title: Novel indole-2-carboxamide compounds are potent broad-spectrum antivirals active against western equine encephalitis virus in vivo.
abstract: Neurotropic alphaviruses, including western, eastern, and Venezuelan equine encephalitis viruses, cause serious and potentially fatal central nervous system infections in humans for which no currently approved therapies exist. We previously identified a series of thieno[3,2-b]pyrrole derivatives as novel inhibitors of neurotropic alphavirus replication, using a cell-based phenotypic assay (W. Peng et al., J. Infect. Dis. 199:950-957, 2009, doi:http://dx.doi.org/10.1086/597275), and subsequently developed second- and third-generation indole-2-carboxamide derivatives with improved potency, solubility, and metabolic stability (J. A. Sindac et al., J. Med. Chem. 55:3535-3545, 2012, doi:http://dx.doi.org/10.1021/jm300214e; J. A. Sindac et al., J. Med. Chem. 56:9222-9241, 2013, http://dx.doi.org/10.1021/jm401330r). In this report, we describe the antiviral activity of the most promising third-generation lead compound, CCG205432, and closely related analogs CCG206381 and CCG209023. These compounds have half-maximal inhibitory concentrations of ∼1 μM and selectivity indices of >100 in cell-based assays using western equine encephalitis virus replicons. Furthermore, CCG205432 retains similar potency against fully infectious virus in cultured human neuronal cells. These compounds show broad inhibitory activity against a range of RNA viruses in culture, including members of the Togaviridae, Bunyaviridae, Picornaviridae, and Paramyxoviridae families. Although their exact molecular target remains unknown, mechanism-of-action studies reveal that these novel indole-based compounds target a host factor that modulates cap-dependent translation. Finally, we demonstrate that both CCG205432 and CCG209023 dampen clinical disease severity and enhance survival of mice given a lethal western equine encephalitis virus challenge. These studies demonstrate that indole-2-carboxamide compounds are viable candidates for continued preclinical development as inhibitors of neurotropic alphaviruses and, potentially, of other RNA viruses. IMPORTANCE There are currently no approved drugs to treat infections with alphaviruses. We previously identified a novel series of compounds with activity against these potentially devastating pathogens (J. A. Sindac et al., J. Med. Chem. 55:3535-3545, 2012, doi:http://dx.doi.org/10.1021/jm300214e; W. Peng et al., J. Infect. Dis. 199:950-957, 2009, doi:http://dx.doi.org/10.1086/597275; J. A. Sindac et al., J. Med. Chem. 56:9222-9241, 2013, http://dx.doi.org/10.1021/jm401330r). We have now produced third-generation compounds with enhanced potency, and this manuscript provides detailed information on the antiviral activity of these advanced-generation compounds, including activity in an animal model. The results of this study represent a notable achievement in the continued development of this novel class of antiviral inhibitors.
authors.affiliation: Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Phillip C
authors.initials: PC
authors.lastname: Delekta
authors.affiliation: Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Dobry
authors.affiliation: Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Janice A
authors.initials: JA
authors.lastname: Sindac
authors.affiliation: Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Barraza
authors.affiliation: Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Pennelope K
authors.initials: PK
authors.lastname: Blakely
authors.affiliation: Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Jianming
authors.initials: J
authors.lastname: Xiang
authors.affiliation: Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Kirchhoff
authors.affiliation: Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Richard F
authors.initials: RF
authors.lastname: Keep
authors.affiliation: Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: David N
authors.initials: DN
authors.lastname: Irani
authors.affiliation: Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Scott D
authors.initials: SD
authors.lastname: Larsen
authors.affiliation: Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA Department of Microbiology & Immunology, University of Michigan, Ann Arbor, Michigan, USA milldavi@umich.edu.
authors.forename: David J
authors.initials: DJ
authors.lastname: Miller
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000138:chemical synthesis / Q000494:pharmacology*; D002043:Bunyaviridae / Q000187:drug effects / Q000254:growth & development; D002460:Cell Line; D004667:Encephalitis Virus, Western Equine / Q000187:drug effects* / Q000254:growth & development / Q000472:pathogenicity; D004683:Encephalomyelitis, Equine / Q000188:drug therapy* / Q000401:mortality / Q000821:virology; D005260:Female; D007211:Indoles / Q000138:chemical synthesis / Q000494:pharmacology*; D020128:Inhibitory Concentration 50; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000187:drug effects / Q000821:virology; D010252:Paramyxoviridae / Q000187:drug effects / Q000254:growth & development; D010849:Picornaviridae / Q000187:drug effects / Q000254:growth & development; D014176:Protein Biosynthesis / Q000187:drug effects; D011725:Pyridines / Q000138:chemical synthesis / Q000494:pharmacology*; D012093:Replicon / Q000187:drug effects; D013329:Structure-Activity Relationship; D016019:Survival Analysis; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; C000592897:CCG205432; D007211:Indoles; D011725:Pyridines