A gut bacterium called Listeria (Listeria monocytogenes), which is often found in soft cheese, is known to present a risk to pregnant women. Listeria uses distinct tactics to breach the intestine and the placenta, using a protein called phosphoinositide-3 kinase (PI3-K).
Listeria has two proteins that help it cross mucosal tissue barriers. Both proteins, called internalins A and B, attach to tissue receptors and are needed for Listeria to invade the placenta, but protein A alone can propel Listeria across the intestine. What underlies these differences has remained unknown.
Study Reveals How Listeria Breaches the Placenta
Image: CDC online