| 1. |
- Borggren, Marie, et al.
(författare)
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Evolution of DC-SIGN use revealed by fitness studies of R5 HIV-I variants emerging during AIDS progression
- 2008
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Ingår i: Retrovirology. - : Springer Science and Business Media LLC. - 1742-4690. ; 5:28
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Tidskriftsartikel (refereegranskat)abstract
- Background: At early stages of infection CCR5 is the predominant HIV-1 coreceptor, but in approximately 50% of those infected CXCR4-using viruses emerge with disease progression. This coreceptor switch is correlated with an accelerated progression. However, those that maintain virus exclusively restricted to CCR5 (R5) also develop AIDS. We have previously reported that R5 variants in these "non-switch virus" patients evolve during disease progression towards a more replicative phenotype exhibiting altered CCR5 coreceptor interactions. DC-SIGN is a C-type lectin expressed by dendritic cells that HIV-1 may bind and utilize for enhanced infection of T cells in trans. To further explore the evolution of the R5 phenotype we analyzed sequential R5 isolates obtained before and after AIDS onset, i.e. at the chronic stage and during end-stage disease, with regard to efficiency of DC-SIGN use in trans-infections. Results: Results from binding and trans-infection assays showed that R5 viruses emerging during end-stage AIDS disease displayed reduced ability to use DC-SIGN. To better understand viral determinants underlying altered DC-SIGN usage by R5 viruses, we cloned and sequenced the HIV-1 env gene. We found that end-stage R5 viruses lacked potential N-linked glycosylation sites (PNGS) in the gp120 V2 and V4 regions, which were present in the majority of the chronic stage R5 variants. One of these sites, amino acid position 160 (aa160) in the V2 region, also correlated with efficient use of DC-SIGN for binding and trans-infections. In fitness assays, where head-to-head competitions between chronic stage and AIDS R5 viruses were setup in parallel direct and DCSIGN-mediated infections, results were further supported. Competitions revealed that R5 viruses obtained before AIDS onset, containing the V2 PNGS at aa160, were selected for in the transinfection. Whereas, in agreement with our previous studies, the opposite was seen in direct target cell infections where end-stage viruses out-competed the chronic stage viruses. Conclusion: Results of our study suggest R5 virus variants with diverse fitness for direct and DCSIGN-mediated trans-infections evolve within infected individuals at end-stage disease. In addition, our results point to the importance of a glycosylation site within the gp120 V2 region for efficient DC-SIGN use of HIV-1 R5 viruses.
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| 2. |
- Borggren, Marie, et al.
(författare)
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Increased Sensitivity to Broadly Neutralizing Antibodies of End-Stage Disease R5 HIV-1 Correlates with Evolution in Env Glycosylation and Charge.
- 2011
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:6
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Tidskriftsartikel (refereegranskat)abstract
- Induction of broadly neutralizing antibodies, such as the monoclonal antibodies IgGb12, 2F5 and 2G12, is the objective of most antibody-based HIV-1 vaccine undertakings. However, despite the relative conserved nature of epitopes targeted by these antibodies, mechanisms underlying the sensitivity of circulating HIV-1 variants to broadly neutralizing antibodies are not fully understood. Here we have studied sensitivity to broadly neutralizing antibodies of HIV-1 variants that emerge during disease progression in relation to molecular alterations in the viral envelope glycoproteins (Env), using a panel of primary R5 HIV-1 isolates sequentially obtained before and after AIDS onset.
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| 3. |
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| 4. |
- Karlsson, Ulf, et al.
(författare)
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Mode of coreceptor use by R5 HIV type 1 correlates with disease stage: a study of paired plasma and cerebrospinal fluid isolates.
