Researchers conducted an emergency study - working sometimes around the clock - to identify what may be a biological connection between the Zika virus and a birth defect that causes undersized heads and brains in newborns, microcephaly.
After working with cells grown in the lab over the past month, researchers led by Johns Hopkins University School of Medicine found that Zika attacks the cell type that makes up the brain's outer layer or cortex. It causes those cells to be more likely to die off and less likely to divide in the normal way and create new brain cells.
"While this study doesn't definitely prove that Zika virus causes microcephaly," Guo-li Ming of JHUMS said, "it's very telling that the cells that form the cortex are potentially susceptible to the virus, and their growth could be disrupted by the virus."
Along with the fact that the World Health Organization recently declared the virus a "public health emergency of international concern," doctors in Brazil and elsewhere in South America have come to feel that Zika can also result in microcephaly in babies born to mothers who were infected while pregnant. Physicians also believe the virus could be associated with cases of Guillain-Barré syndrome, in which the immune system attacks the nerves.
A link with microcephaly that was initially suggested with Zika was identified in fetuses and babies who had small brains and heads, Ming said. A team from the U.S. Centers for Disease Control and Prevention flew to Brazil in February to help in identifying epidemiological proof that the virus causes the development of microcephaly.
Three U.S. universities that make up a task force had set out to search for a potential biological link showing the way that the virus could cause fetuses' normal brain development to be blocked. The research was led by Ming, along with Hongjun Song at Johns Hopkins and Hengli Tang at Florida State University.
In the study, they looked at the way Zika impacts the cortical neural progenitor cells, in comparison with how it affects two other cell types: immature neurons and induced pluripotent stems cells. The latter can be the starting point for any other anatomical cell type, including cortical neural progenitor cells. Those, in turn, can be the origin of immature neurons in the cortex.
In the course of the work, the researchers established which of those cell types was vulnerable to the Zika virus.
"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," Song said.
The study was published in the journal Cell Stem Cell.
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