Evaluation of dendrimer SPL7013, a lead microbicide candidate against herpes simplex viruses

Approved Nanomedicine against Diseases

Nanomedicine is a branch of medicine using nanotechnology to prevent and treat diseases. Nanotechnology represents one of the most effective approaches in elevating a drug‘s treatment efficacy and reducing toxicity by improving drug solubility, altering biodistribution, and controlling the release. The development of nanotechnology and materials has brought a profound revolution to medicine, significantly affecting the treatment of various major diseases such as cancer, injection, and cardiovascular diseases. Nanomedicine has experienced explosive growth in the past few years. Although the clinical transition of nanomedicine is not very satisfactory, traditional drugs still occupy a dominant position in formulation development, but increasingly active drugs have adopted nanoscale forms to limit side effects and improve efficacy. The review summarized the approved nanomedicine, its indications, and the properties of commonly used nanocarriers and nanotechnology.

Progresses in Nano-Enabled Platforms for the Treatment of Vaginal Disorders

BACKGROUND

The most common vaginal disorders are within the uterus. According to the latest statistics, vaginal disorders occur in 50% to 60% of females. Although curative treatments rely on surgical therapy, still first-line treatment is a non invasive drug. Conventional therapies are available in the oral and parenteral route, leading to nonspecific targeting, which can cause dose-related side effects. Vaginal disorders are localized uterine disorders in which intrauterine delivery via the vaginal site is deemed the preferable route to mitigate clinical drug delivery limitations.

OBJECTIVE

This study emphasizes the progress of site-specific and controlled delivery of therapeutics in the treatment of vaginal disorders and systemic adverse effects as well as the therapeutic efficacy.

METHODS

Related research reports and patents associated with topics are collected, utilized, and summarized the key findings.

RESULTS

The comprehensive literature study and patents like (US 9393216 B2), (JP6672370B2), and (WO2018041268A1) indicated that nanocarriers are effective above traditional treatments and have some significant efficacy with novelty.

CONCLUSION

Nowadays, site-specific and controlled delivery of therapeutics for the treatment of vaginal disorders is essential to prevent systemic adverse effects and therapeutic efficacy would be more effective. Nanocarriers have therefore been used to bypass the problems associated with traditional delivery systems for the vaginal disorder.

Astodrimer sodium antiviral nasal spray for reducing respiratory infections is safe and well tolerated in a randomized controlled trial

Astodrimer sodium is a dendrimer molecule with antiviral and virucidal activity against SARS-CoV-2 and other respiratory viruses in vitro, and has previously been shown to be safe and well tolerated, and not systemically absorbed, when applied to the vaginal mucosa. To investigate its potential utility as a topical antiviral, astodrimer sodium has been reformulated for application to the nasal mucosa to help reduce viral load before or after exposure to respiratory infection. The current investigation assessed the safety, tolerability and absorption of astodrimer sodium 1% antiviral nasal spray. This was a single-centre, double-blinded, randomized, placebo-controlled, exploratory clinical investigation. Forty healthy volunteers aged 18 to 65 years with no clinically significant nasal cavity examination findings were randomized 3:1 to astodrimer sodium nasal spray (N = 30) or placebo (N = 10) at an Australian clinical trials facility. An initial cohort of participants (N = 12 astodrimer, N = 4 placebo) received a single application (one spray per nostril) to assess any acute effects, followed by a washout period, before self-administering the spray four times daily for 14 days to represent an intensive application schedule. Extent of absorption of astodrimer sodium via the nasal mucosa was also assessed in this cohort. A second cohort of participants (N = 18 astodrimer, N = 6 placebo) self-administered the spray four times daily for 14 days. The primary endpoint was safety, measured by frequency and severity of treatment emergent adverse events (TEAEs), including clinically significant nasal cavity examination findings, in the safety population (all participants randomized who administered any spray). Participants were randomized between 6 January 2021 and 29 March 2021. TEAEs occurred in 8/10 (80%) participants in the placebo arm and 19/30 (63.3%) participants in the astodrimer sodium arm; all were of mild intensity. TEAEs considered potentially related to study product occurred in 5/10 (50%) participants receiving placebo and 10/30 (33.3%) of participants receiving astodrimer sodium. No participants experienced serious AEs, or TEAEs leading to withdrawal from the study. No systemic absorption of astodrimer sodium via the nasal mucosa was detected. Astodrimer sodium nasal spray was well tolerated and is a promising innovation warranting further investigation for nasal administration to potentially reduce infection and spread of community acquired respiratory virus infections.

Trial Registration: ACTRN12620001371987, first registered 22-12-2020 (Australia New Zealand Clinical Trials Registry, https://anzctr.org.au/).

Baseline and time-updated factors in preclinical development of anionic dendrimers as successful anti-HIV-1 vaginal microbicides

Although a wide variety of topical microbicides provide promising in vitro and in vivo efficacy, most of them failed to prevent sexual transmission of human immunodeficiency virus type 1 (HIV‐1) in human clinical trials. In vitro, ex vivo, and in vivo models must be optimized, considering the knowledge acquired from unsuccessful and successful clinical trials to improve the current gaps and the preclinical development protocols. To date, dendrimers are the only nanotool that has advanced to human clinical trials as topical microbicides to prevent HIV‐1 transmission. This fact demonstrates the importance and the potential of these molecules as microbicides. Polyanionic dendrimers are highly branched nanocompounds with potent activity against HIV‐1 that disturb HIV‐1 entry. Herein, the most significant advancements in topical microbicide development, trying to mimic the real‐life conditions as closely as possible, are discussed. This review also provides the preclinical assays that anionic dendrimers have passed as microbicides because they can improve current antiviral treatments' efficacy.

This article is categorized under:

Nanotechnology Approaches to Biology > Nanoscale Systems in Biology

Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease

Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine

Astodrimer sodium and bacterial vaginosis: a mini review

Bacterial vaginosis (BV) is the most common vaginal infection affecting women of childbearing age, and is associated with a substantial burden on women’s physical, emotional, sexual and social lives, as well as being linked to a number of gynaecological and obstetrical complications and adverse pregnancy outcomes. Antibiotics, such as metronidazole or clindamycin, are recommended as first-line treatment for BV, but may be associated with antibiotic resistance, high rates of recurrence and poor patient treatment satisfaction. Astodrimer sodium gel is a novel, non-antibiotic treatment for BV that is not systemically absorbed. It prevents pathogenic bacteria from adhering to the vaginal wall, and disrupts and inhibits the formation of pathogenic bacterial biofilms. Clinical cure rates of 50–57% were observed in patients with BV treated with astodrimer sodium compared with 17–21% treated with placebo (p < 0.001) in Phase 3 trials. In a separate Phase 3 trial, recurrence of BV occurred in 44% of patients treated with astodrimer sodium compared with 54% of patients who received placebo (p = 0.015). Astodrimer sodium is well tolerated, with vulvovaginal candidosis being the only treatment-related adverse event reported to occur more often than with placebo. The availability of astodrimer sodium, a well-tolerated, convenient, non-antibiotic treatment for BV, represents significant progress in the treatment of this burdensome condition.

