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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

HIV strains were isolated from HIV-infected patients and AIDS patients in CIS. A total of 81 HIV isolates were obtained. The isolates were identified by using immunofluorescence and enzyme immunoassay, by determining the activity of reverse transcriptase, immunoblot, electron microscopy, polymerase chain reaction. Of the 81 isolates 79 were HIV-1 and 2 HIV-2. The strains differed in their infectivity, the kinetics of virus antigen accumulation, and the spectrum of susceptible cell lines. The viruses isolated may be assigned as two groups: high and low infective. The biological properties of the national HIV isolates were shown to be similar to the prototype HIV strains isolated elsewhere.
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PMID:[The characteristics of the HIV isolated from HIV-infected persons and AIDS patients on the territory of the CIS]. 128 12

Azidothymidine (retrovir) and didesoxyinosine, which represent nucleoside agents, are major remedies in the treatment of HIV infection and acquired immunodeficiency syndrome (AIDS). The paper describes the molecular mechanism of their action. It implicates that triphosphates of these nucleosides selectively suppress the activity of reverse transcriptase (RNA-dependent DNA polymerase) of HIV by a termination mechanism. This results in effective inhibition of HIV reproduction and recovery of lymphocyte count and yields marked therapeutical benefits. The new generation anti-HIV agents are nucleoside-based phosphonates which were discovered by Russian investigators in 1987. The agents having a significant anti-HIV activity are low toxic. Emphasis is made on combined therapy of HIV infection, which holds much promise.
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PMID:[Reverse transcriptase inhibitors and the therapy of HIV infection]. 128 19

Catechin derivatives including (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC) and green tea extract (GTE) were found to inhibit the activities of cloned human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT), duck hepatitis B virus replication complexes reverse transcriptase (DHBV RCs RT), herpes simplex virus 1 DNA polymerase (HSV-1 DNAP) and cow thymus DNA polymerase alpha (CT DNAP alpha). EGCG and ECG were shown to be very potent inhibitors of HIV-1 RT. According to the IC50 values for HIV-1 RT, these compounds can be ordered as EGCG 0.0066 mumol/L > ECG 0.084 mumol/L > GTE 0.1 microgram/ml > EGC 7.2 mumol/L. DHBV RCs RT was the least sensitive to these compounds. Kinetic study showed that EGCG exerts a mixed inhibition with respect to external template inducer poly (rA).oligo (dT) 12-18 and a noncompetitive inhibition with respect to substrate dTTP for HIV-1 RT. Bovine serum albumin significantly reduced the inhibitory effects of catechin analogues and GTE on HIV-1 RT. In tissue culture GTE inhibited the cytopathic effect of coxsackie B3 virus, but did not inhibit the cytopathic effects of HSV-1, HSV-2, influenza A or influenza B viruses.
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PMID:[The inhibitory effects of catechin derivatives on the activities of human immunodeficiency virus reverse transcriptase and DNA polymerases]. 128 89

Mechanisms of the effects of the dTTP analogues 3'-azido-3'-deoxythymidine 5'-triphosphate (AZTTP) and 3'-amino-3'-deoxythymidine 5'-triphosphate (NH2 TTP) upon the HIV-1 reverse transcriptase (RT) are discussed. These compounds block the RT in vitro and do so by different kinetic mechanisms. Infidelity of replication is a hallmark of the HIV-1 RT, and replication errors by the enzyme on RNA and DNA templates are discussed. The enzyme's infidelity has ramifications for inhibition: On the one hand, the propensity to produce mutations enhances the ability of the virus to escape inhibitors whereas on the other hand, the infidelity of the reverse transcriptase may allow the development of imaginative inhibitor strategies.
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PMID:Inhibitors of HIV-1 reverse transcriptase and fidelity of in vitro DNA replication. 128 1

We have previously demonstrated that acidic medium inhibits the replication of HIV-1. The present study was designed to examine the effects of other growth conditions and infection of fibroblasts by coculture with HIV infected lymphoid cells. Several lymphoblastoid cell lines normally grown in RPMI-1640 were grown in Eagle's MEM. These cells supported virus replication to higher titres than did RPMI-1640. Peak viral titres were achieved within 24-48 h after newly infected or chronically infected cells were placed in fresh medium. When virus was stored in liquid medium either frozen or at higher temperatures, virus titres were retained for several months while frozen but decreased upon storage at 4 degrees C or higher. If cells were passaged after trypsinization in Ca(++)-depleted medium, then a decreased susceptibility of cells for HIV-1 by 2 log10 at 24 h post infection was observed. Infectivity of cell-free and cell-associated HIV-1 was measured using syncytium formation, reverse transcriptase activity and p24 antigen. No fusion between HIV-1 infected CD4+ lymphoblasts and CD4- fibroblasts was observed but HIV-1 infected lymphoid cells, even in the absence of syncytium formation, exerted a strong toxic effect on fibroblasts. This study extends previous findings that medium acidity was inhibitory to virus replication and survival. Thus, conditions for study of HIV must be well controlled in buffered medium so that misleading results are not obtained regarding virus multiplication and possibly regarding transmission to and pathogenesis in CD4- cells.
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PMID:The influence of cell culture and storage conditions on HIV-1 infectivity and fusogenic activity. 128 37

