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J Virol, March 1998, p. 2456-2462, Vol. 72, No. 3
Biomolecular Research Institute, Parkville,
Australia,1 and
Enzyme Pharmacology
Unit, Glaxo Wellcome Research and Development Ltd., Stevenage SG1
2NY, United Kingdom2
Received 13 October 1997/Accepted 24 November 1997
The influenza virus neuraminidase (NA)-specific inhibitor zanamivir
(4-guanidino-Neu5Ac2en) is effective in humans when administered topically within the respiratory tract. The search for compounds with
altered pharmacological properties has led to the identification of a
novel series of influenza virus NA inhibitors in which the triol group
of zanamivir has been replaced by a hydrophobic group linked by a
carboxamide at the 6 position (6-carboxamide). NWS/G70C variants
generated in vitro, with decreased sensitivity to 6-carboxamide, contained hemagglutinin (HA) and/or NA mutations. HA mutants bound with
a decreased efficiency to the cellular receptor and were cross-resistant to all the NA inhibitors tested. The NA mutation, an
Arg-to-Lys mutation, was in a previously conserved site, Arg292, which
forms part of a triarginyl cluster in the catalytic site. In enzyme
assays, the NA was equally resistant to zanamivir and 4-amino-Neu5Ac2en
but showed greater resistance to 6-carboxamide and was most resistant
to a new carbocyclic NA inhibitor, GS4071, which also has a hydrophobic
side chain at the 6 position. Consistent with enzyme assays, the lowest
resistance in cell culture was seen to zanamivir, more resistance was
seen to 6-carboxamide, and the greatest resistance was seen to GS4071.
Substrate binding and enzyme activity were also decreased in the
mutant, and consequently, virus replication in both plaque assays and
liquid culture was compromised. Altered binding of the hydrophobic side
chain at the 6 position or the triol group could account for the
decreased binding of both the NA inhibitors and substrate.
0022-538X/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Mutations in a Conserved Residue in the Influenza
Virus Neuraminidase Active Site Decreases Sensitivity to
Neu5Ac2en-Derived Inhibitors
*
Corresponding author. Mailing address: Biomolecular
Research Institute, 343 Royal Parade, Parkville, 3052 Australia. Phone: 61 3 9662 7200. Fax: 61 3 9662 7101. E-mail:
jenny.mckimm-breschkin{at}bioresi.com.au.
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