Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We determined the susceptibility to antiviral drugs of clinical isolates of human immunodeficiency virus type 1 (HIV-1) subtypes A, B, C, D, and E. Isolates from treated and untreated patients were tested for sensitivity to zidovudine (ZDV), lamivudine (3TC), didanosine (ddI), nevirapine (NVP), foscarnet (PFA), and ritonavir (RNV). The susceptibility to these different drugs was broadly similar between the different subtypes of HIV-1. Isolates of subtype D showed a tendency toward slightly lower susceptibility to all the antiviral drugs, which could be related to the rapid growth characteristics of these isolates.
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PMID:Drug susceptibility of subtypes A,B,C,D, and E human immunodeficiency virus type 1 primary isolates. 946 26

We compared the development of resistance toward BI-RG-587 (nevirapine) and alpha-APA R89439 (loviride) starting from the wild-type HIV-1 strain IIIB and the 3TC-resistant HIV-1 strain containing the M184V mutation. The reverse transcriptase of the M184V mutant has been reported to have a higher fidelity. Our experiments showed that there was no significant delay in virus breakthrough of the M184V mutant as compared with the wild-type virus. We therefore conclude that the reported higher fidelity of the M184V mutant does not lead to a delay in the development of resistance to the nonnucleoside reverse transcriptase inhibitors nevirapine and loviride.
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PMID:Lamivudine resistance of HIV type 1 does not delay development of resistance to nonnucleoside HIV type 1-specific reverse transcriptase inhibitors as compared with wild-type HIV type 1. 949 15

Treatment of wild-type human immunodeficiency virus [HIV-1(IIIB)]-infected cell cultures with the thiocarboxanilide UC-781 under low selective pressure (i.e., 0.01 microg/ml) resulted in the emergence of V106A RT mutant virus. On increasing drug concentrations (stepwise up to 30 microg/ml) the virus retained the V106A RT mutation but acquired the novel F227L mutation in the RT genome in addition to the L100I, K1O1I, and Y181C mutations. This multiple-mutant virus proved highly resistant to virtually all nonnucleoside RT inhibitors (NNRTIs) (e.g., nevirapine, delavirdine, and loviride), but retained full sensitivity to nucleoside analogs such as AZT, ddI, (-)FTC, and 3TC. The F227 amino acid is highly conserved in HIV-1 strains and forms part of the NNRTI-binding pocket. Our model suggests a hydrophobic interaction between F227 and the chloro atom of UC-781.
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PMID:A novel mutation (F227L) arises in the reverse transcriptase of human immunodeficiency virus type 1 on dose-escalating treatment of HIV type 1-infected cell cultures with the nonnucleoside reverse transcriptase inhibitor thiocarboxanilide UC-781. 949 16

Resistance of HIV-1 reverse transcriptase (RT) to nucleoside analogs (e.g. AZT, ddC and 3TC) is conferred by various amino acid substitutions or combinations thereof on the RT molecule. The M184V mutation, that confers high and low-level resistance to 3TC and ddC, respectively, can restore sensitivity to AZT when introduced into RT against a background of AZT-resistance. The K65R mutation, that confers low level resistance to both 3TC and ddC, can also restore sensitivity to AZT. This information is of potential utility in choosing combinations of anti-viral drugs for clinical use. To explore this subject further, we have used an endogenous RT reaction to study mutated viruses containing M184V alone or M184V combined with each of the K65R, E89G or both the M41L and T215Y substitutions. Endogenous assays possess the advantage of utilizing genomic RNA as template in a reaction mixture that includes each of tRNALys.3 and viral nucleocapsid protein, necessary for specific initiation of reverse transcription, as well as all other viral proteins that might impact on this process. We now show that viruses containing both M184V and K65R displayed synergistic resistance to 3TC triphosphate (3TCTP), while the same combination yielded the same level of resistance to ddC triphosphate (ddCTP) as that manifested by K65R alone. The combination of M184V and E89G displayed synergistic resistance against ddCTP but not 3TCTP, while viruses containing only E89G were highly resistant to 3TCTP and displayed low-level resistance to ddCTP. The results show that endogenous RT assays can reveal variable synergistic, antagonistic, or neutral effects in regard to drug sensitivity, depending on the presence of specific amino acid substitutions in RT itself.
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PMID:Endogenous reverse transcriptase assays reveal synergy between combinations of the M184V and other drug resistance-conferring mutations in interactions with nucleoside analog triphosphates. 951 45

