The Zika virus builds tiny tunnels, called tunneling nanotubes, to stealthily transport material needed to infect nearby cells, including in placental cells, according to a team of researchers from Penn State and Baylor College of Medicine. It’s one way the virus crosses the placental barrier, transmitting from mother to fetus during pregnancy without raising alarm in the immune system. The team also demonstrated, for the first time, that one specific Zika protein — non-structural protein 1 (NS1) — is responsible for the formation of the nanotubes.