HIV Microbicides Research Articles

Superior human leukocyte reconstitution and susceptibility to vaginal HIV transmission in humanized NOD- scid IL-2Rγ −/− (NSG) BLT mice

Humanized Bone marrow/Liver/Thymus (BLT) mice recapitulate the mucosal transmission of HIV, permitting study of early events in HIV pathogenesis and evaluation of preexposure prophylaxis methods to inhibit HIV transmission. Human hematopoiesis is reconstituted in NOD- scid mice by implantation of human fetal liver and thymus tissue to generate human T cells plus intravenous injection of autologous liver-derived CD34 + hematopoietic stem cells to engraft the mouse bone marrow. In side-by-side comparisons, we show that NOD- scid mice homozygous for a deletion of the IL-2Rγ-chain (NOD- scid IL-2Rγ −/−) are far superior to NOD- scid mice in both their peripheral blood reconstitution with multiple classes of human leukocytes (e.g., a mean of 182 versus 14 CD4 + T cells per μl 12 weeks after CD34 + injection) and their susceptibility to intravaginal HIV exposure (84% versus 11% viremic mice at 4 weeks). These results should speed efforts to obtain preclinical animal efficacy data for new HIV drugs and microbicides.

Early identification of availability issues for poorly water-soluble microbicide candidates in biorelevant media: A case study with saquinavir

In the search for a successful HIV microbicide, many poorly water-soluble antiviral agents are currently being investigated. Unfortunately, solubility and precipitation issues may limit intravaginal concentrations and thus availability of these agents upon application of an aqueous gel formulation. In the present study, we evaluated the in vitro precipitation behavior of the HIV protease inhibitor saquinavir in vaginal and seminal fluid simulants (VFS and SFS). Despite its limited solubility, the mesylate salt of saquinavir enables formulation of sufficiently high concentrations (2.5 mM, i.e. ca. 10 5-fold in vitro IC 50 values) in a standard aqueous vehicle. While saquinavir stays in solution upon dilution with VFS, SFS induces precipitation of saquinavir, resulting in a 5-fold reduced availability and antiviral potency. Inclusion of the solubilizing excipients polyethylene glycol 1000 (12%) and hydroxypropyl-β-cyclodextrin (2.5%) was required to avoid saquinavir precipitation in SFS and to restore the antiviral potency of the formulation. This study illustrates the importance of identifying solubility and precipitation issues of microbicide candidates in biorelevant media and provides a simple in vitro procedure to implement this evaluation in early microbicide development.

Rational design of HIV vaccines and microbicides: report of the EUROPRISE network annual conference 2010

Novel, exciting intervention strategies to prevent infection with HIV have been tested in the past year, and the field is rapidly evolving. EUROPRISE is a network of excellence sponsored by the European Commission and concerned with a wide range of activities including integrated developmental research on HIV vaccines and microbicides from discovery to early clinical trials. A central and timely theme of the network is the development of the unique concept of co-usage of vaccines and microbicides. This review, prepared by the PhD students of the network captures much of the research ongoing between the partners. The network is in its 5th year and involves over 50 institutions from 13 European countries together with 3 industrial partners; GSK, Novartis and Sanofi-Pasteur. EUROPRISE is involved in 31 separate world-wide trials of Vaccines and Microbicides including 6 in African countries (Tanzania, Mozambique, South Africa, Kenya, Malawi, Rwanda), and is directly supporting clinical trials including MABGEL, a gp140-hsp70 conjugate trial and HIVIS, vaccine trials in Europe and Africa.

HIV sexual transmission and microbicides

Pathogens often rely on the contacts between hosts for transmission. Most viruses have adapted their transmission mechanisms to defined behaviours of their host(s) and have learned to exploit these for their own propagation. Some viruses, such as HIV, the human papillomavirus (HPV), HSV-2 and HCV, cause sexually transmitted infections (STIs). Understanding the transmission of particular viral variants and comprehending the early adaptation and evolution is fundamental to eventually inhibiting sexual transmission of HIV. Here, we review the current understanding of the mechanisms of sexual transmission and the biology of the transmitted HIV. Next, we present a timely overview of candidate microbicides, including past, ongoing and future clinical trials of HIV topical microbicides.

