Vicious Vesicles

Up to a third of women have group B Streptococcus bacteria (the grey cells, pictured) in their vaginas, and while the microbes rarely cause problems they have been linked to preterm birth in some pregnant women. Intriguingly, such mothers rarely show signs of infection in the uterus itself. Scientists have now figured out how the bacteria might be causing problems at a distance. The bugs produce large numbers of tiny, toxin-containing, membrane-bound sacs called vesicles (seen surrounding the bacteria, coloured pink) that can increase the destructive capacity of the bugs – like grenades launched from the bacterial Humvee. And the small size of the vesicles means they can travel more easily than the bacteria themselves. Thus damage could occur in the uterus with no bugs in the immediate vicinity. Sure enough, when pregnant mice received intrauterine doses of these vesicles without the bugs, most of their pups were stillborn or premature.

Written by Ruth Williams

Ruth Williams

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Ruth is a freelance science journalist based in the US. She's a regular correspondent for The Scientist, and her work has appeared in The Lancet, Nature, Scientific American Mind, BBC Focus and elsewhere. Twitter @rooph

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• Image by Anirban Banerjee and colleagues
• Dept. of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Mumbai, India
• Image originally published under a Creative Commons Licence (BY 4.0)
• Research published in PLOS Pathogens, September 2016