A team of U.S. and European researchers have found that a new vaccine strategy tested in mice provides stronger, more long-lasting protection from tuberculosis (TB) infection than the vaccine currently used in humans, known as BCG. Their findings were published online Jan. 23 in the journal Nature Medicine.
The study was co-funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, and the Bill & Melinda Gates Foundation. It was coordinated by the NIAID-funded TB Vaccine Testing and Research Materials program at Colorado State University, an initiative to speed the development of new TB vaccines and treatments.
Caused by the bacterium Mycobacterium tuberculosis (Mtb), TB remains one of the major causes of disability and death worldwide, with an estimated 1.7 million deaths in 2009 and increasing rates of drug-resistant disease. The BCG vaccine, the only one approved for human use, provides some protection against initial TB illness but does not prevent latent infection, in which Mtb persists in human cells for years and may later develop into active disease.
In this study, the researchers combined two proteins previously found to improve the BCG vaccine's effectiveness with a new component, a stress response protein that mice produce throughout the TB infection process. This three-component vaccine, known as H56, was administered to uninfected mice before and after BCG vaccination. Six weeks later, the mice were exposed to Mtb. The multistage strategy not only protected against initial illness, but controlled reactivation of latent infection and reduced Mtb levels in the lungs more effectively than BCG alone. Because of the success of this study, the vaccine candidate is now entering clinical development.
Reference: C Aagaard et al. A multistage tuberculosis vaccine that confers efficient protection before and after exposure. Nature Medicine. DOI: 10.1038/nm.2285 (2011).