title: A serine palmitoyltransferase inhibitor blocks hepatitis C virus replication in human hepatocytes.
abstract: OBJECTIVE
  Host cell lipid rafts form a scaffold required for replication of hepatitis C virus (HCV). Serine palmitoyltransferases (SPTs) produce sphingolipids, which are essential components of the lipid rafts that associate with HCV nonstructural proteins. Prevention of the de novo synthesis of sphingolipids by an SPT inhibitor disrupts the HCV replication complex and thereby inhibits HCV replication. We investigated the ability of the SPT inhibitor NA808 to prevent HCV replication in cells and mice.
  
  
  METHODS
  We tested the ability of NA808 to inhibit SPT's enzymatic activity in FLR3-1 replicon cells. We used a replicon system to select for HCV variants that became resistant to NA808 at concentrations 4- to 6-fold the 50% inhibitory concentration, after 14 rounds of cell passage. We assessed the ability of NA808 or telaprevir to inhibit replication of HCV genotypes 1a, 1b, 2a, 3a, and 4a in mice with humanized livers (transplanted with human hepatocytes). NA808 was injected intravenously, with or without pegylated interferon alfa-2a and HCV polymerase and/or protease inhibitors.
  
  
  RESULTS
  NA808 prevented HCV replication via noncompetitive inhibition of SPT; no resistance mutations developed. NA808 prevented replication of all HCV genotypes tested in mice with humanized livers. Intravenous NA808 significantly reduced viral load in the mice and had synergistic effects with pegylated interferon alfa-2a and HCV polymerase and protease inhibitors.
  
  
  CONCLUSIONS
  The SPT inhibitor NA808 prevents replication of HCV genotypes 1a, 1b, 2a, 3a, and 4a in cultured hepatocytes and in mice with humanized livers. It might be developed for treatment of HCV infection or used in combination with pegylated interferon alfa-2a or HCV polymerase or protease inhibitors.
authors.affiliation: Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan; Research Division, Chugai Pharmaceutical Co., Ltd., Tokyo, Japan.
authors.forename: Asao
authors.initials: A
authors.lastname: Katsume
authors.forename: Yuko
authors.initials: Y
authors.lastname: Tokunaga
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Hirata
authors.forename: Tsubasa
authors.initials: T
authors.lastname: Munakata
authors.forename: Makoto
authors.initials: M
authors.lastname: Saito
authors.forename: Hitohisa
authors.initials: H
authors.lastname: Hayashi
authors.forename: Koichi
authors.initials: K
authors.lastname: Okamoto
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ohmori
authors.forename: Isamu
authors.initials: I
authors.lastname: Kusanagi
authors.forename: Shinya
authors.initials: S
authors.lastname: Fujiwara
authors.forename: Takuo
authors.initials: T
authors.lastname: Tsukuda
authors.forename: Yuko
authors.initials: Y
authors.lastname: Aoki
authors.forename: Klaus
authors.initials: K
authors.lastname: Klumpp
authors.forename: Kyoko
authors.initials: K
authors.lastname: Tsukiyama-Kohara
authors.forename: Ahmed
authors.initials: A
authors.lastname: El-Gohary
authors.forename: Masayuki
authors.initials: M
authors.lastname: Sudoh
authors.forename: Michinori
authors.initials: M
authors.lastname: Kohara
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D016174:Hepacivirus / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D022781:Hepatocytes / Q000821:virology*; D006801:Humans; D051379:Mice; D012367:RNA, Viral / Q000032:analysis; D051102:Serine C-Palmitoyltransferase / Q000037:antagonists & inhibitors*; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; D012367:RNA, Viral; D051102:Serine C-Palmitoyltransferase
keywords: 50% inhibitory concentration; DAA; DAAs; Direct-Acting Antiviral Agents; Drug; HCV; HCV Lifecycle; IC(50); PCR; PEG-IFN; RBV; SPT; cDNA; complementary DNA; direct-acting antiviral agent; hepatitis C virus; pegylated interferon alfa-2a; polymerase chain reaction; ribavirin; serine palmitoyltransferase