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Washington: A recent study has shown that the Zika virus infects the very cells that are supposed to protect the body from infection.
Macrophages are immune cells that are supposed to protect the body against viruses and bacteria. However, the Zika virus preferentially infects these cells.
In pregnant women, Zika virus can slow down neonatal brain development, resulting in the birth of babies with abnormally small heads, a condition known as microcephaly. Adult brain cells may also be vulnerable to the virus.
Aaron Carlin, lead author of the study, said, "We know that the Zika virus destroys a number of cell types, especially in the brain, but we do not yet understand how cells die or function poorly. and the identity that we have seen in macrophages could also be crucial when a neural stem cell is trying to develop into a new neuron. "
The team of researchers has developed a method for labeling Zika virus in living cells and a mechanism for sorting labeled (infected) and unlabeled (uninfected) human macrophages. Many previous viral studies relied on boxes of cells that had been exposed to the virus, but not all cells were necessarily infected. As a result, the cellular effects measured during an "infection" in the laboratory are often a mixture of what happens inside the infected and uninfected cells.
"If your goal is to see what the virus is doing to a cell, you need to focus only on the infected cells to get a real representation," said Carlin.
Christopher K. Glass, one of the researchers, said, "We were surprised at how different infected and uninfected cells appeared, in terms of genes turned on or off, even two cells one by one next to l & # 39; other.
This approach provided a more accurate account of the effect of Zika on macrophages and revealed that the virus suppresses gene production in cells by two methods. First, the virus specifically blocks hundreds of macrophage genes that should be stimulated by interferon, a molecule that triggers an immune response. For example, the IFITM1 gene, which inhibits Zika virus, is expressed 73 times less in Zika infected cells than in neighboring uninfected cells.
Second, Zika virus infection results in a general suppression of gene production, since the virus targets Pol II RNA, a crucial element of the gene transcription mechanism of the cell. The loss of Pol II RNA is particularly notable in the genes responsible for the function and identity of macrophages.
Collectively, these approaches allow the Zika virus to prevent macrophages from making many genes involved in immune cell recruitment and antiviral defense.
The research team is now interested in applying its new sorting technique to cells infected with other viruses. They also hope to examine other types of cells infected with the Zika virus, such as neural stem cells.
The study was published in the Proceedings of the National Academy of Sciences.
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