Inhibitors of respiratory syncytial virus replication target cotranscriptional mRNA guanylylation by viral RNA-dependent RNA polymerase.
Respiratory syncytial virus (RSV) is a major cause of respiratory illness in infants, immunocompromised patients, and the elderly. New antiviral agents would be important tools in the treatment of acute RSV disease. RSV encodes its own RNA-dependent RNA polymerase that is responsible for the synthesis of both genomic RNA and subgenomic mRNAs. The viral polymerase also cotranscriptionally caps and polyadenylates the RSV mRNAs at their 5' and 3' ends, respectively. We have previously reported the discovery of the first nonnucleoside transcriptase inhibitor of RSV polymerase through high-throughput screening. Here we report the design of inhibitors that have improved potency both in vitro and in antiviral assays and that also exhibit activity in a mouse model of RSV infection. We have isolated virus with reduced susceptibility to this class of inhibitors. The mutations conferring resistance mapped to a novel motif within the RSV L gene, which encodes the catalytic subunit of RSV polymerase. This motif is distinct from the catalytic region of the L protein and bears some similarity to the nucleotide binding domain within nucleoside diphosphate kinases. These findings lead to the hypothesis that this class of inhibitors may block synthesis of RSV mRNAs by inhibiting guanylylation of viral transcripts. We show that short transcripts produced in the presence of inhibitor in vitro do not contain a 5' cap but, instead, are triphosphorylated, confirming this hypothesis. These inhibitors constitute useful tools for elucidating the molecular mechanism of RSV capping and represent valid leads for the development of novel anti-RSV therapeutics.
Liuzzi
Michel
M
Department of Biological Sciences, Boehringer Ingelheim (Canada) Ltd., Laval, Quebec. Liuzzi.Michel@idenix.com
Mason
Stephen W
SW
Cartier
Mireille
M
Lawetz
Carol
C
McCollum
Robert S
RS
Dansereau
Nathalie
N
Bolger
Gordon
G
Lapeyre
Nicole
N
Gaudette
Yvon
Y
Lagacé
Lisette
L
Massariol
Marie-Josée
MJ
Dô
Florence
F
Whitehead
Paul
P
Lamarre
Lyne
L
Scouten
Erika
E
Bordeleau
Josée
J
Landry
Serge
S
Rancourt
Jean
J
Fazal
Gulrez
G
Simoneau
Bruno
B
D000281:Administration, Intranasal; D000595:Amino Acid Sequence; D000818:Animals; D020134:Catalytic Domain / Q000235:genetics; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D020128:Inhibitory Concentration 50; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D012315:RNA Caps / Q000096:biosynthesis / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D018357:Respiratory Syncytial Virus Infections / Q000517:prevention & control / Q000821:virology; D012136:Respiratory Syncytial Viruses / Q000187:drug effects* / Q000201:enzymology* / Q000502:physiology; D012261:Ribonucleoproteins / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D016415:Sequence Alignment; D014779:Virus Replication / Q000187:drug effects
D004791:Enzyme Inhibitors; D012315:RNA Caps; D012333:RNA, Messenger; D012261:Ribonucleoproteins; D012324:RNA-Dependent RNA Polymerase