Using a molecular scalpel to understand virus-host interactions

CRISPR-Cas has been quite popular nowadays, unfortunately, due to controversies about experiments on human babies. However, we applied the CRISPR technology to determine genes that have an important function during Zika virus infection.

Dangerous mosquitos

Zika virus belongs to the family of Flaviviruses, a family of RNA viruses with a lot of mosquito-borne viruses, including Dengue virus, West Nile virus and Yellow Fever virus. You may have heard a lot about Zika in 2016 and 2017 as there was a major outbreak in the northern half of South America. For adults, the Zika virus disease itself generally has mild symptoms like fever, muscle and joint pain, and conjunctivitis. Most people do not develop any symptoms at all, and if they do, they typically last for only a week.

On the other hand, studies show an increased risk of neurologic complications associated with Zika virus infections including the Guillain-Barré syndrome. The most infamous association with Zika virus is that an infection during pregnancy can cause infants to be born with microcephaly and other congenital malformations. Other risks include preterm birth and miscarriage. Unfortunately, there is no vaccine or specific treatment, yet.

The secret of the surviving cells

With our CRISPR study, we aimed to identify host genes that protect and/or rescue host cells from Zika virus infection. Using a modified version of the CRISPR technology, specific genes were activated, which means that they were transcribed and translated into protein at a higher rate than usual. For each cell, a different gene was activated. After Zika infection, we analyzed the transcriptome of the surviving cells: which genes have been strongly activated? Those genes may be the ones rescuing the cell from Zika virus infection. Most of the identified genes have already been reported to have antiviral effects in other viruses as well. Apparently, interferon-stimulated genes have an effect at an early phase of viral infection and our study indicates that they interfere with the formation of the viral replication complex.

Using CRISPR technology to identify crucial host genes for different virus families is a promising tool to understand the virus-host interaction and design novel and specific therapies. We would like to thank our collaborators Anna Dukhovny and Ella Sklan from the Tel Aviv University for joining forces to conduct this exciting and important study.

  • [DOI] A. Dukhovny, K. Lamkiewicz, Q. Chen, M. Fricke, N. Jabrane-Ferrat, M. Marz, J. U. Jung, and E. H. Sklan, “A CRISPR activation screen identifies genes protecting from Zika virus infection,” J Virol, 2019.
    [Bibtex]
    @Article{Dukhovny:19,
    author = {Dukhovny, Anna and Lamkiewicz, Kevin and Chen, Qian and Fricke, Markus and Jabrane-Ferrat, Nabila and Marz, Manja and Jung, Jae U. and Sklan, Ella H.},
    title = {A {CRISPR} activation screen identifies genes protecting from {Z}ika virus infection},
    journal = {{J Virol}},
    year = {2019},
    abstract = {Zika virus (ZIKV) is an arthropod borne emerging pathogen causing febrile illness. ZIKV is associated Guillain-Barr{\'e} syndrome and other neurological complications. Infection during pregnancy is associated with pregnancy complications and developmental and neurological abnormalities collectively defined as congenital Zika syndrome. There is still no vaccine or specific treatment for ZIKV infection. To identify host factors that can rescue cells from ZIKV infection we used a genome scale CRISPR activation screen. Our highly ranking hits included a short list of interferon stimulated genes (ISGs) previously reported to have antiviral activity. Validation of the screen results highlighted IFNL2 and IFI6 as genes providing high levels of protection from ZIKV. Activation of these genes had an effect on an early stage in viral infection. In addition, infected cells expressing sgRNAs for both of these genes displayed lower levels of cell death compared to controls. Furthermore, the identified genes were significantly induced in ZIKV infected placenta explants. Thus, these results highlight a set of ISGs directly relevant for rescuing cells from ZIKV infection or its associated cell death and substantiates CRISPR activation screens as a tool to identify host factors impeding pathogen infection.IMPORTANCE Zika virus (ZIKV) is an emerging vector-borne pathogen causing a febrile disease. ZIKV infection might also trigger Guillain-Barr{\'e} syndrome, neuropathy and myelitis. Vertical transmission of ZIKV can cause fetus demise, still birth or severe congenital abnormalities and neurological complications. There is no vaccine or specific antiviral treatment against ZIKV. We used a genome wide CRISPR activation screen, where genes are activated from their native promoters to identify host cell factors that protect cells from ZIKV infection or associated cell death. The results provide better understanding of key host factors that protect cells from ZIKV infection and might assist in identifying novel antiviral targets.},
    doi = {10.1128/JVI.00211-19},
    elocation-id = {JVI.00211-19},
    eprint = {https://jvi.asm.org/content/early/2019/05/23/JVI.00211-19.full.pdf},
    publisher = {American Society for Microbiology Journals},
    url = {https://jvi.asm.org/content/early/2019/05/23/JVI.00211-19},
    }

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