A vaccine, designed to be used alongside isoniazid preventive therapy to shorten the course of drug treatment in people with latent TB, will shortly undergo trials in South Africa, manufacturer Archivel Farma announced this week.
Latent infection with tuberculosis, in which the bacteria which cause the disease are walled off and unable to multiply in the lungs, is present in around one-third of the world’s population.
Latent TB can quickly turn to active disease in a person with a damaged immune system, and TB is a leading cause of death in people with HIV.
For this reason the World Health Organization recommends a nine-month course of preventive treatment with isoniazid, an antibiotic which can clear the latent infection, for anyone with HIV infection.
However, a shorter course of preventive treatment would be preferable. Not only do patients have difficulty in adhering to such a long course of treatment, they may also suffer liver toxicity (particularly if taking other medications that cause liver toxicity too).
Spanish researchers at the Institut d’Investigació en Ciències de la Salut Germans Trias i Pujol Foundation believe that the course of preventive treatment can be shortened by giving a vaccine that will stimulate the body’s own specific immune responses against TB. They have developed a vaccine called RUTI which uses non-replicating fragments of the TB bacillus to stimulate an immune response.
The vaccine has already showed an immunogenic effect in a phase 1 study in healthy volunteers, and is now to be tested in 96 individuals with and without HIV infection in a phase 2 study at three centres in South Africa.
Results of the trial are expected by the end of 2010, and manufacturer Archivel hopes that, if trials prove successful, the vaccine would be available for licensing within five years and would halve the cost of treating latent TB.
Other TB vaccines are being developed by Aeras Global TB Vaccine Foundation.