Recent Advances in Polymer-Based Vaginal Drug Delivery Systems

The vagina has been considered a potential drug administration route for centuries. Most of the currently marketed and investigated vaginal formulations are composed with the use of natural or synthetic polymers having different functions in the product. The vaginal route is usually investigated as an administration site for topically acting active ingredients; however, the anatomical and physiological features of the vagina make it suitable also for drug systemic absorption. In this review, the most important natural and synthetic polymers used in vaginal products are summarized and described, with special attention paid to the properties important in terms of vaginal application. Moreover, the current knowledge on the commonly applied and innovative dosage forms designed for vaginal administration was presented. The aim of this work was to highlight the most recent research directions and indicate challenges related to vaginal drug administrations. As revealed in the literature overview, intravaginal products still gain enormous scientific attention, and novel polymers and formulations are still explored. However, there are research areas that require more extensive studies in order to provide the safety of novel vaginal products.

Topical Astodrimer Sodium, a Non-Toxic Polyanionic Dendrimer, Demonstrates Antiviral Activity in an Experimental Ocular Adenovirus Infection Model

There is no approved antiviral therapy for adenovirus (HAdV) ocular infections. Astodrimer sodium (SPL7013) is a polyanionic dendrimer with antiviral activity. The current study evaluated the ocular tolerability and anti-adenoviral efficacy of topical SPL7013 in rabbit ocular models. In a tolerability study, rabbits were treated with 3% SPL7013, vehicle, or 0.5% cidofovir. Their eyes were graded using the Draize scale. In antiviral efficacy studies, HAdV5 inoculated eyes were treated with 3% SPL7013, vehicle, or 0.5% cidofovir. Eyes were cultured for the virus on days 0, 1, 3, 4, 5, 7, 9, 11, and 14. Viral titers were determined. There were no differences in Draize scores between 3% SPL7013 and vehicle on any day. Cidofovir produced significantly higher Draize scores on day 12 than SPL7013 and vehicle. The 3% SPL7013 and 0.5% cidofovir significantly reduced daily viral titers and positive cultures per total compared with vehicle on several different days. The 3% SPL7013 and 0.5% cidofovir significantly reduced the duration of HAdV5 shedding compared to vehicle. The 3% SPL7013 demonstrated significantly more antiviral activity compared with vehicle in the Ad5/NZW rabbit ocular model. The 3% SPL7013 induced “minimal” to “practically non-irritating” Draize scores in the ocular tolerability study. Further development of astodrimer sodium as a topical antiviral therapy for adenoviral ocular infections is indicated.

Virucidal and antiviral activity of astodrimer sodium against SARS-CoV-2 in vitro

An effective response to the ongoing coronavirus disease (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) will involve a range of complementary preventive modalities. The current studies were conducted to evaluate the in vitro SARS-CoV-2 antiviral and virucidal (irreversible) activity of astodrimer sodium, a dendrimer with broad spectrum antimicrobial activity, including against enveloped viruses in in vitro and in vivo models, that is marketed for antiviral and antibacterial applications. We report that astodrimer sodium inhibits replication of SARS-CoV-2 in Vero E6 and Calu-3 cells, with 50% effective concentrations (EC₅₀) for i) reducing virus-induced cytopathic effect of 0.002-0.012 mg/mL in Vero E6 cells, and ii) infectious virus release by plaque assay of 0.019-0.032 mg/mL in Vero E6 cells and 0.030-0.037 mg/mL in Calu-3 cells. The selectivity index (SI) in these assays was as high as 2197. Astodrimer sodium was also virucidal, irreversibly reducing SARS-CoV-2 infectivity by >99.9% (>3 log₁₀) within 1 min of exposure, and up to >99.999% (>5 log₁₀) shown at astodrimer sodium concentrations of 10-30 mg/mL in Vero E6 and Calu-3 cell lines. Astodrimer sodium also inhibited infection in a primary human airway epithelial cell line. The data were similar for all investigations and were consistent with the potent antiviral and virucidal activity of astodrimer sodium being due to irreversible inhibition of virus-host cell interactions, as previously demonstrated for other viruses. Further studies will confirm if astodrimer sodium binds to SARS-CoV-2 spike protein and physically blocks initial attachment of the virus to the host cell. Given the in vitro effectiveness and significantly high SI, astodrimer sodium warrants further investigation for potential as a topically administered agent for SARS-CoV-2 therapeutic applications.

Highly Branched Polymers Based on Poly(amino acid)s for Biomedical Application

Polymers consisting of amino acid building blocks continue to receive consideration for biomedical applications. Since poly(amino acid)s are built from natural amino acids, the same building blocks proteins are made of, they are biocompatible, biodegradable and their degradation products are metabolizable. Some amino acids display a unique asymmetrical AB2 structure, which facilitates their ability to form branched structures. This review compares the three forms of highly branched polymeric structures: structurally highly organized dendrimers, dendrigrafts and the less organized, but readily synthesizable hyperbranched polymers. Their syntheses are reviewed and compared, methods of synthesis modulations are considered and variations on their traditional syntheses are shown. The potential use of highly branched polymers in the realm of biomedical applications is discussed, specifically their applications as delivery vehicles for genes and drugs and their use as antiviral compounds. Of the twenty essential amino acids, L-lysine, L-glutamic acid, and L-aspartic acid are asymmetrical AB2 molecules, but the bulk of the research into highly branched poly(amino acid)s has focused on the polycationic poly(L-lysine) with a lesser extent on poly(L-glutamic acid). Hence, the majority of potential applications lies in delivery systems for nucleic acids and this review examines and compares how these three types of highly branched polymers function as non-viral gene delivery vectors. When considering drug delivery systems, the small size of these highly branched polymers is advantageous for the delivery of inhalable drug. Even though highly branched polymers, in particular dendrimers, have been studied for more than 40 years for the delivery of genes and drugs, they have not translated in large scale into the clinic except for promising antiviral applications that have been commercialized.

Combination of G2-S16 dendrimer/dapivirine antiretroviral as a new HIV-1 microbicide

Aim: To research the synergistic activity of G2-S16 dendrimer and dapivirine (DPV) antiretroviral as microbicide candidate to prevent HIV-1 infection. Materials & methods: We assess the toxicity of DPV on cell lines by MTT assay, the anti-HIV-1 activity of G2-S16 and DPV alone or combined at several fixed ratios. Finally, their ability to inhibit the bacterial growth in vitro was assayed. The analysis of combinatorial effects and the effective concentrations were performed with CalcuSyn software. Conclusion: Our results represent the first proof-of-concept study of G2-S16/DPV combination to develop a safe microbicide.

