The microorganism that causes tuberculosis, M. Tuberculosis, infects more than a one third of the world's population. Although the currently used vaccine (M. bovis BCG) provides young children with protection from tuberculosis, it is not effective at preventing the type of tuberculosis that most adolescents and adults suffer from. Therefore, there is an intensive research effort designed to develop new, more efficient vaccines that protect all individuals from tuberculosis.
In a study that appears in the August issue of the Journal of Clinical Investigation, Steven Porcelli and colleagues from the Albert Einstein College of Medicine, New York, show that in mice, immune cells known as CD8+ T cells are more efficiently activated by strains of M. Tuberculosis that lack a protein known as SecA2 than strains of M. Tuberculosis that express SecA2. Efficient CD8+ T cell activation was associated with increased death (by a process known as apoptosis) of another immune cell type, the macrophage. Importantly, vaccination of mice and guinea pigs with M. Tuberculosis lacking SecA2 provided increased protection against infection with M. Tuberculosis than did vaccination with M. bovis BCG. These data led the authors to suggest that this approach, in combination with others currently under development, could be used to generate a new vaccine that protects all individuals from tuberculosis.
The importance of this study for the development of new vaccines to control the tuberculosis pandemic is discussed in more detail in the accompanying commentary by W. Henry Boom from Case Western Reserve University.