Nonlinear tube-fitting for the analysis of anatomical and functional structures

We are concerned with the estimation of the exterior surface and interior summaries of tube-shaped anatomical structures. This interest is motivated by two distinct scientific goals, one dealing with the distribution of HIV microbicide in the colon and the other with measuring degradation in white-matter tracts in the brain. Our problem is posed as the estimation of the support of a distribution in three dimensions from a sample from that distribution, possibly measured with error. We propose a novel tube-fitting algorithm to construct such estimators. Further, we conduct a simulation study to aid in the choice of a key parameter of the algorithm, and we test our algorithm with validation study tailored to the motivating data sets. Finally, we apply the tube-fitting algorithm to a colon image produced by single photon emission computed tomography (SPECT) and to a white-matter tract image produced using diffusion tensor imaging (DTI).

Ethical challenges in HIV microbicide research: What protections do women need?

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Controlled-release Vaginal Ring drug-delivery Systems: a Key Strategy for the Development of Effective HIV Microbicides

Over half of all HIV-infected adults are women and heterosexual intercourse is a significant mode of viral transmission. This review examines the potential for using polymeric vaginal ring systems to provide controlled delivery of HIV microbicides in order to prevent heterosexual transmission of the virus. Continuous delivery of microbicides has the potential to be more effective than one-off dosing. Thus, controlled-release vaginal delivery devices are now a key area of HIV prevention research. Initial clinical trials on vaginal rings loaded with dapivirine (a candidate microbicide) have indicated that these products are safe and well tolerated by women. These devices are female-initiated, robust and capable of long-term delivery of the active agent. Vaginal rings may offer an effective system for the controlled delivery of microbicides to prevent heterosexual transmission of HIV. Candidate vaginal ring microbicide products are now in clinical trials.

First Real Success For Anti-Hiv Gel: A New Start For HIV Microbicides?

First Real Success For Anti-Hiv Gel: A New Start For HIV Microbicides?

Intertwining Biomedical Research and Public Health in HIV Microbicide Research

Finding an effective microbicide that could substantially lower women’s risk of acquiring HIV infection is an ethical imperative. Women and girls continue to be disproportionally affected by HIV in sub-Saharan Africa. Ethics guidelines for conducting preventive HIV microbicide trials call for steps that intertwine biomedical research and public health. Ethical considerations include adequate studies of the safety of microbicides, the use of placebo controls in future trials once a microbicide is shown to be effective, whether leftover microbicide from a trial that demonstrated efficacy should be made available to the public or used in the control group of a future trial, what preventive measures and treatment should be provided for trial participants during and after the research, and what constitute ‘fair benefits’ to the community or country when a trial is completed. The Global Campaign for Microbicides conducted a study of the benefits being provided to participants in microbicide trials and others, and found substantial evidence that researchers and sponsors are meeting the obligations stated in ethical guidelines. A cautionary tale of an HIV prevention trial that was prematurely halted demonstrates the need for engagement with the community where trials are carried out.

Erratum to: Rational design of HIV vaccine and microbicides: report of the EUROPRISE annual conference

Following the publication of this article (Journal of Translational Medicine, 8:72), it was noted that a co-author had been omitted from the authors list. The submitting authors would like to apologise to Hannes Uchtenhagen for this error. The Competing interests and Authors' contributions sections have now been updated to reflect this amendment.

Rational design of HIV vaccine and microbicides: report of the EUROPRISE annual conference.

EUROPRISE is a Network of Excellence sponsored from 2007 to 2011 by the European Commission within the 6th Framework Program. The Network encompasses a wide portfolio of activities ranging from an integrated research program in the field of HIV vaccines and microbicides to training, dissemination and advocacy. The research program covers the whole pipeline of vaccine and microbicide development from discovery to early clinical trials. The Network is composed of 58 partners representing more than 65 institutions from 13 European countries; it also includes three major pharmaceutical companies (GlaxoSmithKline, Novartis and Sanofi-Pasteur) involved in HIV microbicide and vaccine research. The Network displays a dedicated and informative web page: http://www.europrise.org. Finally, a distinguishing trait of EUROPRISE is its PhD School of students from across Europe, a unique example in the world of science aimed at spreading excellence through training.EUROPRISE held its second annual conference in Budapest in November, 2009. The conference had 143 participants and their presentations covered aspects of vaccine and microbicide research, development and discovery. Since training is a major task of the Network, the students of the EUROPRISE PhD program summarized certain presentations and their view of the conference in this paper.