Structure-Activity Relationships of GAG Mimetic-Functionalized Mesoporous Silica Nanoparticles and Evaluation of Acyclovir-Loaded Antiviral Nanoparticles with Dual Mechanisms of Action

Mesoporous silica nanoparticles (MSNs) are drug delivery agents that are able to incorporate drugs within their pores. Furthermore, MSNs can be functionalized by attachment of bioactive ligands on their surface to enhance their activity, and nanoparticles modified with glycosaminoglycan (GAG) mimetics inhibit the entry of herpes simplex virus (HSV) into cells. In this study, structure-activity relationships of GAGs attached to MSNs were investigated in relation to HSV-1 and HSV-2, and acyclovir was loaded into the pores of MSNs. The sulfonate group was demonstrated to be essential for antiviral activity, which was enhanced by incorporating a benzene group within the ligand. Loading acyclovir into GAG mimetic-functionalized MSNs reduced the viral infection, resulting in nanoparticles that simultaneously target two distinct viral pathways, namely, inhibition of viral entry and inhibition of DNA replication.

GAG mimetic functionalised solid and mesoporous silica nanoparticles as viral entry inhibitors of herpes simplex type 1 and type 2 viruses

A glycosaminoglycan mimetic was attached to the surface of solid and mesoporous silica nanoparticles to create novel antiviral agents against herpes simplex type 1 and type 2 viruses. The nanoparticles act as viral entry inhibitors that appear to block viral attachment and penetration into susceptible cells.

Mechanistic Studies of Viral Entry: An Overview of Dendrimer-Based Microbicides As Entry Inhibitors Against Both HIV and HSV-2 Overlapped Infections

This review provides an overview of the development of different dendrimers, mainly polyanionic, against human immunodeficiency virus (HIV) and genital herpes (HSV-2) as topical microbicides targeting the viral entry process. Vaginal topical microbicides to prevent sexually transmitted infections such as HIV and HSV-2 are urgently needed. To inhibit HIV/HSV-2 entry processes, new preventive targets have been established to maximize the current therapies against wild-type and drug-resistant viruses. The entry of HIV/HSV-2 into target cells is a multistep process that triggers a cascade of molecular interactions between viral envelope proteins and cell surface receptors. Polyanionic dendrimers are highly branched nanocompounds with potent activity against HIV/HSV-2. Inhibitors of each entry step have been identified with regard to generations and surface groups, and possible roles for these agents in anti-HIV/HSV-2 therapies have also been discussed. Four potential binding sites for impeding HIV infection (HSPG, DC-SIGN, GSL, and CD4/gp120 inhibitors) and HSV-2 infection (HS, gB, gD, and gH/gL inhibitors) exist according to their mechanisms of action and structures. This review clarifies that inhibition of HIV/HSV-2 entry continues to be a promising target for drug development because nanotechnology can transform the field of HIV/HSV-2 prevention by improving the efficacy of the currently available antiviral treatments.

Nanomedicine in the development of anti-HIV microbicides

Prevention plays an invaluable role in the fight against HIV/AIDS. The use of microbicides is considered an interesting potential approach for topical pre-exposure prophylaxis of HIV sexual transmission. The prospects of having an effective product available are expected to be fulfilled in the near future as driven by recent and forthcoming results of clinical trials. Different dosage forms and delivery strategies have been proposed and tested for multiple microbicide drug candidates presently at different stages of the development pipeline. One particularly interesting approach comprises the application of nanomedicine principles to the development of novel anti-HIV microbicides, but its implications to efficacy and safety are not yet fully understood. Nanotechnology-based systems, either presenting inherent anti-HIV activity or acting as drug nanocarriers, may significantly influence features such as drug solubility, stability of active payloads, drug release, interactions between active moieties and virus/cells, intracellular drug delivery, drug targeting, safety, antiviral activity, mucoadhesive behavior, drug distribution and tissue penetration, and pharmacokinetics. The present manuscript provides a comprehensive and holistic overview of these topics as relevant to the development of vaginal and rectal microbicides. In particular, recent advances pertaining inherently active microbicide nanosystems and microbicide drug nanocarriers are discussed.

Prevention of vaginal and rectal herpes simplex virus type 2 transmission in mice: mechanism of antiviral action

Topical microbicides to stop sexually transmitted diseases, such as herpes simplex virus type 2 (HSV-2), are urgently needed. The emerging field of nanotechnology offers novel suitable tools for addressing this challenge. Our objective was to study, in vitro and in vivo, antiherpetic effect and antiviral mechanisms of several polyanionic carbosilane dendrimers with anti-HIV-1 activity to establish new potential microbicide candidates against sexually transmitted diseases. Plaque reduction assay on Vero cells proved that G2-S16, G1-S4, and G3-S16 are the dendrimers with the highest inhibitory response against HSV-2 infection. We also demonstrated that our dendrimers inhibit viral infection at the first steps of HSV-2 lifecycle: binding/entry-mediated events. G1-S4 and G3-S16 bind directly on the HSV-2, inactivating it, whereas G2-S16 adheres to host cell-surface proteins. Molecular modeling showed that G1-S4 binds better at binding sites on gB surface than G2-S16. Significantly better binding properties of G1-S4 than G2-S16 were found in an important position for affecting transition of gB trimer from G1-S4 prefusion to final postfusion state and in several positions where G1-S4 could interfere with gB/gH-gL interaction. We demonstrated that these polyanionic carbosilan dendrimers have a synergistic activity with acyclovir and tenofovir against HSV-2, in vitro. Topical vaginal or rectal administration of G1-S4 or G2-S16 prevents HSV-2 transmission in BALB/c mice in values close to 100%. This research represents the first demonstration that transmission of HSV-2 can be blocked by vaginal/rectal application of G1-S4 or G2-S16, providing a step forward to prevent HSV-2 transmission in humans.

High Efficiency of Functional Carbon Nanodots as Entry Inhibitors of Herpes Simplex Virus Type 1

Nanostructures have been lately identified as an efficient therapeutic strategy to modulate viral attachment and entry. The high concentrations of ligands present on nanostructures can considerably enhance affinities toward biological receptors. We demonstrate here the potential of carbon nanodots (C-dots) surface-functionalized with boronic acid or amine functions to interfere with the entry of herpes simplex virus type 1 (HSV-1). C-dots formed from 4-aminophenylboronic acid hydrochloride (4-AB/C-dots) using a modified hydrothermal carbonization are shown to prevent HSV-1 infection in the nanograms per milliliter concentration range (EC50 = 80 and 145 ng mL(-1) on Vero and A549 cells, respectively), whereas the corresponding C-dots formed from phenylboronic acid (B/C-dots) have no effects even at high concentrations. Some of the presented results also suggest that C-dots are specifically acting on the early stage of virus entry through an interaction with the virus and probably the cells at the same time.