- 2009
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Ingår i: AIDS research and human retroviruses. - : Mary Ann Liebert Inc. - 1931-8405 .- 0889-2229. ; 25:12, s. 1297-1305
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Tidskriftsartikel (refereegranskat)abstract
- Through the use of chimeric CXCR4/CCR5 receptors we have previously shown that CCR5-tropic (R5) HIV-1 isolates acquire a more flexible receptor use over time, and that this links to a reduced viral susceptibility to inhibition by the CCR5 ligand RANTES. These findings may have relevance with regards to the efficacy of antiretroviral compounds that target CCR5/virus interactions. Compartmentalized discrepancies in coreceptor use may occur, which could also affect the efficacy of these compounds at specific anatomical sites, such as within the CNS. In this cross-sectional study we have used wild-type CCR5 and CXCR4 as well as chimeric CXCR4/CCR5 receptors to characterize coreceptor use by paired plasma and cerebrospinal fluid (CSF) isolates from 28 HIV-1-infected individuals. Furthermore, selected R5 isolates, with varying chimeric receptor use, were tested for sensitivity to inhibition by the CCR5 antagonist TAK-779. Discordant CSF/plasma virus coreceptor use was found in 10/28 patients. Low CD4+ T cell counts correlated strongly with a more flexible mode of R5 virus CCR5 usage, as disclosed by an increased ability to utilize chimeric CXCR4/CCR5 receptors, specifically receptor FC-2. Importantly, an elevated ability to utilize chimeric receptors correlated with a reduced susceptibility to inhibition by TAK-779. Our findings show that a discordant CSF and plasma virus coreceptor use is not uncommon. Furthermore, we provide support for an emerging paradigm, where the acquisition of a more flexible mode of CCR5 usage is a key event in R5 virus pathogenesis. This may, in turn, negatively impact the efficacy of CCR5 antagonist treatment in late stage HIV-1 disease.
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| 5. |
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| 6. |
- Nowroozalizadeh, Salma, et al.
(författare)
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Microbial Translocation Correlates with the Severity of Both HIV-1 and HIV-2 Infections
- 2010
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Ingår i: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 1537-6613 .- 0022-1899. ; 201:8, s. 1150-1154
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Tidskriftsartikel (refereegranskat)abstract
- Microbial translocation has been linked to systemic immune activation during human immunodeficiency virus (HIV) type 1 infection. Here, we show that an elevated level of microbial translocation, measured as plasma lipopolysaccharide (LPS) concentration, correlates with AIDS in both individuals infected with HIV type 1 and individuals infected with HIV type 2. LPS concentration also correlates with CD4(+) T cell count and viral load independently of HIV type. Furthermore, elevated plasma LPS concentration was found to be concomitant with defective innate and mitogen responsiveness. We suggest that microbial translocation may contribute to loss of CD4(+) T cells, increase in viral load, and defective immune stimuli responsiveness during both HIV type 1 and HIV type 2 infections.
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| 7. |
- Nowroozalizadeh, Salma, et al.
(författare)
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Reply to Redd et al
- 2011
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Ingår i: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 1537-6613 .- 0022-1899. ; 203:5, s. 746-746
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Nowroozalizadeh, Salma, et al.
(författare)
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Studies on toll-like receptor stimuli responsiveness in HIV-1 and HIV-2 infections
- 2009
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Ingår i: Cytokine. - : Elsevier BV. - 1096-0023 .- 1043-4666. ; 46:3, s. 325-331
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Tidskriftsartikel (refereegranskat)abstract
- Background: HIV-1 and HIV-2 are two related viruses with distinct clinical outcomes, where HIV-1 is more pathogenic and transmissible than HIV-2. The pathogenesis of both infections is influenced by the dysregulation and deterioration of the adaptive immune system. However, their effects on the responsiveness of innate immunity are less well known. Here, we report on toll-like receptor (TLR) stimuli responsiveness in HIV-1 or HIV-2 infections. Methods: Whole blood from 235 individuals living in Guinea-Bissau who were uninfected, infected with HIV-1, infected with HIV-2, and/or infected with HTLV-1, was stimulated with TLR7/8 and TLR9 agonists, R-848 and unmethylated CpG DNA. After TLR7/8 and TLR9 stimuli, the expression levels of IL-12 and IFN-alpha were related to gender, age, infection status, CD4(+) T cell counts. and plasma viral load. Results: Defective TLR9 responsiveness was observed in the advanced disease stage, along with CD4(+) T cell loss in both HIV-1 and HIV-2 infections. Moreover, TLR7/8 responsiveness was reduced in HIV-1 infected individuals compared with uninfected controls. Conclusions: Innate immunity responsiveness can be monitored by whole blood stimulation. Both advanced HIVA and HIV-2 infections may cause innate immunity dysregulation. (C) 2009 Elsevier Ltd. All rights reserved.
