title: Inhibition of dengue virus through suppression of host pyrimidine biosynthesis.
abstract: Viral replication relies on the host to supply nucleosides. Host enzymes involved in nucleoside biosynthesis are potential targets for antiviral development. Ribavirin (a known antiviral drug) is such an inhibitor that suppresses guanine biosynthesis; depletion of the intracellular GTP pool was shown to be the major mechanism to inhibit flavivirus. Along similar lines, inhibitors of the pyrimidine biosynthesis pathway could be targeted for potential antiviral development. Here we report on a novel antiviral compound (NITD-982) that inhibits host dihydroorotate dehydrogenase (DHODH), an enzyme required for pyrimidine biosynthesis. The inhibitor was identified through screening 1.8 million compounds using a dengue virus (DENV) infection assay. The compound contains an isoxazole-pyrazole core structure, and it inhibited DENV with a 50% effective concentration (EC(50)) of 2.4 nM and a 50% cytotoxic concentration (CC(50)) of >5 μM. NITD-982 has a broad antiviral spectrum, inhibiting both flaviviruses and nonflaviviruses with nanomolar EC(90)s. We also show that (i) the compound inhibited the enzymatic activity of recombinant DHODH, (ii) an NITD-982 analogue directly bound to the DHODH protein, (iii) supplementing the culture medium with uridine reversed the compound-mediated antiviral activity, and (iv) DENV type 2 (DENV-2) variants resistant to brequinar (a known DHODH inhibitor) were cross resistant to NITD-982. Collectively, the results demonstrate that the compound inhibits DENV through depleting the intracellular pyrimidine pool. In contrast to the in vitro potency, the compound did not show any efficacy in the DENV-AG129 mouse model. The lack of in vivo efficacy is likely due to the exogenous uptake of pyrimidine from the diet or to a high plasma protein-binding activity of the current compound.
authors.affiliation: Novartis Institute for Tropical Diseases, 10 Biopolis Road, Chromos Building, Singapore 138670.
authors.forename: Qing-Yin
authors.initials: QY
authors.lastname: Wang
authors.forename: Simon
authors.initials: S
authors.lastname: Bushell
authors.forename: Min
authors.initials: M
authors.lastname: Qing
authors.forename: Hao Ying
authors.initials: HY
authors.lastname: Xu
authors.forename: Aurelio
authors.initials: A
authors.lastname: Bonavia
authors.forename: Sandra
authors.initials: S
authors.lastname: Nunes
authors.forename: Jing
authors.initials: J
authors.lastname: Zhou
authors.forename: Mee Kian
authors.initials: MK
authors.lastname: Poh
authors.forename: Paola
authors.initials: P
authors.lastname: Florez de Sessions
authors.forename: Pornwaratt
authors.initials: P
authors.lastname: Niyomrattanakit
authors.forename: Hongping
authors.initials: H
authors.lastname: Dong
authors.forename: Keith
authors.initials: K
authors.lastname: Hoffmaster
authors.forename: Anne
authors.initials: A
authors.lastname: Goh
authors.forename: Shahul
authors.initials: S
authors.lastname: Nilar
authors.forename: Wouter
authors.initials: W
authors.lastname: Schul
authors.forename: Susan
authors.initials: S
authors.lastname: Jones
authors.forename: Laura
authors.initials: L
authors.lastname: Kramer
authors.forename: Teresa
authors.initials: T
authors.lastname: Compton
authors.forename: Pei-Yong
authors.initials: PY
authors.lastname: Shi
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use*; D002522:Chlorocebus aethiops; D003588:Cytopathogenic Effect, Viral / Q000187:drug effects; D003715:Dengue / Q000188:drug therapy* / Q000821:virology; D003716:Dengue Virus / Q000187:drug effects* / Q000201:enzymology / Q000472:pathogenicity / Q000502:physiology; D000090722:Dihydroorotate Dehydrogenase; D004195:Disease Models, Animal; D057166:High-Throughput Screening Assays; D006801:Humans; D051379:Mice; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011743:Pyrimidines / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D016205:Sigmodontinae; D016896:Treatment Outcome; D014709:Vero Cells; D014779:Virus Replication / Q000187:drug effects
chemical_list: D000998:Antiviral Agents; D000090722:Dihydroorotate Dehydrogenase; D011743:Pyrimidines; D044925:Oxidoreductases Acting on CH-CH Group Donors; C030986:pyrimidine