SA on course to end TB by 2030

SA's commitment to the UN's Sustainable Development Goal of ending the TB epidemic by 2030 is inching closer with the discovery of a potential vaccine to prevent the disease.

According to Wits University, a candidate vaccine for TB was created using a gene-editing approach.

Prof Bavesh Kana — head of the school of pathology and former director of the Centre of Excellence for Biomedical TB Research at Wits University — contributed to the groundbreaking study, the institution said.

Kana, who is also a consultant for the Bill & Melinda Gates Medical Research Institute in Cambridge, Massachusetts in the US, said TB remains the leading cause of death by infectious disease globally, with SA having one of the highest incidence rates in the world. “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.”

Currently, the BCG vaccine was the only existing effective vaccine used to prevent TB, and is widely available for infants. However, no vaccine has shown lasting protection. 

The BCG vaccine is given to children at birth and is effective at preventing TB. It does not protect teenagers and adults, and has not been effective at eradicating TB. This spurred the need to develop novel TB vaccine candidates to replace or boost BCG, said Kana. “We also see that the BCG can evade the immune system, and that this reduces its efficacy as a vaccine.”

He explained that researchers sought to modify the BCG vaccine to make it more effective at controlling the growth of Mycobacterium (M) tuberculosis. They injected mice with the edited BCG vaccine. Those mice were later found to have 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,” said 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.”

According to Kara, the importance of vaccines cannot be overstated. "When humans get sick, their body's defence system spots particular signs, called Pamps (pathogen-associated molecular patterns), on the outside of bacteria, viruses or other harmful germs.

"This helps the body tell the difference between invaders and its own cells, and then starts fighting the infection. Vaccines work by looking like germs, so that they can start the first defence without making a person sick.”

Kana lamented the funding gap in developing tools to eliminate TB, a disease he said dates back more than 9,000 years.

“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,” said Kana.