Humanized mice for studying HIV latency and potentially its eradication

PURPOSE OF THE REVIEW

The quest for an HIV cure faces a formidable challenge: the persistent presence of latent viral infections within the cells and tissues of infected individuals. This review provides a thorough examination of discussions surrounding HIV latency, the use of humanized mouse models, and strategies aimed at eliminating the latent HIV reservoir. It explores the hurdles and advancements in understanding HIV pathogenesis, mainly focusing on establishing latent reservoirs in CD4 + T cells and macrophages. Introducing the concepts of functional and sterile cures, the review underscores the indispensable role of humanized mouse models in HIV research, offering crucial insights into the efficacy of cART and the ongoing pursuit of an HIV cure.

RECENT FINDINGS

Here, we highlight studies investigating molecular mechanisms and pathogenesis related to HIV latency in humanized mice and discuss novel strategies for eradicating latent HIV. Emphasizing the importance of analytical cART interruption in humanized mouse studies to gauge its impact on the latent reservoir accurately, the review underlines the ongoing progress and challenges in harnessing humanized mouse models for HIV research.

SUMMARY

This review suggests that humanized mice models provide valuable insights into HIV latency and potential eradication strategies, contributing significantly to the quest for an HIV cure.

The Humanized Mouse Model: What Added Value Does It Offer for HIV Research?

In the early 2000s, novel humanized mouse models based on the transplantation of human hematopoietic stem and progenitor cells (HSPCs) into immunocompromised mice were introduced (hu mice). The human HSPCs gave rise to a lymphoid system of human origin. The HIV research community has greatly benefitted from these hu mice. Since human immunodeficiency virus (HIV) type 1 infection results in a high-titer disseminated HIV infection, hu mice have been of great value for all types of HIV research from pathogenesis to novel therapies. Since the first description of this new generation of hu mice, great efforts have been expended to improve humanization by creating other immunodeficient mouse models or supplementing mice with human transgenes to improve human engraftment. Many labs have their own customized hu mouse models, making comparisons quite difficult. Here, we discuss the different hu mouse models in the context of specific research questions in order to define which characteristics should be considered when determining which hu mouse model is appropriate for the question posed. We strongly believe that researchers must first define their research question and then determine whether a hu mouse model exists, allowing the research question to be studied.

Fetal-maternal surgery for spina bifida in a HIV-infected mother

INTRODUCTION

In select cases, in utero surgery for MMC leads to better outcomes than postnatal repair. However, maternal HIV infection constitutes a formal exclusion criterion due to the potential of vertical HIV transmission. Encouraged by a previous case of a successful fetal spina bifida repair in a Hepatitis Bs antigen positive woman, a plan was devised allowing for fetal surgery.

CASE REPORT

In utero MMC repair was performed although the mother was HIV-infected. To minimize the risk of in utero HIV transmission, the mother was treated by HAART throughout gestation as well as intravenous zidovudine administration during maternal-fetal surgery. The mother tolerated all procedures very well without any sequelae. The currently 20 month-old toddler, is HIV negative and has significantly benefitted from fetal surgery.

DISCUSSION/CONCLUSION

This case shows that maternal HIV is not a priori a diagnosis that excludes fetal surgery. Rather, it might be a surrogate for moving towards personalized medicine and away from applying too rigorous exclusion criteria in the selection of candidates for maternal-fetal surgery.

The ADAM17-directed Inhibitory Antibody MEDI3622 Antagonizes Radiotherapy-induced VEGF Release and Sensitizes Non-Small Cell Lung Cancer for Radiotherapy

The cellular response to ionizing radiation (IR) depends on tumor cell and microenvironmental factors. Here, we investigated the role of IR-induced ADAM17 matrix metalloproteinase activity for the intercellular communication between tumor cells and the tumor vasculature in non-small cell lung cancer (NSCLC) tumor models. Factors shed by ADAM17 from NSCLC tumor cells (A549, H358) and relevant for endothelial cell migration were investigated using transwell migration assays, ELISA, and flow cytometry. Tumor angiogenesis-related endpoints were analyzed with the chorio-allantoic membrane assay and in murine NSCLC tumor models. Efficacy-oriented experiments were performed in a murine orthotopic NSCLC tumor model using irradiation with an image-guided small-animal radiotherapy platform alone and in combination with the novel ADAM17-directed antibody MEDI3622. In vitro, VEGF was identified as the major factor responsible for IR-induced and ADAM17-dependent endothelial cell migration toward attracting tumor cells. IR strongly enhanced tumor cell-associated ADAM17 activity, released VEGF in an ADAM17-dependent manner, and thereby coordinated the communication between tumor and endothelial cells. In vivo, tumor growth and microvessel size and density were strongly decreased in response to the combined treatment modality of IR and MEDI3622 but not by either treatment modality alone and thus suggest that the supra-additive effect of the combined treatment modality is in part due to abrogation of the ADAM17-mediated IR-induced protective effect on the tumor vasculature. Furthermore, we demonstrate that the novel ADAM17-inhibitory antibody MEDI3622 potently improves the radiotherapy response of NSCLC.

Significance

The tumor response to radiotherapy is influenced by several factors of the tumor microenvironment. We demonstrate that inhibition of the sheddase ADAM17 by the novel antibody MEDI3622 reduces IR-induced VEGF release from tumor cells relevant for endothelial cell migration and vasculature protection, thereby enhancing radiotherapy treatment outcome of NSCLC.

EBV renders B cells susceptible to HIV-1 in humanized mice

HIV and EBV are human pathogens that cause a considerable burden to worldwide health. In combination, these viruses are linked to AIDS-associated lymphomas. We found that EBV, which transforms B cells, renders them susceptible to HIV-1 infection in a CXCR4 and CD4-dependent manner in vitro and that CXCR4-tropic HIV-1 integrates into the genome of these B cells with the same molecular profile as in autologous CD4⁺ T cells. In addition, we established a humanized mouse model to investigate the in vivo interactions of EBV and HIV-1 upon coinfection. The respective mice that reconstitute human immune system components upon transplantation with CD34⁺ human hematopoietic progenitor cells could recapitulate aspects of EBV and HIV immunobiology observed in dual-infected patients. Upon coinfection of humanized mice, EBV/HIV dual-infected B cells could be detected, but were susceptible to CD8⁺ T-cell-mediated immune control.

In utero Hepatitis B Immunization during Fetal Surgery for Spina Bifida

BACKGROUND

Fetal surgery for spina bifida aperta may lead to significantly better outcomes than postnatal repair, particularly regarding shunt-dependent hydrocephalus, independent ambulation, and voiding functions. The "Management of Myelomeningocele Study" (MOMS) represents the current benchmark, also in terms of eligibility criteria.

CASE REPORT

A positive maternal hepatitis B virus (HBV) status is a MOMS exclusion criterion. Here, we report on the first successful active and passive in utero HBV vaccination of a spina bifida fetus carried by a HBV-positive mother undergoing maternal-fetal surgery. The now 2-year-old infant is healthy, HBV negative, and drew maximal benefit from prenatal surgery.

DISCUSSION AND CONCLUSION

Taken together, this patient benefitted maximally from fetal surgery for spina bifida, despite meeting an exclusion criterion. Thus, generally speaking, eligibility criteria for fetal surgery can be challenged under certain circumstances for the benefit of the patient.

Efficient Human Cytomegalovirus Replication in Primary Endothelial Cells Is SOCS3 Dependent

BACKGROUND

In immunocompromised patients, human cytomegalovirus (HCMV) infection is a major cause of morbidity and mortality. Suppressor of cytokine signaling (SOCS) proteins are very potent negative regulators of the janus kinase/signal transducer and activator of transcription (JAK/STAT) pathways. We hypothesized that HCMV exploits SOCS1 and/or SOCS3 to its advantage.

METHODS

All experiments were carried out with primary human lung-derived microvascular endothelial cells (HMVEC). SOCS1 and SOCS3 were silenced by transfecting the cells with siRNA. HCMV was propagated and titered on human lung-derived fibroblasts MRC5. Real-time PCR and Western blot were used to detect mRNA and protein levels, respectively.

RESULTS

The data presented show that an efficient replication of HCMV in HMVEC is dependent on SOCS3 protein. Time course analysis revealed an increase in SOCS3 protein levels in infected cells. Silencing of SOCS3 (siSOCS3) resulted in inhibition of viral immediate early, early, and late antigen production. Consistently, HCMV titers produced by siSOCS3 cultures were significantly decreased when compared to control transfected cultures (siCNTRs). STAT1 and STAT2 phosphorylation was increased in siSOCS3-infected cells when compared to siCNTR-treated cells.

CONCLUSION

These findings indicate the implication of SOCS3 in the mechanism of HCMV-mediated control of cellular immune responses.

Monitoring HIV DNA and cellular activation markers in HIV-infected humanized mice under cART

Background

The major obstacle to cure of HIV type-1 infection is the presence of the HIV reservoir, hidden from the immune system and insensitive to combined antiretroviral therapy (cART). Eradication approaches have been hindered by the difficulty for accurately monitoring its size in vivo, especially in the lymphoid organs. Humanized mouse models are a valuable tool for systematically assess the efficacy of therapeutic interventions in reducing the HIV reservoir. Nonetheless, persistence of the HIV reservoir over time, in the presence of cART, has yet to be analyzed in this in vivo model.

Findings

We found that the proviral DNA as well as the total DNA were very stable in the spleen and mesenteric lymph node irrespective of the length of cART. Notably, the amount of proviral DNA was very similar in the spleen and lymph node. Furthermore, we observed a correlation between the percentage of splenic human CD4+ T-cells with total HIV DNA, between the number of human CD38 + CD8+ T-cells in the spleen with the amount of integrated HIV DNA, and eventually between the hCD4/hCD8 ratio in the spleen with integrated as well as total HIV DNA implying that the CD8+ T cells influence the size of the HIV reservoir.

Conclusions

Here, we demonstrated the stability of this reservoir in humanized mice irrespective of the length of cART, confirming the relevancy of this model for HIV latency eradication investigations. Notably, we also found correlates between the frequency of CD4+ T-cells, their activation status and viral parameters, which were analogous to the ones in HIV-infected patients. Thus, hu-mice represent a very valuable HIV latency model.

