1st International Workshop on HIV Drug Resistance & Treatment Strategies 25-28 June 1997, St. Petersburg, Florida, USA

GENOTYPIC AND PHENOTYPIC CHARACTERIZATION OF HIV-1 STRAINS ISOLATED FROM IN VITRO SELECTION STUDIES WITH NEGATIVELY CHARGED ALBUMINS

Antiviral Therapy 1997;2 (Suppl 5):20 (abstract no. 32)

José A Esté^1,2, Cecilia Cabrera², Dirk KF Meijer³, Bonaventura Clotet², Jan Desmyter¹, Dominique Schols¹ and Erik De Clercq^1
1Rega Institute, Leuven, Belgium; ²Fundació irsiCaixa, Badalona, Spain; ³University Centre for Pharmacy, Groningen, The Netherlands

Negatively charged albumins (NCAs) have been identified as potent inhibitors of HIV-1 replication in vitro. Succinylated and aconitylated human serum albumins (Suc-HSA and Aco-HSA, respectively), the prototypes of these polyanionic proteins, act at an early phase of the virus life-cycle. Surface plasmon resonance (BIAcore) experiments have confirmed the interaction of these NCAs with the HIV-1 gp120 glycoprotein. In this study, resistance to Suc-HSA and Aco-HSA was analysed by characterizing HIV-1 variants that were selected in cell culture following serial passage of the NL4-3 strain in the presence of the compounds. Following 24 passages (126 days), we isolated variants that were resistant to Suc-HSA (EC₅₀ >125 µg/ml) and Aco-HSA (EC₅₀ 56 µg/ml) whilst the wild-type strain remained sensitive to both compounds (Suc-HSA, EC₅₀ 4.7 µg/ml; Aco-HSA, EC₅₀ 1.5 µg/ml). DNA sequence analysis showed the emergence of mutations in the gp120 molecule in the resistant strains but not in the wild-type strain. Despite the close similarities between these two proteins (they differ from one another in that Suc-HSA contains one, and Aco-HSA two carboxylic acid groups per lysine residue), the pattern of mutations for the fully Suc-HSA-resistant virus was different from that for the Aco-HSA-resistant strain. The Suc-HSA-resistant strain was 100-fold cross-resistant to the G-quartet containing oligonucleotide AR177 (zintevir) but was not resistant to dextran sulphate, the bicyclam AMD3100 or the chemokine SDF-1. Preliminary results suggest that the strain isolated in the presence of Aco-HSA had a lower replicative capacity than either the wild-type or the fully Suc-HSA-resistant strain. This phenomenon and the greater potency of Aco-HSA as an anti-HIV agent could explain the slower emergence of resistance to this compound than to Suc-HSA. We have previously selected strains that are resistant to virus-cell binding and fusion inhibitors such as dextran sulphate, AR177 and the bicyclam AMD3100, which share similarities in the mode of action with the NCAs but differ in the mutation patterns of the resistant strains. These results suggest that resistance to polyanions or to compounds that inhibit binding or fusion of HIV with CD4+ cells may not depend solely on the substitution of one or several specific amino acids but rather dependent on the overall change in the conformation of the gp120 molecule.

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1997-06-25
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