Study shows how Zika virus could cause fetal brain defects; direct link not yet shown

World Today

Dallas County Mosquito Lab microbiologist Spencer Lockwood sorts mosquitoes collected in a trap, left, in Hutchins, Texas. (AP Photo/LM Otero)

The Zika virus is capable of quickly infecting and harming developing fetal brain cells, scientists said on Friday in a study that provides insight into how the virus might cause the birth defect microcephaly in fetuses exposed in the womb.

The researchers said their study, published Friday in the journal Cell Stem Cell, does not provide proof of a direct causal link between Zika and microcephaly, but it does identify where the virus may be inflicting the most damage in developing fetuses.

The mosquito-borne virus infects a kind of neural stem cell that goes on to form the cerebral cortex, the brain’s outer layer responsible for intellectual capabilities and higher mental functions, the study showed.

Researchers found that these cells, exposed to the virus in laboratory dishes, were infected within three days, turned into “virus factories” for viral replication and died more quickly than normal.

“Our study shows once the virus gets to the brain it can reach these very important cells,” researcher Hengli Tang, the study’s lead author from Florida State University, said in an interview.

The mosquito-borne virus is spreading in Latin America and the Caribbean. Scientists are alarmed by indications that when it infects a pregnant woman, her baby may be born with a small head and a brain that hasn’t developed properly.

Previous studies have found Zika virus in the brains of babies with the defect who had died. Now the new study finds that in laboratory dishes, Zika can harm specific cells that help the brain develop. But experts caution that this doesn’t prove the virus causes the birth defect.

Traces of Zika virus have been found in the bodily fluids and tissue of mothers and babies affected by microcephaly.

Dr. Lyle Petersen, director of the division of vector-borne diseases at the U.S. Centers for Disease Control and Prevention, told a news briefing on Wednesday at the Pan American Health Organization in Washington that there are numerous lines of evidence now linking Zika with microcephaly.

“I don’t think there is any question about that any longer,” Petersen said.

Story compiled from reports by Reuters and The Associated Press