scholarly journals A genetic-algorithm approach to simulating human immunodeficiency virus evolution reveals the strong impact of multiply infected cells and recombination

2005 ◽  
Vol 86 (11) ◽  
pp. 3109-3118 ◽  
Author(s):  
Gennady Bocharov ◽  
Neville J. Ford ◽  
John Edwards ◽  
Tanja Breinig ◽  
Simon Wain-Hobson ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Copy Number ◽  
Hamming Distance ◽  
Point Mutations ◽  
Strong Impact ◽  
Hiv Replication ◽  
Immunodeficiency Virus ◽  
Genetic Algorithm Approach ◽  
Infected Cells

It has been previously shown that the majority of human immunodeficiency virus type 1 (HIV-1)-infected splenocytes can harbour multiple, divergent proviruses with a copy number ranging from one to eight. This implies that, besides point mutations, recombination should be considered as an important mechanism in the evolution of HIV within an infected host. To explore in detail the possible contributions of multi-infection and recombination to HIV evolution, the effects of major microscopic parameters of HIV replication (i.e. the point-mutation rate, the crossover number, the recombination rate and the provirus copy number) on macroscopic characteristics (such as the Hamming distance and the abundance of n-point mutants) have been simulated in silico. Simulations predict that multiple provirus copies per infected cell and recombination act in synergy to speed up the development of sequence diversity. Point mutations can be fixed for some time without fitness selection. The time needed for the selection of multiple mutations with increased fitness is highly variable, supporting the view that stochastic processes may contribute substantially to the kinetics of HIV variation in vivo.

scholarly journals Failure of dideoxynucleosides to inhibit human immunodeficiency virus replication in cultured human macrophages.

1987 ◽  
Vol 166 (4) ◽  
pp. 1144-1149 ◽  
Author(s):  
D D Richman ◽  
R S Kornbluth ◽  
D A Carson
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Monocyte ◽  
Human Immunodeficiency Virus Replication ◽  
Hiv Replication ◽  
New Therapeutic Approaches ◽  
Immunodeficiency Virus ◽  
Infected Cells ◽  
T Lymphoblasts ◽  
Anti Hiv Agents

Primary human monocyte-derived macrophages (MDM) were shown to have diminished deoxynucleoside kinase activities compared to T lymphoblasts, and a reduced ability to phosphorylate dideoxynucleosides with anti-human immunodeficiency virus (HIV) activity. These drugs, azidothymidine (AZT), dideoxycytidine (ddC), and dideoxyadenosine (ddA), which are potent anti-HIV agents in CD4 lymphocytes, did not inhibit HIV replication in MDM, even at concentrations of 100 microM. This drug concentration of AZT is approximately 100-fold higher than the levels attained in the serum of treated patients and the levels required to inhibit HIV replication in lymphocytes. These observations may explain the failure of AZT therapy to clear viremia, consistent with the presence of a drug-resistant reservoir of infected cells in vivo. New therapeutic approaches to inhibit the replication of HIV in MDM may be needed.

Human herpesvirus 8 enhances human immunodeficiency virus replication in acutely infected cells and induces reactivation in latently infected cells

Blood ◽  
2005 ◽  
Vol 106 (8) ◽  
pp. 2790-2797 ◽  
Author(s):  
Elisabetta Caselli ◽  
Monica Galvan ◽  
Enzo Cassai ◽  
Arnaldo Caruso ◽  
Laura Sighinolfi ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Endothelial Cells ◽  
Mononuclear Cells ◽  
Human Herpesvirus ◽  
Human Herpesvirus 8 ◽  
Human Immunodeficiency Virus Replication ◽  
Hiv Replication ◽  
Herpesvirus 8 ◽  
Immunodeficiency Virus ◽  
Infected Cells

AbstractHuman herpesvirus 8 (HHV-8) is etiologically associated with Kaposi sarcoma (KS), the most common AIDS-associated malignancy. Previous results indicate that the HHV-8 viral transactivator ORF50 interacts synergistically with Tat protein in the transactivation of human immunodeficiency virus (HIV) long terminal repeat (LTR), leading to increased cell susceptibility to HIV infection. Here, we analyze the effect of HHV-8 infection on HIV replication in monocyte-macrophage and endothelial cells, as potential targets of coinfection. Primary or transformed monocytic and endothelial cells were infected with a cell-free HHV-8 inoculum and subsequently infected with lymphotropic or monocytotropic strains of HIV. The results show that HHV-8 coinfection markedly increases HIV replication in both cell types. HHV-8 infection induces also HIV reactivation in chronically infected cell lines and in peripheral blood mononuclear cells (PBMCs) from patients with asymptomatic HIV, suggesting the possibility that similar interactions might take place also in vivo. Furthermore, coinfection is not an essential condition, since contiguity of differently infected cells is sufficient for HIV reactivation. The results suggest that HHV-8 might be a cofactor for HIV progression and that HHV-8-infected endothelial cells might play a relevant role in transendothelial HIV spread. (Blood. 2005;106:2790-2797)