Hiv Microbicides: State-Of-The-Art and New Perspectives on the Development of Entry Inhibitors

Since the discovery of HIV at the beginning of the 1980s, numerous efforts have been devoted to the search of an efficient vaccine. There are at least 25 drugs available for HIV treatment, but no cure is available. The observation that therapy for HIV disease is life long and that these drugs are associated with a number of side effects underlines the need for approaches aimed at preventing rather than treating infection. Additionally, the economic burden of treatment for the HIV infection occupies an increasing share of healthcare expenditure, making current practices likely to become difficult to sustain in the long run. Unfortunately, no effective vaccine for this disease is foreseeable in the near future. Microbicides could be an alternate way to build preventative approaches to HIV infection. Strategies based on preventing the virus from reaching its target cells seem to have some room for development and application. In this review we explore the state-of-the-art of available microbicides, focusing on HIV entry inhibitors. In addition, we discuss new compounds that show anti-HIV activity, which could be effective candidates.

HIV-1 Neutralization Profile and Plant-Based Recombinant Expression of Actinohivin, an Env Glycan-Specific Lectin Devoid of T-Cell Mitogenic Activity

The development of a topical microbicide blocking the sexual transmission of HIV-1 is urgently needed to control the global HIV/AIDS pandemic. The actinomycete-derived lectin actinohivin (AH) is highly specific to a cluster of high-mannose-type glycans uniquely found on the viral envelope (Env). Here, we evaluated AH's candidacy toward a microbicide in terms of in vitro anti-HIV-1 activity, potential side effects, and recombinant producibility. Two validated assay systems based on human peripheral blood mononuclear cell (hPBMC) infection with primary isolates and TZM-bl cell infection with Env-pseudotyped viruses were employed to characterize AH's anti-HIV-1 activity. In hPMBCs, AH exhibited nanomolar neutralizing activity against primary viruses with diverse cellular tropisms, but did not cause mitogenicity or cytotoxicity that are often associated with other anti-HIV lectins. In the TZM-bl-based assay, AH showed broad anti-HIV-1 activity against clinically-relevant, mucosally transmitting strains of clades B and C. By contrast, clade A viruses showed strong resistance to AH. Correlation analysis suggested that HIV-1′s AH susceptibility is significantly linked to the N-glycans at the Env C2 and V4 regions. For recombinant (r)AH expression, we evaluated a tobacco mosaic virus-based system in Nicotiana benthamiana plants as a means to facilitate molecular engineering and cost-effective mass production. Biochemical analysis and an Env-mediated syncytium formation assay demonstrated high-level expression of functional rAH within six days. Taken together, our study revealed AH's cross-clade anti-HIV-1 activity, apparent lack of side effects common to lectins, and robust producibility using plant biotechnology. These findings justify further efforts to develop rAH toward a candidate HIV-1 microbicide.

What is new in HIV/AIDS research in developing countries?

HIV epidemic has had greatest impact in sub-Saharan Africa (SSA) and mainly in East and Southern Africa with HIV prevalence in some parts going up to 30%. In the recent years, considerable HIV research on prevention, treatment and care, and vaccine has been conducted in many developing countries and provided evidence-based knowledge to control the epidemic. However, there have also been disappointing results in HIV prevention trials such as in HIV vaccine and microbicide trials. Despite these outcomes, important lessons have been learnt that help in designing future trials. This article examines the recent advances in HIV research in developing countries. The most recent HIV prevention research has demonstrated the effect of male circumcision on HIV acquisition, and lack of impact of HSV-2 treatment on HIV transmission and acquisition. Use of HIV antiretroviral drugs (ARVs) for HIV prevention is a new area that has attracted interest and a number of trials are examining the effect of oral Pre-Exposure Prophylaxis on HIV acquisition and also looking at the potential of ARVs in reducing infectiousness. Progress has been made in HIV treatment, monitoring treatment efficacy and toxicity as well as evaluation of different models of ART delivery. HIV vaccine research has, however, faced most challenges despite many efforts that have been put in. Looking into the future, there are ongoing trials that will hopefully generate important information to strengthen HIV policies in the next few years. There are, however, many other gaps in HIV research that need to be urgently addressed.