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| 9. |
- Repits, Johanna
(författare)
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Co-evolution of the HIV-1 R5 phenotype and the viral envelope glycoproteins
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- To gain entry into target cells, HIV-1 binds to CD4 via the viral glycoprotein gp120. This interac-tion initiates a series of events including binding of a coreceptor, CCR5 and/or CXCR4, and ulti-mately leads to gp41-mediated fusion of the viral and cell membranes. CCR5-restricted (R5) vi-ruses predominate in early, asymptomatic stages of the infection. Emergence of viruses able to use CXCR4 instead of, or in addition to, CCR5 for cell entry has been correlated with rapid progres-sion to AIDS. Importantly, approximately 50% of HIV-1 infected individuals progress to AIDS while maintaining viruses that are restricted to CCR5. The major reason for today’s inadequate treatment of HIV-1 infection and failure to develop a potent vaccine is the fast evolution of the virus. Due to an error-prone reverse transcriptase en-zyme (RT), mutations are continuously introduced into the viral genome, which result in pheno-typic variation of the virus. Thus, the intra-host virus evolution can be traced by analyzing the changes in the viral genome over time. We have studied the intra-patient evolution of the R5 phe-notype and the viral envelope glycoproteins in patients that maintain an exclusive CCR5-restricted virus population. We used a panel of sequentially isolated viruses from patients who all progressed to AIDS. Isolations were done at the chronic, asymptomatic phase and after AIDS onset, at which time the patients were all severely immunodeficient. Our results revealed emergence of virus vari-ants with enhanced viral fitness during end-stage disease. After AIDS onset viruses with higher infectivity and replicative capacity dominated. These viruses were also more resistant to inhibition by several entry inhibiting compounds, which suggests a central role of the viral Env (gp120/gp41 complex) in the evolution of viral properties towards increased fitness. To dissect the evolution of the viral Env at the molecular level, we cloned, sequenced and analyzed full length gp160 env clones. We discovered that the Env of end-stage R5 viruses were less glycosylated and had higher net charge. These changes were all mapped to gp120 and specifi-cally to the variable regions, i.e., the outer surface of the Env. Furthermore, the reduced glycan shield correlated with a decreased ability to infect target cells in DC-SIGN-mediated trans-infection and increased sensitivity to MAb neutralization. Viruses with increased Env charge are selected for during severe immunodeficiency and correlated with enhanced cell attachment and properties of viral fitness. Both reduced glycosylation and increased net charge of Env correlated with reduced CD4+ T cell count at time of R5 virus isolation. In summary, during end-stage disease, R5 virus variants emerge with increased viral fitness. The elevated fitness is a result of altered phenotypic properties. The underlying mechanisms can be mapped to the molecular properties of the viral Env. Thus, after AIDS onset, viruses with al-tered phenotypic properties may evolve, in an opportunistic manner, and result in the emergence of HIV-1 R5 variants with enhanced pathogenicity.
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| 10. |
- Repits, Johanna, et al.
(författare)
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Primary HIV-1 R5 isolates from end-stage disease display enhanced viral fitness in parallel with increased gp120 net charge.
- 2008
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Ingår i: Virology. - : Elsevier BV. - 1096-0341 .- 0042-6822. ; 379:1, s. 125-134
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Tidskriftsartikel (refereegranskat)abstract
- To better understand the evolution of the viral envelope glycoproteins (Env) in HIV-1 infected individuals who progress to AIDS maintaining an exclusive CCR5-using (R5) virus population, we cloned and sequenced the env gene of longitudinally obtained primary isolates. A shift in the electrostatic potential towards an increased net positive charge was revealed in gp120 of end-stage viruses. Residues with increased positive charge were primarily localized in the gp120 variable regions, with the exception of the V3 loop. Molecular modeling indicated that the modifications clustered on the gp120 surface. Furthermore, correlations between increased Env net charge and lowered CD4(+) T cell counts, enhanced viral fitness, reduced sensitivity to entry inhibitors and augmented cell attachment were disclosed. In summary, this study suggests that R5 HIV-1 variants with increased gp120 net charge emerge in an opportunistic manner during severe immunodeficiency. Thus, we here propose a new mechanism by which HIV-1 may gain fitness.
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