scholarly journals Vpr Is Required for Efficient Nef Expression from Unintegrated Human Immunodeficiency Virus Type 1 DNA

2007 ◽  
Vol 81 (19) ◽  
pp. 10515-10523 ◽  
Author(s):  
Betty Poon ◽  
Michael A. Chang ◽  
Irvin S. Y. Chen
Keyword(s):  
Human Immunodeficiency Virus ◽  
Viral Rna ◽  
Productive Infection ◽  
Hiv Replication ◽  
Viral Dna ◽  
Hiv Tat ◽  
Immunodeficiency Virus ◽  
Unintegrated Dna ◽  
Infected Cells

ABSTRACT Unintegrated human immunodeficiency virus (HIV) DNA are viral DNA products formed naturally during HIV replication. While the integrated proviral DNA form is transcriptionally active and results in productive infection, unintegrated DNA is also capable of expression of viral RNA and proteins. Previously, we showed that HIV Vpr enhances expression from integrase-defective HIV. Here we show that Vpr activation of expression is partially dependent upon the presence of a transcriptionally active HIV promoter and results in increased transcription of unspliced gag and spliced nef viral RNA. While Tat is detectable during infection with integrase-defective HIV, Tat levels are not affected by the presence of Vpr. Mutation studies reveal that Tat is dispensable for the Vpr-mediated enhancement of expression from unintegrated DNA. We find that virion-associated Vpr is sufficient for Nef expression from unintegrated viral DNA, resulting in the efficient downregulation of CD4 from the surface of infected cells. These results provide a mechanism by which Nef expression from unintegrated HIV type 1 DNA expression occurs.

scholarly journals How Many Human Immunodeficiency Virus Type 1-Infected Target Cells Can a Cytotoxic T-Lymphocyte Kill?

2005 ◽  
Vol 79 (21) ◽  
pp. 13579-13586 ◽  
Author(s):  
W. David Wick ◽  
Otto O. Yang ◽  
Lawrence Corey ◽  
Steven G. Self
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Target Cells ◽  
Immunodeficiency Virus ◽  
Infected Cells ◽  
Hiv 1

ABSTRACT The antiviral role of CD8+ cytotoxic T lymphocytes (CTLs) in human immunodeficiency virus type 1 (HIV-1) infection is poorly understood. Specifically, the degree to which CTLs reduce viral replication by killing HIV-1-infected cells in vivo is not known. Here we employ mathematical models of the infection process and CTL action to estimate the rate that CTLs can kill HIV-1-infected cells from in vitro and in vivo data. Our estimates, which are surprisingly consistent considering the disparities between the two experimental systems, demonstrate that on average CTLs can kill from 0.7 to 3 infected target cells per day, with the variability in this figure due to epitope specificity or other factors. These results are compatible with the observed decline in viremia after primary infection being primarily a consequence of CTL activity and have interesting implications for vaccine design.

scholarly journals Human cytomegalovirus modulation of CCR5 expression on myeloid cells affects susceptibility to human immunodeficiency virus type 1 infection

2006 ◽  
Vol 87 (8) ◽  
pp. 2171-2180 ◽  
Author(s):  
Christine A. King ◽  
Joan Baillie ◽  
John H. Sinclair
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Cytomegalovirus ◽  
Cell Types ◽  
Ccr5 Expression ◽  
Immunodeficiency Virus ◽  
Infected Cells ◽  
Bystander Cells ◽  
Hiv 1