Optimizing Synthetic miRNA Minigene Architecture for Efficient miRNA Hairpin Concatenation and Multi-target Gene Knockdown

Synthetic microRNA (miRNA) minigenes (SMIGs) have a major potential for molecular therapy; however, their optimal architecture still needs to be determined. We have previously optimized the stem structure of miRNA hairpins for efficient gene knockdown. Here, we investigate the overall architecture of SMIGs driven by polymerase II-dependent promoters. When miRNA hairpins were placed directly behind the promoter, gene knockdown was inefficient as compared with constructs containing an intercalated sequence (“spacer”). Spacer sequence was relevant for knockdown efficiency and concatenation potential: GFP-based sequences (even when truncated or including stop codons) were particularly efficient. In contrast, a spacer of similar length based on a CD4 intronic sequence was entirely inefficient. Spacer sequences influenced miRNA steady-state levels without affecting transcript stability. We demonstrate that with an optimized spacer, up to five concatenated hairpins targeting two different genes are efficiently expressed and able to knock down their respective targets. Transplantation of hematopoietic stem cells containing a CCR5 knockdown SMIG demonstrated a sustained in vivo efficacy of our approach. In summary, we have defined features that optimize SMIG efficiency. Based on these results, optimized knockdown of genes of interest, such as the HIV co-receptor CCR5 and the NADPH oxidase subunit p22^phox, was achieved.

Impairment of CCR6+ and CXCR3+ Th Cell Migration in HIV-1 Infection Is Rescued by Modulating Actin Polymerization

CD4⁺ T cell repopulation of the gut is rarely achieved in HIV-1-infected individuals who are receiving clinically effective antiretroviral therapy. Alterations in the integrity of the mucosal barrier have been indicated as a cause for chronic immune activation and disease progression. In this study, we present evidence that persistent immune activation causes impairment of lymphocytes to respond to chemotactic stimuli, thus preventing their trafficking from the blood stream to peripheral organs. CCR6⁺ and CXCR3⁺ Th cells accumulate in the blood of aviremic HIV-1-infected patients on long-term antiretroviral therapy, and their frequency in the circulation positively correlates to levels of soluble CD14 in plasma, a marker of chronic immune activation. Th cells show an impaired response to chemotactic stimuli both in humans and in the pathogenic model of SIV infection, and this defect is due to hyperactivation of cofilin and inefficient actin polymerization. Taking advantage of a murine model of chronic immune activation, we demonstrate that cytoskeleton remodeling, induced by okadaic acid, restores lymphocyte migration in response to chemokines, both in vitro and in vivo. This study calls for novel pharmacological approaches in those pathological conditions characterized by persistent immune activation and loss of trafficking of T cell subsets to niches that sustain their maturation and activities.

Proceedings of the Frontiers of Retrovirology Conference 2016

Oral presentations

Session 1: Entry & uncoating

O1 Host cell polo-like kinases (PLKs) promote early prototype foamy virus (PFV) replication

Irena Zurnic, Sylvia Hütter, Ute Lehmann, Nicole Stanke, Juliane Reh, Tobias Kern, Fabian Lindel, Gesche Gerresheim, Martin Hamann, Erik Müllers, Paul Lesbats, Peter Cherepanov, Erik Serrao, Alan Engelman, Dirk Lindemann

O2 A novel entry/uncoating assay reveals the presence of at least two species of viral capsids during synchronized HIV-1 infection

Claire Da Silva Santos, Kevin Tartour, Andrea Cimarelli

O3 Dynamics of nuclear envelope association and nuclear import of HIV-1 complexes

Rya Burdick, Jianbo Chen, Jaya Sastri, Wei-Shau Hu, Vinay Pathak

O4 Human papillomavirus protein E4 potently enhances the susceptibility to HIV infection

Oliver T. Keppler

Session 2: Reverse transcription & integration

O5 Structure and function of HIV-1 integrase post translational modifications

Karine Pradeau, Sylvia Eiler, Nicolas Levy, Sarah Lennon, Sarah Cianferani, Stéphane Emiliani, Marc Ruff

O6 Regulation of retroviral integration by RNA polymerase II associated factors and chromatin structure

Vincent Parissi

Session 3: Transcription and latency

O7 A novel single-cell analysis pipeline to identify specific biomarkers of HIV permissiveness

Sylvie Rato, Antonio Rausell, Miguel Munoz, Amalio Telenti, Angela Ciuffi

O8 A capsid-dependent integration program linking T cell activation to HIV-1 gene expression

Alexander Zhyvoloup, Anat Melamed, Ian Anderson, Delphine Planas, Janos Kriston-Vizi, Robin Ketteler, Chen-Hsuin Lee, Andy Merritt, Petronela Ancuta, Charles Bangham, Ariberto Fassati

O9 Characterisation of new RNA polymerase III and RNA polymerase II transcriptional promoters in the Bovine Leukemia Virus genome

Anthony Rodari, Benoit Van Driessche, Mathilde Galais, Nadége Delacourt, Sylvain Fauquenoy, Caroline Vanhulle, Anna Kula, Arsène Burny, Olivier Rohr, Carine Van Lint

O10 Tissue-specific dendritic cells differentially modulate latent HIV-1 reservoirs

Thijs van Montfort, Renee van der Sluis, Dave Speijer, Ben Berkhout

Session 4: RNA trafficking & packaging

O11 A novel cis-acting element affecting HIV replication

Bo Meng, Andrzej Rutkowski, Neil Berry, Lars Dölken, Andrew Lever

O12 Tolerance of HIV’s late gene expression towards stepwise codon adaptation

Thomas Schuster, Benedikt Asbach, Ralf Wagner

Session 5: Assembly & release

O13 Importance of the tax-inducible actin-bundling protein fascin for transmission of human T cell leukemia virus Type 1 (HTLV-1)

Christine Gross, Veit Wiesmann, Martina Kalmer, Thomas Wittenberg, Jan Gettemans, Andrea K. Thoma-Kress

O14 Lentiviral nef proteins antagonize TIM-mediated inhibition of viral release

Minghua Li, Eric O. Freed, Shan-Lu Liu

Session 6: Pathogenesis & evolution

O15 SEVI and semen prolong the half-life of HIV-1

Janis Müller, Jan Münch

O16 CD169⁺ macrophages mediate retrovirus trans-infection of permissive lymphocytes to establish infection in vivo

Xaver Sewald, Pradeep Uchil, Mark Ladinsky, Jagadish Beloor, Ruoxi Pi, Christin Herrmann, Nasim Motamedi, Thomas Murooka, Michael Brehm, Dale Greiner, Thorsten Mempel, Pamela Bjorkman, Priti Kumar, Walther Mothes

O17 Efficient replication of a vpu containing SIVagm construct in African Green Monkeys requires an HIV-1 nef gene

Simone Joas, Erica Parrish, Clement Wesley Gnanadurai, Edina Lump, Christina M. Stürzel, Nicholas F. Parrish, Ulrike Sauermann, Katharina Töpfer, Tina Schultheiss, Steven Bosinger, Guido Silvestri, Cristian Apetrei, Nicholas Huot, Michaela Müller-Trutwin, Daniel Sauter, Beatrice H. Hahn, Christiane Stahl-Hennig, Frank Kirchhoff

O18 Reprogramming initiates mobilization of endogenous mutagenic LINE-1, Alu and SVA retrotransposons in human induced pluripotent stem cells with consequences for host gene expression

Gerald Schumann, Sabine Jung-Klawitter, Nina V. Fuchs, Kyle R. Upton, Martin Muñoz-Lopez, Ruchi Shukla, Jichang Wang, Marta Garcia-Canadas, Cesar Lopez-Ruiz, Daniel J. Gerhardt, Attila Sebe, Ivana Grabundzija, Patricia Gerdes, Sylvia Merkert, Andres Pulgarin, Anja Bock, Ulrike Held, Anett Witthuhn, Alexandra Haase, Ernst J. Wolvetang, Ulrich Martin, Zoltán Ivics, Zsuzsanna Izsvák, J. Garcia-Perez, Geoffrey J. Faulkner

O19 NF-κB activation induces expression of human endogenous retrovirus and particle production

Tara Hurst, Aris Katzourakis, Gkikas Magiorkinis

Session 7a and b: Innate sensing & intrinsic immunity

O20 Identification of the phosphatase acting on T592 in SAMHD1 during M/G₁ transition

Kerstin Schott, Rita Derua, Janna Seifried, Andreas Reuter, Heike Schmitz, Christiane Tondera, Alberto Brandariz-Nuñez, Felipe Diaz-Griffero, Veerle Janssens, Renate König

O21 Vpx overcomes a SAMHD1-independent block to HIV reverse transcription that is specific to resting CD4 T cells

Hanna-Mari Baldauf, Lena Stegmann, Sarah-Marie Schwarz, Maud Trotard, Margarethe Martin, Gina Lenzi, Manja Burggraf, Xiaoyu Pan, Oliver I. Fregoso, Efrem S. Lim, Libin Abraham, Elina Erikson, Laura Nguyen, Ina Ambiel, Frank Rutsch, Renate König, Baek Kim, Michael Emerman, Oliver T. Fackler, Oliver T. Keppler

O22 The role of SAMHD1 in antiviral restriction and immune sensing in the mouse

Sabine Wittmann, Rayk Behrendt, Bianca Volkmann, Kristin Eissmann, Thomas Gramberg

O23 T cells expressing reduced restriction factors are preferentially infected in therapy naïve HIV-1 patients

Sebastian Bolduan, Herwig Koppensteiner, Stefanie Regensburg, Ruth Brack-Werner, Rika Draenert, Michael Schindler

O24 cGAS-mediated innate immunity spreads through HIV-1 env-induced membrane fusion sites from infected to uninfected primary HIV-1 target cells

Aurélie Ducroux, Shuting Xu, Aparna Ponnurangam, Sergej Franz, Angelina Malassa, Ellen Ewald, Christine Goffinet

O25 Perturbation of innate RNA and DNA sensing by human T cell leukemia virus type 1 oncoproteins

Sin-Yee Fung, Ching-Ping Chan, Chun-Kit Yuen, Kin-Hang Kok, Chin-Ping Chan, Dong-Yan Jin

O26 Induction and anti-viral activity of Interferon α subtypes in HIV-1 infection

Ulf Dittmer

O27 Vpu-mediated counteraction of tetherin is a major determinant of HIV-1 interferon resistance

Dorota Kmiec, Shilpa Iyer, Christina Stürzel, Daniel Sauter, Beatrice Hahn, Frank Kirchhoff

O28 DNA repair protein Rad18 restricts HIV-1 and LINE-1 life cycle

Yasuo Ariumi, Mariko Yasuda-Inoue, Koudai Kawano, Satoshi Tateishi, Priscilla Turelli

O29 Natural mutations in IFITM3 allow escape from post-translational regulation and toggle antiviral specificity

Alex Compton, Nicolas Roy, Françoise Porrot, Anne Billet, Nicoletta Casartelli, Jacob Yount, Chen Liang, Oliver Schwartz

Session 8: Adaptive immunity & immune evasion

O30 Observing evolution in HIV-1 infection: phylogenetics and mutant selection windows to infer the influence of the autologous antibody response on the viral quasispecies

Carsten Magnus, Lucia Reh, Penny Moore, Therese Uhr, Jacqueline Weber, Lynn Morris, Alexandra Trkola

O31 Dose and subtype specific analyses of the anti-HIV effects of IFN-alpha family members

Rashel V. Grindberg, Erika Schlaepfer, Gideon Schreiber, Viviana Simon, Roberto F. Speck

