title: Resistance to a drug blocking human immunodeficiency virus type 1 entry (RPR103611) is conferred by mutations in gp41.
abstract: A triterpene derived from betulinic acid (RPR103611) blocks human immunodeficiency virus type 1 (HIV-1) infection and fusion of CD4+ cells with cells expressing HIV-1 envelope proteins (gp120 and gp41), suggesting an effect on virus entry. This compound did not block infection by a subtype D HIV-1 strain (NDK) or cell-cell fusion mediated by the NDK envelope proteins. The genetic basis of drug resistance was therefore addressed by testing envelope chimeras derived from NDK and a drug-sensitive HIV-1 strain (LAI, subtype B). A drug-resistant phenotype was observed for all chimeras bearing the ectodomain of NDK gp41, while the origins of gp120 and of the membrane anchor and cytoplasmic domains of gp41 had no apparent role. The envelope gene of a LAI variant, fully resistant to the antiviral effect of RPR103611, was cloned and sequenced. Its product differed from the parental sequence at two positions in gp41, with changes of arginine 22 to alanine (R22A) and isoleucine 84 to serine (I84S), the gp120 being identical. In the context of LAI gp41, the I84S substitution was sufficient for drug resistance. Therefore, in two different systems, differences in gp41 were associated with sensitivity or resistance to RPR103611. Modifications of gp41 can affect the quaternary structure of gp120 and gp41 and the accessibility of gp120 to antiviral agents such as neutralizing antibodies. However, a direct effect of RPR103611 on a gp41 target must also be envisioned, in agreement with the blocking of apparently late steps of HIV-1 entry. This compound could be a valuable tool for structure-function studies of gp41.
authors.affiliation: INSERM, Institut Cochin de Génétique Moléculaire, Paris, France.
authors.forename: B
authors.initials: B
authors.lastname: Labrosse
authors.forename: O
authors.initials: O
authors.lastname: Pleskoff
authors.forename: N
authors.initials: N
authors.lastname: Sol
authors.forename: C
authors.initials: C
authors.lastname: Jones
authors.forename: Y
authors.initials: Y
authors.lastname: Hénin
authors.forename: M
authors.initials: M
authors.lastname: Alizon
mesh_terms: D000595:Amino Acid Sequence; D019380:Anti-HIV Agents / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D015752:Genes, env; D015700:HIV Envelope Protein gp41 / Q000737:chemistry* / Q000235:genetics; D015497:HIV-1 / Q000187:drug effects*; D006367:HeLa Cells; D006801:Humans; D008561:Membrane Fusion / Q000187:drug effects; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins; D016415:Sequence Alignment; D013329:Structure-Activity Relationship; D014315:Triterpenes / Q000494:pharmacology*; D014779:Virus Replication / Q000187:drug effects
chemical_list: D019380:Anti-HIV Agents; D015700:HIV Envelope Protein gp41; D011993:Recombinant Fusion Proteins; D014315:Triterpenes; C098649:RPR 103611