Application Studies of Animal Models in Evaluating Safety and Efficacy of HIV-1 Microbicides

As the HIV/AIDS pandemic continues unabated, novel prophylactic strategy for the spread of HIV are urgently needed. Topical microbicides are designed to prevent transmission of HIV when applied vaginally or rectally. Although there are many microbicide candidates in the pipeline, animal models for evaluating their safety and efficacy are urgently needed. On the basis of comparing the non-primate small animal models and the non-human primate animal models in evaluating safety and efficacy of HIV microbicides, this review summarizes the major advantages and disadvantages of the relevant animal models. The suggested direction of research that would benefit the development of microbicides is also reviewed.

Application Studies of Animal Models in Evaluating Safety and Efficacy of HIV-1 Microbicides

As the HIV/AIDS pandemic continues unabated, novel prophylactic strategy for the spread of HIV are urgently needed. Topical microbicides are designed to prevent transmission of HIV when applied vaginally or rectally. Although there are many microbicide candidates in the pipeline, animal models for evaluating their safety and efficacy are urgently needed. On the basis of comparing the non-primate small animal models and the non-human primate animal models in evaluating safety and efficacy of HIV microbicides, this review summarizes the major advantages and disadvantages of the relevant animal models. The suggested direction of research that would benefit the development of microbicides is also reviewed.

Development of Epigallocatechin Gallate as an HIV-1 Microbicide Agent: Impact on Dendritic Cell Innate Immune Responses (46.12)

Abstract Langerhans cells (LC) and monocyte-derived dendritic cells (MDDC), the first line of defense against viral infection, initiate innate immune responses via toll-like receptors (TLR). Previously, we showed inhibition of HIV-1-gp120 binding to CD4 on T cells by the green tea catechin, epigallocatechin gallate (EGCG). We present evidence of EGCG inhibition of the mucosal route of HIV-1 without alteration of dendritic cell (DC) innate immune responses. Methods utilized were CD34+ hematopoietic stem cells and CD14+ cells differentiated to LC and MDDC, respectively, isolated from peripheral blood of HIV-1 seronegative donors, flow cytometry of HIV-1-gp120 binding and TLR profiling with RT-PCR, radioisotope assays for antigen (Ag) studies, MTT assay for cytotoxicity, p24 ELISA for HIV-1 infectivity studies and statistical significance by Student’s t test. EGCG significantly inhibited HIV-1 infectivity in LC in a dose-dependent manner; 100%(50uM;p<0.001), 67%(25uM;p<0.01), 45%(10uM;p<0.05). EGCG significantly inhibited HIV-1-gp120 binding to CD4 in a dose-dependent manner on LC by 95%(50uM;p<0.001), 70%(25uM;p<0.01) and 27%(10uM;p<0.05). Similar results on MDDC. Control catechin did not alter HIV-1-gp120 binding nor infectivity. Neither DC function, as measured by Ag uptake/presentation, nor viability was significantly altered by EGCG. The inhibitory effect on HIV-1-gp120 binding and infectivity of mucosal cells by EGCG may be beneficial in the development of an HIV-1 microbicide.

Assessment of mucosal immunity to HIV-1

A key gap in the development and evaluation of HIV-1 vaccines is insufficient knowledge with regard to sampling techniques and assessment of mucosal immune responses required for early prevention and inhibition of viral dissemination. In an attempt to start bridging this gap, the EUROPRISE network of scientists working on HIV-1 vaccine and microbicide research organized a workshop with the aim to review the types of mucosal responses/biomarkers currently measured in mucosal immunology and to define how the mucosal responses/biomarkers are measured and/or the assays and sampling methods used. The Workshop addressed two critical questions: first whether, with current knowledge, it would be possible to define a consensus set of mucosal sampling methods to facilitate cross-species comparisons and ensure standardized implementation in clinical trials; second to determine the remaining challenges (technical and logistical) and their possible solutions for assessing mucosal responses to HIV-1 vaccines.

