Hunting Viral Receptors Using Haploid Cells

Abstract

Viruses have evolved intricate mechanisms to gain entry into the host cell. Identification of critical receptors has enabled insights into virus particle internalization, host and tissue tropism, and viral pathogenesis. In this review we discuss the most commonly employed methods for virus receptor discovery, specifically highlighting the use of forward genetic screens in human haploid cells. The ability to generate true knockout alleles at high saturation provides a sensitive means to study virus-host interactions. As an example, haploid genetic screens identified the lysosomal proteins, NPC1 and LAMP1, as intracellular receptors for Ebola virus and Lassa virus, respectively. From these studies emerges the notion that receptor usage by these viruses is highly dynamic involving a programmed switch from cell surface receptor to intracellular receptor. Broad application of genetic knockout approaches will chart functional landscapes of receptors and endocytic pathways hijacked by viruses.

Haploid Mammalian Genetic Screen Identifies UBXD8 as a Key Determinant of HMGCR Degradation and Cholesterol Biosynthesis

“…Haploid genetic screens have been only recently applied to mammalian cells and provide a powerful means to identify genotype–phenotype associations. 18 These screens have been used to investigate, among others, viral entry, 31 , 32 signaling pathways, 33 modes of toxin action, 18 , 34 and gene essentiality 23 but have not been applied to the study of lipid-related traits. The power of our screen is manifested by the identification of several genes that have been previously implicated in the metabolically regulated degradation of HMGCR.…”

Glycomics and Proteomics Approaches to Investigate Early Adenovirus–Host Cell Interactions

“…Other powerful methods to be used in combination with glycomics and proteomics include RNA interference, CRISPR/Cas9 knockout, genome-wide haploid screens, cell-based arrays, drug-based approaches, and utilization of the microarray-characterized set of cells provided by US National Cancer Institute. We refer the reader elsewhere for further information on these methods [160][161][162][163][164][165][166]. A clear advantage of labelfree glycomics and proteomics technologies is, however, the minimal system perturbation in particular when untagged endogenous bait glycans and proteins are used.…”

Diverse Viruses Require the Calcium Transporter SPCA1 for Maturation and Spread

“…This is likely because cell-surface sugars play an important role in virus attachment prior to receptor engagement. While these genome-wide KO screens were highly successful in identifying entry factors and virus receptors (Pillay and Carette, 2015), few host factors have been described and characterized that interfere with later steps in the viral life cycle such as virus maturation and egress. And unlike receptors, which are often virus specific, host genes required for late stages of the viral life cycle might affect many viruses of the same family or even viruses from different families.…”