Defining the roles of host lipids in flavivirus infection

Abstract

The flavivirus family includes Zika virus (ZIKV), Dengue virus, West Nile virus, Japanese Encephalitis and Yellow Fever virus, each of which causes a major global health threat. During their long‐lasting co‐existence with their host, these viruses have developed sophisticated strategies to co‐opt thecellular machinery including, host lipid metabolism, to effectively establish infection. They enter the host cells through receptor‐mediated endocytosis. In endosomes, the acidic environment induces fusion between the virus and the host membrane resulting in viral genome release. The viral RNA is translated into a polyprotein, which is post‐translationally cleaved by cellular and viral proteases into three structural proteins including capsid, membrane, and envelope, and seven nonstructural proteins. During viral infection cell membranes are co‐opted for virtually every step of the viral life cycle: entry, replication, assembly and release. The role of host factors, especially that of lipids, in pathogenesis of flaviviruses is largely unknown, and there exists a gap in understanding the basic biology of these viruses. This is especially true for ZIKV, which until recently was one of the most understudied flaviviruses. Because lipids are an important interface in host‐virus interactions, studying these biomolecules may provide strategies to combat diseases caused by these pathogens. Zika virus (ZIKV) is a positive‐sense RNA virus that remodels host membrane to establish sites of replication and assembly. To determine how ZIKV modulates the host lipid repertoire in an unbiased manner, we performed comprehensive lipid profiling of human cells infected with ZIKV. We found that ZIKV replication triggers significant changes in the cellular sphingolipidomes especially that of ceramide and sphingomyelin highly enriched during infection. Disruption of sphingolipid biosynthesis with CRISPR/Cas9 gene‐editing or small molecule inhibitors effectively blocks ZIKV replication. Both sphingomyelin and ceramide redistribute to ZIKV replication sites, and the sphingomyelinase‐catalyzed degradation of sphingomyelin to ceramide is the critical pathway to establish infection effectively. Inhibition of sphingomyelinase attenuated ZIKV replication, while the accumulation of intracellular ceramide through knockout of sphingomyelin synthesis enhanced ZIKV infection. Thus, we identify a sphingolipid salvage pathway with a critical role in ZIKV replication and show that ceramide is a key mediator of ZIKV pathogenesis.Support or Funding InformationThis work was supported by the Collins Medical Trust and NIH grant R21AI133631. W.B.M. and J.B.W. were supported by the Medical Research Foundation of Oregon, the Oregon Clinical and Translational Research Institute, and the Sunlin and Priscilla Chou Foundation. D.K. was supported by the Summer Equity Internship Program of the OHSU Center for Diversity and Inclusion. E.B. was supported by NIH grants R01GM060170 and R01GM101983. E.A.D. and A.R.N. were supported by NIH grants R01DK105961, U19AI106754, and U54GM069338.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.