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
Ja. Partaledis et al., 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, Journal of virology, 69(9), 1995, pp. 5228-5235
Human immunodeficiency virus type 1 (HIV-1) variants with reduced sens
itivity 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 popu
lations with greater than 100-fold-increased resistance to both inhibi
tors compared with the parental virus have been obtained, DNA sequence
analyses of the protease genes from VB-11,328- and VX-478-resistant v
ariants reveal a Sequential accumulation of point mutations, with simi
lar resistance patterns occurring for the two inhibitors. The deduced
amino acid substitutions in the resistant protease are Leu-10-->Phe, M
et-46-->Ile, Ile-47-->Val, and Ile-50-->Val. This is the first observa
tion in HIV protease resistance studies of an Ile-50-->Val mutation, a
mutation that appears to arise uniquely against the sulfonamide inhib
itor class. When the substitutions observed were introduced as single
mutations into an HIV-1 infectious done (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 mutati
ons 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 i
nhibitors than the parent enzyme (less than or equal to 80-fold), The
protease triply mutated at Met-46-->Ile, Ile-47-->Val, and Ile-50-->Va
l shows an even greater decrease in inhibitor binding (less than or eq
ual to 270-fold). The sulfonamide-resistant HIV protease variants rema
in sensitive to inhibitors from other chemical classes (Ro 31-8959 and
L-735,524), suggesting possibilities for clinical use of HN protease
inhibitors in combination or serially.