ABSTRACT
Mammarenaviruses cause chronic infections in rodents, which are their predominant natural hosts. Human infection with some of these viruses causes high-consequence disease, posing significant issues in public health. Currently, no FDA-licensed mammarenavirus vaccines are available, and anti-mammarenavirus drugs are limited to an off-label use of ribavirin, which is only partially efficacious and associated with severe side effects. Dihydroorotate dehydrogenase (DHODH) inhibitors, which block de novo pyrimidine biosynthesis, have antiviral activity against viruses from different families, including Arenaviridae, the taxonomic home of mammarenaviruses. Here, we evaluate five novel DHODH inhibitors for their antiviral activity against mammarenaviruses. All tested DHODH inhibitors were potently active against lymphocytic choriomeningitis virus (LCMV) (half-maximal effective concentrations [EC50] in the low nanomolar range, selectivity index [SI] > 1000). The tested DHODH inhibitors did not affect virion cell entry or budding, but rather interfered with viral RNA synthesis. This interference resulted in a potent interferon-independent inhibition of mammarenavirus multiplication in vitro, including the highly virulent Lassa and Junín viruses.
Subject(s)
Antiviral Agents/pharmacology , Arenaviridae/drug effects , Enzyme Inhibitors/pharmacology , Oxidoreductases Acting on CH-CH Group Donors/antagonists & inhibitors , Animals , Arenaviridae/classification , Arenaviridae/physiology , Chlorocebus aethiops , Dihydroorotate Dehydrogenase , Drug Evaluation, Preclinical , Enzyme Inhibitors/chemistry , HEK293 Cells , Humans , Interferons , Mice , Mice, Inbred C57BL , Nucleic Acid Synthesis Inhibitors/chemistry , Nucleic Acid Synthesis Inhibitors/pharmacology , Pyrimidines/biosynthesis , Vero Cells , Virus Replication/drug effectsABSTRACT
Currently available antiviral drugs frequently induce side-effects or selection of drug-resistant viruses. We describe a novel antiviral principle based on targeting the cellular enzyme dihydroorotate dehydrogenase (DHODH). In silico drug design and biochemical evaluation identified Compound 1 (Cmp1) as a selective inhibitor of human DHODH in vitro (IC50 1.5±0.2nM). Crystallization data specified the mode of drug-target interaction. Importantly, Cmp1 displayed a very potent antiviral activity that could be reversed by co-application of uridine or other pyrimidine precursors, underlining the postulated DHODH-directed mode of activity. Human and animal cytomegaloviruses as well as adenoviruses showed strong sensitivity towards Cmp1 in cell culture-based infection systems with IC50 values in the low micromolar to nanomolar range. Particularly, broad inhibitory activity was demonstrated for various types of laboratory and clinically relevant adenoviruses. For replication of human cytomegalovirus in primary fibroblasts, antiviral mode of activity was attributed to the early stage of gene expression. A mouse in vivo model proved reduced replication of murine cytomegalovirus in various organs upon Cmp1 treatment. These findings suggested Cmp1 as drug candidate and validated DHODH as a promising cellular target for antiviral therapy.
Subject(s)
Antimetabolites/pharmacology , Antiviral Agents/pharmacology , Drug Design , Drug Evaluation, Preclinical/methods , Enzyme Inhibitors/pharmacology , Oxidoreductases Acting on CH-CH Group Donors/antagonists & inhibitors , Pyrimidines/biosynthesis , Adenoviruses, Human/drug effects , Animals , Antimetabolites/chemical synthesis , Antimetabolites/chemistry , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Cells, Cultured , Computer Simulation , Cytomegalovirus/drug effects , Dihydroorotate Dehydrogenase , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Fibroblasts/drug effects , Fibroblasts/enzymology , Fibroblasts/virology , Ganciclovir/pharmacology , Herpesviridae/drug effects , Humans , Inhibitory Concentration 50 , Mice , Models, Molecular , Molecular Structure , Specific Pathogen-Free Organisms , Structure-Activity Relationship , Vaccinia virus/drug effects , Virus CultivationABSTRACT
The appearance of pandemic H1N1 and highly pathogenic avian H5N1 viruses in humans as well as the emergence of seasonal H1N1 variants resistant against neuraminidase inhibitors highlight the urgent need for new and amply available antiviral drugs. We and others have demonstrated that influenza virus misuses the cellular IKK/NF-kappaB signaling pathway for efficient replication suggesting that this module may be a suitable target for antiviral intervention. Here, we show that the novel NF-kappaB inhibitor SC75741 significantly protects mice against infection with highly pathogenic avian influenza A viruses of the H5N1 and H7N7 subtypes. Treatment was efficient when SC75741 was given intravenously in a concentration of 5mg/kg/day. In addition, application of SC75741 via the intraperitoneal route resulted in a high bioavailability and was also efficient against influenza when given 15 mg/kg/day or 7.5 mg/kg/twice a day. Protection was achieved when SC75741 was given for seven consecutive days either prior to infection or as late as four days after infection. SC75741 treatment showed no adverse effects in the concentrations required to protect mice against influenza virus infection. Although more pre-clinical studies are needed SC75741 might be a promising candidate for a novel antiviral drug against influenza viruses that targets the host cell rather than the virus itself.