Found by University of Texas Southwestern Medical Center researchers using CRISPR.

Interferon is a cytokine known to play an important role in cellular responses to pathogens. Researchers at the University of Texas Southwestern Medical Center combined their knowledge of interferon with Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) gene-editing technology to identify a gene that aids human cells in fighting infection by flaviviruses like Zika.

The scientists used CRISPR technology to knock out each of approximately 19,000 genes in human liver cells one by one. They then observed the response of the edited cells to stimulation by interferon to see which would (and would not) resist infection. The cells that did not resist infection were missing the desirable gene; next-generation sequencing was used to determine the identity of the missing genes. 

The study revealed the cells with the IFI6 gene showed robust resistance to yellow fever, dengue, Zika and West Nile viruses, while cells with this gene knocked out were highly susceptible to infections.

In a separate program, Albert Einstein College of Medicine and Pennsylvania State University have found that the RSAD2 gene causes the production of a molecule that is effective against Zika. Meanwhile, researchers at Washington University School of Medicine in St. Louis reported that the malaria drug hydroxychloroquine can block the transmission of Zika to the fetus via suppression of autophagy, a waste-management process. 

The UT Southwestern team is hoping to do further research to determine if CRISPR screening is effective in other types of cells, such as neurons—applying CRISPR editing to brain cells is challenging, however.