The AGMA1 poly(amidoamine) inhibits the infectivity of herpes simplex virus in cell lines, in human cervicovaginal histocultures, and in vaginally infected mice

The development of topical microbicides is a valid approach to protect the genital mucosa from sexually transmitted infections that cannot be contained with effective vaccination, like HSV and HIV infections. A suitable target of microbicides is the interaction between viral proteins and cell surface heparan sulfate proteoglycans (HSPGs). AGMA1 is a prevailingly cationic agmatine-containing polyamidoamine polymer previously shown to inhibit HSPGs dependent viruses, including HSV-1, HSV-2, and HPV-16. The aim of this study was to elucidate the mechanism of action of AGMA1 against HSV infection and assess its antiviral efficacy and biocompatibility in preclinical models. The results show AGMA1 to be a non-toxic inhibitor of HSV infectivity in cell cultures and human cervicovaginal histocultures. Moreover, it significantly reduced the burden of infection of HSV-2 genital infection in mice. The investigation of the mechanism of action revealed that AGMA1 reduces cells susceptibility to virus infection by binding to cell surface HSPGs thereby preventing HSV attachment. This study indicates that AGMA1 is a promising candidate for the development of a topical microbicide to prevent sexually transmitted HSV infections.

Dendrimeric based microbicides against sexual transmitted infections associated to heparan sulfate

Cell surface heparan sulfate (HS) represents a common link that many sexually transmitted infections (STIs) require for infection.

Dendrimers as tunable vectors of drug delivery systems and biomedical and ocular applications

Dendrimers are large polymeric structures with nanosize dimensions (1-10 nm) and unique physicochemical properties. The major advantage of dendrimers compared with linear polymers is their spherical-shaped structure. During synthesis, the size and shape of the dendrimer can be customized and controlled, so the finished macromolecule will have a specific "architecture" and terminal groups. These characteristics will determine its suitability for drug delivery, diagnostic imaging, and as a genetic material carrier. This review will focus initially on the unique properties of dendrimers and their use in biomedical applications, as antibacterial, antitumor, and diagnostic agents. Subsequently, emphasis will be given to their use in drug delivery for ocular diseases.

Nanoparticles as potential new generation broad spectrum antimicrobial agents

The rapid emergence of antimicrobial resistant strains to conventional antimicrobial agents has complicated and prolonged infection treatment and increased mortality risk globally. Furthermore, some of the conventional antimicrobial agents are unable to cross certain cell membranes thus, restricting treatment of intracellular pathogens. Therefore, the disease-causing-organisms tend to persist in these cells. However, the emergence of nanoparticle (NP) technology has come with the promising broad spectrum NP-antimicrobial agents due to their vast physiochemical and functionalization properties. In fact, NP-antimicrobial agents are able to unlock the restrictions experienced by conventional antimicrobial agents. This review discusses the status quo of NP-antimicrobial agents as potent broad spectrum antimicrobial agents, sterilization and wound healing agents, and sustained inhibitors of intracellular pathogens. Indeed, the perspective of developing potent NP-antimicrobial agents that carry multiple-functionality will revolutionize clinical medicine and play a significant role in alleviating disease burden.

Soluble Immune Mediators and Vaginal Bacteria Impact Innate Genital Mucosal Antimicrobial Activity in Young Women

INTRODUCTION

Innate activity against Escherichia coli in female genital secretions may represent contributions from vaginal bacteria and host soluble immune mediators. We analyzed the relationship between E. coli inhibitory activity, soluble immune mediators, and vaginal bacteria in participants in MTN-004, a placebo-controlled trial of VivaGel(®) , a candidate product for topical HIV pre-exposure prophylaxis.

METHODS

Escherichia coli inhibitory activity was quantified by colony reduction assay. Endocervical concentrations of interleukin (IL)-1β, IL-6, IL-12p40, macrophage inflammatory protein (MIP)-1α, granulocyte-macrophage colony-stimulating factor (GM-CSF), lactoferrin, and secretory leukocyte protease inhibitor (SLPI) were quantified to generate a cumulative mediator score. Vaginal bacteria were characterized by quantitative cultures.

RESULTS

In the two placebo arms, higher soluble immune mediator score was associated with greater E. coli inhibitory activity (β = 17.49, 95% CI [12.77, 22.21] and β = 13.28, 95% CI [4.76, 21.80]). However, in the VivaGel arm, higher concentrations of E. coli (β = -3.80, 95% CI [-6.36, -1.25]) and group B Streptococcus (β = -3.91, 95% CI [-6.21, -1.60]) were associated with reduced E. coli inhibitory activity.

CONCLUSIONS

Both host mediators and vaginal bacteria impact E. coli inhibition in genital secretions. The relative contributions of host mediators and bacteria varied between women who used VivaGel vs placebos.

Nanotech-derived topical microbicides for HIV prevention: the road to clinical development

More than three decades since its discovery, HIV infection remains one of the most aggressive epidemics worldwide, with more than 35 million people infected. In sub-Saharan Africa, heterosexual transmissions represent nearly 80% of new infections, with 50% of these occurring in women. In an effort to stop the dramatic spread of the HIV epidemic, new preventive treatments, such as microbicides, have been developed. Nanotechnology has revolutionized this field by designing and engineering novel highly effective nano-sized materials as microbicide candidates. This review illustrates the most recent advances in nanotech-derived HIV prevention strategies, as well as the main steps required to translate promising in vitro results into clinical trials.

A modified zinc acetate gel, a potential nonantiretroviral microbicide, is safe and effective against simian-human immunodeficiency virus and herpes simplex virus 2 infection in vivo

We previously showed that a prototype gel comprising zinc acetate (ZA) in carrageenan (CG) protected mice against vaginal and rectal herpes simplex virus 2 (HSV-2) challenge as well as macaques against vaginal simian-human immunodeficiency virus reverse transcriptase (SHIV-RT) challenge. In this work, we modified buffers and cosolvents to obtain a stable, nearly iso-osmolal formulation and evaluated its safety and efficacy against SHIV-RT and HSV-2. In vitro toxicity to lactobacilli and Candida albicans was determined. Macaques were given daily doses of ZA and CG (ZA/CG) or CG alone vaginally for 14 days and challenged with SHIV-RT 24 h later. Mice were challenged vaginally or rectally with HSV-2 immediately after a single gel treatment to measure efficacy or vaginally 12 h after daily gel treatment for 7 days to evaluate the gel's impact on susceptibility to HSV-2 infection. The modified ZA/CG neither affected the viability of lactobacilli or C. albicans nor enhanced vaginal HSV-2 infection after daily ZA/CG treatment. Vaginal SHIV-RT infection of macaques was reduced by 66% (P = 0.006) when macaques were challenged 24 h after the last dose of gel. We observed 60% to 80% uninfected mice after vaginal (P < 0.0001) and rectal (P = 0.008) high-dose HSV-2 challenge. The modified ZA/CG gel is safe and effective in animal models and represents a potential candidate to limit the transmission of HIV and HSV-2.

