Antibiotic may help stop Zika from damaging fetal brains: study

U.S. researchers said Tuesday they have identified fetal brain tissue cells that are targeted by the Zika virus and determined that azithromycin, a common antibiotic regarded as safe for use during pregnancy, can block this infection, at least in brain cells grown in lab dishes.

Researchers at the University of California San Francisco (UCSF) reported that the Zika virus preferentially infects brain cells with an abundance of a protein called AXL, which spans the outer cell membrane of several cell types and serves as a gateway for the invading virus.

The fetal brain cells that incorporate this protein included neural stem cells and progenitor cells that eventually form other types of brain cells and that play an especially crucial role in early brain growth and development.

Other cells with AXL included microglia, which are the brain's immune cells, and astrocytes, a fully developed and specialized type of brain cell that serves to support the signal-conducting neurons.

Neurons, which lack AXL, were not easily infected, in contrast to what had been observed in mice previously used to study Zika infection.

The researchers then screened 2,177 U.S. Food and Drug Administration-approved drugs for their ability to block Zika infection of brain cells cultured in the lab, and identified several that did, including azithromycin, a widely used antibiotic.

The findings, published online in the U.S. journal Proceedings of the National Academy of Sciences, were led by Joseph DeRisi, chair of the UCSF Department of Biochemistry and Biophysics, and Arnold Kriegstein, director of the Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research at UCSF.

"Our characterization of infection in the developing human brain clarifies the pathogenesis of congenital ZIKV (Zika virus) infection and provides the basis for investigating possible therapeutic strategies to safely alleviate or prevent the most severe consequences of the epidemic," they concluded in their paper.

Zika is transmitted primarily by the tropical mosquito Aedes aegypti. It's estimated that between one percent and 13 percent of women infected during early pregnancy by the virus are giving birth to infants with microcephaly, a condition that is characterized by an undersized head and brain damage.

Currently, there is no treatment to prevent the Zika virus from harming the fetus, and the biological mechanism through which microcephaly arises as a result of infection remains unclear. Endit