Anti-infective activity of apolipoprotein domain derived peptides in vitro: identification of novel antimicrobial peptides related to apolipoprotein B with anti-HIV activity

BackgroundPrevious reports have shown that peptides derived from the apolipoprotein E receptor binding region and the amphipathic α-helical domains of apolipoprotein AI have broad anti-infective activity and antiviral activity respectively. Lipoproteins and viruses share a similar cell biological niche, being of overlapping size and displaying similar interactions with mammalian cells and receptors, which may have led to other antiviral sequences arising within apolipoproteins, in addition to those previously reported. We therefore designed a series of peptides based around either apolipoprotein receptor binding regions, or amphipathic α-helical domains, and tested these for antiviral and antibacterial activity.ResultsOf the nineteen new peptides tested, seven showed some anti-infective activity, with two of these being derived from two apolipoproteins not previously used to derive anti-infective sequences. Apolipoprotein J (151-170) - based on a predicted amphipathic alpha-helical domain from apolipoprotein J - had measurable anti-HSV1 activity, as did apolipoprotein B (3359-3367) dp (apoBdp), the latter being derived from the LDL receptor binding domain B of apolipoprotein B. The more active peptide - apoBdp - showed similarity to the previously reported apoE derived anti-infective peptide, and further modification of the apoBdp sequence to align the charge distribution more closely to that of apoEdp or to introduce aromatic residues resulted in increased breadth and potency of activity. The most active peptide of this type showed similar potent anti-HIV activity, comparable to that we previously reported for the apoE derived peptide apoEdpL-W.ConclusionsThese data suggest that further antimicrobial peptides may be obtained using human apolipoprotein sequences, selecting regions with either amphipathic α-helical structure, or those linked to receptor-binding regions. The finding that an amphipathic α-helical region of apolipoprotein J has antiviral activity comparable with that for the previously reported apolipoprotein AI derived peptide 18A, suggests that full-length apolipoprotein J may also have such activity, as has been reported for full-length apolipoprotein AI. Although the strength of the anti-infective activity of the sequences identified was limited, this could be increased substantially by developing related mutant peptides. Indeed the apolipoprotein B-derived peptide mutants uncovered by the present study may have utility as HIV therapeutics or microbicides.

In vitro and ex vivo testing of tenofovir shows it is effective as an HIV-1 microbicide.

BackgroundTenofovir gel has entered into clinical trials for use as a topical microbicide to prevent HIV-1 infection but has no published data regarding pre-clinical testing using in vitro and ex vivo models. To validate our findings with on-going clinical trial results, we evaluated topical tenofovir gel for safety and efficacy. We also modeled systemic application of tenofovir for efficacy.Methods and FindingsFormulation assessment of tenofovir gel included osmolality, viscosity, in vitro release, and permeability testing. Safety was evaluated by measuring the effect on the viability of vaginal flora, PBMCs, epithelial cells, and ectocervical and colorectal explant tissues. For efficacy testing, PBMCs were cultured with tenofovir or vehicle control gels and HIV-1 representing subtypes A, B, and C. Additionally, polarized ectocervical and colorectal explant cultures were treated apically with either gel. Tenofovir was added basolaterally to simulate systemic application. All tissues were challenged with HIV-1 applied apically. Infection was assessed by measuring p24 by ELISA on collected supernatants and immunohistochemistry for ectocervical explants. Formulation testing showed the tenofovir and vehicle control gels were >10 times isosmolar. Permeability through ectocervical tissue was variable but in all cases the receptor compartment drug concentration reached levels that inhibit HIV-1 infection in vitro. The gels were non-toxic toward vaginal flora, PBMCs, or epithelial cells. A transient reduction in epithelial monolayer integrity and epithelial fracture for ectocervical and colorectal explants was noted and likely due to the hyperosmolar nature of the formulation. Tenofovir gel prevented HIV-1 infection of PBMCs regardless of HIV-1 subtype. Topical and systemic tenofovir were effective at preventing HIV-1 infection of explant cultures.ConclusionsThese studies provide a mechanism for pre-clinical prediction of safety and efficacy of formulated microbicides. Tenofovir was effective against HIV-1 infection in our algorithm. These data support the use of tenofovir for pre-exposure prophylaxis.