title: HIV-1 clones resistant to a small molecule CCR5 inhibitor use the inhibitor-bound form of CCR5 for entry.
abstract: Human immunodeficiency virus type 1 (HIV-1) infection can be inhibited by small molecules that target the CCR5 coreceptor. Here, we describe some properties of clonal viruses resistant to one such inhibitor, SCH-D, using both chimeric, infectious molecular clones and Env-pseudotypes. Studies using combinations of CCR5 ligands, including small molecule inhibitors, monoclonal antibodies (MAbs) and chemokine derivatives such as PSC-RANTES, show that the fully SCH-D-resistant viruses enter target cells by using the SCH-D-bound form of CCR5. However, the way resistance to SCH-D and other small molecule CCR5 inhibitors is manifested depends on the target cell and the nature of the assay (single- vs. multi-cycle). In multi-cycle assays using primary lymphocytes, SCH-D does not inhibit resistant molecular clones, and it can even enhance their infectivity modestly. In contrast, the same viruses (as Env-pseudotypes) are significantly inhibited by SCH-D in single-cycle entry assays using U87-CD4/CCR5 cells, resistance being manifested by incomplete inhibition at high SCH-D concentrations. When a single-cycle, Env-pseudotype entry assay was performed using either U87-CD4/CCR5 cells or PBMC under comparable conditions, entry was inhibited by up to 88% in the former cells but by only 28% in the PBMC. Hence, there are both cell- and assay-dependent influences on how resistance is manifested. We also take this opportunity to correct our previous report that SCH-D-resistant isolates are also substantially cross-resistant to PSC-RANTES [Marozsan, A.J., Kuhmann, S.E., Morgan, T., Herrera, C., Rivera-Troche, E., Xu, S., Baroudy, B.M., Strizki, J., Moore, J.P., 2005. Generation and properties of a human immunodeficiency virus type 1 isolate resistant to the small molecule CCR5 inhibitor, SCH-417690 (SCH-D). Virology 338 (1), 182-199]. A substantial element of this resistance was attributable to the unappreciated carry-over of SCH-D from the selection cultures into analytical assays.
authors.affiliation: Department of Microbiology and Immunology, Weill Medical College of Cornell University, 1300 York Avenue, Box 62, New York, NY 10021, USA.
authors.forename: Pavel
authors.initials: P
authors.lastname: Pugach
authors.forename: Andre J
authors.initials: AJ
authors.lastname: Marozsan
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Ketas
authors.forename: Elissa L
authors.initials: EL
authors.lastname: Landes
authors.forename: John P
authors.initials: JP
authors.lastname: Moore
authors.forename: Shawn E
authors.initials: SE
authors.lastname: Kuhmann
mesh_terms: D065100:CCR5 Receptor Antagonists; D002478:Cells, Cultured; D024882:Drug Resistance, Viral; D015658:HIV Infections / Q000821:virology*; D015497:HIV-1 / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D010879:Piperazines / Q000378:metabolism* / Q000494:pharmacology*; D011743:Pyrimidines / Q000378:metabolism* / Q000494:pharmacology*; D019713:Receptors, CCR5 / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D065100:CCR5 Receptor Antagonists; D010879:Piperazines; D011743:Pyrimidines; D019713:Receptors, CCR5; C486781:vicriviroc