New TB Vaccine in Development
Two billion people, one third of the Earth’s population—have been exposed to the tuberculosis pathogen. Each year, 8 million people become ill with tuberculosis, and 2 million people die from the disease worldwide.
An urgently needed new tuberculosis vaccine has completed a vital step in testing, an important advance at time when a third of the world’s population is believed to be have latent tuberculosis infection (LTBI), which, when re-activated, can cause full-blown disease.
The results of the Phase I trial of a leading new TB vaccine, MVA85A, appeared in the April 15th issue of the American Journal of Respiratory and Critical Care Medicine. MVA85A is scientific shorthand for Recombinant Modified Vaccinia Ankara expressing Antigen 85A.
“A more effective vaccine regimen than the currently available bacillus Calmette-Guérin (BCG) would have a major impact on the global TB burden, and ultimately, will be the most efficient way to control this pandemic,” wrote principal investigator, Helen McShane, M.D., Ph.D., reader in vaccinology and Wellcome senior fellow at the University of Oxford’s Jenner Institute in England.
One-third of the world’s population is latently infected with M. tuberculosis. Any new TB vaccine must be developed with this huge reservoir of infection in mind, as latent infection may decrease the therapeutic value of new vaccines or worsen vaccine-related adverse events. With this in mind, Dr. McShane and fellow researchers investigated the effects of MVA85A specifically in individuals who had LTBI.
“While BCG gives good protection against severe forms of TB…it does not provide adequate protection against adult pulmonary TB,” noted Hazel Dockrell, Ph.D., and Ying Zhang, Ph.D.
The investigators found the vaccine was safe and did not induce any immunopathology in this group, and also that the vaccine was as immunogenic in this group, as in the BCG-vaccinated individuals. Dr. McShane calls these results “very important in the further development of this vaccine.”