An azidothymidine (AZT)-resistant virus strain (HIV-1/AZT) (containing the 67 Asp --> Asn, 70 Lys --> Arg, 215 Thr --> Phe and 219 Lys --> Gln mutations into its reverse transcriptase) was grown in the combined presence of 2',3'-dideoxy-3'-thiacytidine (3TC, lamivudine) and the nonnucleoside reverse transcriptase inhibitor (S)-4-isopropoxycarbonyl-6-methoxy-3-(methylthiomethyl)-3,4-dih ydroquinoxaine-2(1H)-thione (quinoxaline HBY 097). Replication of HIV-1/AZT was inhibited to a significantly greater extent by the combination of 3TC and quinoxaline HBY 097 than by either drug alone. Virus breakthrough was markedly delayed in the combined presence of 3TC and HBY 097 at drug concentrations as low as 0.05 microg/mL and 0.0025 microg/mL, respectively. The virus that was recovered after exposure to the compounds (3TC and HBY 097) individually had acquired, in the genetic AZT-resistance background of HIV-1/AZT, 103 Lys --> Glu and 106 Val --> Ala mutations. The 103 Lys --> Glu mutation had not been observed before. However, both virus mutants retained marked sensitivity to HBY 097. In all cases, the genotypic AZT-resistance mutations were maintained in the mutant virus RT genomes, and the viruses also remained phenotypically resistant to AZT. Given the exquisite potency of a concomitant combination of 3TC and HBY 097 in suppressing virus replication, this drug combination should be further pursued in clinical trials in HIV-1-infected individuals.
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PMID:Retention of marked sensitivity to (S)-4-isopropoxycarbonyl-6-methoxy-3-(methylthiomethyl)-3,4-di hydroquin oxaline-2(1H)-thione (HBY 097) by an azidothymidine (AZT)-resistant human immunodeficiency virus type 1 (HIV-1) strain subcultured in the combined presence of quinoxaline HBY 097 and 2',3'-dideoxy-3'-thiacytidine (lamivudine). 951 72

Lipophilic masked aryloxyaminoacylphosphoramidate derivatives of 2',3'-dideoxynucleoside (ddN) analogues with potent anti-HIV activity (i.e., stavudine [d4T], azidothymidine [AZT], dideoxycytidine [ddC], 3'thio-2',3'-dideoxy cytidine [3TC], dideoxyadenosine [ddA], and 2',3'-didehydro-2',3'-dideoxyadenosine [d4A]) activity were evaluated for their activity against visna virus (VV) in sheep choroid plexus (SCP) cells. The activity of several prodrug derivatives against VV proved markedly superior to that of the corresponding free ddN analogues. In particular, the d4A and ddA prodrug derivatives were exquisitely inhibitory in this model system (50% effective concentration [EC50], < or = 0.003 microM), and their anti-VV potency exceeded by at least 200-fold the antiviral potency of the corresponding free nucleosides. Marked differences were noted in the anti-VV potencies of several of the test compounds depending on the nature of the amino acid linked to the 5'-phosphate moiety, the nature of the nucleoside, or both. In view of the stability of the prodrugs in lamb serum, the VV infection model in lambs may be considered highly useful for investigating the in vivo antiretroviral efficacy of these type of drugs, particularly the d4T, ddA, and d4A prodrug derivatives.
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PMID:Marked inhibitory activity of masked aryloxy aminoacyl phosphoramidate derivatives of dideoxynucleoside analogues against visna virus infection. 952 29

In the article summarized here, the authors present the most important achievements in the research on pathogenesis and treatment of AIDS, with particular consideration of psychiatric disturbances occurring in the course of infection by AIDS. Since the 1 st of January 1993, a new definition of AIDS has been obligatory. This definition is based on immunological criteria (HIV seropositivity and number of limphocytes CD4 < 200/microliter). There is a considerable progress in the scope of laboratory diagnostics of the infection by HIV (a method of polimerase chain reaction has been introduced) and in the laboratory and clinical appraisal of the development of AIDS. An astonishing capability of HIV to mutation has been proved. Asymptomatic HIV carriers show about 10(6) genetically different variants of HIV, and subjects showing symptoms of AIDS may prove over 10(8) HIV variants. This extreme dynamics of HIV causes that even the subjects who are not pharmacologically treated (but who are HIV seropositive) indicate the formation of mutants resistant to medicines applied in the treatment of AIDS. The only one and relatively efficient means of treatment of AIDS is combined therapy applied from the first weeks of the infection by HIV. Professor Luc Montanier, a co-discoverer of HIV virus suggests that the most efficient therapy is that by a medicine known as 3TC, in combination with DDI or DDC and with one of the drugs named anti-proteases. This method of treatment inhibits the activity of virus protease--one of 3 enzymes indispensable for replication of HIV. Recently (at the turn of the years 1995/1996) three medicines from the anti-protease group: saquinavir, ritonavir and indinavir have been admitted to be used for treatment of AIDS by the American agency for the control of drugs and foods. FDA, in the exceptionally short time. In the article there is also a description of a concept represented by R. Price, concerning the origin of psychiatric disturbances in the course of AIDS, as well as some results of recent clinical studies on psychiatric disturbances in the course of AIDS.
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PMID:[HIV follow-up. New data on pathophysiology and treatment of psychiatric disturbances in the course of AIDS]. 952 65

