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

Prospective Antiviral Effect of Ulva lactuca Aqueous Extract against COVID-19 Infection

Marine algal extracts exhibit a potent inhibitory effect against several enveloped and non-enveloped viruses. The infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has several adverse effects, including an increased mortality rate. The anti-COVID-19 agents are still limited; this issue requires exploring novel, effective anti-SARS-CoV-2 therapeutic approaches. This study investigated the antiviral activity of an aqueous extract of Ulva lactuca, which was collected from the Gulf of Suez, Egypt. The aqueous extract of Ulva lactuca was characterized by high-performance liquid chromatography (HPLC), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Energy Dispersive X-ray (EDX) analyses. According to the HPLC analysis, the extract comprises several sugars, mostly rhamnose (32.88%). The FTIR spectra showed numerous bands related to the functional groups. EDX analysis confirmed the presence of different elements, such as oxygen (O), carbon (C), sulfur (S), magnesium (Mg), potassium (K), calcium (Ca), and sodium (Na), with different concentrations. The aqueous extract of U. lactuca (0.0312 mg/mL) exhibited potent anti-SARS-CoV-2 activity via virucidal activity, inhibition of viral replication, and interference with viral adsorption (% inhibitions of 64%, 33.3%, and 31.1%, respectively). Consequently, ulvan could be a promising compound for preclinical study in the drug development process to combat SARS-CoV-2.

A state-of-the-art review on fucoidan as an antiviral agent to combat viral infections

As a significant public health hazard with several drug side effects during medical treatment, searching for novel therapeutic natural medicines is promising. Sulfated polysaccharides from algae, such as fucoidan, have been discovered to have a variety of medical applications, including antibacterial and immunomodulatory properties. The review emphasized on the utilization of fucoidan as an antiviral agent against viral infections by inhibiting their attachment and replication. Moreover, it can also trigger immune response against viral infection in humans. This review suggested to be use the fucoidan for the potential protective remedy against COVID-19 and addressing the antiviral activities of sulfated polysaccharide, fucoidan derived from marine algae that could be used as an anti-COVID19 drug in near future.

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

Safety of G2-S16 Polyanionic Carbosilane Dendrimer as Possible HIV-1 Vaginal Microbicide

The UNAIDS objective for 2020 was 500,000 new HIV-1 infections per year; however, the latest annual reported data confirmed 1.7 million new HIV-1 infections in that year. Those data evidences the need for new prevention strategies and prophylactic treatments. This prevention crisis occurred in spite of the knowledge and availability of efficient prevention strategies. The G2-S16 is a microbicidal polyanionic carbosilane dendrimer currently being tested for topical vaginal application, which has been shown to be efficient in the prevention of HIV-1 infection. However, safety tests were lacked. For this purpose, we injected intravenously G2-S16 dendrimer to CD1 mice, thereby analyzing the hemogram, blood biochemical markers of systemic damage, accumulation in the organs and organ-tissue damage in heart, spleen, kidney, liver and brain. This work shows that even if the G2-S16 dendrimer penetrates the epithelial tissue, it does not cause vaginal irritation or tissue damage. Moreover, the i.v. injection of the G2-S16 dendrimer did not cause a damaging effect on the studied organs and it did not modify the hemogram or the biochemical plasma markers. In conclusion, the G2-S16 dendrimer has a very good safety profile, indicating that this molecule can be a very safe and efficient vaginal microbicide.

Molecular prospect of type-2 diabetes: Nanotechnology based diagnostics and therapeutic intervention

About ninety percent of all diabetic conditions account for T2D caused due to abnormal insulin secretion/ action or increased hepatic glucose production. Factors that contribute towards the aetiology of T2D could be well explained through biochemical, molecular, and cellular aspects. In this review, we attempt to explain the recent evolving molecular and cellular advancement associated with T2D pathophysiology. Current progress fabricated in T2D research concerning intracellular signaling cascade, inflammasome, autophagy, genetic and epigenetics changes is discretely explained in simple terms. Present available anti-diabetic therapeutic strategies commercialized and their limitations which are needed to be acknowledged are addressed in the current review. In particular, the pre-eminence of nanotechnology-based approaches to nullify the inadequacy of conventional anti-diabetic therapeutics and heterogeneous nanoparticulated systems exploited in diabetic researches are also discretely mentioned and are also listed in a tabular format in the review. Additionally, as a future prospect of nanotechnology, the review presents several strategic hypotheses to ameliorate the austerity of T2D by an engineered smart targeted nano-delivery system. In detail, an effort has been made to hypothesize novel nanotechnological based therapeutic strategies, which exploits previously described inflammasome, autophagic target points. Utilizing graphical description it is explained how a smart targeted nano-delivery system could promote β-cell growth and development by inducing the Wnt signaling pathway (inhibiting Gsk3β), inhibiting inflammasome (inhibiting NLRP3), and activating autophagic target points (protecting Atg3/Atg7 complex from oxidative stress) thereby might ameliorate the severity of T2D. Additionally, several targeting molecules associated with autophagic and epigenetic factors are also highlighted, which can be exploited in future diabetic research.

