How the Zika Virus Destroys Brain Cells, Likely Causes Microcephaly

The Zika virus has been strongly believed to cause the neurological disorders microcephaly and Guillain-Barré syndrome, and new evidence supports the association.

When Zika diagnoses began popping up on the map last year, microcephaly was at the top of health-related concerns. The significant amount of children born with microcephaly in Brazil, where the current Zika outbreak all began, has made it nearly impossible to deny that something was going on.

A collaborative team of researchers from Johns Hopkins University School of Medicine, Florida State University, and Emory University found that Zika does in fact infect cells which form in the brain’s cortex.

“Studies of fetuses and babies with the telltale small brains and heads of microcephaly in Zika-affected areas have found abnormalities in the cortex, and Zika virus has been found in the fetal tissue,” Guo-li Ming, MD, PHD, from Johns Hopkins, said in a news release.

The team conducted multiple experiments using lab-grown human stem cells. The cells were exposed to Zika and their genetic expression was analyzed. Three days after exposure, 90% of the cortical neural progenitor cells were infected and began producing copies of the virus, as described in Cell Stem Cell.

First author Hengli Tang, PhD, a virologist at Florida State University, explained that the virus-fighting genes didn’t turn on, which is very unusual. Another observation revealed that many of the infected cells died and others showed a disrupted expression — which means that new cells could not be created properly.

“Now that we know cortical neural progenitor cells are the vulnerable cells, they can likely also be used to quickly screen potential new therapies for effectiveness,” continued Hongiun Song, PhD, from Johns Hopkins.

Different case reports have shown that certain brain areas have developed normally with the Zika infection, but the cortical structures are most often what’s missing.

The authors stressed that the studies do not prove the direct link between Zika and microcephaly — but they do show that the virus infects and destroys cells needed for brain development. The findings also indicate that the lab-grown cells can be used to test potential vaccines and drugs, according to the researchers. They continue to work to fill the knowledge gap between Zika and neurological effects.

“So a very important question that emerges from our work is whether the Zika virus specifically targets the neural progenitor mostly responsible for generating the cortex,” Ming concluded in a report.