title: Constrained evolution of human immunodeficiency virus type 1 protease during sequential therapy with two distinct protease inhibitors.
abstract: Human immunodeficiency virus type 1 (HIV-1) variants that have developed protease (PR) inhibitor resistance most often display cross-resistance to several molecules within this class of antiretroviral agents. The clinical benefit of the switch to a second PR inhibitor in the presence of such resistant viruses may be questionable. We have examined the evolution of HIV-1 PR genotypes and phenotypes in individuals having failed sequential treatment with two distinct PR inhibitors: saquinavir (SQV) followed by indinavir (IDV). In viruses where typical SQV resistance mutations were detected before the change to IDV, the corresponding mutations were maintained under IDV, while few additional mutations emerged. In viruses where no SQV resistance mutations were detected before the switch to IDV, typical SQV resistance profiles emerged following the introduction of IDV. We conclude that following suboptimal exposure to a first PR inhibitor, the introduction of a second molecule of this class can lead to rapid selection of cross-resistant virus variants that may not be detectable by current genotyping methods at the time of the inhibitor switch. Viruses committed to resistance to the first inhibitor appear to bear the "imprint" of this initial selection and can further adapt to the selective pressure exerted by the second inhibitor following a pathway that preserves most of the initially selected mutations.
authors.affiliation: Service de Médecine Interne, Hôpital Antoine Béclère, Clamart, Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Dulioust
authors.forename: S
authors.initials: S
authors.lastname: Paulous
authors.forename: L
authors.initials: L
authors.lastname: Guillemot
authors.forename: A M
authors.initials: AM
authors.lastname: Delavalle
authors.forename: F
authors.initials: F
authors.lastname: Boué
authors.forename: F
authors.initials: F
authors.lastname: Clavel
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000188:drug therapy* / Q000821:virology; D004351:Drug Resistance; D016333:HIV Protease / Q000737:chemistry / Q000235:genetics*; D017320:HIV Protease Inhibitors / Q000627:therapeutic use*; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D019469:Indinavir / Q000627:therapeutic use*; D009154:Mutation; D019258:Saquinavir / Q000627:therapeutic use*
chemical_list: D017320:HIV Protease Inhibitors; D019469:Indinavir; D016333:HIV Protease; D019258:Saquinavir