The imidazopyrrolopyridine analogue AG110 is a novel, highly selective inhibitor of pestiviruses that targets the viral RNA-dependent RNA polymerase at a hot spot for inhibition of viral replication.
Ethyl 2-methylimidazo[1,2-a]pyrrolo[2,3-c]pyridin-8-carboxylate (AG110) was identified as a potent inhibitor of pestivirus replication. The 50% effective concentration values for inhibition of bovine viral diarrhea virus (BVDV)-induced cytopathic effect, viral RNA synthesis, and production of infectious virus were 1.2 +/- 0.5 microM, 5 +/- 1 microM, and 2.3 +/- 0.3 microM, respectively. AG110 proved inactive against the hepatitis C virus and a flavivirus. AG110 inhibits BVDV replication at a time point that coincides with the onset of intracellular viral RNA synthesis. Drug-resistant mutants carry the E291G mutation in the viral RNA-dependent RNA polymerase (RdRp). AG110-resistant virus is cross-resistant to the cyclic urea compound 1453 which also selects for the E291G drug resistance mutation. Moreover, BVDV that carries the F224S mutation (because of resistance to the imidazopyridine 5-[(4-bromophenyl)methyl]-2-phenyl-5H-imidazo[4,5-c]pyridine [BPIP]and VP32947) is also resistant to AG110. AG110 did not inhibit the in vitro activity of recombinant BVDV RdRp but inhibited the activity of BVDV replication complexes (RCs). Molecular modeling revealed that E291 is located in a small cavity near the tip of the finger domain of the RdRp about 7 A away from F224. Docking of AG110 in the crystal structure of the BVDV RdRp revealed several potential contacts including with Y257. The E291G mutation might enable the free rotation of Y257, which might in turn destabilize the backbone of the loop formed by residues 223 to 226, rendering more mobility to F224 and, hence, reducing the affinity for BPIP and VP32947. It is concluded that a single drug-binding pocket exists within the finger domain region of the BVDV RdRp that consists of two separate but potentially overlapping binding sites rather than two distinct drug-binding pockets.
Rega Institute for Medical Research, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
Jan
J
Paeshuyse
Jean-Michel
JM
Chezal
Matheus
M
Froeyen
Pieter
P
Leyssen
Hélène
H
Dutartre
Robert
R
Vrancken
Bruno
B
Canard
Carine
C
Letellier
Tong
T
Li
Harald
H
Mittendorfer
Frank
F
Koenen
Pierre
P
Kerkhofs
Erik
E
De Clercq
Piet
P
Herdewijn
Gerhard
G
Puerstinger
Alain
A
Gueiffier
Olivier
O
Chavignon
Jean-Claude
JC
Teulade
Johan
J
Neyts
D000818:Animals; D000998:Antiviral Agents / Q000737:chemistry*; D001665:Binding Sites; D002417:Cattle; D001908:Diarrhea Viruses, Bovine Viral / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D008958:Models, Molecular; D010576:Pestivirus / Q000187:drug effects; D018182:Pestivirus Infections / Q000188:drug therapy; D011720:Pyrazoles / Q000737:chemistry / Q000494:pharmacology*; D012324:RNA-Dependent RNA Polymerase / Q000037:antagonists & inhibitors*; D013329:Structure-Activity Relationship; D014779:Virus Replication / Q000187:drug effects*
D000998:Antiviral Agents; D004791:Enzyme Inhibitors; D011720:Pyrazoles; C026262:imidazopyrazole; D012324:RNA-Dependent RNA Polymerase