Edited BCG offers potential vaccine to prevent tuberculosis in people of all ages

TB remains the leading cause of death by infectious disease globally, with South Africa having one of the highest incidence rates in the world.

While the BCG vaccine used to prevent TB is widely available for infants, no vaccine has shown lasting protection. The BCG is also the only existing effective vaccine.

“South Africa committed to the Sustainable Development Goal of ending the TB epidemic by 2030. While we are doing relatively well as a country – TB deaths have come down since 2015 – we need to do a lot better to reach the milestones,” says Professor Bavesh Kana.

Kana, the Head of the School of Pathology and former director of the Centre of Excellence for Biomedical TB Research at Wits University (University of the Witwatersrand), contributed to the groundbreaking study.

Modifying the vaccine

Researchers sought to modify the BCG vaccine to make it more effective at controlling the growth of M. tuberculosis. Mice injected with the edited BCG vaccine had less M. tuberculosis growth in their lungs than mice that received the original vaccine.

“We can now offer a new candidate vaccine in the fight against this deadly disease,” says Kana. “The work also demonstrates that gene editing is a powerful way to develop vaccines. This is particularly important for researchers working on vaccine development.”

The BCG vaccine is given to children around the time of birth and is effective at preventing TB disease. However, BCG does not protect teenagers and adults and has not been effective at eradicating TB. This has spurred the need to develop novel TB vaccine candidates to replace or boost BCG.

Evading the immune system

“We also see that the BCG can evade the immune system and that this reduces its efficacy as a vaccine,” says Kana.

He noted that the importance of vaccines cannot be overstated.

Kana has lamented the funding gap in developing tools to eliminate TB.

“Until recently, our diagnostic approaches were a century old. With some novel vaccine candidates in the pipeline, we can finally begin to adequately address this devastating illness.”