Session 9: Novel antiviral strategies

O32 LEDGIN-mediated inhibition of the integrase-LEDGF/p75 interaction reduces reactivation of residual latent HIV

Zeger Debyser, Lenard Vranckx, Jonas Demeulemeester, Suha Saleh, Eric Verdin, Anna Cereseto, Frauke Christ, Rik Gijsbers

O33 NKG2D-mediated clearance of reactivated viral reservoirs by natural killer cells

O34 Inhibition of HIV reactivation in brain cells by AAV-mediated delivery of CRISPR/Cas9

O35 CRISPR-Cas9 as antiviral: potent HIV-1 inhibition, but rapid virus escape and the subsequent design of escape-proof antiviral strategies

Ben Berkhout, Gang Wang, Na Zhao, Atze T. Das

Session 10: Recent advances in HIV vaccine development

O36 Priming with a potent HIV-1 DNA vaccine frames the quality of T cell and antibody responses prior to a poxvirus and protein boost

Benedikt Asbach, Josef Köstler, Beatriz Perdiguero, Mariano Esteban, Bertram L. Jacobs, David C. Montefiori, Celia C. LaBranche, Nicole L. Yates, Georgia D. Tomaras, Guido Ferrari, Kathryn E. Foulds, Mario Roederer, Gary Landucci, Donald N. Forthal, Michael S. Seaman, Natalie Hawkins, Steven G. Self, Sanjay Phogat, James Tartaglia, Susan W. Barnett, Brian Burke, Anthony D. Cristillo, Song Ding, Jonathan L. Heeney, Giuseppe Pantaleo, Ralf Wagner

O37 Passive immunisation with a neutralising antibody against HIV-1 Env prevents infection of the first cells in a mucosal challenge rhesus monkey model

Christiane Stahl-Hennig, Viktoria Stab, Armin Ensser, Ulrike Sauermann, Bettina Tippler, Dennis Burton, Matthias Tenbusch, Klaus Überla

O38 HIV antibody Fc-glycoforms drive B cell affinity maturation

Galit Alter, Giuseppe Lofano, Anne-Sophie Dugast, Viraj Kulkarni, Todd Suscovich

Poster presentations

Topic 1: Entry & uncoating

P1 Dynein light chain is required for murine leukemia virus infection

Tatiana Opazo, Felipe Barraza, Diego Herrera, Andrea Garces, Tomas Schwenke, Diego Tapia, Jorge Cancino, Gloria Arriagada

P2 Peptide paratope mimics of the broadly neutralising HIV-1 antibody b12

Christina Haußner, Dominik Damm, Anette Rohrhofer, Barbara Schmidt, Jutta Eichler

P3 Investigating cellular pathways involved in the transmission of HIV-1 between dendritic cells and T cells using RNAi screening techniques

Rebecca Midgley, James Wheeldon, Vincent Piguet

P4 Co-receptor tropism in HIV-1, HIV-2 monotypic and dual infections

Priyanka Khopkar, Megha Rohamare, Smita Kulkarni

P5 Characterisation of the role of CIB1 and CIB2 as HIV-1 helper factors

Ana Godinho-Santos, Allan Hance, Joao Goncalves, Fabrizio Mammano

P6 Buffering deleterious polymorphisms in the highly constrained C2 region of HIV-1 envelope by the flexible V3 domain

Romain Gasser, Meriem Hamoudi, Martina Pellicciotta, Zhicheng Zhou, Clara Visdeloup, Philippe Colin, Martine Braibant, Bernard Lagane, Matteo Negroni

P7 Entry inhibition of HERV-K(HML-2) by an Env-IgG fusion protein

Jula Wamara, Norbert Bannert

Topic 2: Reverse transcription & integration

P8 The R263K/H51Y resistance substitutions in HIV integrase decreases levels of integrated HIV DNA over time

Thibault Mesplede, Nathan Osman, Kaitlin Anstett, Jiaming Calvin Liang, Hanh Thi Pham, Mark Wainberg

P9 The Retrovirus Integration Database (RID)

Wei Shao, Jigui Shan, Mary Kearney, Xiaolin Wu, Frank Maldarelli, John Mellors, Brian Luke, John Coffin, Stephen Hughes

P10 The small molecule 3G11 inhibits HIV-1 reverse transcription

Thomas Fricke, Silvana Opp, Caitlin Shepard, Dmitri Ivanov, Baek Kim, Jose Valle-Casuso, Felipe Diaz-Griffero

P11 Dual and opposite regulation of HIV-1 integration by hRAD51: impact on therapeutical approaches using homologous DNA repair modulators

Vincent Parissi

P12 A flexible motif essential for integration by HIV-1 integrase

Marine Kanja, Pierre Cappy, Matteo Negroni, Daniela Lener

P13 Interaction between HIV-1 integrase and the host protein Ku70: identification of the binding site and study of the influence on integrase-proteasome interplay

Ekaterina Knyazhanskaya, Andrey Anisenko, Timofey Zatsepin, Marina Gottikh

P14 Normalisation based method for deep sequencing of somatic retroelement integrations in human genome

Alexander Komkov, Anastasia Minervina, Gaiaz Nugmanov, Vadim Nazarov, Konstantin Khodosevich, Ilgar Mamedov, Yuri Lebedev

Topic 3: Transcription and latency

P15 BCA2/RABRING7 restricts HIV-1 transcription by preventing the nuclear translocation of NF-κB

Marta Colomer-Lluch, Ruth Serra-Moreno

P16 MATR3 post-transcriptional regulation of HIV-1 transcription during latency

Ambra Sarracino, Anna Kula, Lavina Gharu, Alexander Pasternak, Carine Van Lint, Alessandro Marcello

P17 HIV-1 tat intersects the SUMO pathway to regulate HIV-1 promoter activity

Ann Marie McCartin, Anurag Kulkarni, Valentin Le Douce, Virginie Gautier

P18 Conservation in HIV-1 Vpr guides tertiary gRNA folding and alternative splicing

Ann Baeyens, Evelien Naessens, Anouk Van Nuffel, Karin Weening, Anne-Marie Reilly, Eva Claeys, Wim Trypsteen, Linos Vandekerckhove, Sven Eyckerman, Kris Gevaert, Bruno Verhasselt

P19 The majority of reactivatable latent HIV are genetically distinct

Hoi Ping Mok, Nicholas Norton, Axel Fun, Jack Hirst, Mark Wills, Andrew Lever

P20 Do mutations in the tat exonic splice enhancer contribute to HIV-1 latency?

Nicholas Norton, Hoi Ping Mok, Jack Hirst, Andrew Lever

P21 Culture-to-Ct: A fast and direct RT-qPCR HIV gene reactivation screening method using primary T cell culture

Valentin Le Douce, Ann Marie McCartin, Virginie Gautier

P22 A novel approach to define populations of early silenced proviruses

Dalibor Miklik, Filip Senigl, Jiri Hejnar

Topic 4: RNA trafficking & packaging

P23 Functional analysis of the structure and conformation of HIV-1 genome RNA DIS

Jun-ichi Sakuragi, Sayuri Sakuragi, Masaru Yokoyama, Tatsuo Shioda, Hironori Sato

P24 Regulation of foamy viral env splicing controls gag and pol expression

Jochen Bodem, Rebecca Moschall, Sarah Denk, Steffen Erkelenz, Christian Schenk, Heiner Schaal

Topic 5: Assembly & release

P25 Transfer of HTLV-1 p8 to target T cells depends on VASP: a novel interaction partner of p8

Norbert Donhauser, Ellen Socher, Sebastian Millen, Heinrich Sticht, Andrea K. Thoma-Kress

P26 COL4A1 and COL4A2 are novel HTLV-1 tax targets with a putative role in virus transmission

Christine Gross, Sebastian Millen, Melanie Mann, Klaus Überla, Andrea K. Thoma-Kress

P27 The C terminus of foamy virus gag protein is required for particle formation, and virus budding: starting assembly at the C terminus?

Guochao Wei, Matthew J. Betts, Yang Liu, Timo Kehl, Robert B. Russell, Martin Löchelt

P28 Generation of an antigen-capture ELISA and analysis of Rec and Staufen-1 effects on HERV-K(HML-2) virus particle production

Oliver Hohn, Saeed Mostafa, Kirsten Hanke, Stephen Norley, Norbert Bannert

P29 Antagonism of BST-2/tetherin is a conserved function of primary HIV-2 Env glycoproteins

Chia-Yen Chen, Masashi Shingai, Pedro Borrego, Nuno Taveira, Klaus Strebel

P30 Mutations in the packaging signal region of the HIV-1 genome cause a late domain mutant phenotype

Chris Hellmund, Bo Meng, Andrew Lever

P31 p6 regulates membrane association of HIV-1 gag

Melanie Friedrich, Friedrich Hahn, Christian Setz, Pia Rauch, Kirsten Fraedrich, Alina Matthaei, Petra Henklein, Maximilian Traxdorf, Torgils Fossen, Ulrich Schubert

Topic 6: Pathogenesis & evolution

P32 Molecular and structural basis of protein evolution during viral adaptation

Aya Khwaja, Meytal Galilee, Akram Alian

P33 HIV-1 enhancement and neutralisation by soluble gp120 and its role for the selection of the R5-tropic “best fit”

Birco Schwalbe, Heiko Hauser, Michael Schreiber

P34 An insertion of seven amino acids in the Env cytoplasmic tail of Human Immunodeficiency Virus type 2 (HIV-2) selected during disease progression enhances viral replication

François Dufrasne, Mara Lucchetti, Patrick Goubau, Jean Ruelle

P35 Cell-associated HIV-1 unspliced to multiply spliced RNA ratio at 12 weeks ART correlates with markers of immune activation and apoptosis and predicts the CD4 T-cell count at 96 weeks ART

Mirte Scherpenisse, Ben Berkhout, Alexander Pasternak

P36 Faster progression in non-B subtype HIV-1-infected patients than Korean subclade of subtype B is accompanied by higher variation and no induction of gross deletion in non-B nef gene by Korean red ginseng treatment

Young-Keol Cho, Jungeun Kim, Daeun Jeong

P37 Aberrant expression of ERVWE1 endogenous retrovirus and overexpression of TET dioxygenases are characteristic features of seminoma

Katerina Trejbalova, Martina Benesova, Dana Kucerova, Zdenka Vernerova, Rachel Amouroux, Petra Hajkova, Jiri Hejnar

P38 Life history of the oldest lentivirus: characterisation of ELVgv integrations and the TRIM5 selection pattern in dermoptera

Daniel Elleder, Tomas Hron, Helena Farkasova, Abinash Padhi, Jan Paces

P39 Characterisation of a highly divergent endogenous retrovirus in the equine germ line