Polymer-based nano-therapies to combat COVID-19 related respiratory injury: progress, prospects, and challenges

The recent coronavirus disease-2019 (COVID-19) outbreak has increased at an alarming rate, representing a substantial cause of mortality worldwide. Respiratory injuries are major COVID-19 related complications, leading to poor lung circulation, tissue scarring, and airway obstruction. Despite an in-depth investigation of respiratory injury's molecular pathogenesis, effective treatments have yet to be developed. Moreover, early detection of viral infection is required to halt the disease-related long-term complications, including respiratory injuries. The currently employed detection technique (quantitative real-time polymerase chain reaction or qRT-PCR) failed to meet this need at some point because it is costly, time-consuming, and requires higher expertise and technical skills. Polymer-based nanobiosensing techniques can be employed to overcome these limitations. Polymeric nanomaterials have the potential for clinical applications due to their versatile features like low cytotoxicity, biodegradability, bioavailability, biocompatibility, and specific delivery at the targeted site of action. In recent years, innovative polymeric nanomedicine approaches have been developed to deliver therapeutic agents and support tissue growth for the inflamed organs, including the lung. This review highlights the most recent advances of polymer-based nanomedicine approaches in infectious disease diagnosis and treatments. This paper also focuses on the potential of novel nanomedicine techniques that may prove to be therapeutically efficient in fighting against COVID-19 related respiratory injuries.

There and back again: a dendrimer's tale

The development of molecular nanostructures with well-defined particle size and shape is of eminent interest in biomedicine. Among many studied nanostructures, dendrimers represent the group of those most thoroughly characterized ones. Due to their unique structure and properties, dendrimers are very attractive for medical and pharmaceutical applications. Owing to the controllable cavities inside the dendrimer, guest molecules may be encapsulated, and highly reactive terminal groups are susceptible to further modifications, e.g., to facilitate target delivery. To understand the potential of these nanoparticles and to predict and avoid any adverse cellular reactions, it is necessary to know the mechanisms responsible for an efficient dendrimer uptake and the destination of their intracellular journey. In this article, we summarize the results of studies describing the dendrimer uptake, traffic, and efflux mechanisms depending on features of specific nanoparticles and cell types. We also present mechanisms of dendrimers responsible for toxicity and alteration in signal transduction pathways at the cellular level.

BMS Derivatives C7-Linked to β-Cyclodextrin and Hyperbranched Polyglycerol Retain Activity against R5-HIV-1NLAD8 Isolates and Can Be Deemed Potential Microbicides

Amides from indole-3-glyoxylic acid and 4-benzoyl-2-methylpiperazine, which are related to entry inhibitors developed by Bristol-Myers Squibb (BMS), have been synthesized with aliphatic chains located at the C7 position of the indole ring. These spacers contain an azido group suitable for the well-known Cu(I)-catalyzed (3+2)-cycloaddition or an activated triple bond for the nucleophilic addition of thiols under physiological conditions. Reaction with polyols (β-cyclodextrin and hyperbranched polyglycerol) decorated with complementary click partners has afforded polyol-BMS-like conjugates that are not cytotoxic (TZM.bl cells) and retain the activity against R5-HIV-1_NLAD8 isolates. Thus, potential vaginal microbicides based on entry inhibitors, which can be called of 4^th generation, are reported here for the first time.

HIV co-receptor-tropism: cellular and molecular events behind the enigmatic co-receptor switching

Recognition of cell-surface receptors and co-receptors is a crucial molecular event towards the establishment of HIV infection. HIV exists as several variants that differentially recognize the principal co-receptors, CCR5 and CXCR4, in different cell types, known as HIV co-receptor-tropism. The relative levels of these variants dynamically adjust to the changing host selection pressures to infect a vast repertoire of cells in a stage-specific manner. HIV infection sets in through immune cells such as dendritic cells, macrophages, and T-lymphocytes in the acute stage, while a wide range of other cells, including astrocytes, glial cells, B-lymphocytes, and epithelial cells, are infected during chronic stages. A change in tropism occurs during the transition from acute to a chronic phase, termed as co-receptor switching marked by a change in disease severity. The cellular and molecular events leading to co-receptor switching are poorly understood. This review aims to collate our present understanding of the dynamics of HIV co-receptor-tropism vis-à-vis host and viral factors, highlighting the cellular and molecular events involved therein. We present the possible correlations between virus entry, cell tropism, and co-receptor switching, speculating its consequences on disease progression, and proposing new scientific pursuits to help in an in-depth understanding of HIV biology.

Nanotechnology against human cytomegalovirus in vitro: polyanionic carbosilane dendrimers as antiviral agents

BACKGROUND

Human cytomegalovirus (HCMV) is a worldwide infection, causing different troublesome in immunosupressed patients and very related to Human Immunodeficiency Virus 1 (HIV-1) infection, mainly in developing countries, with a co-infection rate of 80% in Africa. The high cost of present treatments and the lack of routinely tests in these countries urge the necessity to develop new molecules or strategies against HCMV. The new treatments should be low-cost and capable of avoiding the emerging problem of resistant virus. Nanoparticles play an important role in several viral infections. Our main focus is to study the potential activity of polyanionic carbosilane dendrimers (PDC), which are hyperbranched molecules with several sulfonate or sulfate groups in their periphery, against different viruses.

