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发表于 2016-3-7 11:06:11 | 显示全部楼层 |阅读模式
Zika virus kills developing brain cellsAs fear of the Zika virus spreads nearly as quickly as the pathogen itself, two new laboratory studies offer the first solid evidence for how it could cause brain defects in babies: The virus appears to preferentially kill developing brain cells. The observation bolsters the growing case for a connection between the virus, which is spreading rapidly across Latin America, and an increase in the number of cases of microcephaly, a birth defect in which the brain fails to grow properly. The new work, done independently by two groups, shows that the virus readily infects neural stem cells—the precursors of neurons and other brain cells—whether they are grown on cell culture plates or coaxed to form 3D minibrains called cerebral organoids.
The work “is going to be very important,” says Madeline Lancaster, a developmental biologist who studies human brain development at the Medical Research Council Laboratory of Molecular Biology in Cambridge, U.K. The results “are quite consistent with what you’re seeing in the babies with microcephaly.”
“这个工作将是非常重要的,”Madeline Lancaster,剑桥发育生物学家,在英国分子生物学医学研究委员会实验室研究人类大脑发育,”结果与你所看到的婴儿小头畸形是相当一致的。”
Zika virus, named after a forest in Uganda where it was first isolated decades ago, usually causes only mild symptoms in people, including fever and rash. But after the virus started spreading across northeastern Brazil last year, doctors there noticed a striking increase in the number of babies born with microcephaly. Many of the mothers reported having symptoms consistent with Zika infection during their pregnancies. But it has been difficult to prove a link between the virus and the birth defects because blood tests for Zika virus are only accurate for about a week after infection.
Nevertheless, circumstantial evidence has accumulated. Researchers have identified the virus in amniotic fluid of pregnant women whose fetuses were diagnosed with microcephaly and also in the brain tissue of a fetus diagnosed with the disorder. But because researchers had conducted scant research on the virus before this year, they had little data to suggest how the virus could cause such damage.
To gauge the virus’s possible effects on the developing brain, researchers at Johns Hopkins University in Baltimore, Maryland, and Florida State University in Tallahassee used induced pluripotent stem (iPS) cells to grow, in lab dishes, immature brain cells called human cortical neural progenitor cells. (iPS cells are adult cells that have been reprogrammed into stem cells that can grow into most of the tissues in the body.) They then exposed the neural progenitor cells to a lab strain of Zika virus.
The virus readily infected the neural stem cells, neuroscientists Hongjun Song and Guo-li Ming, virologist Hengli Tang, and their colleagues report today in Cell Stem Cell. Three days after the virus was applied, 85% of the cells in the culture dishes were infected. In contrast, when the virus was applied to cultures of fetal kidney cells, embryonic stem cells, and undifferentiated iPS cells, it infected fewer than 10% of the cells by day 3. Immature neurons derived from the neural progenitor cells were also less susceptible to the virus; 3 days after receiving a dose of the virus, fewer than 20% of those cells were infected.
该病毒容易感染神经干细胞,神经科学家Hongjun Song和郭李明,病毒学家亨利唐及其同事报告今天在干细胞。三天后,病毒被应用,85%的细胞在培养皿中被感染。相反,当病毒应用于胎肾细胞培养、胚胎干细胞和未分化的iPS细胞,它感染了少于3天10%的细胞。未成熟的神经前体细胞的神经元也不太容易受到病毒的感染,3天后,接受剂量的病毒,不到20%的这些细胞被感染。
The researchers noticed that the infected progenitor cells were not killed right away. Instead, the virus “hijacked the cells,” using the cellular machinery to replicate themselves, Song says. That helped the virus to spread quickly through the cell population, he says.  His team also reports that infected cells grew more slowly and had interrupted cell division cycles, which could also contribute to microcephaly.
原文链接:http://www.sciencemag.org/news/2 ... eloping-brain-cells


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