Why Zika virus ravages the budding eye and brain

A developing infant’s stem cells that go on to become brain and retinal cells have a protein that allows Zika virus easy access, new research hypothesises.

These stems cells have high numbers of a ‘receptor’ protein, known as AXL, in comparison to other cells of the developing foetus, which might explain why the infection has a disproportionate effect on the brain and eye.

Viruses have been known to gain access through cell surface proteins like AXL, and a recent study showed that blocking the AXL protein in skin cells can dramatically reduce the virulence of Zika.

Now, a University of California, San Francisco team has looked at the stems cells that have the most AXL protein, in a paper published in the journal Cell Stem Cell.

The team found brain and retinal stem cells have the highest rates of AXL, aligning with their hypothesis that high levels of the proteins makes a cell more vulnerable to the virus.

The researchers behind the study speculate that blocking the AXL receptor could protect individual cells from Zika virus infection, but that the act could bring about nerve cell destruction anyway.

In their day-to-day role, AXL receptors are involved with nerve cell creation and survival. “Therefore, while blocking AXL may protect against cellular infection or viral replication, [disturbance] of AXL function may also have multiple adverse consequences.”

The paper authors say their work, when combined with other studies on Zika virus, will help medical researchers to better understand how and why the disease affects developing infants.

With Zika virus declared a global public health emergency by the World Health Organisation in February, researchers are racing to develop a vaccine. In March, a US company announced that it planned to begin a Phase I trial of its candidate during the summer.