RESULTS

We studied the activity of G1-S4, G2-S16 and G2-S24P PDCs in MRC-5 cell line against HCMV infection by several plaque reduction assays. Our results show that dendrimers present good biocompatibility at the concentrations tested (1-50 µM) for 6 days in cell culture. Interestingly, both G2-S16 and G2-S24P showed a remarked inhibition at 10 µM against HCMV infection. Results on attachment and virucidal assays indicated that the inhibition was not directed to the virus or the virus-cell attachment. However, results of time of addition, showed a longer lasting activity of these dendrimers in comparison to ganciclovir, and the combination of G2-S16 or G2-S24P with ganciclovir increases the HCMV inhibition around 90 %.

CONCLUSIONS

Nanotechnology, in particular polyanionic carbosilane dendrimers, have proved their potential application against HCMV, being capable of inhibiting the infection by themselves or enhancing the activity of ganciclovir, the actual treatment. These compounds represent a low-cost approach to fight HCMV infections.

Advances in Targeting HPV Infection as Potential Alternative Prophylactic Means

Infection by oncogenic human papillomavirus (HPV) is the primary cause of cervical cancer and other anogenital cancers. The majority of cervical cancer cases occur in low- and middle- income countries (LMIC). Concurrent infection with Human Immunodeficiency Virus (HIV) further increases the risk of HPV infection and exacerbates disease onset and progression. Highly effective prophylactic vaccines do exist to combat HPV infection with the most common oncogenic types, but the accessibility to these in LMIC is severely limited due to cost, difficulties in accessing the target population, cultural issues, and maintenance of a cold chain. Alternative preventive measures against HPV infection that are more accessible and affordable are therefore also needed to control cervical cancer risk. There are several efforts in identifying such alternative prophylactics which target key molecules involved in early HPV infection events. This review summarizes the current knowledge of the initial steps in HPV infection, from host cell-surface engagement to cellular trafficking of the viral genome before arrival in the nucleus. The key molecules that can be potentially targeted are highlighted, and a discussion on their applicability as alternative preventive means against HPV infection, with a focus on LMIC, is presented.

Sulfoglycodendrimer Therapeutics for HIV-1 and SARS-CoV-2

Hexavalent sulfoglycodendrimers (SGDs) are synthesized as mimics of host cell heparan sulfate proteoglycans (HSPGs) to inhibit the early stages in viral binding/entry of HIV‐1 and SARS‐CoV‐2. Using an HIV neutralization assay, the most promising of the seven candidates are found to have sub‐micromolar anti‐HIV activities. Molecular dynamics simulations are separately implemented to investigate how/where the SGDs interacted with both pathogens. The simulations revealed that the SGDs: 1) develop multivalent binding with polybasic regions within and outside of the V3 loop on glycoprotein 120 (gp120) for HIV‐1, and consecutively bind with multiple gp120 subunits, and 2) interact with basic amino acids in both the angiotensin‐converting enzyme 2 (ACE2) and HSPG binding regions of the Receptor Binding Domain (RBD) from SARS‐CoV‐2. These results illustrate the considerable potential of SGDs as inhibitors in viral binding/entry of both HIV‐1 and SARS‐CoV‐2 pathogens, leading the way for further development of this class of molecules as broad‐spectrum antiviral agents.

Antiviral activity of sulfated polysaccharides from marine algae and its application in combating COVID-19: Mini review

Marine-derived sulfated polysaccharides possess various antiviral activities against a broad range of enveloped and non-enveloped viruses. It has become the potential source of antiviral drugs for pharmaceutical development. In this review, we will discuss the different types of sulfated polysaccharides and their structural classification. Some of the major sulfated polysaccharides with potent antiviral activity, including carrageenan, agar, ulvan, fucoidan, and alginates, are considered in this review. The mechanism of these sulfated polysaccharides in inhibiting the different stages of the viral infection process inside the host cell is also demonstrated. It involves blocking the initial entry of the virus or inhibiting its transcription and translation by modulating the immune response of the host cell. In addition, we explore the potential of sulfated polysaccharides as antiviral agents in preventing recent Corona Virus Disease-2019 (COVID-19).

