title: Susceptibility of HIV-2, SIV and SHIV to various anti-HIV-1 compounds: implications for treatment and postexposure prophylaxis.
abstract: Limited information is available on the activity of antiretroviral drugs against human immunodeficiency virus type 2 (HIV-2) and simian immunodeficiency virus (SIV) strains to guide their use in treatment or prophylaxis. We evaluated the antiviral activity of 16 approved drugs and one experimental drug, AMD3100, against two wild-type HIV-2 (ROD and EHO) isolates, two strains of SIV (mac251 and B670), and two strains of simian-human immunodeficiency virus (SHIV) that contain the reverse transcriptase (RTSHIV) or envelope glycoprotein (SHIV89.6) of human immunodeficiency virus type 1 (HIV-1) in a SIV(mac239) background. Drug susceptibility was measured conventionally by the MT-4/MTT assay, and results were analysed as fold changes in 50% effective concentration (EC50) relative to the EC50 for HIV-1 (IIIB). The nucleoside reverse transcriptase inhibitors (NRTIs) zidovudine, lamivudine, stavudine, didanosine, zalcitabine and abacavir as well as the nucleotide reverse transcriptase inhibitor tenofovir retained full activity against all six viruses except for SIV and SHIV89.6 that showed low-level resistance to didanosine. The protease inhibitors (PIs) ritonavir, indinavir, saquinavir and nelfinavir were found to be active against some HIV-2 or SIV strains. However, a significant reduction in susceptibility was seen with indinavir against SHIV89.6 (3.3-fold), and with amprenavir against HIV-2(ROD) (8.8-fold). All viruses except for RTSHIV showed a >200-fold decrease in susceptibility for the non-nucleoside reverse transcriptase inhibitors (NNRTIs) nevirapine, delavirdine and efavirenz, indicating high-level resistance. AMD3100, a CXCR4 antagonist, was active against HIV-2 and SHIV89.6, a finding consistent with the use of the CXCR4 co-receptor by these isolates, but was inactive against SIV strains. In contrast, enfuvirtide (T-20) was active against SHIV89.6 but had reduced inhibitory activity against both HIV-2 and SIV strains predicting little therapeutic value against these viruses. These findings support the use of NRTIs, tenofovir, but not NNRTIs, for treating HIV-2-infected persons or for prophylaxis against HIV-2 and SIV. The clinical significance of the low-level resistance of HIV-2 and SIV to some PIs is unclear. Co-receptor antagonists such as AMD3100 show promising anti-HIV-2 therapeutic modalities. Both AMD3100 and enfuvirtide could be used for prophylaxis against SHIV89.6.
authors.affiliation: Rega Institute for Medical Research, Katholieke Universiteit Leuven, Leuven, Belgium. myriam.witvrouw@uz.kuleuven.ac.be
authors.forename: Myriam
authors.initials: M
authors.lastname: Witvrouw
authors.forename: Christophe
authors.initials: C
authors.lastname: Pannecouque
authors.forename: William M
authors.initials: WM
authors.lastname: Switzer
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Folks
authors.forename: Erik
authors.initials: E
authors.lastname: De Clercq
authors.forename: Walid
authors.initials: W
authors.lastname: Heneine
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019380:Anti-HIV Agents / Q000494:pharmacology*; D016384:Consensus Sequence; D006678:HIV / Q000187:drug effects*; D054303:HIV Reverse Transcriptase / Q000235:genetics; D015498:HIV-2 / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D011480:Protease Inhibitors / Q000494:pharmacology; D012194:RNA-Directed DNA Polymerase / Q000235:genetics; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015302:Simian Immunodeficiency Virus / Q000187:drug effects*
chemical_list: D019380:Anti-HIV Agents; D011480:Protease Inhibitors; D018894:Reverse Transcriptase Inhibitors; C072416:reverse transcriptase, Human immunodeficiency virus 2; D054303:HIV Reverse Transcriptase; D012194:RNA-Directed DNA Polymerase