How Does the Zika Virus Cross the Placenta?

Lenore Pereira, PhD, professor of Cell and Tissue Biology at University of California, San Francisco, discusses how Zika crosses the Placenta.

Interview Transcript (slightly modified for readability)

“Well, we proposed in our publication that the [Zika] virus would come from the maternal bloodstream carried by viremia into the maternal blood space. This is the space between the developing placenta and the decidua. This would be very easy for the virus to do during the first trimester.

We also proposed, based on infections of primary cells from the placenta, and this included amniotic epithelial cells from the amniotic membranes. We discovered that the virus grows very well in this cell type, and even better in cells from mid-gestation rather than late-gestation. It told us that if a person was infected during pregnancy at the time when the baby was getting larger, the parietal decidua, the decidua that lines the uterine wall and comes in close contact with the amniochorionic membranes, [or] the fetal membranes, then the possibility would be that the maternal blood would again infect the trophoblasts in those membranes and then could cross into the fetal compartment and infect the baby in that direction. So, a more direct route in late-gestation could be possible.

Of course, the third possibility, which we didn’t mention in our paper was the possibility that the virus could come from the sexual route, and, again, cross the fetal membranes, because they then abut the access from the vagina— which of course there’s a plug in-between, but still virus might get through. The possibility then, is crossing from the maternal bloodstream, either in the first trimester from the basal decidua, or, at late-gestation through the parietal decidua to the fetal compartment.”