This study explores whether previous failures on antiretroviral drug regimens preclude the possibility of immune restoration. This was assessed by evaluating T cell subset changes in individuals who received a salvage regimen of highly active antiretroviral therapy (HAART) after initially failing protease inhibitor monotherapy. Ten HIV-1-infected asymptomatic patients received a regimen of indinavir, zidovudine, and 3TC after failing saquinavir monotherapy. Changes in absolute numbers of naive, memory, and activated CD4+ and CD8+ T cells expressing a selection of CD45RA, CD62L, CD45RO, HLA-DR, and CD38 markers were monitored prospectively over 6 months. These measurements were correlated with plasma viral load along with alterations in a selected CD8+ V alpha/Vbeta T cell receptor (TCR) repertoire. Over 6 months there was a progressive increase in numbers of CD4+ memory (CD45RA-CD62L+) and naive (CD45RA+CD62L+) T cells, which displayed a modest inverse correlation with viral load. Two phases of CD8+ memory cell changes were identified, consisting of a transient increase in CD45RA+CD62L- numbers after 2 months and thereafter a progressive rise in CD45RA-CD62L+ cells until 6 months. A strong correlation existed between reduced viral load and loss of activated CD8+CD38+HLA-DR+ cell numbers. There was also a temporary broadening of the CD8+ V alpha/Vbeta TCR repertoire at 8 weeks, which became skewed after 6 months in parallel with reduced viral suppression. Closer analysis of naive and memory cell subset proportions in individual patients revealed that enlarged pools of naive subsets were evident in those patients with rebounds in viral load. Overall, drug-experienced patients responding to HAART displayed increased numbers of naive and memory CD4+ subsets, and reduced CD8+ cell activation with a loss of TCR skewing.
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PMID:Changes in CD4+ and CD8+ T cell subsets in response to highly active antiretroviral therapy in HIV type 1-infected patients with prior protease inhibitor experience. 959 10

Human immunodeficiency virus type 1 (HIV-1) strains dually resistant to zidovudine and lamivudine (3TC) may arise during zidovudine-3TC combination therapy. The objective of this cross-sectional study (n = 43 patients) was to test the association between therapy response (clinical and immunologic) to zidovudine-3TC and the level of phenotypic zidovudine resistance and zidovudine resistance-associated genotype of 3TC-resistant isolates. Other variables included were baseline CD4+ cell count, baseline Centers for Disease Control and Prevention (CDC) classification, virus load, and time receiving zidovudine. Phenotypic resistance was assessed using a recombinant virus assay. Genotypic analysis was based on population sequencing of plasma HIV-1. In a univariate analysis using a logistic regression model, it was found that therapy response was significantly associated with phenotypic and genotypic zidovudine resistance, baseline CD4+ cell count, and virus load. After adjustment for all variables, phenotypic resistance to zidovudine remained the only significantly associated factor, independent of baseline CD4+ cell count, baseline CDC classification, and virus load.
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PMID:Dual resistance to zidovudine and lamivudine in patients treated with zidovudine-lamivudine combination therapy: association with therapy failure. 960 29

The appearance in the clinic of two to three new antiretroviral agents yearly since 1995 has permitted unprecedented advances in HIV treatment. This remarkable pace of drug development is a testimony to an extraordinary international effort involving scientists, clinicians, governments, community activists and industry dedicated to the rapid and safe development of novel therapies. New drugs present the opportunity to improve HIV therapy. They also create an enormous challenge to the clinician, who must constantly assimilate data on new drugs and incorporate this information into practical management strategies. Combination therapy has proven the most effective approach to treat HIV disease. The profound and sustained viral suppression achievable with combinations such as indinavir (IDV), lamivudine (3TC) and zidovudine (ZDV) have resulted in a dramatic shift in HIV treatment paradigms over the last year. The full potential of combination therapy with available drugs has yet to be realized as only a limited number of the possible combinations incorporating new drugs have been fully tested. Even drugs available for many years may have untapped potential. Didanosine (ddI) and stavudine (d4T), once thought to be contraindicated in combination because of their overlapping peripheral neuropathy toxicity, have proven well tolerated and effective. Combination therapy can increase antiviral suppression, prevent drug resistance, optimize drug exposure and simplify dosing, but it can also result in pharmacologic antagonism, subtherapeutic drug concentrations and unexpected toxicities. Clinical studies have confirmed in vitro studies showing pharmacologic antagonism for the combination of ZDV and d4T. Combining protease inhibitors with each other or with non-nucleoside reverse transcriptase inhibitors is complicated by effects both classes of drugs have on drug metabolism and clearance. These observations underline the importance of carefully conducted clinical studies to characterize safety, pharmacokinetics and efficacy of combination therapies. In this review, we will first summarize the clinical profile of new drugs which either became commercially available last year [nelfinavir, nevirapine, delavirdine (DLV)] or are in the late stages of clinical development (DMP-266, abacavir and 141W94). Later we will summarize new data on nucleoside, protease inhibitor and non-nucleoside reverse transcriptase combination regimens. Finally, we will briefly mention new drugs in early stages of development.
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PMID:New antiretrovirals and new combinations. 963 99


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