A key virus fighter is implicated in pregnancy woes

Fetal mice whose immune system revved up in response to their mom’s Zika infection died or grew poorly

Placental tissue

KNOTTY ISSUES  Placental tissue (on the right) treated with an immune protein that fights viruses developed knotty structures that resembled those associated with pregnancy complications. Untreated placental tissue (on the left) does not show these structures.

L. Yockey et al/Science Immunology 2018, Carolyn Coyne

An immune system mainstay in the fight against viruses may harm rather than help a pregnancy.