Comparison of inhibitory activities of various antiretroviral agents against particle-derived and recombinant human immunodeficiency virus type 1 reverse transcriptases

The effects of three molecular weight ranges of dextran sulfate on five different human immunodeficiency virus (HIV) isolates (from patients with acquired immunodeficiency syndrome), alone and in combination with dideoxynucleosides, were investigated in vitro. The higher the molecular weight range of dextran sulfate, the more potent the activity as assessed by a quantitative syncytium formation assay. Although all five HIV isolates had similar susceptibilities to the inhibitory effects of dideoxynucleosides, the two clinical isolates of HIV (HIV type 1 [HIV-1] TM and SP) exhibited a pattern of reduced susceptibility to dextran sulfate when compared with the two cloned isolates (HIV-1 WMF and HIV-2 ROD) and a prototype laboratory strain (HIV-1 IIIB). In combination with dideoxynucleosides, the high-molecular-weight range of dextran sulfate (500,000) resulted in an antagonistic response directed against the two clinical isolates of HIV (HIV-1 TM and SP) when the antiviral concentrations of dextran sulfate were in the ineffective range. Additive or synergistic effects were seen with the other three HIV isolates and all five HIV isolates when the low-molecular-weight range of dextran sulfate (8,000) was used. The results of these studies raise issues on the impact of drug-resistant strains on disease progression and the use of dextran sulfate in combination with nucleoside analogs for the clinical management of HIV disease.

Section: Methodsmentioning

confidence: 99%

Anti-human immunodeficiency virus effects of dextran sulfate are strain dependent and synergistic or antagonistic when dextran sulfate is given in combination with dideoxynucleosides

Busso

Resnick

1990

“…We found that the inhibition pattern of MuLV RT was significantly different from that of HIV-1 RT. The RNase H activity, for example, was about twofold less sensitive to illimaquinone; the calculated IC50 was approximately 29 jiM. On the other hand, the RDDP and DDDP activities of MuLV RT were more susceptible to the inhibitory compound (IC50s of about 19 and 15 jig/ml, respectively) than the corresponding functions of HIV-1 RT (more than 50 ,ug/ml for both activities; Table 1).…”

mentioning

confidence: 99%

Illimaquinone, a selective inhibitor of the RNase H activity of human immunodeficiency virus type 1 reverse transcriptase

Loya

Tal

Kashman

et al. 1990

125

We studied the effect of the natural marine substance mimaquinone on the catalytic activities of reverse transcriptase from human immunodeficiency virus type 1. Illimaquinone inhibited the RNase H activity of the enzyme at concentrations of 5 to 10 ,ug/ml, whereas RNA-dependent DNA polymerase and DNA-dependent DNA polymerase activities were considerably less susceptible to this inhibition. Two synthetic derivatives of illimaquinone, in which the 6'-hydroxyl group at the ortho position to one of the carbonyl groups of the quinone ring was modified, proved ineffective in inhibiting the human immunodeficiency virus type 1 reverse transcriptase RNase H function, suggesting involvement of the 6'-hydroxyl group in blocking the enzymatic activity.Reverse transcriptases (RTs) are key enzymes in the life cycle of retroviruses, since they are responsible for the transcription of the viral RNA into the provirus DNA that is subsequently integrated into the host cell DNA (34). RT is a multifunctional enzyme; the same protein molecules exhibit both RNA-dependent DNA polymerase (RDDP) and DNAdependent DNA polymerase (DDDP) activities as well as an inherent RNase H activity (32). Drugs acting at the reverse transcription level block specifically the replication of human immunodeficiency virus (HIV), the human retrovirus that causes acquired immunodeficiency syndrome, by preventing the unique transcription of genomic viral RNA. Several compounds with diverse molecular structures, including various 2',3'-dideoxynucleosides (14, 21, 22) and 3'-azidothymidine (9, 23, 35) that inhibit the viral RT in the form of 5'-triphosphates, foscarnet (28, 33), suramine (2, 7), rifabutin (1), and HPA 23 (26), have been shown to be active against HIV RT in vitro. In contrast to the relatively large volume of research on the inhibition of the DNA polymerase activities associated with various retroviral RTs, there is a paucity of information on the inhibition of the RT-associated RNase H function. RNase H specifically degrades the RNA in the RNA-DNA heteroduplex after the minus-strand DNA has been synthesized. Removal of the RNA strand enables the synthesis of the plus strand of DNA and the formation of the proviral double-stranded DNA, which is subsequently inserted into the host cellular genome (34). The fact that there is a distinction between the DNA polymerase and RNase H activities of retroviral RTs, including that of HIV (11,25,30,31), could be utilized to develop drugs that will specifically inhibit the RNase H function without appreciably affecting the DNA-polymerizing function. Since the physiological significance of RNase H in mammalian cells is far from clear (6), it is possible that even a partial inhibition of this activity would have minimal effects on the metabolism of normal cells but a substantial inhibitory effect on the virus. The availability of large amounts of nearly authentic (560 amino acids long with an apparent molecular weight of * Corresponding author. 66,000) enzymatically active and soluble recombinant HIV type 1 (HI...

“…However, it is highly likely that residual drug may inactivate the virus directly, resulting in an overestimation of the potency of the fulleroid in chronically infected H9 cells. The compound was also evaluated for its inhibitory effect on recombinant p66/51 HIV-1 RT by using poly(rA)n oligo(T) 12 18 as the template-primer (17). Compound 1 was active against this enzyme, with a median inhibitory concentration (IC50) of 4.6 ,uM.…”

mentioning

confidence: 99%

Synthesis and virucidal activity of a water-soluble, configurationally stable, derivatized C60 fullerene

Schinazi

Sijbesma

Srdanov

et al. 1993

Self Cite

205

120

The bis(monosuccinimide) derivative of p,p'-bis(2-aminoethyl)diphenyl-C60 (compound 1), prepared by the fulleroid route, is active against human immunodeficiency virus type 1 (HIV-1) and HIV-2 (50% effective concentration [EC50] averaging approximately 6 microM) in acutely or chronically infected human lymphocytes and is active in vitro against 3'-azido-3'-deoxythymidine-resistant HIV-1 (EC50, approximately 3 microM). The virucidal properties of compound 1 were confirmed by virus inactivation assays. Compound 1 was noncytotoxic up to 100 microM in peripheral blood mononuclear cells and H9, Vero, and CEM cells. In cell-free assays, whereas the fullerene showed comparable activity against HIV-1 reverse transcriptase and DNA polymerase alpha (50% inhibitory concentration of approximately 5 microM), it demonstrated selective activity against HIV-1 protease.