title: Hypervariable region 1 deletion and required adaptive envelope mutations confer decreased dependency on scavenger receptor class B type I and low-density lipoprotein receptor for hepatitis C virus.
abstract: Hypervariable region 1 (HVR1) of envelope protein 2 (E2) of hepatitis C virus (HCV) serves important yet undefined roles in the viral life cycle. We previously showed that the viability of HVR1-deleted JFH1-based recombinants with Core-NS2 of H77 (H77(ΔHVR1), genotype 1a) and S52 (S52(ΔHVR1), genotype 3a) in Huh7.5 cells was rescued by E2 substitutions N476D/S733F and an E1 substitution, A369V, respectively; HVR1-deleted J6 (J6(ΔHVR1), genotype 2a) was fully viable. In single-cycle production assays, where HCV RNA was transfected into entry-deficient Huh7-derived S29 cells with low CD81 expression, we found no effect of HVR1 deletion on replication or particle release for H77 and S52. HCV pseudoparticle assays in Huh7.5 cells showed that HVR1 deletion decreased entry by 20- to 100-fold for H77, J6, and S52; N476D/S733F restored entry for H77(ΔHVR1), while A369V further impaired S52(ΔHVR1) entry. We investigated receptor usage by antibody blocking and receptor silencing in Huh7.5 cells, followed by inoculation of parental and HVR1-deleted HCV recombinants. Compared to parental viruses, scavenger receptor class B type I (SR-BI) dependency was decreased for H77(ΔHVR1/N476D/S733F), H77(N476D/S733F), S52(ΔHVR1/A369V), and S52(A369V), but not for J6(ΔHVR1). Low-density lipoprotein receptor (LDLr) dependency was decreased for HVR1-deleted viruses, but not for H77(N476D/S733F) and S52(A369V). Soluble LDLr neutralization revealed strong inhibition of parental HCV but limited effect against HVR1-deleted viruses. Apolipoprotein E (ApoE)-specific HCV neutralization was similar for H77, J6, and S52 viruses with and without HVR1. In conclusion, HVR1 and HVR1-related adaptive envelope mutations appeared to be involved in LDLr and SR-BI dependency, respectively. Also, LDLr served ApoE-independent but HVR1-dependent functions in HCV entry.
authors.affiliation: Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases and Clinical Research Centre, Hvidovre Hospital and Department of International Health, Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Jannick
authors.initials: J
authors.lastname: Prentoe
authors.forename: Stéphanie B N
authors.initials: SB
authors.lastname: Serre
authors.forename: Santseharay
authors.initials: S
authors.lastname: Ramirez
authors.forename: Alfredo
authors.initials: A
authors.lastname: Nicosia
authors.forename: Judith M
authors.initials: JM
authors.lastname: Gottwein
authors.forename: Jens
authors.initials: J
authors.lastname: Bukh
mesh_terms: D045744:Cell Line, Tumor; D016174:Hepacivirus / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D006526:Hepatitis C / Q000235:genetics / Q000378:metabolism* / Q000821:virology; D006801:Humans; D011973:Receptors, LDL / Q000235:genetics / Q000378:metabolism*; D011991:Receptors, Virus / Q000235:genetics / Q000378:metabolism*; D051122:Scavenger Receptors, Class B / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D053586:Virus Internalization
chemical_list: D011973:Receptors, LDL; D011991:Receptors, Virus; C495124:SCARB1 protein, human; D051122:Scavenger Receptors, Class B; D014759:Viral Envelope Proteins; C091015:glycoprotein E2, Hepatitis C virus