Henan Zhu, Robert Gifford, Pablo Murcia

P40 The emergence of pandemic retroviral infection in small ruminants

Maria Luisa Carrozza, Anna-Maria Niewiadomska, Maurizio Mazzei, Mounir Abi-Said, Joseph Hughes, Stéphane Hué, Robert Gifford

P41 Near full-length genome (NFLG) Characterisation of HIV-1 subtype B identified in South Africa

Adetayo Obasa, Graeme Jacobs, Susan Engelbrecht

P42 Acquisition of Vpu-mediated tetherin antagonism by an HIV-1 group O strain

Katharina Mack, Kathrin Starz, Daniel Sauter, Matthias Geyer, Frederic Bibollet-Ruche, Christina Stürzel, Marie Leoz, Jean Christophe Plantier, Beatrice H. Hahn, Frank Kirchhoff

P43 The human endogenous retrovirus type K is involved in cancer stem cell markers expression and in human melanoma malignancy

Ayele Argaw-Denboba, Emanuela Balestrieri, Annalucia Serafino, Ilaria Bucci, Chiara Cipriani, Corrado Spadafora, Paolo Sinibaldi-Vallebona, Claudia Matteucci

P44 Natural infection of Indian non-human primates by unique lentiviruses

S. Nandi Jayashree, Ujjwal Neogi, Anil K. Chhangani, Shravan Sing Rathore, Bajrang R. J. Mathur

P45 Free cervical cancer screening among HIV-positive women receiving antiretroviral treatment in Nigeria

Adeyemi Abati

P46 Molecular evolutionary status of feline immunodeficiency virus in Turkey

B. Taylan Koç, Tuba Çiğdem Oğuzoğlu

Topic 7: Innate sensing & intrinsic immunity

P47 Cell-to-cell contact with HTLV-1-infected T cells reduces dendritic cell immune functions and contributes to infection in trans.

Takatoshi Shimauchi, Stephan Caucheteux, Jocelyn Turpin, Katja Finsterbusch, Charles Bangham, Yoshiki Tokura, Vincent Piguet

P48 Deciphering the mechanisms of HIV-1 exacerbation induced by Mycobacterium tuberculosis in monocytes/macrophages

Shanti Souriant, Luciana Balboa, Karine Pingris, Denise Kviatcowsky, Brigitte Raynaud-Messina, Céline Cougoule, Ingrid Mercier, Marcelo Kuroda, Pablo González-Montaner, Sandra Inwentarz, Eduardo Jose Moraña, Maria del Carmen Sasiain, Olivier Neyrolles, Isabelle Maridonneau-Parini, Geanncarlo Lugo-Villarino, Christel Vérollet

P49 The SAMHD1-mediated inhibition of LINE-1 retroelements is regulated by phosphorylation

Alexandra Herrmann, Sabine Wittmann, Caitlin Shepard, Dominique Thomas, Nerea Ferreirós Bouzas, Baek Kim, Thomas Gramberg

P50 Activities of nuclear envelope protein SUN2 in HIV infection

Xavier Lahaye, Anvita Bhargava, Takeshi Satoh, Matteo Gentili, Silvia Cerboni, Aymeric Silvin, Cécile Conrad, Hakim Ahmed-Belkacem, Elisa C. Rodriguez, Jean-François Guichou, Nathalie Bosquet, Matthieu Piel, Roger Le Grand, Megan King, Jean-Michel Pawlotsky, Nicolas Manel

P51 Activation of TLR7/8 with a small molecule agonist induces a novel restriction to HIV-1 infection of monocytes

Henning Hofmann, Benedicte Vanwalscappel, Nicolin Bloch, Nathaniel Landau

P52 Steady state between the DNA polymerase and Rnase H domain activities of reverse transcriptases determines the sensitivity of retroviruses to inhibition by APOBEC3 proteins

Stanislav Indik, Benedikt Hagen

P53 HIV restriction in mature dendritic cells is related to p21 induction and p21-mediated control of the dNTP pool and SAMHD1 activity.

José Carlos Valle-Casuso, Awatef Allouch, Annie David, Françoise Barré-Sinoussi, Michaela Müller-Trutwin, Monsef Benkirane, Gianfranco Pancino, Asier Saez-Cirion

P54 IFITM protens restrict HIV-1 protein synthesis

Wing-Yiu Lee, Chen Liang, Richard Sloan

P55 Characterisation and functional analysis of the novel restriction factor Serinc5

Bianca Schulte, Silvana Opp, Felipe Diaz-Griffero

P56 piRNA sequences are common in Human Endogenous Retroviral Sequences (HERVs): An antiretroviral restriction mechanism?

Jonas Blomberg, Luana Vargiu, Patricia Rodriguez-Tomé, Enzo Tramontano, Göran Sperber

P57 Ferroportin restricts HIV-1 infection in sickle cell disease

Namita Kumari, Tatiana Ammosova, Sharmeen Diaz, Patricia Oneal, Sergei Nekhai

P58 APOBEC3G modulates the response to antiretroviral drugs in humanized mice

Audrey Fahrny, Gustavo Gers-Huber, Annette Audigé, Roberto F. Speck, Anitha Jayaprakash, Ravi Sachidanandam, Matt Hernandez, Marsha Dillon-White, Viviana Simon

P59 High-throughput epigenetic analysis of evolutionarily young endogenous retrovirus presents in the mule deer (Odocoileus hemionus) genome

Tomas Hron, Helena Farkasova, Daniel Elleder

P60 Characterisation of the expression of novel endogenous retroviruses and immune interactions in a macaque model

Neil Berry, Emmanuel Maze, Claire Ham, Neil Almond, Greg Towers, Robert Belshaw

P61 HIV-1 restriction by orthologs of SERINC3 and SERINC5

Patrícia de Sousa-Pereira, Joana Abrantes, Massimo Pizzato, Pedro J. Esteves, Oliver T. Fackler, Oliver T. Keppler, Hanna-Mari Baldauf

P62 TRIM19/PML restricts HIV infection in a cell type-dependent manner

Bianca Volkmann, Tanja Kahle, Kristin Eissmann, Alexandra Herrmann, Sven Schmitt, Sabine Wittmann, Laura Merkel, Nina Reuter, Thomas Stamminger, Thomas Gramberg

P63 Recent invasion of the mule deer genome by a retrovirus

Helena Farkasova, Tomas Hron, Daniel Elleder

P64 Does the antiviral protein SAMHD1 influence mitochondrial function?

Ilaria Dalla Rosa, Kate Bishop, Antonella Spinazzola, Harriet Groom

P65 cGAMP transfers intercellularly via HIV-1 Env-mediated cell–cell fusion sites and triggers an innate immune response in primary target cells

Shuting Xu, Aurélie Ducroux, Aparna Ponnurangam, Sergej Franz, Gabrielle Vieyres, Mathias Müsken, Thomas Zillinger, Angelina Malassa, Ellen Ewald, Veit Hornung, Winfried Barchet, Susanne Häussler, Thomas Pietschmann, Christine Goffinet

P66 Pre-infection transcript levels of FAM26F in PBMCS inform about overall plasma viral load in acute and postacute phase after SIV-infection

Ulrike Sauermann, Aneela Javed, Nicole Leuchte, Gabriela Salinas, Lennart Opitz, Christiane Stahl-Hennig, Sieghart Sopper

P67 Sequence-function analysis of three T cell receptors targeting the HIV-1 p17 epitope SLYNTVATL

Christiane Mummert, Christian Hofmann, Angela G. Hückelhoven, Silke Bergmann, Sandra M. Müller-Schmucker, Ellen G. Harrer, Jan Dörrie, Niels Schaft, Thomas Harrer

P68 An immunodominant region of the envelope glycoprotein of small ruminant lentiviruses may function as decoy antigen

Laure Cardinaux, M.-L. Zahno, H.-R. Vogt, R. Zanoni, G. Bertoni

P69 Impact of immune activation, immune exhaustion, broadly neutralising antibodies and viral reservoirs on disease progression in HIV-infected children

Maximilian Muenchhoff, Philip Goulder, Oliver Keppler

Topic 9: Novel antiviral strategies

P70 Identification of natural compounds as new antiviral products by bioassay-guided fractionation

Alexandra Herrmann, Stephanie Rebensburg, Markus Helfer, Michael Schindler, Ruth Brack-Werner

P71 The PPARG antagonism disconnects the HIV replication and effector functions in Th17 cells

Yuwei Zhang, Huicheng Chen, Delphine Planas, Annie Bernier, Annie Gosselin, Jean-Pierre Routy, Petronela Ancuta

P72 Characterisation of a multiresistant subtype AG reverse transcriptase: AZT resistance, sensitivity to RNase H inhibitors and inhibitor binding

Birgitta Wöhrl, Anna Schneider, Angela Corona, Imke Spöring, Mareike Jordan, Bernd Buchholz, Elias Maccioni, Roberto Di Santo, Jochen Bodem, Enzo Tramontano, Kristian Schweimer

P73 Insigths into the acetylation pattern of HDAC inhibitors and their potential role in HIV therapy

Christian Schölz, Brian Weinert, Sebastian Wagner, Petra Beli, Yasuyuki Miyake, Jun Qi, Lars Jensen, Werner Streicher, Anna McCarthy, Nicholas Westwood, Sonia Lain, Jürgen Cox, Patrick Matthias, Matthias Mann, James Bradner, Chunaram Choudhary

P74 HPV-derived and seminal amyloid peptides enhance HIV-1 infection and impair the efficacy of broadly neutralising antibodies and antiretroviral drugs

Marcel Stern, Oliver T. Keppler

P75 D(−)lentiginosine inhibits both proliferation and virus expression in cells infected by HTLV-1 in vitro

Elena Valletta, Caterina Frezza, Claudia Matteucci, Francesca Marino-Merlo, Sandro Grelli, Anna Lucia Serafino, Antonio Mastino, Beatrice Macchi

P76 HIV-1 resistance analyses of the Cape Winelands districts, South Africa

Sello Mikasi, Graeme Jacobs, Susan Engelbrecht

Topic 10: Recent advances in HIV vaccine development

P77 Induction of complex retrovirus antigen-specific immune responses by adenovirus-based vectors depends on the order of vector administration

Meike Kaulfuß, Sonja Windmann, Wibke Bayer

P78 Direct impact of structural properties of HIV-1 Env on the regulation of the humoral immune response

Rebecca Heß, Michael Storcksdieck gen. Bonsmann, Viktoria Stab, Carsten Kirschning, Bernd Lepenies, Matthias Tenbusch, Klaus Überla

P79 Lentiviral virus-like particles mediate gerenration of T-follicular helper cells in vitro

Anne Kolenbrander, Klaus Überla, Vladimir Temchura

P80 Recruitment of HIV-1 Vpr to DNA damage sites and protection of proviral DNA from nuclease activity

Kenta Iijima, Junya Kobayashi, Yukihito Ishizaka

Similar efficacy of broad-range ITS PCR and conventional fungal culture for diagnosing fungal infections in non-immunocompromised patients

Background

Broad-range fungal inter spacer region (ITS) polymerase chain reaction (PCR) has been evaluated for the detection and identification of fungi in clinical specimens from severely immunocompromised patients, but not in non-selected patients. Thus, the aim of this study was to compare the diagnostic performance of ITS PCR with that of fungal culture and to investigate its clinical impact on the diagnosis of fungal infections in non-immunocompromised patients. The corresponding patients’ data were retrieved by detailed medical chart reviews.