Emergence of Nanotechnology to Fight HIV Sexual Transmission: The Trip of G2-S16 Polyanionic Carbosilane Dendrimer to Possible Pre-Clinical Trials

Development of new, safe, and effective microbicides to prevent human immunodeficiency virus HIV sexual transmission is needed. Unfortunately, most microbicides proved ineffective to prevent the risk of HIV-infection in clinical trials. We are working with G2-S16 polyanionic carbosilane dendrimer (PCD) as a new possible vaginal topical microbicide, based on its short reaction times, wide availability, high reproducibility, and quantitative yields of reaction. G2-S16 PCD exerts anti-HIV activity at an early stage of viral replication, by blocking gp120/CD4/CCR5 interaction, and providing a barrier against infection for long periods of time. G2-S16 PCD was stable at different pH values, as well as in the presence of seminal fluids. It maintained the anti-HIV activity against R5/X4 HIV over time, did not generate any type of drug resistance, and retained the anti-HIV effect when exposed to semen-enhanced viral infection. Importantly, G2-S16 PCD did not modify vaginal microbiota neither in vitro or in vivo. Histopathological examination did not show vaginal irritation, inflammation, lesions, or damage in the vaginal mucosa, after administration of G2-S16 PCD at different concentrations and times in female mice and rabbit animal models. Based on these promising data, G2-S16 PCD could become a good, safe, and readily available candidate to use as a topical vaginal microbicide against HIV.

Novel Applications of Nanotechnology in Controlling HIV and HSV Infections

Infectious diseases have been prevalent since many decades and viral pathogens have caused global health crisis and economic meltdown on a devastating scale. High occurrence of newer viral infections in the recent years, in spite of the progress achieved in the field of pharmaceutical sciences defines the critical need for newer and more effective antiviral therapies and diagnostics. The incidence of multi-drug resistance and adverse effects due to the prolonged use of anti-viral therapy is also a major concern. Nanotechnology offers a cutting edge platform for the development of novel compounds and formulations for biomedical applications. The unique properties of nano-based materials can be attributed to the multi-fold increase in the surface to volume ratio at the nano-scale, tunable surface properties of charge and chemical moieties. Idealistic pharmaceutical properties such as increased bioavailability and retention times, lower toxicity profiles, sustained release formulations, lower dosage forms and most importantly, targeted drug delivery can be achieved through the approach of nanotechnology. The extensively researched nano-based materials are metal and polymeric nanoparticles, dendrimers and micelles, nano-drug delivery vesicles, liposomes and lipid based nanoparticles. In this review article, the impact of nanotechnology on the treatment of Human Immunodeficiency Virus (HIV) and Herpes Simplex Virus (HSV) viral infections during the last decade are outlined.

COVID-19: Pathophysiology, treatment options, nanotechnology approaches, and research agenda to combating the SARS-CoV2 pandemic

The recent corona virus disease (COVID-19) outbreak has claimed the lives of many around the world and highlighted an urgent need for experimental strategies to prevent, treat and eradicate the virus. COVID-19, an infectious disease caused by a novel corona virus and no approved specific treatment is available yet. A vast number of promising antiviral treatments involving nanotechnology are currently under investigation to aid in the development of COVID-19 drug delivery. The prospective treatment options integrating the ever-expanding field of nanotechnology have been compiled, with the objective to show that these can be potentially developed for COVID-19 treatment. This review summarized the current state of knowledge, research priorities regarding the pandemic and post COVID-19. We also focus on the possible nanotechnology approaches that have proven to be successful against other viruses and the research agenda to combat COVID-19.

An Efficient Microwave-Mediated Synthesis of Hexavalent Sialic Acid Sulfoglycodendrimers as Potential Anti-HIV Agents

A series of four sialic acid-containing hexavalent sulfoglycodendrimers (SGDs) were synthesized in excellent yields using an efficient strategy involving multiple microwave-mediated reactions. Four sugars, sialic acid, and the dimer through tetramer of α-2→8-linked oligosialic acid were added to an aminooxy-terminated hexavalent dendrimer core using a chemoselective oxime-forming reaction. This method resulted in substantial improvements in reaction time and product yields over previous methods. These multivalent glycopolymers were designed as potential topical agents for preventing the sexual transmission of HIV-1. While inactive against HIV-1, the SGDs were also not cytotoxic, opening a pathway for the further development of anti-HIV SGDs.

High Preventive Effect of G2-S16 Anionic Carbosilane Dendrimer against Sexually Transmitted HSV-2 Infection

Anionic carbosilane dendrimers such as G2-S16 are very effective in preventing HSV-2 infection both in vitro and in vivo. We present the main achievements obtained for the G2-S16 dendrimer in vivo, especially related to its efficacy against HSV-2 infection. Moreover, we discuss the mechanisms by which the G2-S16 dendrimer applied vaginally as a topical microbicide has been demonstrated to be safe and harmless for the vaginal microbiome balance, as both conditions present an essential step that has to be overcome during microbicide development. This review points to the marked protective effect of the G2-S16 dendrimer against sexually transmitted HSV-2 infection, supporting its role as a possible microbicide against HSV-2 infection.

