How shigella causes dysentery

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French scientists say they believe they’ve discovered how shigella bacteria survive in the gut to be able to cause dysentery.
Laurence Arbibe and colleagues at the Pasteur Institute in Paris found a protein produced by shigella is injected into host cells and blocks production of immune signals required for preventing the infection.
Shigella affects millions of people worldwide, killing hundreds of thousands annually.
The researchers studied Shigella flexneri infection of human colon cells to understand the bacterial factors required to initiate disease. Shigella bacteria are known to inject up to 20 proteins into intestinal cells for the purpose of promoting infection and for dampening immune responses.
They found one of the injected proteins, OpsF, could prevent gut cells from switching on genes involved in immune responses. As a consequence, Shigella flexneri avoids being killed by their host’s immune cells and is able to spread throughout the gut.
The scientists say their study highlights the precision with which pathogens such as shigella can dramatically alter host cells. It also suggests blocking OspF may provide a target for treating bacterial dysentery.
The study is reported in the January issue of the journal Nature Immunology.