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J. Virol., 09 1995, 5228-5235, Vol 69, No. 9
JA Partaledis, K Yamaguchi, M Tisdale, EE Blair, C Falcione, B Maschera, RE Myers, S Pazhanisamy, O Futer and AB Cullinan
Human immunodeficiency virus type 1 (HIV-1) variants with reduced
sensitivity to the hydroxyethylamino sulfonamide protease inhibitors VB-
11,328 and VX-478 have been selected in vitro by two independent serial
passage protocols with HIV-1 in CEM-SS and MT-4 cell lines. Virus
populations with greater than 100-fold-increased resistance to both
inhibitors compared with the parental virus have been obtained. DNA
sequence analyses of the protease genes from VB-11,328- and VX-478-
resistant variants reveal a sequential accumulation of point mutations,
with similar resistance patterns occurring for the two inhibitors. The
deduced amino acid substitutions in the resistant protease are Leu-10--
>Phe, Met-46-->Ile, Ile-47-->Val, and Ile-50-->Val. This is the
first observation in HIV protease resistance studies of an Ile-50-->Val
mutation, a mutation that appears to arise uniquely against the sulfonamide
inhibitor class. When the substitutions observed were introduced as single
mutations into an HIV-1 infectious clone (HXB2), only the Ile-50-->Val
mutant showed reduced sensitivity (two- to threefold) to VB-11,328 and
VX-478. A triple protease mutant infectious clone carrying the mutations
Met-46-->Ile, Ile-47-->Val, and Ile-50-- >Val, however, showed
much greater reduction in sensitivity (14- to 20- fold) to VB-11,328 and
VX-478. The same mutations were studied in recombinant HIV protease. The
mutant protease Ile-50-->Val displays a much lower affinity for the
inhibitors than the parent enzyme (< or = 80-fold). The protease triply
mutated at Met-46-->Ile, Ile-47-->Val, and Ile-50-->Val shows an
even greater decrease in inhibitor binding (< or = 270-fold). The
sulfonamide-resistant HIV protease variants remain sensitive to inhibitors
from other chemical classes (Ro 31-8959 and L- 735,524), suggesting
possibilities for clinical use of HIV protease inhibitors in combination or
serially.
Copyright © 1995, American Society for Microbiology
In vitro selection and characterization of human immunodeficiency virus type 1 (HIV-1) isolates with reduced sensitivity to hydroxyethylamino sulfonamide inhibitors of HIV-1 aspartyl protease
Vertex Pharmaceuticals Incorporated, Cambridge, Massachusetts 02139- 4211, USA.
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