title: Hepatitis B virus replication is blocked by a 2-hydroxyisoquinoline-1,3(2H,4H)-dione (HID) inhibitor of the viral ribonuclease H activity.
abstract: Nucleos(t)ide analog drugs profoundly suppress Hepatitis B virus (HBV) replication but rarely cure the infection, so therapy is usually life-long. The nucleos(t)ide analogs inhibit the viral DNA polymerase and often push HBV to the brink of extinction, so it may be possible to eradicate HBV by suppressing HBV replication further. The HBV ribonuclease H (RNaseH) is a logical new drug target because it is the second of only two viral enzymes essential for viral replication. We recently developed a low throughput screening pipeline for inhibitors of the HBV RNaseH and viral replication. Here, we screened a series of twenty-three nitrogen-based polyoxygenated heterocycles including sixteen 2-hydroxyisoquinoline-1,3(2H,4H)-dione derivatives for anti-HBV RNaseH activity. Nine compounds inhibited the HBV RNaseH, but activity was marginal for eight of them. Compound #1 [2-hydroxyisoquinoline-1,3(2H,4H)-dione, HID] was the best hit with an IC50 of 28.1μM and an EC50 of 4.2μM. It preferentially suppressed accumulation of the viral plus-polarity DNA strand in replication inhibition assays, indicating that replication was blocked due to suppression of HBV RNaseH activity. It had a CC50 of 75μM, yielding a therapeutic index of ∼18. The EC50 value was 7-fold lower than the IC50, possibly due to cellular retention or metabolism of the compound, or higher affinity for the full-length enzyme than the recombinant form used for screening. These data indicate that the 2-hydroxyisoquinoline-1,3(2H,4H)-diones will have different structure-activity relationships for the HBV and HIV RNaseHs. Therefore, HID compounds may provide a foundation for development of more effective RNaseH inhibitors of HBV replication.
authors.affiliation: Department of Molecular Microbiology and Immunology, Saint Louis University, 1100 S. Grand Blvd., Saint Louis, MO 63104, USA. Electronic address: ccai@slu.edu.
authors.forename: Catherine W
authors.initials: CW
authors.lastname: Cai
authors.affiliation: Department of Molecular Microbiology and Immunology, Saint Louis University, 1100 S. Grand Blvd., Saint Louis, MO 63104, USA; Saint Louis University Liver Center, Saint Louis University, 1100 S. Grand Blvd., Saint Louis, MO 63104, USA. Electronic address: lomonoe@slu.edu.
authors.forename: Elena
authors.initials: E
authors.lastname: Lomonosova
authors.affiliation: Department of Molecular Microbiology and Immunology, Saint Louis University, 1100 S. Grand Blvd., Saint Louis, MO 63104, USA. Electronic address: eileenmoran@slu.edu.
authors.forename: Eileen A
authors.initials: EA
authors.lastname: Moran
authors.affiliation: Department of Molecular Microbiology and Immunology, Saint Louis University, 1100 S. Grand Blvd., Saint Louis, MO 63104, USA. Electronic address: xcheng1@slu.edu.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Cheng
authors.affiliation: Department of Molecular Microbiology and Immunology, Saint Louis University, 1100 S. Grand Blvd., Saint Louis, MO 63104, USA. Electronic address: kpatel65@slu.edu.
authors.forename: Kunjan B
authors.initials: KB
authors.lastname: Patel
authors.affiliation: Chimie Moléculaire et Formulation, EA 4478 CMF, Université de Lille 1/ENSCL, 59655 Villeneuve d'Ascq, France. Electronic address: Fabrice.Bailly@univ-lille1.fr.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Bailly
authors.affiliation: Chimie Moléculaire et Formulation, EA 4478 CMF, Université de Lille 1/ENSCL, 59655 Villeneuve d'Ascq, France. Electronic address: Philippe.Cotelle@univ-lille1.fr.
authors.forename: Philippe
authors.initials: P
authors.lastname: Cotelle
authors.affiliation: Center for World Health and Medicine, Saint Louis University, 1100 S. Grand Blvd., Saint Louis, MO 63104, USA. Electronic address: mmeyers8@slu.edu.
authors.forename: Marvin J
authors.initials: MJ
authors.lastname: Meyers
authors.affiliation: Department of Molecular Microbiology and Immunology, Saint Louis University, 1100 S. Grand Blvd., Saint Louis, MO 63104, USA; Saint Louis University Liver Center, Saint Louis University, 1100 S. Grand Blvd., Saint Louis, MO 63104, USA. Electronic address: tavisje@slu.edu.
authors.forename: John E
authors.initials: JE
authors.lastname: Tavis
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D006515:Hepatitis B virus / Q000187:drug effects* / Q000201:enzymology* / Q000502:physiology; D006801:Humans; D020128:Inhibitory Concentration 50; D007546:Isoquinolines / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D016914:Ribonuclease H / Q000037:antagonists & inhibitors*; D013329:Structure-Activity Relationship; D014779:Virus Replication / Q000187:drug effects
chemical_list: C558516:2-hydroxyisoquinoline-1,3(2H,4H)-dione; D000998:Antiviral Agents; D007546:Isoquinolines; D016914:Ribonuclease H
keywords: 2-Hydroxyisoquinoline-13(2H,4H)-diones; Hepatitis B virus; Ribonuclease H; Viral replication