Methods for screening and profiling inhibitors of herpes simplex viruses

Herpes simplex viruses (HSV) establish lifelong latent infections in infected hosts that reactivate -periodically and result in virus shedding and recurrent diseases, such as genital herpes. Sexually transmitted infections (STIs) caused by HSV are a major public health problem worldwide. At present, the only effective antiviral drugs for treatment of HSV are nucleoside analogues, which are incorporated into the DNA chain and terminate the chain elongation during virus replication. With increasing emergence of drug resistance, novel drugs for new viral targets are warranted. In this chapter, several screening and profiling assays including plaque reduction assays, cytopathic effect inhibition assay, and in vitro cytotoxicity assay for identifying and evaluating inhibitors of HSV are described. Assays for mode of action studies, such as virus adsorption and penetration, are also presented.

Exploiting herpes simplex virus entry for novel therapeutics

Herpes Simplex virus (HSV) is associated with a variety of diseases such as genital herpes and numerous ocular diseases. At the global level, high prevalence of individuals who are seropositive for HSV, combined with its inconspicuous infection, remains a cause for major concern. At the molecular level, HSV entry into a host cell involves multiple steps, primarily the interaction of viral glycoproteins with various cell surface receptors, many of which have alternate substitutes. The molecular complexity of the virus to enter a cell is also enhanced by the existence of different modes of viral entry. The availability of many entry receptors, along with a variety of entry mechanisms, has resulted in a virus that is capable of infecting virtually all cell types. While HSV uses a wide repertoire of viral and host factors in establishing infection, current therapeutics aimed against the virus are not as diversified. In this particular review, we will focus on the initial entry of the virus into the cell, while highlighting potential novel therapeutics that can control this process. Virus entry is a decisive step and effective therapeutics can translate to less virus replication, reduced cell death, and detrimental symptoms.

Peptide inhibitors against herpes simplex virus infections

Herpes simplex virus (HSV) is a significant human pathogen causing mucocutaneous lesions primarily in the oral or genital mucosa. Although acyclovir (ACV) and related nucleoside analogs provide successful treatment, HSV remains highly prevalent worldwide and is a major cofactor for the spread of human immunodeficiency virus. Encephalitis, meningitis, and blinding keratitis are among the most severe diseases caused by HSV. ACV resistance poses an important problem for immunocompromised patients and highlights the need for new safe and effective agents; therefore, the development of novel strategies to eradicate HSV is a global public health priority. Despite the continued global epidemic of HSV and extensive research, there have been few major breakthroughs in the treatment or prevention of the virus since the introduction of ACV in the 1980s. A therapeutic strategy at the moment not fully addressed is the use of small peptide molecules. These can be either modeled on viral proteins or derived from antimicrobial peptides. Any peptide that interrupts protein-protein or viral protein-host cell membrane interactions is potentially a novel antiviral drug and may be a useful tool for elucidating the mechanisms of viral entry. This review summarizes current knowledge and strategies in the development of synthetic and natural peptides to inhibit HSV infectivity.

Dendrimers functionalized with membrane-interacting peptides for viral inhibition

This contribution reports the synthesis of a poly(amide)-based dendrimer functionalized at the termini with a membrane-interacting peptide derived from the herpes simplex virus (HSV) type 1 glycoprotein H, namely gH625–644. This peptide has been shown to interact with model membranes and to inhibit viral infectivity. The peptidodendrimer inhibits both HSV-1 and HSV-2 at a very early stage of the entry process, most likely through an interaction with the viral envelope glycoproteins; thus, preventing the virus from coming into close contact with cellular membranes, a prerequisite of viral internalization. The 50% inhibitory concentration was 100 and 300 nM against HSV-1 and HSV-2 respectively, with no evidence of cell toxicity at these concentrations. These results show that the functionalization of a dendrimer with the peptide sequence derived from an HSV glycoprotein shows promising inhibitory activity towards viruses of the Herpesviridae family.

Crafting precise multivalent architectures

Development of elaborate three-dimensional multivalent displays appended on natural or synthetic molecular scaffolds.

Antiviral activity of Bifidobacterium adolescentis SPM 0214 against herpes simplex virus type 1

Herpes Simplex Virus type 1 (HSV-1) antibodies are found in up to 90 percent of the general population. About 30% of patients who have been exposed to HSV-1 develop recurrent infections, and this degree is continually increasing. In addition, resistance to all major anti-herpetic drugs such as acyclovir (ACV) has been increasingly reported. These observations underscore the importance of discovering new therapeutic tools for the treatment of HSV-1 infections. Bifidobacterium spp. has been studied in various fields including antibacterial and anticancer effect, but the antiviral activity was studied very little. The aim of this study was to test the antiviral activity of Bifidobacterium spp. against HSV-1. The Bifidobacterium adolescentis SPM 0214 used in this study through the screening of 23 Bifidobacterium spp. by plaque assay was assessed the cell viability assay in Vero cells. We also measured the plaque reduction assay and yield reduction assay after B. adolescentis SPM 0214 treatment at concentrations ranging between 10 and 10⁴ μg/mL. The B. adolescentis SPM 0214 was not toxic to Vero cells, and the inhibition of plaque and yield formation was obviously increased compared to those of the control (no additive). Therefore, these results indicate that antiviral activity of B. adolescentis SPM 0214 against HSV-1.

Dendrimers--revolutionary drugs for infectious diseases

Over recent years innovative nanomolecules in a form of dendrimers have been gaining increasing interest. These compounds can be designed and modified in many ways giving a molecule which meets required expectations. For this reason dendrimers are the object of intensive studies in many fields of nanoscience including one of the most thriving--biomedicine. Numerous studies provide evidence that some dendrimers exhibit activities against many species/strains of viruses, bacteria, fungi, and prions. These types of dendritic nanostructures which are distinguished by antipathogenic properties and low cytotoxicity to eukaryotic cells may be potentially applied in medicine as novel drugs for various infectious diseases, especially those which are persistent, marked by high mortality rate, or untreatable. Dendrimers can exert their effect via different mechanisms of action, which are, in most cases, related to multivalency of the nanomolecule. The application of dendrimers is likely to be a breakthrough in prevention and treatment of infectious diseases which still beset humanity and may significantly improve the quality of people's life.

