Human infection model drives forward TB vaccine development

Scan of the lungs showing tuberculosis

For the first time, a controlled human infection model for tuberculosis (TB) has been developed and could help with the future development of TB vaccines.

Researchers from the University of Oxford developed the infection model, which replicates how TB enters the body by infecting people via the lung, using the bacille Calmette-Guerin (BCG) vaccine delivered via aerosol into participants’ lungs.

The team states that it’s the first step towards establishing a challenge model that can be used to test new vaccines for TB.

Human challenge models have contributed significantly to the development of vaccines for diseases such as malaria or typhoid, especially in early phase trials. They help scientists select which vaccines should be taken forward into larger field efficacy studies and could be particularly useful with pathogens like tuberculosis, where vaccine development is very difficult.

Since there aren’t any quick and effective treatments for TB, researchers in clinical trials aren’t able to give patients the disease when there since there would be know quick way of knowing if that patient had been cured.

Trial details

The BCG vaccine was used in this trial because it is a live attenuated strain of Mycobacterium bovis – which is related to Mycobacterium tuberculosis, the bacterium which causes tuberculosis in humans – and BCG is known to be safe in humans.

Healthy people who had never had the BCG vaccine before were recruited into the trial. They were given BCG by aerosol using a nebuliser into the lungs, whilst a control group had BCG injected into the arm.

The dose given was gradually increased to ensure it was safe. The team found that the highest dose did not induce troublesome side effects. They then compared how much BCG could be recovered after administering it in the lungs and through the skin.

The doses of aerosol-inhaled BCG were found to be well tolerated by the participants and there was no significant difference in the frequency of adverse events between the two groups.

Professor Helen McShane, Professor of Vaccinology in the Nuffield Department of Medicine, who led the study, said: “When we did lung washes of the participants, we recovered BCG, which is a positive sign in a challenge study. When we eventually test a new vaccine using this method, if we can’t find BCG in the lung washings it would suggest that the vaccine has induced protection. If we hadn’t found BCG in the lung fluid, we would not have been able to move forward with this as a model.”

Megan Thomas, Multimedia Editor, DDW

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