Results

Results from 251 specimens showed a high concordance of 89.6 % for ITS PCR and fungal culture. The analytical sensitivity and specificity of ITS PCR considering culture as gold standard were 87.7 and 90.3 %, respectively, the positive and negative predictive value (PPV and NPV) were 76 and 95.5 %, respectively. Assessing the clinical probability of a fungal infection based on detailed chart reviews, PCR had a clinical sensitivity of 88.9 %, a specificity of 86.3 %, a PPV of 64.0 % and a NPV of 96.6 %. The overall performance of fungal broad-range PCR was similar to that of culture.

Conclusions

Our data show that, in non-selected and non-immunocompromised patients, the performance of ITS PCR is similar to that of culture for detecting fungal infections, not the least because sensitivity of culture in patients under antifungal treatment is surprisingly high. Compared to culture, PCR has the advantage of a rapid time-to-result (approximately two working days), proper identification of rare pathogens, prompt initiation of a species-targeted antifungal treatment, and prospects for automation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0752-1) contains supplementary material, which is available to authorized users.

Interferon α-Enhanced Clearance of Group A Streptococcus Despite Neutropenia

BACKGROUND

Neutrophils and monocytes are crucial for controlling bacterial infections. More-frequent bacterial infections are accordingly encountered in neutropenic patients undergoing chemotherapy. This is not the case for pegylated interferon α (IFN-α)-induced neutropenia. We hypothesized that IFN-α induces a compensatory innate antibacterial state that prevents bacterial infections despite the neutropenia.

METHODS

To investigate whether patients with hepatitis C virus infection treated with IFN-α killed group A Streptococcus (GAS) better than before initiating therapy, whole blood was used to perform ex vivo GAS killing assays before, during, and after IFN-α therapy.

RESULTS

We found that IFN-α therapy enhanced GAS killing in whole blood ex vivo despite the decreased neutrophil and monocyte numbers during IFN-α therapy. IFN-α also boosted neutrophil- and monocyte-mediated GAS killing in vitro. Underlying mechanisms included increased production of the antibacterial properdin, a regulator of the complement activation, as well as reactive oxygen species.

CONCLUSIONS

These findings help to explain the rather discrepant facts of neutropenia but preserved antibacterial immune defenses in patients treated with IFN-α.

Repeated Cycles of Recombinant Human Interleukin 7 in HIV-Infected Patients With Low CD4 T-Cell Reconstitution on Antiretroviral Therapy: Results of 2 Phase II Multicenter Studies

BACKGROUND

Phase I/II studies in human immunodeficiency virus (HIV)-infected patients receiving antiretroviral therapy have shown that a single cycle of 3 weekly subcutaneous (s/c) injections of recombinant human interleukin 7 (r-hIL-7) is safe and improves immune CD4 T-cell restoration. Herein, we report data from 2 phase II trials evaluating the effect of repeated cycles of r-hIL-7 (20 µg/kg) with the objective of restoring a sustained CD4 T-cell count >500 cells/µL.

METHODS

INSPIRE 2 was a single-arm trial conducted in the United States and Canada. INSPIRE 3 was a 2 arm trial with 3:1 randomization to r-hIL-7 versus control conducted in Europe and South Africa. Participants with plasma HIV RNA levels <50 copies/mL during antiretroviral therapy and with CD4 T-cell counts between 101 and 400 cells/µL were eligible. A repeat cycle was administered when CD4 T-cell counts fell to <550 cells/µL.

RESULTS

A total of 107 patients were treated and received 1 (n = 107), 2 (n = 74), 3 (n = 14), or 4 (n = 1) r-hIL-7 cycles during a median follow-up of 23 months. r-hIL-7 was well tolerated. Four grade 4 events were observed, including 1 case of asymptomatic alanine aminotransferase elevation. After the second cycle, anti-r-hIL-7 binding antibodies developed in 82% and 77% of patients in INSPIRE 2 and 3, respectively (neutralizing antibodies in 38% and 37%), without impact on the CD4 T-cell response. Half of the patients spent >63% of their follow-up time with a CD4 T-cell count >500 cells/µL.

CONCLUSIONS

Repeated cycles of r-hIL-7 were well tolerated and achieved sustained CD4 T-cell restoration to >500 cells/µL in the majority of study participants.

CLINICAL TRIALS REGISTRATION

INSPIRE II: clinicaltrials.gov (NCT01190111) and INSPIRE III: EudraCT (No. 2010-019773-15) and clinicaltrials.gov (NCT01241643).

Ribavirin Concentrations Do Not Predict Sustained Virological Response in HIV/HCV-Coinfected Patients Treated with Ribavirin and Pegylated Interferon in the Swiss HIV Cohort Study

Background

Ribavirin (RBV) is an essential component of most current hepatitis C (HCV) treatment regimens and still standard of care in the combination with pegylated interferon (pegIFN) to treat chronic HCV in resource limited settings. Study results in HIV/HCV-coinfected patients are contradicting as to whether RBV concentration correlates with sustained virological response (SVR).

Methods

We included 262 HCV treatment naïve HIV/HCV-coinfected Swiss HIV Cohort Study (SHCS) participants treated with RBV and pegIFN between 01.01.2001-01.01.2010, 134 with HCV genotype (GT) 1/4, and 128 with GT 2/3 infections. RBV levels were measured retrospectively in stored plasma samples obtained between HCV treatment week 4 and end of therapy. Uni- and multivariable logistic regression analyses were used to evaluate the association between RBV concentration and SVR in GT 1/4 and GT 2/3 infections. The analyses were repeated stratified by treatment phase (week 4-12, 13-24, >24) and IL28B genotype (CC versus CT/TT).

Results

SVR rates were 35.1% in GT 1/4 and 70.3% in GT 2/3 infections. Overall, median RBV concentration was 2.0 mg/L in GT 1/4, and 1.9 mg/L in GT 2/3, and did not change significantly across treatment phases. Patients with SVR had similar RBV concentrations compared to patients without SVR in both HCV genotype groups. SVR was not associated with RBV levels ≥2.0 mg/L (GT 1/4, OR 1.19 [0.5-2.86]; GT 2/3, 1.94 [0.78-4.80]) and ≥2.5 mg/L (GT 1/4, 1.56 [0.64-3.84]; GT 2/3 2.72 [0.85-8.73]), regardless of treatment phase, and IL28B genotype.

Conclusion

In HIV/HCV-coinfected patients treated with pegIFN/RBV, therapeutic drug monitoring of RBV concentrations does not enhance the chance of HCV cure, regardless of HCV genotype, treatment phase and IL28B genotype.

Vpx mediated degradation of SAMHD1 has only a very limited effect on lentiviral transduction rate in ex vivo cultured HSPCs

Understanding how to achieve efficient transduction of hematopoietic stem and progenitor cells (HSPCs), while preserving their long-term ability to self-reproduce, is key for applying lentiviral-based gene engineering methods. SAMHD1 is an HIV-1 restriction factor in myeloid and resting CD4⁺ T cells that interferes with reverse transcription by decreasing the nucleotide pools or by its RNase activity. Here we show that SAMHD1 is expressed at high levels in HSPCs cultured in a medium enriched with cytokines. Thus, we hypothesized that degrading SAMHD1 in HSPCs would result in more efficient lentiviral transduction rates. We used viral like particles (VLPs) containing Vpx, shRNA against SAMHD1, or provided an excess of dNTPs or dNs to study this question. Regardless of the method applied, we saw no increase in the lentiviral transduction rate. The result was different when we used viruses (HR-GFP-Vpx+) which carry Vpx and encode GFP. These viruses allow assessment of the effects of Vpx specifically in the transduced cells. Using HR-GFP-Vpx+ viruses, we observed a modest but significant increase in the transduction efficiency. These data suggest that SAMHD1 has some limited efficacy in blocking reverse transcription but the major barrier for efficient lentiviral transduction occurs before reverse transcription.

Long lasting control of viral rebound with a new drug ABX464 targeting Rev - mediated viral RNA biogenesis

BACKGROUND

Current therapies have succeeded in controlling AIDS pandemic. However, there is a continuing need for new drugs, in particular those acting through new and as yet unexplored mechanisms of action to achieve HIV infection cure. We took advantage of the unique feature of proviral genome to require both activation and inhibition of splicing of viral transcripts to develop molecules capable of achieving long lasting effect on viral replication in humanized mouse models through inhibition of Rev-mediated viral RNA biogenesis.

RESULTS

Current HIV therapies reduce viral load during treatment but titers rebound after treatment is discontinued. We devised a new drug that has a long lasting effect after viral load reduction. We demonstrate here that ABX464 compromises HIV replication of clinical isolates of different subtypes without selecting for drug resistance in PBMCs or macrophages. ABX464 alone, also efficiently compromised viral proliferation in two humanized mouse models infected with HIV that require a combination of 3TC, Raltegravir and Tenofovir (HAART) to achieve viral inhibition in current protocols. Crucially, while viral load increased dramatically just one week after stopping HAART treatment, only slight rebound was observed following treatment cessation with ABX464 and the magnitude of the rebound was maintained below to that of HAART for two months after stopping the treatment. Using a system to visualize single HIV RNA molecules in living cells, we show that ABX464 inhibits viral replication by preventing Rev-mediated export of unspliced HIV-1 transcripts to the cytoplasm and by interacting with the Cap Binding Complex (CBC). Deep sequencing of viral RNA from treated cells established that retained viral RNA is massively spliced but importantly, normal cellular splicing is unaffected by the drug. Consistently ABX464 is non-toxic in humans and therefore represents a promising complement to current HIV therapies.

CONCLUSIONS

ABX464 represents a novel class of anti-HIV molecules with unique properties. ABX464 has a long lasting effect in humanized mice and neutralizes the expression of HIV-1 proviral genome of infected immune cells including reservoirs and it is therefore a promising drug toward a functional cure of HIV.

