HealthDay News — New research, published online May 27 in Cell Host & Microbe, sheds light on how the Zika virus infects, but doesn’t kill, placenta cells.

Scientists conducted experiments using immune cells from placentas of healthy women who had full-term babies delivered by cesarean section. The Zika virus used in the study is the strain circulating in Puerto Rico. The researchers said it’s closely related to the strain in Brazil, where the virus-related birth defects became apparent last spring.

The researchers found that Zika can replicate in immune cells from the placenta without killing them. They said this may explain how the virus can pass through the placenta of a pregnant woman and infect developing brain cells in her fetus. When they examined placenta cells from different women, the researchers also found wide variation in the levels of Zika virus replication. This suggests some women may be more susceptible to infection than others.

“Not every pregnant woman who is infected by Zika transmits the virus to her fetus,” senior author Mehul Suthar, PhD, an assistant professor of pediatrics at the Emory University School of Medicine in Atlanta, said in a university news release. “Host genetics and nonviral factors, including nutrition and microbiota, as well as timing may be influencing infectivity.”

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