Vaccine helps to banish tuberculosis
Mouse results raise hope in fight against drug-resistant bacteria.
A tuberculosis vaccine containing DNA from the bacterium that causes the disease can cure mice when it is combined with drugs, says a team of researchers from Korea.
The therapy offers the hope of a tuberculosis treatment that works more quickly and effectively than current, drug-only methods.
Tuberculosis, which is caused by the bacterium Mycobacterium tuberculosis, kills about 2 million people worldwide each year: more than any other single infectious disease. Cases began rising in 1985, owing to the emergence of drug-resistant bacteria and HIV infections; 13% of AIDS deaths are attributed to the disease.
Drug-resistant strains have emerged partly because patients often fail to complete their therapy. Tuberculosis can be tackled with a cocktail of antibiotics, but up to 12 months of treatment are needed. If patients stop taking their drugs too soon, the disease can come back.
"Chemotherapy in its present form is falling short of what is needed," says Douglas Lowrie, an immunologist with the National Institute for Medical Research, London.
A treatment is needed that clears the body of M. tuberculosis in a relatively short time and prevents re-infection from any new source of bacteria.
Researchers led by Youngchul Sung of Pohang University of Science and Technology, Republic of Korea, now report that they have found a treatment that does just those things in mice. Their results are published in Gene Therapy1.
Sung's team took mice with tuberculosis and gave them standard drug therapy with or without an experimental DNA vaccine containing two of the microbe's genes.
In mice given drugs alone, bacteria numbers rose after treatment was stopped. Mice given the combined treatment showed no such flare-up. In addition, the combination therapy triggered an immune response that significantly reduced re-infection with tuberculosis bacteria.
This is the first study showing that giving vaccination and drugs together can accelerate the disappearance of bacteria as well as protecting against re-infection, says Lowrie.
Although this study involved mice, the combination treatment "may get into the clinic faster than one might think", says Lowrie. With the increasing threat of multi-drug-resistant strains, there is a push to get promising therapies into clinical trials.
- Ha S.-J., et al. Gene Therapy published online (2005). doi:10.1038/sj.gt.3302465