European Journal of Medical Research - Deutsche AIDS ...

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June 27, 2007 EUROPEAN JOURNAL OF MEDICAL RESEARCH 129 Conclusion: Our results demonstrate that expression of tBid under the control of the HIV-1 LTR promoter preferentially induces apoptosis in Tat- and Rev-positive cells suggesting that this suicide vector has the potential for effective use in a gene therapy to exclusively eliminate HIV-1 infected cells. F.25 (Poster) Induction of immune responses by Human Immunodeficiency Virus Type-1 (HIV-1) Pr55Gag virus-like particles (VLP) and the impact of the producer system upon activation of innate immune responses Bredl S. 1 , Sertl S. 1 , Wiesel M. 1 , Wild J. 1 , Deml L. 1 , Wagner R. 1 1 Universität Regensburg, Institut für Medizinsche Mikrobiologie und Hygiene, Molekulare Mikrobiologie und Gentherapie, Regensburg, Germany Objective: HIV-1 Pr55Gag virus-like particles (VLP) produced in the baculovirus expression system have been shown to represent strong inducers of the humoral and CMI in mice and non-human primates. This study aimed towards investigating the molecular mechanisms underlying the strong immunogenicity and adjuvanticity of such VLP. Methods: Pr55Gag VLP were produced (i) using the baculovirus (BV) expression system and (ii) mammalian 293T cells coexpressing the BV envelope protein gp64. Cytokine production (release of gIFN, IL5, others) from splenic cells of naïve mice and human monocyte derived DC (huMDDC) and the upregulation of costimulatory molecules (CD40, 80, 83, HAL DR, CCR7) on the surface of huMDDC were used as a measure for the activation of innate immunity by VLP antigens. Results: Ex vivo studies on huMDDC clearly demonstrated that VLP of BV origin, but not VLP produced in mammalian cells triggered MDDC maturation, activation and cytokine secretion. This lack of mammalian cell derived VLP to activate huMDDC could not be rescued by pseudotyping these VLP with BV gp64. Comparable results were obtained when murine splenic cells were used for the ex vivo studies. However, splenic cells from TLR9 knockout mice could be stimulated neither by mammalian, nor by BV produced VLP. Conclusion: These results clearly indicated that the potency of VLP to induce innate immune responses is not an intrinsic property of VLP rather than mediated by BV or insect cell derived components. The BV Env protein gp64 is clearly not contributing to TLR triggering, may however play a beneficial role in uptake of VLP by APC. F.26 (Poster) HIV vaccine candidates in cross-validation on dendritic cells Köstler J. 1 , Hofmann H. 1 , Böckl K. 1 , Tischer K. 2 , Osterrieder N. 3 , Wild J. 1 , Wagner R. 1 1 Universität Regensburg, Institut für Medizinsche Mikrobiologie und Hygiene, Molekulare Mikrobiologie und Gentherapie, Regensburg, Germany, 2 University Medical Center, Institut für Medizinische Mikrobiologie und Virologie, Kiel, Germany, 3 Cornell University, Microbiology and Immunology, Ithaca, United States of America Objectives: Recently we have generated a new HIV Vaccine candidate based on the Equine Herpesvirus I (EHV-1). The primary goal of the current study is to compare a clinical trial lot of a recombinant New-York-Vaccinia Virus based HIV vaccine candidate (NYVAC-C; expressing Gag/Pol/Nef) with a corresponding EHV-based vaccine construct (EHV-C) regarding their capacity to induce maturation of monocyte derived dendritic cells (MDDC). Methods: A recombinant EHV-1 C-GagPolNef (EHV-C) was generated using BAC-technology and RED-Recombination. MDDCs were infected with EHV-C and NYVAC-C at different MOIs. Expression of the transgenes was monitored by FACS and Western Blot analysis. Maturation of MDDCs was determined by FACS analysis of differentiation markers and in ELISA assay measuring secreted proinflammatory cytokine levels. Furthermore, early/late gene expression and antigen expression of the HIV vaccine candidates was measured via RNA quantification. Results: Depending on the used MOI a substantial fraction (~40%) of EHV-C infected MDDCs displayed expression of significant amounts of GagPolNef immunogens. MDDCs infected with EHV-C show various markers for DC maturation and activation as monitored by release of cytokines and surface expression of costimulatory signals. In contrast, MDDCs infected with NYVAC-C only weakly express HIV transgenes and do, upon direct infection, not support DC maturation or activation. NYVAC-C expresses very low amounts of a late gene F17R on MDDC, which could be interpreted as a block in the viral replication and responsible for the low transgene expression. Conclusion: EHV derived vectors support efficient transgene expression and provide signals required for DC maturation & activation. F.27 (Poster) Detection of distinct mutants of TRIM5-alpha mRNA derived from SIV infected macaques and HIV-1 infected individuals Jensen N. 1 , Stahmer I. 1 , Hoffmann D. 2 , Krepstakies M. 2 , Hauber I. 2 , Stahl-Hennig C. 3 , Jordan S. 1 , Hauber J. 2 , Van Lunzen J. 1 1 HIV Research Laboratory, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, 2 Heinrich-Pette- Institute for Experimental Virology and Immunology, Hamburg, Germany, 3 German Primate Center (DPZ), Dept. of Immunology and Virology, Goettingen, Germany Background: Recently the tripartite motif protein TRIM5a was identified as an intracellular restriction factor against HIV-1.Although unmodified human TRIM5-alpha is not active against HIV-1, its restriction potential was significantly increased by different modifications in the SPRY domain of the protein, which was defined earlier as the region responsible for inhibitory activity. Thus certain mutated TRIM5a variants may exist, which play a role in the delayed disease progression of so called Long-Term-Non-Progressors (LTNP). Objective: To study the genetic sequence of human and simian TRIM5a and its potential role in the restriction of HIV-1 and SIV infection. Materials and methods: Cloning and sequencing of TRIM5a cDNA was performed in blood PBL from 10 subjects of either of the following groups: a) LTNP or “slow progressors”, who maintain a viral load < 2000 copies/ml and CD4 counts > 500 cells/l without any treatment for up to 10 years;
130 EUROPEAN JOURNAL OF MEDICAL RESEARCH June 27, 2007 b) patients in various stages of disease progression and c) HIV-1 negative individuals as normal controls. Moreover, we started to sequence simian TRIM5a variants obtained from 10 SIV-infected monkeys with LTNP characteristics and compared the sequences to a group with rapid disease progression. Results: A TRIM5-a specific Nested-PCR was developed allowing for the detection of sufficient amounts of TRIM5a cDNA for cloning and sequencing. So far this was performed for 10 LTNP macaques and 10 HIV-1 negative human controls. In controls a total of 7 mutations compared to wild type was found. As of yet the significance of these mutations cannot be determined. Two distinct mutations in the SPRY region were detected in 10/10 LTNP monkeys. Additional mutation patterns were detected in different regions of the protein. These mutations differed from the consensus sequence reported so far but the clinical significance remains to be elucidated as results from the group with progressive disease are still pending. Conclusions: Analysis of the LTNP macaques and normal human controls showed mutations which differed from consensus sequences. The analysis of all subjects is required in order to assess the significance and relevance of these findings.
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