SPL7013 Gel (VivaGel®) retains potent HIV-1 and HSV-2 inhibitory activity following vaginal administration in humans

SPL7013 Gel (VivaGel^®) is a microbicide in development for prevention of HIV and HSV. This clinical study assessed retention and duration of antiviral activity following vaginal administration of 3% SPL7013 Gel in healthy women. Participants received 5 single doses of product with ≥5 days between doses. A cervicovaginal fluid (CVF) sample was collected using a SoftCup™ pre-dose, and immediately, or 1, 3, 12 or 24 h post-dose. HIV-1 and HSV-2 antiviral activities of CVF samples were determined in cell culture assays. Antiviral activity in the presence of seminal plasma was also tested. Mass and concentration of SPL7013 in CVF samples was determined. Safety was assessed by reporting of adverse events. Statistical analysis was performed using the Wilcoxon signed-rank test with Bonferroni adjustment; p≤0.003 was significant. Eleven participants completed the study. Inhibition of HIV-1 and HSV-2 by pre-dose CVF samples was negligible. CVF samples obtained immediately after dosing almost completely inhibited (median, interquartile range) HIV-1 [96% (95,97)] and HSV-2 [86% (85,94)], and activity was maintained in all women at 3 h (HIV-1 [96% (95,98), p = 0.9]; HSV-2 [94% (91,97), p = 0.005]). At 24 h, >90% of initial HIV-1 and HSV-2 inhibition was maintained in 6/11 women. SPL7013 was recovered in CVF samples obtained at baseline (46% of 105 mg dose). At 3 and 24 h, 22 mg and 4 mg SPL7013, respectively, were recovered. More than 70% inhibition of HIV-1 and HSV-2 was observed if there was >0.5 mg SPL7013 in CVF samples. High levels of antiviral activity were retained in the presence of seminal plasma. VivaGel was well tolerated with no signs or symptoms of vaginal, vulvar or cervical irritation reported. Potent antiviral activity was observed against HIV-1 and HSV-2 immediately following vaginal administration of VivaGel, with activity maintained for at least 3 h post-dose. The data provide evidence of antiviral activity in a clinical setting, and suggest VivaGel could be administered up to 3 h before coitus.

Inhibition of herpes simplex virus type 1 and type 2 infections by peptide-derivatized dendrimers

In response to the need for new antiviral agents, dendrimer-based molecules have been recognized as having a large number of potential therapeutic applications. They include peptide-derivatized dendrimers, which are hyperbranched synthetic well-defined molecules which consist of a peptidyl branching core and covalently attached surface functional peptides. However, few studies have addressed their applications as direct-acting antiviral agents. Here, we report on the ability of the peptide dendrimer SB105 and its derivative, SB105_A10, to directly inhibit herpes simplex virus 1 (HSV-1) and HSV-2 in vitro replication, with favorable selective indexes discerned for both compounds. An analysis of their mode of action revealed that SB105 and SB105_A10 prevent HSV-1 and HSV-2 attachment to target cells, whereas SB104, a dendrimer with a different amino acid sequence within the functional group and minimal antiviral activity, was ineffective in blocking HSV attachment. Moreover, both SB105 and SB105_A10 retained their ability to inhibit HSV adsorption at pH 3.0 and 4.0 and in the presence of 10% human serum proteins, conditions mimicking the physiological properties of the vagina, a potential therapeutic location for such compounds. The inhibition of HSV adsorption is likely to stem from the ability of SB105_A10 to bind to the glycosaminoglycan moiety of cell surface heparan sulfate proteoglycans, thereby blocking virion attachment to target cells. Finally, when combined with acyclovir in checkerboard experiments SB105_A10 exhibited highly synergistic activity. Taken together, these findings suggest that SB105 and SB105_A10 are promising candidates for the development of novel topical microbicides for the prevention of HSV infections.

Virucidal activity of the dendrimer microbicide SPL7013 against HIV-1

Topical microbicides for use by women to prevent the transmission of human immunodeficiency virus (HIV) and other sexually transmitted infections are urgently required. Dendrimers are highly branched nanoparticles being developed as microbicides. SPL7013 is a dendrimer with broad-spectrum activity against HIV type I (HIV-1) and -2 (HIV-2), herpes simplex viruses type-1 (HSV-1) and -2 (HSV-2) and human papillomavirus. SPL7013 [3% (w/w)] has been formulated in a mucoadhesive carbopol gel (VivaGel®) for use as a topical microbicide. Previous studies showed that SPL7013 has similar potency against CXCR4-(X4) and CCR5-using (R5) strains of HIV-1 and that it blocks viral entry. However, the ability of SPL7013 to directly inactivate HIV-1 is unknown. We examined whether SPL7013 demonstrates virucidal activity against X4 (NL4.3, MBC200, CMU02 clade EA and 92UG046 clade D), R5 (Ba-L, NB25 and 92RW016 clade A) and dual-tropic (R5X4; MACS1-spln) HIV-1 using a modified HLA-DR viral capture method and by polyethylene glycol precipitation. Evaluation of virion integrity was determined by ultracentrifugation through a sucrose cushion and detection of viral proteins by Western blot analysis. SPL7013 demonstrated potent virucidal activity against X4 and R5X4 strains, although virucidal activity was less potent for the 92UG046 X4 clade D isolate. Where potent virucidal activity was observed, the 50% virucidal concentrations were similar to the 50% effective concentrations previously reported in drug susceptibility assays, indicating that the main mode of action of SPL7013 is by direct viral inactivation for these strains. In contrast, SPL7013 lacked potent virucidal activity against R5 HIV-1 strains. Evaluation of the virucidal mechanism showed that SPL7013-treated NL4.3, 92UG046 and MACS1-spln virions were intact with no significant decrease in gp120 surface protein with respect to p24 capsid content compared to the corresponding untreated virus. These studies demonstrate that SPL7013 is virucidal against HIV-1 strains that utilize the CXCR4 coreceptor but not viruses tested in this study that solely use CCR5 by a mechanism that is distinct from virion disruption or loss of gp120. In addition, the mode of action by which SPL7013 prevents infection of cells with X4 and R5X4 strains is likely to differ from R5 strains of HIV-1.

A phase I randomized placebo controlled trial of the safety of 3% SPL7013 Gel (VivaGel®) in healthy young women administered twice daily for 14 days

Objective

To assess the safety of VivaGel® used vaginally twice daily for 14 days among healthy, sexually-abstinent women, aged 18–24 years in the USA and Kenya.

Design

Randomized placebo controlled trial.

Methods

Participants were randomized 2∶1, VivaGel to placebo. Safety was assessed by comparing genitourinary (GU) adverse events (AEs), colposcopy findings, vaginal lactobacilli and laboratory abnormalities by arm.

