A small molecule fusion inhibitor of dengue virus.
The dengue virus envelope protein plays an essential role in viral entry by mediating fusion between the viral and host membranes. The crystal structure of the envelope protein shows a pocket (located at a "hinge" between Domains I and II) that can be occupied by ligand n-octyl-beta-D-glucoside (betaOG). Compounds blocking the betaOG pocket are thought to interfere with conformational changes in the envelope protein that are essential for fusion. Two fusion assays were developed to examine the anti-fusion activities of compounds. The first assay measures the cellular internalization of propidium iodide upon membrane fusion. The second assay measures the protease activity of trypsin upon fusion between dengue virions and trypsin-containing liposomes. We performed an in silico virtual screening for small molecules that can potentially bind to the betaOG pocket and tested these candidate molecules in the two fusion assays. We identified one compound that inhibits dengue fusion in both assays with an IC(50) of 6.8 microM and reduces viral titers with an EC(50) of 9.8 microM. Time-of-addition experiments showed that the compound was only active when present during viral infection but not when added 1h later, in agreement with a mechanism of action through fusion inhibition.
Dengue Unit, Novartis Institute for Tropical Diseases, 10 Biopolis Road, Chromos #05-01, Singapore 138670, Singapore.
Mee Kian
MK
Poh
Andy
A
Yip
Summer
S
Zhang
John P
JP
Priestle
Ngai Ling
NL
Ma
Jolanda M
JM
Smit
Jan
J
Wilschut
Pei-Yong
PY
Shi
Markus R
MR
Wenk
Wouter
W
Schul
D000330:Aedes; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D006224:Cricetinae; D003716:Dengue Virus / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology; D008826:Microbial Sensitivity Tests; D011485:Protein Binding / Q000187:drug effects; D011487:Protein Conformation / Q000187:drug effects; D054852:Small Molecule Libraries / Q000494:pharmacology*; D014759:Viral Envelope Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry; D053586:Virus Internalization / Q000187:drug effects*
D000998:Antiviral Agents; D054852:Small Molecule Libraries; D014759:Viral Envelope Proteins