Telomerase activity impacts on Epstein-Barr virus infection of AGS cells

The Epstein-Barr virus (EBV) is transmitted from host-to-host via saliva and is associated with epithelial malignancies including nasopharyngeal carcinoma (NPC) and some forms of gastric carcinoma (GC). Nevertheless, EBV does not transform epithelial cells in vitro where it is rapidly lost from infected primary epithelial cells or epithelial tumor cells. Long-term infection by EBV, however, can be established in hTERT-immortalized nasopharyngeal epithelial cells. Here, we hypothesized that increased telomerase activity in epithelial cells enhances their susceptibility to infection by EBV. Using HONE-1, AGS and HEK293 cells we generated epithelial model cell lines with increased or suppressed telomerase activity by stable ectopic expression of hTERT or of a catalytically inactive, dominant negative hTERT mutant. Infection experiments with recombinant prototypic EBV (rB95.8), recombinant NPC EBV (rM81) with increased epithelial cell tropism compared to B95.8, or recombinant B95.8 EBV with BZLF1-knockout that is not able to undergo lytic replication, revealed that infection frequencies positively correlate with telomerase activity in AGS cells but also partly depend on the cellular background. AGS cells with increased telomerase activity showed increased expression mainly of latent EBV genes, suggesting that increased telomerase activity directly acts on the EBV infection of epithelial cells by facilitating latent EBV gene expression early upon virus inoculation. Thus, our results indicate that infection of epithelial cells by EBV is a very selective process involving, among others, telomerase activity and cellular background to allow for optimized host-to-host transmission via saliva.

Antibiotic susceptibility of Clostridium difficile is similar worldwide over two decades despite widespread use of broad-spectrum antibiotics: an analysis done at the University Hospital of Zurich

BACKGROUND

Clostridium difficile infection (CDI) remains a major health problem worldwide. Antibiotic use, in general, and clindamycin and ciprofloxacin, in particular, have been implicated in the pathogenesis of CDI. Here, we hypothesized that antibiotics that are highly active in vitro against C. difficile are less frequently associated with CDI than others. The primary goals of our study were to determine if antibiotic susceptibility and CDI are associated and whether the antimicrobial susceptibility of C. difficile changed over the years.

METHODS AND RESULTS

We examined a large panel of C. difficile strains collected in 2006-2008 at the University Hospital of Zurich. We found that the antimicrobial susceptibilities to amoxicillin/clavulanate, piperacillin/tazobactam, meropenem, clindamycin, ciprofloxacin, ceftriaxone, metronidazole and vancomycin were similar to those reported in the literature and that they are similar to those reported in other populations over the last two decades. Antibiotic activity did not prevent CDI. For example, thre use of meropenem, which is highly active against all strains tested, was a clear risk factor for CDI. Most of the antibiotics tested also showed a higher minimum inhibitory concentration distribution than that of EUCAST. All strains were susceptible to metronidazole. One strain was resistant to vancomycin.

CONCLUSIONS

Antibiotic susceptibilities of the collection of C. difficile from the University Hospital of Zurich are similar to those reported by others since the 1980. Patients treated with carbapenems and cephalosporins had the highest risk of developing CDI irrespective of the antimicrobial activity of carbapenems.

Optimization of Critical Hairpin Features Allows miRNA-based Gene Knockdown Upon Single-copy Transduction

Gene knockdown using micro RNA (miRNA)-based vector constructs is likely to become a prominent gene therapy approach. It was the aim of this study to improve the efficiency of gene knockdown through optimizing the structure of miRNA mimics. Knockdown of two target genes was analyzed: CCR5 and green fluorescent protein. We describe here a novel and optimized miRNA mimic design called mirGE comprising a lower stem length of 13 base pairs (bp), positioning of the targeting strand on the 5′ side of the miRNA, together with nucleotide mismatches in upper stem positions 1 and 12 placed on the passenger strand. Our mirGE proved superior to miR-30 in four aspects: yield of targeting strand incorporation into RNA-induced silencing complex (RISC); incorporation into RISC of correct targeting strand; precision of cleavage by Drosha; and ratio of targeting strand over passenger strand. A triple mirGE hairpin cassette targeting CCR5 was constructed. It allowed CCR5 knockdown with an efficiency of over 90% upon single-copy transduction. Importantly, single-copy expression of this construct rendered transduced target cells, including primary human macrophages, resistant to infection with a CCR5-tropic strain of HIV. Our results provide new insights for a better knockdown efficiency of constructs containing miRNA. Our results also provide the proof-of-principle that cells can be rendered HIV resistant through single-copy vector transduction, rendering this approach more compatible with clinical applications.

[Diagnosing HIV in Switzerland]

The diagnosis "HIV infection" has severe consequences. False positive or false negative HIV results must be avoided. The Swiss Federal Office of Public Health generated a concept for HIV testing which also includes the characterization of HIV for optimal medical care of the HIV-infected patient. This concept requests that the following four questions are answered: 1. Is the patient indeed HIV-infected? 2. Is it HIV-1 or HIV-2, and if the patient is tested positive for HIV-1, what group, M or O? Are drug resistances present? 3. What is the HIV copy number in the blood? 4. What is the percentage of recent HIV-infections (< 12 months) among all tested positive test results? We also present a short summary how to approach the HIV-infected patient at the initial and subsequent visits.

[Prevention of HIV and other sexually transmitted infections (STI)]

The number of new HIV-1 infections remains stable in Switzerland over the last years thanks to the effective prevention programs. However, the aim to halve the new HIV infection rate has not been reached. Early identification of patients at risk of acquiring HIV infection and counselling "safer sex" rules as well as treating HIV-infected patients plays a decisive role in this program. Studies are -ongoing to investigate additional preventive measures such as pre-exposure prophylaxis, microbicides and vaccines, but none of those approaches permit omitting "safer sex". Incidences of other sexual transmitted infections are increasing rapidly, in particular the incidence of Syphilis. Transmission occurs more often orally or rectally than vaginally and patients are often asymptomatic. Condoms provide only limited protection. In addition antibiotic resistance emerges complicating the therapy, as for example for gonorrhea. Testing and treatment of infected patients is primordial as well as contact tracing. In this work, we discuss the different elements for preventing STIs with major emphasis on HIV.

Early gene expression changes by Epstein-Barr virus infection of B-cells indicate CDKs and survivin as therapeutic targets for post-transplant lymphoproliferative diseases

Lymphoproliferative diseases (LPDs) associated with Epstein-Barr virus (EBV) infection cause significant morbidity and mortality in bone marrow and solid organ transplant recipients. To gain insight into LPD pathogenesis and to identify potential effective therapeutic approaches, we investigated early molecular events leading to B-cell transformation by gene expression profiling of EBV-infected B-cells from tonsils by Affymetrix microarray 72 hr postinfection when the B-cells hyperproliferation phase starts. Cell cycle and apoptosis were the most significantly affected pathways and enriched gene sets. In particular, we found significantly increased expression of cyclin-dependent kinase (CDK)1 and CCNB1 (cyclin B1) and of one of their downstream targets BIRC5 (survivin). Importantly, the strong upregulation of the antiapoptotic protein survivin was confirmed in lymphoblastoid cell lines (LCLs) and 71% of EBV-positive post-transplant EBV-LPD lesions scored positive for survivin. The validity of early transforming events for the identification of therapeutic targets for EBV-LPD was confirmed by the marked antiproliferative effect of the CDK inhibitor flavopiridol on LCLs and by the strong induction of apoptosis by survivin inhibition with YM155 or terameprocol. Our results suggest that targeting of CDKs and/or survivin in post-transplant EBV-LPD by specific inhibitors might be an important approach to control and eliminate EBV-transformed B-cells that should be further considered.

Evaluation of the immunomodulatory and antiviral effects of the cytokine combination IFN-α and IL-7 in the lymphocytic choriomeningitis virus and Friend retrovirus mouse infection models

Existing therapies for chronic viral infections are still suboptimal or have considerable side effects, so new therapeutic strategies need to be developed. One option is to boost the host's immune response with cytokines. We have recently shown in an acute ex vivo HIV infection model that co-administration of interferon (IFN)-α and interleukin (IL)-7 allows us to combine the potent anti-HIV activity of IFN-α with the beneficial effects of IL-7 on T-cell survival and function. Here we evaluated the effect of combining IFN-α and IL-7 on viral replication in vivo in the chronic lymphocytic choriomeningitis virus (LCMV) and acute Friend retrovirus (FV) infection models. In the chronic LCMV model, cytokine treatment was started during the early replication phase (i.e., on day 7 post-infection [pi]). Under the experimental conditions used, exogenous IFN-α inhibited FV replication, but had no effect on viral replication in the LCMV model. There was no therapeutic benefit of IL-7 either alone or in combination with IFN-α in either of the two infection models. In the LCMV model, dose-dependent effects of the cytokine combination on T-cell phenotype/function were observed. It is possible that these effects would translate into antiviral activity in re-challenged mice. It is also possible that another type of IFN-α/β or induction of endogenous IFN-α/β alone or in combination with IL-7 would have antiviral activity in the LCMV model. Furthermore, we cannot exclude that some effect on viral titers would have been seen at later time points not investigated here (i.e., beyond day 34 pi). Finally, IFN-α/IL-7 may inhibit the replication of other viruses. Thus it might be worth testing these cytokines in other in vivo models of chronic viral infections.

Nodular regenerative hyperplasia of the liver associated with didanosine persists for years even after its interruption

The authors describe an HIV-positive patient with nodular regenerative hyperplasia of the liver with non-cirrhotic portal hypertension. Despite stopping the culprit drug, didanosine, the radiologic changes persisted for years. When evaluating liver pathologies, antiretroviral drugs must be included in the differential diagnosis, even when they have been stopped years ago.

HIV interferes with SOCS-1 and -3 expression levels driving immune activation

HIV infection is characterized by sustained immune activation, which is reflected by activated T cells and, in particular, by increased levels of phosphorylated STAT proteins. Here, we hypothesized that T-cell activation in HIV infection is partially due to the inability of SOCS-1 and SOCS-3 to control the JAK/STAT pathway. We found higher levels of SOCS-1/3 mRNA levels in CD4(+) T cells of HIV-infected patients than in healthy controls. However, SOCS protein levels were lower, explaining the lack of attenuation of the JAK/STAT pathway. Infection of CD4(+) T cells alone did not activate STATs, while ex vivo infection of PBMC did, indicating that non-T cells critical for shaping the immune response, e.g. DC were responsible for the STAT-1 activation. Supernatants from ex vivo-infected PBMC transferred to CD4(+) T cells induced JAK/STAT activation, pointing to a central role of soluble factors. Notably, over-expression of SOCS-1/3 in CD4(+) T cells prevented JAK/STAT activation. Thus, HIV infection interferes with SOCS-1/3 expression driving immune activation. Sustained immune activation disrupts the lymphoid system and favors HIV replication since HIV preferentially infects activated cells. We speculate that regulating SOCS may be a potential way to counteract immune activation in HIV disease.

