A representation of the surface of the Zika virus with protruding envelope glycoproteins (red) shown. (credit: Courtesy of Kuhn and Rossmann research groups, Purdue University)

The Zika virus made headlines worldwide over the last few years, though news on its outbreak has slowed down in recent months. Zika is transmitted via mosquitoes and sexual contact, and it causes flu-like fever and aches. It’s a particularly worrying disease because it causes microcephaly in babies if their mothers contract Zika while pregnant.

This occurs because Zika has the ability to cross the placental barrier, even though other related viruses cannot. A recent study published in PNAS describes the mechanism that this virus may be using to cross this barrier—Zika is able to infect the cells that line blood vessel walls, which are a major part of the placenta. The research also identifies the protein on the cells’ surface that Zika latches onto, a revelation that provides avenues for developing potential treatments.

Zika is part of a genus of viruses known as the flaviviruses; other members of this group include Dengue and West Nile. All of them can cause serious health consequences, but only Zika causes microcephaly in the fetuses of infected mothers. Fetuses aren’t afflicted many by maternal infections because the placenta provides a barrier that many pathogens are unable to cross. The placenta is an effective barrier because it separates the maternal blood from the fetus’s, using tissue that is partially made up of fetal endothelial cells, which line the blood vessels on the fetal side of the barrier.