For some time there has been evidence suggesting an interaction between human cytomegalovirus (HCMV) and Human immunodeficiency virus (HIV) in the pathogenesis of AIDS. Here, the interaction of HCMV and HIV-1 was examined in monocyte/macrophage cells, two cell types known to be targets for both viruses in vivo. Infection experiments demonstrated that prior infection with HCMV impeded subsequent superinfection with HIV-1. In contrast, uninfected bystander cells within the population were still permissive for HIV-1 infection and were also found to express increased levels of Gag after HIV-1 superinfection. Analysis of CCR5, a co-receptor for HIV-1, on HCMV-infected and bystander cells showed a substantial loss of surface CCR5 expression on infected cells due to HCMV-induced reduction of total cellular CCR5. In contrast, uninfected bystander cells displayed increased surface CCR5 expression. Furthermore, the data suggested that soluble factor(s) secreted from HCMV-infected cells were responsible for the observed upregulation of CCR5 on uninfected bystander cells. Taken together, these results suggest that, whilst HCMV-infected monocytes/macrophages are refractory to infection with HIV-1, HCMV-uninfected bystander cells within a population are more susceptible to HIV-1 infection. On this basis, HCMV infection may contribute to the pathogenesis of HIV-1.

scholarly journals Use of recombinant viruses to assess the pattern of early human immunodeficiency virus breakthrough infection in the presence of stavudine

1999 ◽  
Vol 80 (9) ◽  
pp. 2361-2367
Author(s):  
Daniel J. Medina ◽  
Peter P. Tung ◽  
Roger K. Strair
Keyword(s):  
Human Immunodeficiency Virus ◽  
High Efficiency ◽  
Mononuclear Cells ◽  
Cell Types ◽  
Small Subset ◽  
Hiv Replication ◽  
Recombinant Viruses ◽  
Immunodeficiency Virus ◽  
Infected Cells ◽  
Early Human

A variety of cell lines were infected with replication-defective recombinant retroviruses in the presence of stavudine (d4T). Cells which were infected despite the presence of d4T were isolated and subjected to infection with other retroviruses [replication-competent human immunodeficiency virus (HIV), replication-defective HIV or replication-defective recombinant murine retroviruses]. Each of the host cell types tested had a small subset of cells that were infected with HIV or murine retroviruses in the presence of d4T. Some of these infected cells could be infected repeatedly at high efficiency in the presence of d4T. This phenotype of ‘persistent refractoriness’ to the antiviral effects of d4T could be overcome by the addition of 5-fluoro-2-deoxyuridine (floxuridine) to d4T. The d4T–floxuridine combination also had potent antiretroviral effects in primary blood mononuclear cells.

scholarly journals Effect of Latent Human Immunodeficiency Virus Infection on Cell Surface Phenotype

2002 ◽  
Vol 76 (4) ◽  
pp. 1673-1681 ◽  
Author(s):  
David G. Brooks ◽  
Jerome A. Zack
Keyword(s):  
Human Immunodeficiency Virus ◽  
Highly Active Antiretroviral Therapy ◽  
Virus Production ◽  
Cellular Interactions ◽  
Cellular Activation ◽  
Highly Active ◽  
Immunodeficiency Virus ◽  
Latently Infected ◽  
Infected Cells

ABSTRACT Highly active antiretroviral therapy has succeeded in many cases in suppressing virus production in patients infected with human immunodeficiency virus (HIV); however, once treatment is discontinued, virus replication is rekindled. One reservoir capable of harboring HIV in a latent state and igniting renewed infection once therapy is terminated is a resting T cell. Due to the sparsity of T cells latently infected with HIV in vivo, it has been difficult to study viral and cellular interactions during latency. The SCID-hu (Thy/Liv) mouse model of HIV latency, however, provides high percentages of latently infected cells, allowing a detailed analysis of phenotype. Herein we show that latently infected cells appear phenotypically normal. Following cellular stimulation, the virus completes its life cycle and induces phenotypic changes, such as CD4 and major histocompatibility complex class I down-regulation, in the infected cell. In addition, HIV expression following activation did not correlate with expression of the cellular activation marker CD25. The apparently normal phenotype and lack of HIV expression in latently infected cells could prevent recognition by the immune response and contribute to the long-lived nature of this reservoir.

scholarly journals Saquinavir-mediated inhibition of human immunodeficiency virus (HIV) infection in SCID mice implanted with human fetal thymus and liver tissue: an in vivo model for evaluating the effect of drug therapy on HIV infection in lymphoid tissues.