B cells from HIV-infected patients with primary central nervous system lymphoma display an activated phenotype and have a blunted TNF-α response to TLR9 triggering

Each cell in HIV-associated primary central nervous system lymphoma (PCNSL) harbors latent EBV. Notably, the triggering of TLR9, a key event in HIV pathogenesis, also promotes EBV latency and transformation. We hypothesized that because only a minority of HIV-infected patients develops PCNSL, their B cells exhibit aberrant signaling responses to TLR9 triggering. We found higher levels of IL-6, CD80, and CD86 expression at baseline in B cells of those patients than in B cells of matched controls, whereas TNF-a expression was lower. Notably, on TLR9 triggering with CpG 2006, CD80 and TNF-α were up-regulated to a lesser extent in B cells of the former than in those of matched controls. The reduced up-regulation of CD80 might be explained by its higher baseline expression resulting in a more blunted response rather than a specific deficit of the signaling response to TLR9 triggering. However, this cannot explain the blunted TNF-α response, which warrants further investigation. Finally, since increased IL-6 expression is linked to EBV-associated Hodgkin’s lymphoma, the enhanced baseline expression of IL-6 might be important in the pathogenesis of PCNSL in HIV-infected patients.

Low postseroconversion CD4 count and rapid decrease of CD4 density identify HIV+ fast progressors

CD4 expression in HIV replication is paradoxical: HIV entry requires high cell-surface CD4 densities, but replication requires CD4 down-modulation. However, is CD4 density in HIV+ patients affected over time? Do changes in CD4 density correlate with disease progression? Here, we examined the role of CD4 density for HIV disease progression by longitudinally quantifying CD4 densities on CD4+ T cells and monocytes of ART-naive HIV+ patients with different disease progression rates. This was a retrospective study. We defined three groups of HIV+ patients by their rate of CD4+ T cell loss, calculated by the time between infection and reaching a CD4 level of 200 cells/microl: fast (<7.5 years), intermediate (7.5-12 years), and slow progressors (>12 years). Mathematical modeling permitted us to determine the maximum CD4+ T cell count after HIV seroconversion (defined as "postseroconversion CD4 count") and longitudinal profiles of CD4 count and density. CD4 densities were quantified on CD4+ T cells and monocytes from these patients and from healthy individuals by flow cytometry. Fast progressors had significantly lower postseroconversion CD4 counts than other progressors. CD4 density on T cells was lower in HIV+ patients than in healthy individuals and decreased more rapidly in fast than in slow progressors. Antiretroviral therapy (ART) did not normalize CD4 density. Thus, postseroconversion CD4 counts define individual HIV disease progression rates that may help to identify patients who might benefit most from early ART. Early discrimination of slow and fast progressors suggests that critical events during primary infection define long-term outcome. A more rapid CD4 density decrease in fast progressors might contribute to progressive functional impairments of the immune response in advanced HIV infection. The lack of an effect of ART on CD4 density implies a persistent dysfunctional immune response by uncontrolled HIV infection.

Inadequate clearance of translocated bacterial products in HIV-infected humanized mice

Bacterial translocation from the gut and subsequent immune activation are hallmarks of HIV infection and are thought to determine disease progression. Intestinal barrier integrity is impaired early in acute retroviral infection, but levels of plasma lipopolysaccharide (LPS), a marker of bacterial translocation, increase only later. We examined humanized mice infected with HIV to determine if disruption of the intestinal barrier alone is responsible for elevated levels of LPS and if bacterial translocation increases immune activation. Treating uninfected mice with dextran sodium sulfate (DSS) induced bacterial translocation, but did not result in elevated plasma LPS levels. DSS-induced translocation provoked LPS elevation only when phagocytic cells were depleted with clodronate liposomes (clodrolip). Macrophages of DSS-treated, HIV-negative mice phagocytosed more LPS ex vivo than those of control mice. In HIV-infected mice, however, LPS phagocytosis was insufficient to clear the translocated LPS. These conditions allowed higher levels of plasma LPS and CD8+ cell activation, which were associated with lower CD4+/CD8+ cell ratios and higher viral loads. LPS levels reflect both intestinal barrier and LPS clearance. Macrophages are essential in controlling systemic bacterial translocation, and this function might be hindered in chronic HIV infection.

HIV infection leads to continuous destruction of the body's immune defenses. Furthermore, disease progression is linked to heightened levels of immune activation. However, the underlying activating factors and their relationships to HIV pathogenesis are controversial. In patients with chronic HIV infection, bacteria and their products, such as lipopolysaccharide (LPS), translocate from the intestinal lumen into the systemic circulation. In the current study, we investigated the pathogenic potential of bacterial translocation in HIV-infected humanized mice. By modulating the amount of bacterial translocation in the mice, we determined that LPS elevation depends on intestinal barrier dysfunction and defective LPS clearance by macrophages. HIV-infected mice showed inadequate LPS clearance, leading to a cascade of uncontrolled bacterial translocation, T-cell activation, HIV replication, and T-cell loss. Our study highlights how important the interplay between different immune cells is for maintaining a healthy balance between immune activation with the goal to defend the body against microbes and detrimental activation that fuels HIV replication.

Plasma cell toll-like receptor (TLR) expression differs from that of B cells, and plasma cell TLR triggering enhances immunoglobulin production

Toll-like receptors (TLRs) are key receptors of the innate immune system and show cell subset-specific expression. We investigated the messenger RNA (mRNA) expression of TLR genes in human haematopoietic stem cells (HSC), in naïve B cells, in memory B cells, in plasma cells from palatine tonsils and in plasma cells from peripheral blood. HSC and plasma cells showed unrestricted expression of TLR1-TLR9, in contrast to B cells which lacked TLR3, TLR4 and TLR8 but expressed mRNA of all other TLRs. We demonstrated, for the first time, that TLR triggering of terminally differentiated plasma cells augments immunoglobulin production. Thus, boosting the immediate antibody response by plasma cells upon pathogen recognition may point to a novel role of TLRs.

Disturbance of the gut-associated lymphoid tissue is associated with disease progression in chronic HIV infection

Why and how HIV makes people sick is highly debated. Recent evidence implicates heightened immune activation due to breakdown of the gastrointestinal barrier as a determining factor of lentiviral pathogenesis. HIV-mediated loss of Th17 cells from the gut-associated lymphoid tissue (GALT) impairs mucosal integrity and innate defense mechanisms against gut microbes. Translocation of microbial products from the gut, in turn, correlates with increased immune activation in chronic HIV infection and may further damage the immune system by increasing viral and activation-induced T cell death, by reducing T cell reconstitution due to tissue scarring, and by impairing the function of other cell types, such as gammadelta T cells and epithelial cells. Maintaining a healthy GALT may be the key to reducing the pathogenic potential of HIV.

Immuno-chemotherapy reduces recurrence of malignant pleural mesothelioma: an experimental setting

OBJECTIVE

To assess the effect of immuno-chemotherapy on the extent of local tumour recurrence in an established rat model of malignant pleural mesothelioma (MPM).

METHODS

Six days after subpleural inoculation of a syngeneic MPM cell line Interleukin-45 (IL-45), left-sided pneumonectomy and resection of the tumour nodule was performed. Animals were randomised into four treatment groups for intrapleural therapy: control (n=6), 500 microg cytosine phosphate guanosine oligodeoxynucleotide (CpG-ODN) (n=6), cisplatin-fibrin (n=6), cisplatin-fibrin+500 microg CpG (n=6). Six days later the volume of tumour recurrence was assessed, which was the primary endpoint. Secondary endpoints were quantification of the ratio host/tumour cells in the local recurrence and cytokine expression profile in the tumour tissue by real time quantitative PCR (qPCR). T lymphocyte subpopulations in the tumour recurrence tissue were evaluated by immunohistochemistry. Treatment-related toxicity was monitored by measuring blood chemistry and complete blood count.

RESULTS

The volume of tumour recurrence was significantly reduced from 610 mm(3) in the control group to 11.7 mm(3) in the cisplatin-fibrin group (p=0.004) and to 21.8mm(3) in the cisplatin-fibrin+CpG group (p=0.004). Pro-inflammatory cytokines (Interferon-gamma (IFN-gamma), Interleukin-6 (IL-6), Interleukin-12 (IL-12)) were increased after treatment with cisplatin-fibrin+CpG in comparison to cisplatin-fibrin alone but differences were not statistically significant. We found a higher ratio of host/tumour cells in the cisplatin-fibrin+CpG group (45/55%) compared to the cisplatin-fibrin group (27/73%). In comparison to the control group, animals treated with cisplatin-fibrin+CpG showed a higher number of CD8+ T-cells in the tumour tissue. No significant treatment-related toxicity was observed.

CONCLUSIONS

Adjuvant treatment with chemotherapy or immuno-chemotherapy leads to significant reduction of mesothelioma recurrence after surgery in this rat MPM model. Immuno-chemotherapy resulted in an increased recruitment of inflammatory cells to the site of tumourigenesis and elicited higher level of tumour growth inhibiting cytokines.

Antigen kinetics determines immune reactivity

A current paradigm in immunology is that the strength of T cell responses is governed by antigen dose, localization, and costimulatory signals. This study investigates the influence of antigen kinetics on CD8 T cell responses in mice. A fixed cumulative antigen dose was administered by different schedules to produce distinct dose-kinetics. Antigenic stimulation increasing exponentially over days was a stronger stimulus for CD8 T cells and antiviral immunity than a single dose or multiple dosing with daily equal doses. The same was observed for dendritic cell vaccination, with regard to T cell and anti-tumor responses, and for T cells stimulated in vitro. In conclusion, stimulation kinetics per se was shown to be a separate parameter of immunogenicity. These findings warrant a revision of current immunization models and have implications for vaccine development and immunotherapy.

Human T cell development and HIV infection in human hemato-lymphoid system mice

Advances in generation of mice that on human hematopoietic stem and progenitor cell transplantation develop and maintain human hemato-lymphoid cells have fueled an already thriving field of research. We focus here on human T cell development and HIV infection in Rag2 -/- gamma(c) -/- mice transplanted as newborns with human CD34+ cord blood hematopoietic stem and progenitor cells.

Adaptation of the ultrasensitive HIV-1 p24 antigen assay to dried blood spot testing

Implementation of molecular tests for the assessment of pediatric HIV-1 infection in resource-limited countries is difficult because of technical complexity and costs. Alternatives like the ultrasensitive HIV-1 p24 antigen enzyme-linked immunosorbent assay have therefore been proposed. We have now adapted this test to dried blood spot (DBS) plasma p24 antigen (p24). High background activity was recognized as originating from endogenous peroxidase and eliminated by H2O2 quenching. The assay was evaluated with 72 pediatric specimens from Tanzania and with 210 pediatric or adult specimens from Switzerland. A real-time polymerase chain reaction assay for DBS DNA and/or plasma RNA identified HIV-1 infection in 38 Tanzanian children. HIV-1 subtypes included 18 C, 9 A1, 8 D, 1 AC, 1 J-like, and 1 unidentified. The detection rates for the different assays were as follows: DBS-p24, 32 (84%) of 38 samples; DBS DNA, 30 (79%) of 38 samples; plasma-p24, 23 (85%) of 27 samples; and plasma RNA, 30 (100%) of 30 samples. False-negative DBS-p24 was associated with subtype D (P < 0.01). DBS-p24 detection for non-D subtypes was 93% (95% confidence interval: 81% to 99%), and for subtype C, it was 94% (95% confidence interval: 76% to 99%). Specificity among 193 HIV-negative DBS samples was 100%. Correlation of DBS-p24 and plasma-p24 concentrations was excellent (R = 0.83, P < 0.0001). DBS-p24 is thus a promising alternative to molecular tests for HIV-1 in subtype C regions. It should now be evaluated in large studies of children for accurate assessment of diagnostic sensitivity.

