How Zika virus infects developing brain

Zika virus is transmitted from mother to fetus by infected cells that later develop into the brain's first and primary form of defense against invasive pathogens. During embryogenesis- the early stages of prenatal development cells called microglia form in the yolk sac and then disperse throughout the central nervous system CNS of the developing fetus.

In the brain, these microglia will become resident macrophages whose job is to constantly clear away plaques, damaged cells and infectious agents. The Zika virus can infect these early microglia, moving into the brain where they transmit the virus to other brain cells, leading to devastating neurological damage.

The Zika virus is transmitted to people through the bite of infected Aedes species mosquitoes. However, a pregnant woman can also pass the virus to her fetus, the researchers used human induced pluripotent stem cells to create two relevant CNS cell types: microglia and neural progenitor cells (NPCs), which generate the millions of neurons and glial cells required during embryonic development.

Then they established a co-culture system that mimicked the interactions of the two cell types in vitro when exposed to the Zika virus. They discovered that the microglia cells engulfed Zika-infected NPCs, doing their job. But when these microglia carrying the virus were placed in contact with non-infected NPCs, they transmitted the virus to the latter.
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