title: Complete inhibition of viral breakthrough by combination of MKC-442 with AZT during a long-term culture of HIV-1 infected cells.
abstract: We have investigated viral breakthrough during a long-term culture of HIV-1-infected cells with the non-nucleoside reverse transcriptase inhibitors (NNRTIs) 6-benzyl-1-ethoxymethyl-5-isopropyluracil (MKC-442), nevirapine and loviride (alpha-APA). When the compounds were examined for their inhibitory effects on HIV-1 (HE strain) replication in MT-4 cells on day 4 after virus infection, the 50% effective concentrations (EC50) of MKC-442, nevirapine and loviride were 9.4, 98 and 21 nM, respectively. After a 48-day culture period, MKC-442, nevirapine and loviride completely inhibited viral breakthrough at concentrations of 1, 5 and 1 microM, respectively. These concentrations were 50-100-fold higher than their EC50 values. When the cells were treated with either MKC-442 (0.04 and 0.2 microM), nevirapine (0.2 and 1 microM) or loviride (0.04 and 0.2 microM) in combination with AZT (0.005 microM), only the combination of 0.2 microM MKC-442 with 0.005 microM AZT could completely inhibit the breakthrough of HIV-1 after a 68-day culture period. Polymerase chain reaction (PCR) analysis revealed that no proviral DNA was detected in the cells treated with this combination. Except for two combinations (0.04 microM MKC-442 + 0.005 microM AZT and 0.04 microM loviride + 0.005 microM AZT), all of the viruses isolated during combination treatments had various amino acid mutations in their reverse transcriptase (RT). These results indicate that the combination treatment with a relatively high dose of MKC-442 and a low dose of AZT may have potential to suppress the emergence of drug resistance during a long-term treatment in vivo and should be further pursued in HIV-1-infected patients.
authors.affiliation: Division of Human Retroviruses, Faculty of Medicine, Kagoshima University 8-35-1, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Okamoto
authors.forename: M
authors.initials: M
authors.lastname: Makino
authors.forename: K
authors.initials: K
authors.lastname: Yamada
authors.forename: K
authors.initials: K
authors.lastname: Nakade
authors.forename: S
authors.initials: S
authors.lastname: Yuasa
authors.forename: M
authors.initials: M
authors.lastname: Baba
mesh_terms: D000081:Acetamides / Q000737:chemistry / Q000494:pharmacology*; D000098:Acetophenones / Q000737:chemistry / Q000494:pharmacology*; D002461:Cell Line, Transformed; D006678:HIV / Q000187:drug effects; D016655:HIV Core Protein p24 / Q000378:metabolism; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D019829:Nevirapine; D011725:Pyridines / Q000737:chemistry / Q000494:pharmacology*; D018894:Reverse Transcriptase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D014498:Uracil / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D015215:Zidovudine / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000081:Acetamides; D000098:Acetophenones; D016655:HIV Core Protein p24; D011725:Pyridines; D018894:Reverse Transcriptase Inhibitors; C080073:loviride; D015215:Zidovudine; D014498:Uracil; D019829:Nevirapine; C083858:emivirine