1997 ◽  
Vol 41 (9) ◽  
pp. 1880-1887 ◽  
Author(s):  
M Pettoello-Mantovani ◽  
T R Kollmann ◽  
C Raker ◽  
A Kim ◽  
S Yurasov ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Hiv Infection ◽  
Scid Mice ◽  
Therapeutic Interventions ◽  
In Vivo Model ◽  
Lymphoid Tissues ◽  
Hiv Replication ◽  
Viral Loads ◽  
Immunodeficiency Virus

Treatment with protease inhibitors alone or in combination with inhibitors of reverse transcriptase potently suppresses levels of human immunodeficiency virus (HIV) RNA in plasma and thereby may significantly delay the progression of HIV-mediated disease. To investigate the effect of treatment with the protease inhibitor saquinavir on HIV replication in the lymphoid tissues, we used a SCID-hu mouse model that we developed, in which human thymic and liver tissues (hu-thy/liv) were implanted under both kidney capsules in SCID mice (thy/liv-SCID-hu mice). These mice are populated in the periphery with large numbers of human T cells and develop disseminated HIV infection after intraimplant injection. thy/liv-SCID-hu mice with established HIV infection that were treated for 1 month with saquinavir had a significantly lower viral load present in the implanted hu-thy/liv and mouse spleen than did the untreated HIV-infected thy/liv-SCID-hu mice. To examine the capacity of acute treatment with saquinavir to prevent HIV infection, some thy/liv-SCID-hu mice were inoculated with HIV and then immediately started on saquinavir. Although treated mice had markedly lower viral loads in the thy/liv implants and spleens, HIV infection was not completely prevented. Thus, the effect of antiviral therapy on HIV infection in the major site of HIV replication, the lymphoid tissues, can be readily evaluated in our thy/liv-SCID-hu mice. These mice should prove to be a useful model for determining the in vivo effectiveness of different therapeutic interventions on acute and chronic HIV infection.

scholarly journals Human Immunodeficiency Virus Type 1 Protease Cleaves Procaspase 8 In Vivo

2007 ◽  
Vol 81 (13) ◽  
pp. 6947-6956 ◽  
Author(s):  
Zilin Nie ◽  
Gary D. Bren ◽  
Stacey R. Vlahakis ◽  
Alicia Algeciras Schimnich ◽  
Jason M. Brenchley ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Specific Product ◽  
Immunodeficiency Virus ◽  
Infected Cells ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) infection causes apoptosis of infected CD4 T cells as well as uninfected (bystander) CD4 and CD8 T cells. It remains unknown what signals cause infected cells to die. We demonstrate that HIV-1 protease specifically cleaves procaspase 8 to create a novel fragment termed casp8p41, which independently induces apoptosis. casp8p41 is specific to HIV-1 protease-induced death but not other caspase 8-dependent death stimuli. In HIV-1-infected patients, casp8p41 is detected only in CD4+ T cells, predominantly in the CD27+ memory subset, its presence increases with increasing viral load, and it colocalizes with both infected and apoptotic cells. These data indicate that casp8p41 independently induces apoptosis and is a specific product of HIV-1 protease which may contribute to death of HIV-1-infected cells.

scholarly journals Vpu Increases Susceptibility of Human Immunodeficiency Virus Type 1-Infected Cells to Fas Killing

1999 ◽  
Vol 73 (1) ◽  
pp. 92-100 ◽  
Author(s):  
Carolyn R. Casella ◽  
Eric L. Rapaport ◽  
Terri H. Finkel
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Jurkat T Cells ◽  
Blood Leukocytes ◽  
Immunodeficiency Virus ◽  
Infected Cells ◽  
Increased Sensitivity ◽  
The Subject

ABSTRACT The importance of the Fas death pathway in human immunodeficiency virus (HIV) infection has been the subject of many studies. Missing from these studies is direct measurement of infected cell susceptibility to Fas-induced death. To address this question, we investigated whether T cells infected with HIV are more susceptible to Fas-induced death. We found that Fas cross-linking caused a decrease in the number of HIV-infected Jurkat T cells and CD4+peripheral blood leukocytes (PBLs). We confirmed this finding by demonstrating that there were more apoptotic infected than uninfected cells after Fas ligation. The increase in sensitivity of HIV-infected cells to Fas killing mapped to vpu, whilenef, vif, vpr, and second exon oftat did not appear to contribute. Furthermore, expression of Vpu in Jurkat T cells rendered them more susceptible to Fas-induced death. These results show that HIV-infected cells are more sensitive to Fas-induced death and that the Vpu protein of HIV contributes to this sensitivity. The increased sensitivity of HIV-infected cells to Fas-induced death might help explain why these cells have such a short in vivo half-life.

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