The anti-HIV activities of two new polyanionic polymers (AM 242 and AM 612) were investigated in cell culture-based and biochemical antiviral assays. These compounds inhibited the reverse transcriptases from HIV-1 and HIV-2, using enzyme purified from virions and either a ribosomal RNA or gapped duplex DNA as the template. With the ribosomal RNA template, AM 242 and AM 612 had ID50 values of 1.1 and 0.10 micrograms/ml against the HIV-1 reverse transcriptase. In vitro cell based assays determined that both compounds significantly inhibited both the cytopathic effects associated with HIV-1 infection and the replication of virus in infected cells. AM 242 had an IC50 of approximately 1.0 micrograms/ml, while that of AM 612 was 0.19 micrograms/ml. These two active polyanionic polymers were effective in inhibiting the growth of a panel of HIV-1 isolates and were also active against HIV-2. Although the compounds were toxic at high concentration, they had antiviral activity over a wide range of nontoxic concentrations, yielding a high selectivity index. AM 612 was 100% protective for CEM cells from 320 ng/ml to 1 microgram/ml. Both compounds caused a significant increase in cellular proliferation as determined by the concentration-dependent increase in incorporation of radioactive precursors into cellular macromolecules.
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PMID:Significant anti-HIV activity of new modified polyanionic polymers in vitro. 129 18

Bovine immunodeficiency-like virus (BIV) is a recently identified lentivirus that infects cattle. The virus has structural and genetic similarities to human HIV. The present study demonstrates that BIV can be activated by bovine herpesvirus type 1 (BHV-1), a pathogen frequently associated with cattle diseases. Activation of BIV expression can be detected as increased BIV reverse transcriptase activity, increased in the number of syncytia induced by BIV, and increased in the steady state level of BIV-specific RNA upon BHV-1 super-infection. Additional transactivation studies using the BIV-LTR (long terminal repeat) were conducted. The BIV-LTR was linked to the chloramphenicol acetyl transferase gene (CAT) and transfected into bovine cell cultures in order to quantitate the levels of BIV-LTR expression. When the transfected cells were infected by BHV-1, there was an increase in CAT expression, indicating transactivation of the BIV-LTR by BHV-1. Most of the transactivation activities were abolished with an LTR construct that has deleted the NF-kappa B-like sequence located in the U3 region of the LTR. In order to further demonstrate that activation of the BIV-LTR involves factors that may bind to the LTR sequences, gel retardation assays were carried out using the BIV-LTR U3 region as probe. Our results showed that BHV-1 infection resulted in an induction of factor(s) that binds to the NF-kappa B-like sequence on the BIV-LTR. This suggests that transactivation of BIV by BHV-1 may be mediated by a bovine NF-kappa B-like protein that binds to the target sequence in the BIV promoter region.
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PMID:Activation of bovine immunodeficiency-like virus expression by bovine herpesvirus type 1. 131 80

The role of drugs inhibiting viral replication in patients infected with HIV has been confirmed. Until now only dideoxynucleosides, which are reverse transcriptase inhibitors, have demonstrated antiviral activity in humans. A number of compounds acting on other steps of the viral cycle are currently being evaluated and clinical trials are being performed. Some investigators are attempting to inhibit the binding of viral particles to target cells and their penetration into these by acting on the interaction between HIV ant the CD4 molecule. Another approach consists in the characterization of enzymatic activities which are specific of HIV, other than reverse transcriptase, such as ribonuclease H, integrase or protease, in order to prepare specific inhibitors. Attempts are made to inhibit retroviral gene expression and production of viral particles in infected cells. The development of new nucleoside analogues and drugs with mechanisms of action and toxicities different from those of zidovudine should allow in the near future combination chemotherapy of HIV infection.
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PMID:[Chemotherapy for human immunodeficiency virus infection. Current status and perspectives]. 134 31

To assess the correlations between clinical and biological stages of HIV infection and HIV isolation, peripheral blood mononuclear cells from 389 HIV-infected patients were studied by 30-day cocultures with normal lymphocytes. HIV isolation was successful in 279/389 patients (71.7%). Positive isolation was more frequent in CDC IV cases (82%) than in CDC II and III cases (63.6% and 78.4% respectively). There was a close correlation between culture positivity and serum beta 2-microglobulin, CD4+ cell counts and serum p24 antigen. The day of peak detection of reverse transcriptase activity or peak p24 antigen in coculture supernatants was selected as a coculture kinetic parameter. The day of peak detection of HIV in culture occurred earlier in CDC IV cases than in CDC II and III cases, and was a prognostic factor in AIDS progression at 2 years. These data suggest that in vitro parameters related to both viral burden and replicative capacity of HIV isolates are relevant indicators of disease progression.
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PMID:Prognostic value of kinetic parameters of HIV isolation from peripheral blood mononuclear cells. 136 81

A semimicromethod was established for isolating human immunodeficiency virus (HIV) in plasma using 48-well plates and a pool of peripheral blood mononuclear cells (PBMC) from several donors as targets for infection, which increases the efficiency of isolation by reducing the effect of variability due to diverse donor cell susceptibility to HIV infection. The addition of H9 cells to the PBMC cultures did not affect measurable titers. Nevertheless, it potentiated strongly virus replication in terms of p24 production in the supernatant of the wells with HIV isolates, thus facilitating interpretation of the results. The titration of a virus strain of a known titre and reverse transcriptase activity in parallel provided a constant parameter of efficiency and reproducibility within each experiment, permitting comparison with results from other laboratories. The reproducibility of the method was highly significant (r = 0.97, P < 0.001); 68% of the 22 plasma samples from HIV-infected individuals tested by this method were positive. The presence of plasma HIV titer correlated well (P < 0.02) with the low count of CD4+ cells of less than 300/mm3, but not with the presence of the p24 antigen in the serum.
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PMID:Efficient and reproducible new semimicromethod for the detection and titration of HIV in human plasma. 136 19


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