A genome-wide CRISPR/Cas9 gene knockout screen identifies immunoglobulin superfamily DCC subclass member 4 as a key host factor that promotes influenza virus endocytosis.

Yangming Song,Xin Yin,Fang Li,Jiwen Zhang,Haixiang Huang,Yanbing Li,Hualan Chen,Yuzhen Hu,Jianzhong Shi,Chengjun Li,Dongming Zhao,Jacob S Yount

doi:10.1371/journal.ppat.1010141

Abstract

Influenza virus infection is dependent on host cellular factors, and identification of these factors and their underlying mechanisms can provide important information for the development of strategies to inhibit viral infection. Here, we used a highly pathogenic H5N1 influenza virus to perform a genome-wide CRISPR/Cas9 gene knockout screen in human lung epithelial cells (A549 cells), and found that knockout of transmembrane protein immunoglobulin superfamily DCC subclass member 4 (IGDCC4) significantly reduced the replication of the virus in A549 cells. Further studies showed that IGDCC4 interacted with the viral hemagglutinin protein and facilitated virus internalization into host cells. Animal infection studies showed that replication of H5N1 virus in the nasal turbinates, lungs, and kidneys of IGDCC4-knockout mice was significantly lower than that in the corresponding organs of wild-type mice. Half of the IGDCC4-knockout mice survived a lethal H5N1 virus challenge, whereas all of the wild-type mice died within 11 days of infection. Our study identifies a novel host factor that promotes influenza virus infection by facilitating internalization and provides insights that will support the development of antiviral therapies.

Highlights

Influenza virus continuously evolves in nature and severely threatens both human and animal health with considerable impact on the global economy
Influenza virus infection is initiated by the attachment of the viral HA protein to sialic acid receptors on the host cell surface; most of the virus particles enter cells through clathrin-mediated endocytosis (CME)
We found that the single-pass type I transmembrane protein immunoglobulin superfamily DCC subclass member 4 (IGDCC4) plays a key role in influenza virus internalization into host cells

Summary

Introduction

Influenza virus continuously evolves in nature and severely threatens both human and animal health with considerable impact on the global economy. H5N1 viruses have caused disease outbreaks in poultry and wild birds in more than 60 countries across three continents since 2003 [6,7,8], and over 850 human infections have been reported in 16 countries with a mortality rate of nearly 52% [9]. Vaccination and antiviral drugs are effective ways to prevent influenza virus infection. At the beginning of an emerging pandemic, antiviral drugs will be on the frontline to prevent virus infection while a corresponding specific vaccine is developed [5]. Favipiravir is a broad-spectrum antiviral that was recently developed to prevent influenza virus infection, but it still faces the issue of the emergence of resistant variants with its extensive use. There is an urgent need to identify novel targets for influenza antiviral drug development

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Conclusion