Cationic Dendrimer G2-S16 Inhibits Herpes Simplex Type 2 Infection and Protects Mice Vaginal Microbiome

The G2-S16 polyanionic carbosilane dendrimer is a promising microbicide that inhibits HSV-2 infection in vitro and in vivo in mice models. This G2-S16 dendrimer inhibits HSV-2 infection even in the presence of semen. Murine models, such as BALB/c female mice, are generally used to characterize host-pathogen interactions within the vaginal tract. However, the composition of endogenous vaginal flora remains largely undefined with modern microbiome analyses. It is important to note that the G2-S16 dendrimer does not change healthy mouse vaginal microbiome where Pseudomonas (10.2–79.1%) and Janthinobacterium (0.7–13%) are the more abundant genera. The HSV-2 vaginally infected female mice showed a significant microbiome alteration because an increase of Staphylococcus (up to 98.8%) and Escherichia (30.76%) levels were observed becoming these bacteria the predominant genera. BALB/c female mice vaginally-treated with the G2-S16 dendrimer and infected with the HSV-2 maintained a healthy vaginal microbiome similar to uninfected female mice. Summarizing, the G2-S16 polyanionic carbosilane dendrimer inhibits the HSV-2 infection in the presence of semen and prevents the alteration of mice female vaginal microbiome.

Antiviral effect of Chinese herbal prescription JieZe-1 on adhesion and penetration of VK2/E6E7 with herpes simplex viruses type 2

ETHNOPHARMACOLOGICAL RELEVANCE

The Chinese Herbal Prescription JieZe-1(JZ-1), added and subtracted from Yihuang Decoction, a famous formula in the 12th year of Kangxi in Qing Dynasty, has a clear effect on Genital Herpes (GH) and no obvious adverse reactions occur clinically. JZ-1 also has preventive and therapeutic effects on Trichomonas vaginitis, Candida albicans vaginitis and GH in vitro and in vivo experiments.

AIM OF STUDY

The effect and mechanism of JZ-1 on anti-herpes simplex virus type 2(HSV-2) in vitro focusing on adhesion and penetration stages were investigated.

MATERIALS AND METHODS

A model of HSV-2 infection of VK2/E6E7 was developed. In order to explore JZ-1's anti-HSV-2 effect in vitro, cell morphology, ultrastructural pathology, cell viability and expression of viral glycoprotein D (gD) were assessed at 6 h, 12 h, 18 h, and 24 h of JZ-1 treatment. Then we measured the exact time required for adhesion and penetration of HSV-2 into VK2/E6E7 among a series of times at room temperature and under temperature control techniques. We treated VK2/E6E7 with JZ-1, penciclovir, or berberine and explored the mechanism of JZ-1 in blocking HSV-2 adhesion and penetration of host cells by assessing the cell ultrastructural pathology, viability, viral proteins gB, gD, VP16, ICP5, and ICP4 and host cell proteins HVEM, Nectin-1, and Nectin-2.

RESULTS

HSV-2 can fully adhere and penetrate into VK/E6E7 within 5 mins at room temperature while it takes 60mins under temperature control techniques. JZ-1 and penciclovir showed significant anti-HSV-2 effects, with improved host cell morphologies and increased host cell viabilities observed after treatment for 24 h. The anti-HSV-2 effect of JZ-1 can be detected after treatment for 6 h while that of penciclovir was not obvious until treatment for 12 h. JZ-1 showed distinct effect on HSV-2 adhesion and penetration stages by significantly reducing the expression of viral proteins gB, gD, VP16, ICP5, and ICP4, improving cell morphology and increasing cell viability. However, these effects were not exerted via downregulated expression of membrane fusion-related proteins such as HVEM, Nectin-1, or Nectin-2. The specific anti-HSV-2 mechanism of JZ-1 need to be further explored.

CONCLUSION

The anti-HSV-2 effect of JZ-1 was superior to that of penciclovir and berberine in vitro, and was mainly mediated by enhancing host cell defense and blocking adhesion and penetration of HSV-2.

Vaginal multipurpose prevention technologies: promising approaches for enhancing women's sexual and reproductive health

Introduction: Multipurpose prevention technologies (MPTs) have the potential to avert multiple concomitant sexual and reproductive health issues in women such as sexually transmitted infections and unintended pregnancy. MPTs incorporate one or more active pharmaceutical ingredients in a single product, which adds more convenience for users and may promote increased adherence. Various vaginal dosage forms/delivery systems have been studied for designing MPTs. However, several challenges remain that are mainly related to requirements of individual drugs or intended multiple applications.Areas covered: This review focuses on the emerging need and development of vaginal MPTs. It illustrates numerous examples that are currently in the preclinical and clinical development pipeline, highlighting the concept behind vaginal MPTs. The article also highlights the challenges associated with formulation design and development, including regulatory issues that need to be addressed.Expert opinion: Vaginal MPTs present great potential to empower women with novel, efficient, and safe products for protection against sexually transmitted infections and unintended pregnancy. However, several technological issues and regulatory gaps still need to be addressed in order to meet real-world needs.

High antiviral activity of mercaptoethane sulfonate functionalized Te/BSA nanostars against arterivirus and coronavirus

Mercaptoethane sulfonate functionalised Te/BSA nanostars are prepared and exhibit excellent antiviral activity against arteriviruses and coronaviruses.

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.

