In vitro Anti-HIV-1 Activity of sn-2-Substituted 1-O-Octadecyl-sn-Glycero-3-Phosphonoformate Analogues and Synergy with Zidovudine

Hostetler, Karl Y.; Hammond, Jennifer; Kini, Ganesh D.; Hostetler, Saskia E; Beadle, James R.; Aldern, Kathy A.; Chou, Ting‐Chao; Richman, Douglas D.; Mellors, John W.

doi:10.1177/095632020001100304

Cited by 10 publications

(12 citation statements)

References 19 publications

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“…This discrepancy is probably due to the limited ability of foscarnet to penetrate into cells, so that high concentrations of extracellular foscarnet are needed to reach inhibitory levels intracellularly. The permeability barrier can be circumvented by the use of alkylglycerol-conjugated derivatives of foscarnet, which are 10-to 35-fold more potent inhibitors of HIV-1 replication than is free foscarnet because they readily penetrate into cells and are then cleaved to form free intracellular foscarnet (13)(14)(15)21). These findings probably explain the differences in foscarnet sensitivity between our cell-based and enzyme assays.…”

Section: Resultsmentioning

confidence: 94%

“…W88G, E89K, L92I, S156A, and Q161L/H208Y were obtained by serial passage of HIV in MT-2 cells in the presence of escalating concentrations of foscarnet (13,31,52). Alkyglycerol conjugates of foscarnet have been developed to improve cellular uptake and reduce toxicity (14,15,21). Serial passage of HIV-1 in the presence of these conjugated forms of foscarnet yielded additional mutations including S117T, F160Y, and M164I (usually in combination with the L214F mutation) (13), which also conferred resistance to unconjugated foscarnet in virus culture assays.…”

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confidence: 99%

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Relationship between 3′-Azido-3′-Deoxythymidine Resistance and Primer Unblocking Activity in Foscarnet-Resistant Mutants of Human Immunodeficiency Virus Type 1 Reverse Transcriptase

Meyer

Matsuura

Zonarich

et al. 2003

J Virol

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Phosphonoformate (foscarnet) is a pyrophosphate (PP i ) analogue and a potent inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT), acting through the PP i binding site on the enzyme. HIV-1 RT can unblock a chain-terminated DNA primer by phosphorolytic transfer of the terminal residue to an acceptor substrate (PP i or a nucleotide such as ATP) which also interacts with the PP i binding site. Primer-unblocking activity is increased in mutants of HIV-1 that are resistant to the chain-terminating nucleoside inhibitor 3-azido-3-deoxythymidine (AZT). We have compared the primer-unblocking activity for HIV-1 RT containing various foscarnet resistance mutations (K65R, W88G, W88S, E89K, S117T, Q161L, M164I, and the double mutant Q161L/H208Y) alone or in combination with AZT resistance mutations. The level of primer-unblocking activity varied over a 150-fold range for these enzymes and was inversely correlated with foscarnet resistance and directly correlated with AZT resistance. Based on published crystal structures of HIV-1 RT, many of the foscarnet resistance mutations affect residues that do not make direct contact with the catalytic residues of RT, the incoming deoxynucleoside triphosphate (dNTP), or the primer-template. These mutations may confer foscarnet resistance and reduce primer unblocking by indirectly decreasing the binding and retention of foscarnet, PP i , and ATP. Alternatively, the binding position or orientation of PP i , ATP, or the primer-template may be changed in the mutant enzyme complex so that molecular interactions required for the unblocking reaction are impaired while dNTP binding and incorporation are not.Phosphonoformate (foscarnet) inhibits a wide variety of DNA and RNA polymerases including human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) (40, 43). Foscarnet competes with pyrophosphate (PP i ) for binding in PP i exchange reactions, suggesting that foscarnet interacts with the site on the enzyme where PP i is formed (7, 38). On structural grounds, the site of interaction for PP i (and, presumably, for foscarnet) should lie within the deoxynucleoside triphosphate (dNTP) binding site since PP i is formed from the ␤ and ␥ phosphates of the dNTP substrate, but foscarnet inhibition of DNA synthesis in vitro is noncompetitive with dNTP substrates (58), indicating that foscarnet and dNTP bind to distinguishable forms of RT. In addition, median-effect analysis comparing foscarnet and 3Ј-azido-3Ј-deoxythymidine (AZT) triphosphate (AZTTP) alone or as mixtures has shown that inhibition by these compounds is mutually exclusive (10, 22, 50), implying that binding of either inhibitor prevents binding of the other to the same enzyme molecule.In intact cells, the inhibition of HIV-1 by foscarnet and AZT is synergistic (10,22). The mechanism of this synergy is unclear, but it has recently been demonstrated that AZT monophosphate (AZTMP) incorporation can be reversed by the primer-unblocking activity of RT, in which the chain-terminating residue is trans...

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Section: Resultsmentioning

confidence: 94%

mentioning

confidence: 99%

Relationship between 3′-Azido-3′-Deoxythymidine Resistance and Primer Unblocking Activity in Foscarnet-Resistant Mutants of Human Immunodeficiency Virus Type 1 Reverse Transcriptase

Meyer

Matsuura

Zonarich

et al. 2003

J Virol

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“…In the present study, we have obtained several lines of additional evidence that support our prior findings that the prodrugs are cleaved intracellularly to yield free and active PFA. First, we have shown that the PFA prodrugs inhibit HIV-1 in vitro (13). Second, the prodrugs have activity profiles against a panel of drug-resistant mutants similar to that of unmodified PFA.…”

Section: Discussionmentioning

confidence: 93%

“…1) are potent inhibitors of wild-type HIV-1 LAI . The IC 50 s for B-PFA, MB-PFA, and EB-PFA against HIV-1 LAI are 1.40, 0.28, and 0.39 M, respectively (13). In the present study, we evaluated the activities of these three analogs against a panel of NRTIresistant HIV-1 variants.…”

Section: Activities Of Pfa Prodrugs Against Nrti-resistant Hiv-1mentioning

confidence: 97%

“…Modifications at the sn-1 and sn-2 sites of the glycerol backbone can improve antiviral activity and reduce cytotoxicity (13,16). Previous structure-activity studies involving these compounds have shown that prodrugs containing alkyl chains of 14 to 22 carbons at the sn-1 position and alkyl chains of 1 to 3 carbons at the sn-2 position have optimal activity, with submicromolar 50% inhibitory concentrations (IC 50 s) against wild-type HIV-1 and better selectivity indexes than unmodified PFA (13,16). These prodrugs also have greater oral bioavailability in mice than unmodified PFA (K. Y. Hostetler, K. N. Wright, M. F. Gardner, and J. R. Beadle, Antivir.…”

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