title: Allosteric heat shock protein 70 inhibitors block hepatitis C virus assembly.
abstract: The human molecular chaperones heat shock protein 70 (Hsp70) and heat shock cognate protein 70 (Hsc70) bind to the hepatitis C viral nonstructural protein 5A (NS5A) and regulate its activity. Specifically, Hsp70 is involved in NS5A-augmented internal ribosomal entry site (IRES)-mediated translation of the viral genome, whilst Hsc70 appears to be primarily important for intracellular infectious virion assembly. To better understand the importance of these two chaperones in the viral life cycle, infected human cells were treated with allosteric Hsp70/Hsc70 inhibitors (AHIs). Treatment with AHIs significantly reduced the production of intracellular virus at concentrations that were non-toxic to human hepatoma Huh7.5 cells. The supernatant of treated cultures was then used to infect naïve cells, revealing that AHIs also lowered levels of secreted virus. In contrast to their effects on virion assembly, AHIs did not impact the stability of NS5A or viral protein translation in IRES assays. These results suggest that Hsc70 plays a particularly important and sensitive role in virion assembly. Indeed, it was found that combination of AHIs with a peptide-based viral translation inhibitor exhibited additive antiviral activity. Together these results suggest that the host Hsc70 is a new antiviral target and that its inhibitors utilise a new mechanism of action.
authors.affiliation: Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, CA, USA.
authors.forename: Ronik
authors.initials: R
authors.lastname: Khachatoorian
authors.affiliation: Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, CA, USA.
authors.forename: Rana
authors.initials: R
authors.lastname: Riahi
authors.affiliation: Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, CA, USA.
authors.forename: Ekambaram
authors.initials: E
authors.lastname: Ganapathy
authors.affiliation: Department of Pharmaceutical Chemistry, Institute for Neurodegenerative Diseases, University of California, San Francisco (UCSF), San Francisco, CA, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Shao
authors.affiliation: Doe Institute for Genomics and Proteomics, University of California, Los Angeles (UCLA), Los Angeles, CA, USA.
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Wheatley
authors.affiliation: Department of Human Genetics, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, CA, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Sundberg
authors.affiliation: Department of Medicine, David Geffen School of Medicine at University of California Los Angeles (UCLA), Los Angeles, CA, USA.
authors.forename: Chun-Ling
authors.initials: CL
authors.lastname: Jung
authors.affiliation: Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, CA, USA.
authors.forename: Piotr
authors.initials: P
authors.lastname: Ruchala
authors.affiliation: Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, CA, USA; Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, CA, USA; UCLA AIDS Institute, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, CA, USA.
authors.forename: Asim
authors.initials: A
authors.lastname: Dasgupta
authors.affiliation: Department of Surgery, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, CA, USA; Department of Surgery, The Board of Governors Regenerative Medicine Institute at Cedars-Sinai Medical Center, Los Angeles, CA, USA.
authors.forename: Vaithilingaraja
authors.initials: V
authors.lastname: Arumugaswami
authors.affiliation: Department of Pharmaceutical Chemistry, Institute for Neurodegenerative Diseases, University of California, San Francisco (UCSF), San Francisco, CA, USA.
authors.forename: Jason E
authors.initials: JE
authors.lastname: Gestwicki
authors.affiliation: Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, CA, USA; Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, CA, USA; UCLA AIDS Institute, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, CA, USA. Electronic address: SFrench@mednet.ucla.edu.
authors.forename: Samuel W
authors.initials: SW
authors.lastname: French
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology* / Q000633:toxicity; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology* / Q000633:toxicity; D050883:HSC70 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D016174:Hepacivirus / Q000187:drug effects* / Q000502:physiology*; D022781:Hepatocytes / Q000187:drug effects / Q000502:physiology / Q000821:virology; D006801:Humans; D019065:Virus Assembly / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; D004791:Enzyme Inhibitors; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins
keywords: Allosteric heat shock protein inhibitors; Hepatitis C virus; Hsc70; Hsp70; Viral assembly; Viral translation