A new treatment that protects the babies of pregnant mice infected with Zika could help us create a similar therapy for humans.

The mosquito-borne Zika virus has “spread explosively” through the Americas, leading to health and travel advisories in many countries. The virus can cause a severe neurological disorder called Guillain-Barré syndrome. It is especially dangerous for pregnant women whose children could be born with very small heads, a condition called microcephaly. The World Health Organization has declared Zika a global emergency.

There is currently no Zika vaccine; in the US, the FDA is trying to fight the disease using genetically modified mosquitoes. But a study published today in Nature suggests another avenue of research. Scientists led by James Crowe at Vanderbilt University took proteins that fight viruses, called antibodies, from the white blood cells of humans who had been infected by Zika. After testing these antibodies, they decided to focus on a specific strain called ZIKV-117 because it seemed the most effective at fighting the virus.

Next, the team put ZIKV-117 in pregnant mice. Some pregnant mice received it before they were infected with Zika, some after. In both cases, the antibody seemed to fight the Zika virus; additionally, the mice fetuses ended up bigger than without the antibodies, and the placenta was not as damaged.

Pregnancy in mice is very different from pregnancy in humans, so this work is limited. A lot more research is needed, but this treatment still gives us some insight into potential ways to help pregnant women infected with the virus.