title: Potent, selective and cell-mediated inhibition of human herpesvirus 6 at an early stage of viral replication by the non-nucleoside compound CMV423.
abstract: CMV423 (2-chloro-3-pyridin-3-yl-5,6,7,8-tetrahydroindolizine-1-carboxamide) is a new antiviral agent with potent and selective in vitro activity against the beta-herpesvirus human cytomegalovirus (HCMV), but not against alpha- or gamma-herpesviruses. Here we report that its activity also extends to human herpesvirus 6 (HHV-6) and 7 (HHV-7). When compared in vitro to ganciclovir and foscarnet (the standard drugs recommended for treatment of HHV-6 infections), CMV423 showed a superior selectivity, due to its high activity (antiviral IC(50): 53nM) and low cytotoxicity (CC(50): 144microM), both in continuous cell lines and in CBLCs infected with HHV-6. From mechanistic experiments at the level of viral mRNA and protein expression, we learned that CMV423 targets an event following viral entry but preceding viral DNA replication. Its antiviral action was dependent on the cell line used, implying involvement of a cellular component. When compared to a panel of known protein kinase inhibitors, CMV423 was found to share anti-HHV-6 characteristics with herbimycin A, which affects tyrosine kinase activity through heat shock protein 90 (Hsp90) inhibition. We demonstrated that high concentrations of CMV423 have an inhibitory effect on the total cellular protein tyrosine kinase activity, and that CMV423 and herbimycin A, when combined, act synergistically against HHV-6. The activities of cyclin-dependent kinases, protein kinases A and C, and the HHV-6-encoded pU69 kinase were not affected. We, therefore, conclude that CMV423 exerts its activity against HHV-6 through inhibition of a cellular process that is critical at early stages of viral replication and that may affect protein tyrosine kinase activity.
authors.affiliation: Rega Institute for Medical Research, Katholieke Universiteit Leuven, 3000, Leuven, Belgium.
authors.forename: Leen
authors.initials: L
authors.lastname: De Bolle
authors.forename: Graciela
authors.initials: G
authors.lastname: Andrei
authors.forename: Robert
authors.initials: R
authors.lastname: Snoeck
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Alfons
authors.initials: A
authors.lastname: Van Lommel
authors.forename: Michael
authors.initials: M
authors.lastname: Otto
authors.forename: Anne
authors.initials: A
authors.lastname: Bousseau
authors.forename: Christine
authors.initials: C
authors.lastname: Roy
authors.forename: Erik
authors.initials: E
authors.lastname: De Clercq
authors.forename: Lieve
authors.initials: L
authors.lastname: Naesens
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D002352:Carrier Proteins / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D017245:Foscarnet / Q000494:pharmacology; D015774:Ganciclovir / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D015654:Herpesvirus 6, Human / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D016199:Herpesvirus 7, Human / Q000187:drug effects; D006801:Humans; D007212:Indolizines / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins; D008826:Microbial Sensitivity Tests; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011725:Pyridines / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured; D014779:Virus Replication / Q000187:drug effects*
chemical_list: C434923:2-chloro-3-pyridine-3-yl-5,6,7,8-tetrahydroindolizine-1-carboxamide; D000998:Antiviral Agents; D002352:Carrier Proteins; D007212:Indolizines; D047908:Intracellular Signaling Peptides and Proteins; D011725:Pyridines; C015482:protein kinase modulator; D017245:Foscarnet; D017853:Phosphotransferases (Alcohol Group Acceptor); C464753:pU69 kinase, human herpesvirus 6; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D004259:DNA-Directed DNA Polymerase; D015774:Ganciclovir