIDING MEDICAL OR LEGAL ADVICE.  THE DECISION WHETHER OR NOT TO VACCINATE IS AN IMPORTANT AND COMPLEX ISSUE AND SHOULD BE MADE BY YOU, AND YOU ALONE, IN CONSULTATION WITH YOUR HEALTH CARE PROVIDER.