Results

Fifty-four women were enrolled; 35 in the VivaGel arm and 19 in the placebo arm. Twenty-six (74%) and 10 (53%) women reported taking all doses of VivaGel and placebo, respectively. No grade 3 or 4 AEs, or serious AEs occurred. Twenty-five (71%) participants in the VivaGel arm compared to 10 (53%) participants in the placebo arm had at least one grade 1 or 2 GU AE associated with product use (RR = 1.4, 95% CI 0.8-2.2). All seven grade 2 GU AEs associated with product use occurred among four women in the VivaGel arm. Vulvar and cervical erythema, cervical lesions, symptomatic BV, urinary frequency and metrorrhagia were more common in the VivaGel arm than the placebo arm. Twenty-nine (83%) participants in the VivaGel arm had a colposcopic finding compared to 10 (53%) participants in the placebo arm (RR = 1.6, 95%CI = 1.0-2.5). Two women in the VivaGel arm prematurely discontinued product use themselves due to a reported GU AE. Persistence of H₂O₂-producing and non-producing lactobacilli did not differ by study arm.

Conclusions

GU AEs and colposcopic findings consistent with mild epithelial irritation and inflammation occurred more commonly among women in the VivaGel arm.

Trial Registration

ClinicalTrials.gov NCT003311032

Structure activity relationship of dendrimer microbicides with dual action antiviral activity

BACKGROUND

Topical microbicides, used by women to prevent the transmission of HIV and other sexually transmitted infections are urgently required. Dendrimers are highly branched nanoparticles being developed as microbicides. However, the anti-HIV and HSV structure-activity relationship of dendrimers comprising benzyhydryl amide cores and lysine branches, and a comprehensive analysis of their broad-spectrum anti-HIV activity and mechanism of action have not been published.

METHODS AND FINDINGS

Dendrimers with optimized activity against HIV-1 and HSV-2 were identified with respect to the number of lysine branches (generations) and surface groups. Antiviral activity was determined in cell culture assays. Time-of-addition assays were performed to determine dendrimer mechanism of action. In vivo toxicity and HSV-2 inhibitory activity were evaluated in the mouse HSV-2 susceptibility model. Surface groups imparting the most potent inhibitory activity against HIV-1 and HSV-2 were naphthalene disulfonic acid (DNAA) and 3,5-disulfobenzoic acid exhibiting the greatest anionic charge and hydrophobicity of the seven surface groups tested. Their anti-HIV-1 activity did not appreciably increase beyond a second-generation dendrimer while dendrimers larger than two generations were required for potent anti-HSV-2 activity. Second (SPL7115) and fourth generation (SPL7013) DNAA dendrimers demonstrated broad-spectrum anti-HIV activity. However, SPL7013 was more active against HSV and blocking HIV-1 envelope mediated cell-to-cell fusion. SPL7013 and SPL7115 inhibited viral entry with similar potency against CXCR4-(X4) and CCR5-using (R5) HIV-1 strains. SPL7013 was not toxic and provided at least 12 h protection against HSV-2 in the mouse vagina.

CONCLUSIONS

Dendrimers can be engineered with optimized potency against HIV and HSV representing a unique platform for the controlled synthesis of chemically defined multivalent agents as viral entry inhibitors. SPL7013 is formulated as VivaGel(R) and is currently in clinical development to provide protection against HIV and HSV. SPL7013 could also be combined with other microbicides.

Inhibition of HSV-1 attachment, entry, and cell-to-cell spread by functionalized multivalent gold nanoparticles

The use of modified nanoparticles in interactions with biological targets is attracting rapidly increasing attention. In this Full Paper, the application of gold nanoparticles capped with mercaptoethanesulfonate (Au-MES NPs) as effective inhibitors of Herpes simplex virus type 1 infection based on their ability to mimic cell-surface-receptor heparan sulfate is described. Mechanistic studies reveal that Au-MES NPs interfere with viral attachment, entry, and cell-to-cell spread, thereby preventing subsequent viral infection in a multimodal manner. The ligand multiplicity achieved with carrier nanoparticles is crucial in generating polyvalent interactions with the virus at high specificity, strength, and efficiency. Such multivalent-nanoparticle-mediated inhibition is a promising approach for alternative antiviral therapy.

Safety, tolerability, and pharmacokinetics of SPL7013 gel (VivaGel): a dose ranging, phase I study

OBJECTIVES

To evaluate safety, tolerability and systemic pharmacokinetics of escalating doses of SPL7013 Gel in healthy women.

DESIGN

: Randomized, double-blind, placebo-controlled dose-escalation trial.

METHODS

Thirty-seven healthy women were randomized to receive 3.5 g of 0.5% (N = 8), 1% (N = 8), or 3% (N = 9) SPL7013 Gel or placebo gel (N = 12), applied vaginally once daily for 7 consecutive days. Genital toxicity was determined by interview, physical examination, assessment of vaginal microflora and colposcopy. Systemic toxicity was determined by nongenital adverse events (AEs) and laboratory assessments. Plasma was collected for pharmacokinetic analysis.

RESULTS

Genital AEs considered potentially product-related were all mild and reported by 5 (20%) women receiving SPL7013 Gel and 2 (17%) women receiving placebo gel. The most common were abdominal pain or discomfort, with no reports of vaginal burning or malodour, or genital-tract pain. There were no clinically significant colposcopic findings, including of genital inflammation or epithelial disruption. Lower concentrations of normal lactobacillary flora occurred during SPL7013 Gel and placebo gel use, with a decrease in anaerobes in the SPL7013 Gel groups. There were no reported cases of bacterial vaginosis, and lactobacilli returned to predose levels in most women after treatment. All nongenital AEs were of mild or moderate severity, expect for a severe tension headache in a woman receiving placebo. There was no absorption of SPL7013 into the systemic circulation.

CONCLUSIONS

SPL7013 Gel applied vaginally once daily for 7 days at concentrations of 0.5% to 3% was safe and well tolerated in healthy, sexually abstinent women, with no evidence of systemic toxicity or absorption.

Aplicações farmacêuticas de polímeros

Os polímeros representam uma das classes de materiais mais versáteis disponíveis para aplicações em diversas áreas, inclusive a farmacêutica. Polímeros naturais, naturais modificados e sintéticos são empregados como excipientes farmacêuticos para a formulação de cosméticos e medicamentos de liberação convencional e de liberação modificada. Nos dias atuais, polímeros são desenvolvidos para atuarem como moduladores e direcionadores da liberação de fármacos em sítios específicos no organismo. Polímeros biodegradáveis, bioadesivos, biomiméticos e hidrogéis responsivos têm sido amplamente incluídos em formulações farmacêuticas. Os avanços na idealização de novos Sistemas de Liberação de Fármacos somente são e serão permitidos a partir do desenvolvimento de polímeros projetados especificamente para a área farmacêutica. Neste sentido, o presente artigo visa a revisar e apresentar informações sobre o uso de polímeros em aplicações farmacêuticas que poderão ser úteis no planejamento de novos sistemas com desempenhos superiores.

