Tuberculosis (TB) gets its name from the bacterium that causes it, Mycobacterium tuberculosis. Despite being curable, it remains a global health threat and has become resistant to many antibiotics. Using real-time live-cell imaging, scientists have uncovered a defence mechanism within TB-infected cells that regulates infection. Usually, TB (in green) is detected by immune cells called macrophages (nuclei shown in blue), which then envelop the bacterium in cell membrane and ingest it, forming phagosomes (red rings). In a bid to survive, the bacteria punch holes in the phagosome membrane, and leak out into the cell to feed off its nutrients. However, the macrophages are sometimes able to counteract this, thanks to the actions of the Rab20 protein. Rab20 instructs the cell to send more membrane to tight phagosomes to make them more spacious. By enlarging the phagosomes, the bacteria are immobilised, allowing the delivery of antibacterial agents to destroy them.
Written by Soumya Perinparajah
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