Nano-based approach to combat emerging viral (NIPAH virus) infection

Emergence of new virus and their heterogeneity are growing at an alarming rate. Sudden outburst of Nipah virus (NiV) has raised serious question about their instant management using conventional medication and diagnostic measures. A coherent strategy with versatility and comprehensive perspective to confront the rising distress could perhaps be effectuated by implementation of nanotechnology. But in concurrent to resourceful and precise execution of nano-based medication, there is an ultimate need of concrete understanding of the NIV pathogenesis. Moreover, to amplify the effectiveness of nano-based approach in a conquest against NiV, a list of developed nanosystem with antiviral activity is also a prerequisite. Therefore the present review provides a meticulous cognizance of cellular and molecular pathogenesis of NiV. Conventional as well several nano-based diagnosis experimentations against viruses have been discussed. Lastly, potential efficacy of different forms of nano-based systems as convenient means to shield mankind against NiV has also been introduced.

New anionic poly(alkylideneamine) dendrimers as microbicide agents against HIV-1 infection

Acquired immune deficiency syndrome (AIDS) due to human immunodeficiency virus type-1 (HIV-1) represents one of the most important sexually transmitted infections (STI) worldwide. Great international efforts have been made to stop new infections but, to date, several compounds failed as microbicides at different stages of clinical trials. The quest to design new molecules that could prevent these infections is essential. In this work, we synthesized the first, second and third generations of anionic dendrimers having carboxylate and sulfonate terminal groups, respectively named G1C, G2C, G3C and G1S, G2S, and G3S, starting from a family of poly(alkylideneamine) dendrimers with nitrile termini. The anionic terminal groups of these dendrimers were expected to prompt them to act against HIV-1 infection. All dendrimers were fully characterized by 1H- and 13C-NMR, FTIR, MS and zeta potential techniques. Importantly, they were able to remain stable in the solid state and aqueous solutions at least for one and a half years. Screening of these six new dendrimers was then performed to shed light on their potential anti-HIV-1 activity and their mechanism of action. Results showed that the dendrimers were cytocompatible and that G1C and G1S dendrimers had important activity against R5-HIV-1NLAD8 and X4-HIV-1NL4.3 isolates by acting directly on viral particles and blocking their entry in host cells. Additionally, G1C and G1S dendrimers maintained their inhibitory effect at different pH values. Through a vaginal irritation assay carried out in BALB/c mice, the safety of these new dendrimers for topical application was also shown. Taken together, our results clearly show that G1C and G1S dendrimers are strong candidates for developing an effective microbicide to prevent HIV-1 new infections.

G2-S16 sulfonate dendrimer as new therapy for treatment failure in HIV-1 entry inhibitors

Aim: Polyanionic carbosilane dendrimers have been shown to be safe and block human immunodeficiency virus type 1 (HIV-1) infection in a multifunctional manner. The aim of this study is to evaluate the appearance of HIV-1 resistance mutations after treatment with polyanionic carbosilane dendrimers. Materials & methods: A resistance mutation assay was performed on MT2 cells, viral quantity was measured by ELISA HIVp24^gag and titration was carried out on TZM.bl. Next generation sequencing for HIV-1 Env was performed on G1-S4 or G2-S16 dendrimers supernatants. Results: Data showed the appearance of mutation resistance to G1-S4 treatment, inducing three significant mutations. G2-S16 did not generate any mutations and, furthermore, inhibited G1-S4-resistant viruses. Conclusion: G1-S4 treatment generates significant mutations in HIV-1_NL4.3. G2-S16 does not generate resistance-associated mutation, suggesting that G2-S16 is safe as a HIV-entry inhibitor.

Pharmaceutical Vehicles for Vaginal and Rectal Administration of Anti-HIV Microbicide Nanosystems

Prevention strategies play a key role in the fight against HIV/AIDS. Vaginal and rectal microbicides hold great promise in tackling sexual transmission of HIV-1, but effective and safe products are yet to be approved and made available to those in need. While most efforts have been placed in finding and testing suitable active drug candidates to be used in microbicide development, the last decade also saw considerable advances in the design of adequate carrier systems and formulations that could lead to products presenting enhanced performance in protecting from infection. One strategy demonstrating great potential encompasses the use of nanosystems, either with intrinsic antiviral activity or acting as carriers for promising microbicide drug candidates. Polymeric nanoparticles, in particular, have been shown to be able to enhance mucosal distribution and retention of promising antiretroviral compounds. One important aspect in the development of nanotechnology-based microbicides relates to the design of pharmaceutical vehicles that allow not only convenient vaginal and/or rectal administration, but also preserve or even enhance the performance of nanosystems. In this manuscript, we revise relevant work concerning the selection of vaginal/rectal dosage forms and vehicle formulation development for the administration of microbicide nanosystems. We also pinpoint major gaps in the field and provide pertinent hints for future work.

Ramified derivatives of 5-(perylen-3-ylethynyl)uracil-1-acetic acid and their antiviral properties

The propargylamide of N3-Pom-protected 5-(perylen-3-ylethynyl)uracil acetic acid, a universal precursor, was used in a CuAAC click reaction for the synthesis of several derivatives, including three ramified molecules with high activities against tick-borne encephalitis virus (TBEV). Pentaerythritol-based polyazides were used for the assembly of molecules containing 2⋯4 antiviral 5-(perylen-3-ylethynyl)uracil scaffolds, the first examples of polyvalent perylene antivirals. Cluster compounds showed enhanced absorbance, however, their fluorescence was reduced due to self-quenching. Due to the solubility issues, Pom group removal succeeded only for compounds with one peryleneethynyluracil unit. Four compounds, including one ramified cluster 9f, showed remarkable 1⋯3 nM EC₅₀ values against TBEV in cell culture.