Immune activation suppresses initiation of lytic Epstein-Barr virus infection

Primary infection with Epstein-Barr virus (EBV) is asymptomatic in children with immature immune systems but may manifest as infectious mononucleosis, a vigorous immune activation, in adolescents or adults with mature immune systems. Infectious mononucleosis and chronic immune activation are linked to increased risk for EBV-associated lymphoma. Here we show that EBV initiates progressive lytic infection by expression of BZLF-1 and the late lytic genes gp85 and gp350/220 in cord blood mononuclear cells (CBMC) but not in peripheral blood mononuclear cells (PBMC) from EBV-naive adults after EBV infection ex vivo. Lower levels of proinflammatory cytokines in CBMC, used to model a state of minimal immune activation and immature immunity, than in PBMC were associated with lytic EBV infection. Triggering the innate immunity specifically via Toll-like receptor-9 of B cells substantially suppressed BZLF-1 mRNA expression in acute EBV infection ex vivo and in anti-IgG-stimulated chronically latently EBV-infected Akata Burkitt lymphoma cells. This was mediated in part by IL-12 and IFN-gamma. These results identify immune activation as critical factor for the suppression of initiation of lytic EBV infection. We hypothesize that immune activation contributes to EBV-associated lymphomagenesis by suppressing lytic EBV and in turn promotes latent EBV with transformation potential.

Polymorphisms in Toll-like receptor 9 influence the clinical course of HIV-1 infection

BACKGROUND

The clinical course of HIV-1 infection is highly variable among individuals, at least in part as a result of genetic polymorphisms in the host. Toll-like receptors (TLRs) have a key role in innate immunity and mutations in the genes encoding these receptors have been associated with increased or decreased susceptibility to infections.

OBJECTIVES

To determine whether single-nucleotide polymorphisms (SNPs) in TLR2-4 and TLR7-9 influenced the natural course of HIV-1 infection.

METHODS

Twenty-eight SNPs in TLRs were analysed in HAART-naive HIV-positive patients from the Swiss HIV Cohort Study. The SNPs were detected using Sequenom technology. Haplotypes were inferred using an expectation-maximization algorithm. The CD4 T cell decline was calculated using a least-squares regression. Patients with a rapid CD4 cell decline, less than the 15th percentile, were defined as rapid progressors. The risk of rapid progression associated with SNPs was estimated using a logistic regression model. Other candidate risk factors included age, sex and risk groups (heterosexual, homosexual and intravenous drug use).

RESULTS

Two SNPs in TLR9 (1635A/G and +1174G/A) in linkage disequilibrium were associated with the rapid progressor phenotype: for 1635A/G, odds ratio (OR), 3.9 [95% confidence interval (CI),1.7-9.2] for GA versus AA and OR, 4.7 (95% CI,1.9-12.0) for GG versus AA (P = 0.0008).

CONCLUSION

Rapid progression of HIV-1 infection was associated with TLR9 polymorphisms. Because of its potential implications for intervention strategies and vaccine developments, additional epidemiological and experimental studies are needed to confirm this association.

Anti-HIV state but not apoptosis depends on IFN signature in CD4+ T cells

To gain insights into the molecular mechanisms underlying early host responses to HIV in the CD4(+) T cell target population, we examined gene expression in CD4(+) T cells isolated 24 h after ex vivo HIV infection of lymphocyte aggregate cultures derived from human tonsils. Gene profiling showed a distinct up-regulation of genes related to immune response and response to virus, notably of IFN-stimulated genes (ISGs), irrespective of the coreceptor tropism of the virus. This mostly IFN-alpha-dependent gene signature suggested the involvement of plasmacytoid dendritic cells, a principal component of the antiviral immune response. Indeed, depletion of plasmacytoid dendritic cells before HIV inoculation abrogated transcriptional up-regulation of several ISGs and resulted in increased levels of HIV replication. Treatment with a blocking anti-IFN-alphaR Ab yielded increased HIV replication; conversely, HIV replication was decreased in pDC-depleted cultures treated with IFN-alpha. Among up-regulated ISGs was also TRAIL, indicating a potential role of the IFN signature in apoptosis. However, a blocking anti-TRAIL Ab did not abrogate apoptosis of CD4(+) T cells in CXCR4-tropic HIV-infected cultures, suggesting the involvement of pathways other than TRAIL mediated. We conclude that acute HIV infection of lymphoid tissue results in up-regulation of ISGs in CD4(+) T cells, which induces an anti-HIV state but not apoptosis.

Disseminated and sustained HIV infection in CD34+ cord blood cell-transplanted Rag2-/-gamma c-/- mice

Because of species selectivity, HIV research is largely restricted to in vitro or clinical studies, both limited in their ability to rapidly assess new strategies to fight the virus. To prospectively study some aspects of HIV in vivo, immunodeficient mice, transplanted with either human peripheral blood leukocytes or human fetal tissues, have been developed. Although these are susceptible to HIV infection, xenoreactivity, and short infection spans, resource and ethical constraints, as well as biased HIV coreceptor tropic strain infection, pose substantial problems in their use. Rag2(-/-)gamma(c)(-/-) mice, transplanted as newborns with human CD34(+) cells, were recently shown to develop human B, T, and dendritic cells, constituting lymphoid organs in situ. Here we tested these mice as a model system for HIV-1 infection. HIV RNA levels peaked to up to 2 x 10(6) copies per milliliter of plasma early after infection, and viremia was observed for up to 190 days, the longest time followed. A marked relative CD4(+) T cell depletion in peripheral blood occurred in CXCR4-tropic strain-infected mice, whereas this was less pronounced in CCR5-tropic strain-infected animals. Thymus infection was almost exclusively observed in CXCR4-tropic strain-infected mice, whereas spleen and lymph node HIV infection occurred irrespective of coreceptor selectivity, consistent with respective coreceptor expression on human CD4(+) T cells. Thus, this straightforward to generate and cost-effective in vivo model closely resembles HIV infection in man and therefore should be valuable to study virus-induced pathology and to rapidly evaluate new approaches aiming to prevent or treat HIV infection.

Human tonsillar tissue block cultures differ from autologous tonsillar cell suspension cultures in lymphocyte subset activation and cytokine gene expression

Lymphoid tissues cultured either as tissue blocks or as cell suspensions are used to study the behaviour of immune cells within their habitat. The preservation of tissue structures in tissue blocks, which is considered to be a major advantage, has been poorly defined. We characterised the morphological evolution of tissue cultures from human palatine tonsils and compared their lymphocyte subsets and the constitutive cytokine gene expression to those in autologous tonsillar single-cell suspension cultures over time, and after adding cyclosporin A (CsA) to mimic the situation in individuals treated with immunosuppressive drugs. Density and morphology of follicles were conserved up to 4 days, during which tissue cultures exhibited similar cell viability as suspension cultures, but a significantly less frequent increase of CD95 expression in T cells, smaller variation of the proportion of CD4(+) cells and better CD21(+)/CD23(-) B-cell survival. Treatment with cyclosporin A at higher concentrations resulted in superior histologic preservation of lymphoid tissue structures and seemed to further prevent the expression of CD95 by CD3(+) cells and the activation in tissue culture of CD21(+) cells. Constitutive gene expression levels of the stromal cytokines interleukin (IL)-1beta and interleukin-6 in tissue culture were significantly higher than those in suspension cultures. These results suggest that tonsillar tissue cultures preserve their structure only for a limited time, during which they more closely reflect processes in vivo, including a state of iatrogenic immunosuppression, than do their cell suspension counterparts.

Ultrasensitive quantitative HIV-1 p24 antigen assay adapted to dried plasma spots to improve treatment monitoring in low-resource settings

BACKGROUND

Our group has previously developed a quantitative and ultrasensitive HIV-1 p24 antigen assay that is inexpensive, easy-to-perform, and can be carried out in low-resource settings. Since antiretroviral therapies are becoming more accessible in resource-constrained countries, methods to assess HIV-1 viraemia are urgently needed to achieve a high standard of care in HIV-1 management.

OBJECTIVES

To adapt our quantitative assay to dried plasma spots (DPS), in order to further simplify this test and make it more accessible to resource-constrained countries.

STUDY DESIGN

DPS from 47 HIV-seropositive, treated or untreated adult individuals and 30 healthy individuals were examined.

RESULTS

A specificity of 100% was observed when p24 antigen was measured using DPS, and no differences of p24 concentration could be seen between DPS and venous plasma. The correlation between DPS and venous plasma p24 was excellent (R=0.93, CI(95%)=0.88-0.96, p<0.0001). Similarly, p24 antigen concentrations using DPS were well correlated with RNA viral load (R=0.53, CI(95%)=0.27-0.72, p=0.0002).

CONCLUSIONS

This quantitative p24 antigen test has similar sensitivity and specificity using DPS and venous plasma, and has the potential to improve health care delivery to HIV-affected individuals in resource-constrained countries.

TLR7/8 Triggering Exerts Opposing Effects in Acute versus Latent HIV Infection

TLRs trigger innate immunity by recognizing conserved motifs of microorganisms. Recently, ssRNAs from HIV and influenza virus were shown to trigger TLR7 and 8. Thus, we hypothesized that HIV ssRNA, by triggering TLR7/8, affects HIV pathogenesis. Indeed, HIV ssRNA rendered human lymphoid tissue of tonsillar origin or PBMC barely permissive to HIV replication. The synthetic compound R-848, which also triggers TLR7/8, showed similar anti-HIV activity. Loss of R-848's activity in lymphoid tissue depleted of B cells suggested a role for B cells in innate immunity. TLR7/8 triggering appears to exert antiviral effects through soluble factors: conditioned medium reduced HIV replication in indicator cells. Although a number of cytokines and chemokines were increased upon adding R-848 to lymphoid tissue, blocking those cytokines/chemokines (i.e., IFN-alpha receptor, IFN-gamma, MIP-1alpha, -1beta, RANTES, and stromal cell-derived factor-1) did not result in the reversal of R-848's anti-HIV activity. Thus, the nature of this soluble factor(s) remains unknown. Unlike lymphoid tissue acutely infected with HIV, triggering latently infected promonocytic cells induced the release of HIV virions. The anti-HIV effects of triggering TLR7/8 may inhibit rapid killing, while pro-HIV effects may guarantee a certain replication level. Compounds triggering TLR7/8 may be attractive drug candidates to purge latent HIV while preventing new infections.