Peptide-derivatized dendrimers inhibit human cytomegalovirus infection by blocking virus binding to cell surface heparan sulfate

Dendrimers are hyperbranched synthetic well-defined molecules with a number of potential applications, especially in relation to the need for new antiviral agents. One subclass of dendrimers are peptide-derivatized dendrimers which consist of a peptidyl branching core and covalently attached surface peptide functional units. Few studies have addressed the potential uses of peptide dendrimers as direct-acting antiviral agents. Here, we report on the ability of two peptide dendrimers, SB105 and SB105_A10, to directly and almost completely inhibit human cytomegalovirus (HCMV) replication in both primary fibroblasts and endothelial cells; the agents were also found to inhibit murine CMV replication, whereas they were not able to inhibit adenovirus or vesicular stomatitis virus. The peptide dendrimers prevented adsorption of the HCMV to cells at 4 degrees C, whereas SB104, a dendrimer with a different amino acid sequence within the functional group and minimal anticytomegaloviral activity, was ineffective in blocking HCMV attachment. In effect, SB105_A10 bound to human cells through an interaction with cell surface heparan sulfate and thereby blocked virion attachment to target cells. These results indicate that the SB105 and SB105_A10 dendrimers could provide a useful starting point for the development of novel molecules to block HCMV infection.

Evaluation of WLBU2 peptide and 3-O-octyl-sn-glycerol lipid as active ingredients for a topical microbicide formulation targeting Chlamydia trachomatis

Topical microbicides for prevention of sexually transmitted diseases (STDs) would be especially useful for women who are not able to persuade their partner(s) to take precautions. Many topical microbicides are in various stages of development, based on a variety of active ingredients. We investigated the in vitro activity of an engineered antimicrobial peptide (WLBU2) and a lipid (3-O-octyl-sn-glycerol [3-OG]) which could potentially be used as active ingredients in such a product. Using commercially available cytotoxicity reagents [Alamar Blue, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), and lactate dehydrogenase (LDH)], we first determined the toxicity of WLBU2 and 3-OG to the host cells in our assay procedure and excluded toxic concentrations from further testing. To determine activity against Chlamydia trachomatis, we used an assay previously developed by our laboratory in which chlamydial elementary bodies (EBs) were exposed to microbicides prior to contact with epithelial cells: the minimum (microbi)cidal concentration (MCC) assay. To further simulate conditions of transmission, we carried out the same assay in the presence of a simulated vaginal fluid, a simulated seminal fluid, human serum albumin, and a range of pH values which might be found in the human vagina at the time of exposure. Last, we tested WLBU2 and 3-OG in combination to determine if adding them together resulted in synergistic activity. We found that WLBU2 and 3-OG both have excellent activity in vitro against C. trachomatis and significantly more activity when added together. The simulated fluids reduced activity, but the synergy seen is good evidence that they would be effective when combined in a microbicide formulation.

Design of antimicrobially active small amphiphilic peptide dendrimers

Novel polyfunctional small amphiphilic peptide dendrimers characterized by incorporation of a new core compounds – tris-amino acids or tetrakis-amino alcohols that originated from a series of basic amino acids – were efficiently synthesized. These new core elements yielded molecules with multiple branching and (+5)/(+6) charge at the 1-st dendrimer generation. Dendrimers exhibited significant antimicrobial potency against Gram(+) and Gram(-) strains involving also multiresistant reference strains (S. aureus ATCC 43300 and E. coli ATCC BAA-198). In addition, high activity against fungi from the Candida genus was detected. More charged and more hydrophobic peptide dendrimers expressed hemolytic properties.

Novel approaches in fighting herpes simplex virus infections

The development of novel strategies to eradicate herpes simplex virus (HSV) is a global public health priority. While acyclovir and related nucleoside analogues provide successful modalities for treatment and suppression, HSV remains highly prevalent worldwide and is a major cofactor fueling the HIV epidemic. HSV is the predominant cause of genital ulcerative disease, and neonatal and sporadic infectious encephalitis. Asymptomatic shedding, which occurs more frequently than previously appreciated, contributes to viral transmission. Acyclovir resistance may be problematic for immunocompromised patients and highlights the need for new safe and effective agents. Ideally, vaccines to prevent infection, drugs to inhibit the establishment of or reactivation from latency, or vaginal microbicides to prevent sexual and perinatal transmission are needed to control the epidemic. This review summarizes current therapeutic options and strategies in development.

Formulating a sulfonated antiviral dendrimer in a vaginal microbicidal gel having dual mechanisms of action

SPL7013 is the sodium salt of a sulfonated dendrimer that has potent antiviral properties. VivaGel, a topical gel containing 3% (wt/wt) SPL7013, is in development as a vaginal microbicide. BufferGel is a Carbopol-based acidic buffering gel that enhances the natural protective action of the vagina to produce a broad-spectrum microbicidal environment. The positive attributes of both gels were combined into a combination vaginal microbicidal gel having dual mechanisms of action. A 3% (wt/wt) SPL7013 combination gel, pH 3.7, was developed and fully characterized and was shown to have more than twofold greater acidic buffering capacity than BufferGel. Ultracentrifugation experiments demonstrated that SPL7013 was not sequestered or entropically trapped in the viscous gel, thereby confirming, along with viral challenge studies, that SPL7013 has sufficient mobility in the viscous gel to exert antiviral properties.

A randomized controlled trial of the safety of candidate microbicide SPL7013 gel when applied to the penis

OBJECTIVES

To determine the safety of the candidate vaginal microbicide SPL7013 gel (VivaGel) when applied to the penis.

METHODS

A randomized, double-blind, placebo-controlled study. Thirty-six healthy men (18 circumcised, 18 uncircumcised) were randomized in a 2:1 ratio and treated with 3% SPL7013 gel (n = 24) or placebo gel (n = 12), applied once daily for 7 days. Genital toxicity was determined by interview, diary, and examination.

RESULTS

There were 10 genital adverse events (AEs) in 6 men (25%) receiving SPL7013 gel and 5 genital AEs in 4 men (33%) receiving the placebo that were possibly or probably related to the study product (difference of -8%, 95% confidence interval: -40% to 23%, P = 0.70). The most common genital AEs were genital pruritus and application site erythema. All genital AEs were mild (grade 1), and all but 1 in the placebo group were transient. Analysis of vital signs, nongenital AEs, and laboratory results indicated no safety or tolerability issues with SPL7013 gel, irrespective of circumcision status. There was no detectable absorption of SPL7013 into the plasma.

CONCLUSIONS

Three percent SPL7013 gel was safe and well tolerated, and comparable with placebo, when administered to the penis of both circumcised and uncircumcised men once daily for 7 days, with no evidence of systemic absorption or toxicity.