Ramified clusters of antiviral perylenylethynyl scaffold were prepared using CuAAC reaction of 5-(perylen-3-ylethynyl)-3-pivaloyloxymethyl-1-(propargylamidomethyl)uracil with azides. Compounds inhibited TBEV reproduction at nanomolar concentrations.

Anionic Carbosilane Dendrimers Destabilize the GP120-CD4 Complex Blocking HIV-1 Entry and Cell to Cell Fusion

Cell-to-cell transmission is the most effective pathway for the spread of human immunodeficiency virus (HIV-1). Infected cells expose virus-encoded fusion proteins on their surface as a consequence of HIV-1 replicative cycle that interacts with noninfected cells through CD4 receptor and CXCR4 coreceptor leading to the formation of giant multinucleated cells known as syncytia. Our group previously described the potent activity of dendrimers against CCR5-tropic viruses. Nevertheless, the study of G1-S4, G2-S16, and G3-S16 dendrimers in the context of X4-HIV-1 tropic cell-cell fusion referred to syncytium formation remains still unknown. These dendrimers showed a suitable biocompatibility in all cell lines studied and our results demonstrated that anionic carbosilane dendrimers G1-S4, G2-S16, and G3-S16 significantly inhibit the X4-HIV-1 infection, as well as syncytia formation, in a dose dependent manner. We also demonstrated that G2-S16 and G1-S4 significantly reduced syncytia formation in HIV-1 Env-mediated cell-to-cell fusion model. Molecular modeling and in silico models showed that G2-S16 dendrimer interfered with gp120-CD4 complex and demonstrated its potential use for a treatment.

Recent progress in dendrimer-based nanomedicine development

Dendrimers offer well-defined nanoarchitectures with spherical shape, high degree of molecular uniformity, and multiple surface functionalities. Such unique structural properties of dendrimers have created many applications for drug and gene delivery, nanomedicine, diagnostics, and biomedical engineering. Dendrimers are not only capable of delivering drugs or diagnostic agents to desired sites by encapsulating or conjugating them to the periphery, but also have therapeutic efficacy in their own. When compared to traditional polymers for drug delivery, dendrimers have distinct advantages, such as high drug-loading capacity at the surface terminal for conjugation or interior space for encapsulation, size control with well-defined numbers of peripheries, and multivalency for conjugation to drugs, targeting moieties, molecular sensors, and biopolymers. This review focuses on recent applications of dendrimers for the development of dendrimer-based nanomedicines for cancer, inflammation, and viral infection. Although dendrimer-based nanomedicines still face some challenges including scale-up production and well-characterization, several dendrimer-based drug candidates are expected to enter clinical development phase in the near future.

Nanotechnologies for early diagnosis, in situ disease monitoring, and prevention

Nanotechnology is an enabling technology with great potential for applications in stem cell research and regenerative medicine. Fluorescent nanodiamond (FND), an inherently biocompatible and nontoxic nanoparticle, is well suited for such applications. We had developed a prospective isolation method using CD157, CD45, and CD54 to obtain lung stem cells. Labeling of CD45⁻CD54⁺CD157⁺ cells with FNDs did not eliminate their abilities for self-renewal and differentiation. The FND labeling in combination with cell sorting, fluorescence lifetime imaging microscopy, and immunostaining identified transplanted stem cells allowed tracking of their engraftment and regenerative capabilities with single-cell resolution. Time-gated fluorescence (TGF) imaging in mouse tissue sections indicated that they reside preferentially at the bronchoalveolar junctions of lungs, especially in naphthalene-injured mice. Our results presented in Subchapter 1.1 demonstrate not only the remarkable homing capacity and regenerative potential of the isolated stem cells, but also the ability of finding rare lung stem cells in vivo using FNDs.

The topical use of antiretroviral-based microbicides, namely of a dapivirine ring, has been recently shown to partially prevent transmission of HIV through the vaginal route. Among different formulation approaches, nanotechnology tools and principles have been used for the development of tentative vaginal and rectal microbicide products. Subchapter 1.2 provides an overview of antiretroviral drug nanocarriers as novel microbicide candidates and discusses recent and relevant research on the topic. Furthermore, advances in developing vaginal delivery platforms for the administration of promising antiretroviral drug nanocarriers are reviewed. Although mostly dedicated to the discussion of nanosystems for vaginal use, the development of rectal nanomicrobicides is also addressed.

