Working with lab-grown human stem cells, scientists found that the virus selectively infected cells forming the brain’s cortex, the thin outer layer of folded gray matter. There’s also no evidence that the cells are employing antiviral responses, which means we don’t know whether or how the virus is being cleared from the precursor cells.
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Dr. Guo-li Ming of Johns Hopkins University, another lead study author, said researchers can now explore questions like how Zika infects the cells. But the virus has been suspected of causing a serious birth defect called microcephaly in which babies are born with abnormally small heads. But they noted that “a major ominous difference” between the recent Zika outbreak in Brazil and the rubella infections in the United States more than half a century ago.
“This is a first step, and there’s a lot more that needs to be done”, Hongjun Song of the Johns Hopkins University School of Medicine said in a statement.
According to the CDC, almost 80 percent of people infected with the virus have no symptoms. A few cases of Zika have been identified in the US, mostly from travel or sexual transmission. Sometimes there are no symptoms at all.
The virus has been linked to birth defects in the children of women who caught the virus while pregnant. Research is underway to find other causes, but the World Health Organization said in February that Zika is guilty until proven innocent. Brazil said it has confirmed more than 640 cases of microcephaly and considers most to be related to Zika infections in the mothers.
There isn’t now a vaccine for the Zika virus.
Of the 42 infected women who had ultrasounds, major fetal abnormalities were found in 12 of them – almost a third.
That belief was bolstered Friday by two studies published in medical journals.
The Atlanta-based agency is warning pregnant women to avoid more than 30 areas where the Zika virus is actively spreading. Researchers say the Zika virus may be linked to a wider variety of ¿grave outcomes¿ for developing babies than previously reported and that threats can come at any stage of pregnancy.
And, although it might be logical to conclude from the study that the Zika virus attacks, damages and kills important cells that build the brain, Ming said they now have to “determine whether the Zika virus infection can lead to microcephaly in a different cultural model system, a three-dimensional model”.
The researchers acknowledged that Friday’s study has some weaknesses.
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Nielsen says their study and others like it could help eliminate theories that the pesticides used against mosquitoes (and not the virus itself) are the culprit.