Infectious diseases are currently responsible for over 8 million deaths per year. Efficient treatments require accurate recognition of pathogens at low concentrations, which in the case of blood infection (septicemia) can go as low as 1 mL^–1. Detecting and quantifying bacteria at such low concentrations is challenging and typically demands cultures of large samples of blood (∼1 mL) extending over 24–72 h. This delay seriously compromises the health of patients and is largely responsible for the death toll of bacterial infections. Recent advances in nanoscience, spectroscopy, plasmonics, and microfluidics allow for the development of optical devices capable of monitoring minute amounts of analytes in liquid samples. In Subchapter 1.3 we critically discuss these recent developments that will, in the future, enable the multiplex identification and quantification of microorganisms directly on their biological matrix with unprecedented speed, low cost, and sensitivity.

Radiolabeled nanoparticles (NPs) are finding an increasing interest in a broad range of biomedical applications. They may be used to detect and characterize diseases, to deliver relevant therapeutics, and to study the pharmacokinetic/pharmacodynamic parameters of nanomaterials. The use of radiotracer techniques in the research of novel NPs offers many advantages, but there are still some limitations. The binding of radionuclides to NPs has to be irreversible to prevent their escape to other tissues or organs. Due to the short half-lives of radionuclides, the manufacturing process is time limited and difficult, and there is also a risk of contamination. Subchapter 1.4 presents the main selection criteria for radionuclides and applicable radiolabeling procedures used for the radiolabeling of various NPs. Also, an overview of different types of NPs that have so far been labeled with radionuclides is presented.

Carbosilane dendrons with fatty acids at the core as a new potential microbicide against HSV-2/HIV-1 co-infection

Herpes simplex virus type 2 (HSV-2) and human immunodeficiency virus type 1 (HIV-1) represent the two most frequent sexually transmitted infections (STI) worldwide. Epidemiological studies suggest that HSV-2 increases the risk of HIV-1 acquisition approximately 3-fold mainly due to the clinical and immunological manifestations. In the absence of vaccines against both STI, the development of new preventive strategies has become essential for further studies. We performed the screening of six novel polyanionic carbosilane dendrons to elucidate their potential activity against HSV-2/HIV-1 co-infection and their mechanism of action. These new nanoparticles are carbosilane branched dendrons from first to third generation, with palmitic or hexanoic fatty acids as the core and capped with sulfonate groups, named G1_d-STE2Hx, G2_d-STE4Hx, G3_d-STE8Hx, G1_d-STE2Pm, G2_d-STE4Pm and G3_d-STE8Pm. G3_d-STE8Hx and G3_d-STE8Pm carbosilane branched dendrons showed high viability. These dendrons also showed a great broad-spectrum antiviral activity, as well as a suitable efficacy against HIV-1 even if the mucosal disruption occurs as a consequence of HSV-2 infection. Our results exert high inhibition against HSV-2 and HIV-1 by blocking the entry of both viruses with the median effective concentration EC₅₀ values in the nanomolar range. Additionally, G3_d-STE8Hx and G3_d-STE8Pm retained their anti-HSV-2/HIV-1 activity at different pH values. G3_d-STE8Hx and G3_d-STE8Pm dendrons may be potential candidates as dual-acting microbicides against HSV-2/HIV-1 co-infection.

Function Oriented Molecular Design: Dendrimers as Novel Antimicrobials

In recent years innovative nanostructures are attracting increasing interest and, among them, dendrimers have shown several fields of application. Dendrimers can be designed and modified in plentiful ways giving rise to hundreds of different molecules with specific characteristics and functionalities. Biomedicine is probably the field where these molecules find extraordinary applicability, and this is probably due to their multi-valency and to the fact that several other chemicals can be coupled to them to obtain desired compounds. In this review we will describe the different production strategies and the tools and technologies for the study of their characteristics. Finally, we provide a panoramic overview of their applications to meet biomedical needs, especially their use as novel antimicrobials.

From optimized monovalent ligands to size-controlled dendrimers: an efficient strategy towards high-activity DC-SIGN antagonists

This short review describes our work on the development of dendrimeric antagonists of DC-SIGN, a dendritic cells (DCs) receptor recognizing highly mannosylated structures and primarily involved in the recognition of viruses such as HIV. The structure of pseudo-di-mannoside and pseudo-tri-mannoside compounds was first finely modified to obtain DC-SIGN ligands that were more stable and selective than mannose. Their DC-SIGN affinity differences were amplified once presented on multivalent dendrimer-like scaffolds, including poly-alkyne terminated and phenylene-ethynylene rod-like ones. Libraries of mannosylated dendrimers were synthesized, improving their stability and maximizing their monodispersity. The effect of the dendrimers valency, structure, and size on DC-SIGN affinity and antiviral potency was investigated. Both the valency and the topology of the architectures were revealed as key parameters for activity optimization, together with the intrinsic affinity of the monovalent ligand. The stability, rigidity, and length of the scaffolds were also tuned. The design of geometrically adapted scaffolds afforded one of the most potent inhibitors of DC-SIGN mediated HIV infections to date. This monodispersed, not cytotoxic, and highly active compound was also tested with DCs; its internalization into endolysosomal compartments and its ability to induce the overexpression of signaling molecules makes it a good precursor to produce pathogen-entry inhibitors with immunomodulant properties.