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.

Antiviral mechanism of polyanionic carbosilane dendrimers against HIV-1

Nanotechnology-derived platforms, such as dendrimers, are very attractive in several biological applications. In the case of human immunodeficiency virus (HIV) infection, polyanionic carbosilane dendrimers have shown great potential as antiviral agents in the development of novel microbicides to prevent the sexual transmission of HIV-1. In this work, we studied the mechanism of two sulfated and naphthylsulfonated functionalized carbosilane dendrimers, G3-S16 and G2-NF16. They are able to inhibit viral infection at fusion and thus at the entry step. Both compounds impede the binding of viral particles to target cell surface and membrane fusion through the blockage of gp120–CD4 interaction. In addition, and for the first time, we demonstrate that dendrimers can inhibit cell-to-cell HIV transmission and difficult infectious synapse formation. Thus, carbosilane dendrimers’ mode of action is a multifactorial process targeting several proteins from viral envelope and from host cells that could block HIV infection at different stages during the first step of infection.

HIV-antigens charged on phosphorus dendrimers as tools for tolerogenic dendritic cells-based immunotherapy

AIMS

The objective was to study if cationic phosphorus dendrimers can be used as DC-based vaccine or adjuvant in anti-HIV-1 vaccine development when associated with HIV-1 derived peptides.

MATERIALS & METHODS

The HIV derived peptides uptake in DC and the phenotype of iDC and mDC were studied using Flow Cytometry analysis. Migration of mDC was evaluated by an in vitro chemotaxis assay. Allogenic T-cells proliferative response induced by DC was studied using Flow Cytometry assays. Cytokines production was analysed by Diaclon DIAplex Th1/Th2/Inflammation kit.

RESULTS

All phosphorus dendrimers showed the ability to deliver HIV-derived peptides in DC. The phosphorus dendrimers from second and third generations induced important changes in phenotype. Moreover, the treatment of mDC with the second generation dendrimer and derivated dendriplexes modified cellular migratory properties, altered their capacity to stimulate allogenic naïve T cells in vitro and impeded the production of pro-inflammatory cytokines.

CONCLUSIONS

The phosphorus dendrimers cannot be used as vaccines because they would not have the ability to induce an immune response. The cationic phosphorus dendrimers associated with HIV-derived peptides have the ability to deliver peptides as non-viral vectors. However, there are other potential therapeutic applications of these compounds, for instance as topical antiinflammatory agents, as compounds for allograft rejection or autoimmune diseases and as agents inducing specific tolerance with antigen-loaded DC against allergy reaction. Nevertheless, these applications need to be evaluated.

Dendrimers as nonviral vectors in dendritic cell-based immunotherapies against human immunodeficiency virus: steps toward their clinical evaluation

Although the antiretroviral therapy has led to a long-term control of HIV-1, it does not cure the disease. Therefore, several strategies are being explored to develop an effective HIV vaccine, such as the use of dendritic cells (DCs). DC-based immunotherapies bear different limitations, but one of the most critical point is the antigen loading into DCs. Nanotechnology offers new tools to overcome these constraints. Dendrimers have been proposed as carriers for targeted delivery of HIV antigens in DCs. These nanosystems can release the antigens in a controlled manner leading to a more potent specific immune response. This review focuses on the first steps for clinical development of dendrimers to assess their safety and potential use in DC-based immunotherapies against HIV.

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.

Enhanced activity of carbosilane dendrimers against HIV when combined with reverse transcriptase inhibitor drugs: searching for more potent microbicides

Self-administered topical microbicides or oral preexposure prophylaxis could be very helpful tools for all risk groups to decrease the human immunodeficiency virus (HIV)-1 infection rates. Up until now, antiretrovirals (ARVs) have been the most advanced microbicide candidates. Nevertheless, the majority of clinical trials has failed in HIV-1 patients. Nanotechnology offers suitable approaches to develop novel antiviral agents. Thereby, new nanosystems, such as carbosilane dendrimers, have been shown to be safe and effective compounds against HIV with great potential as topical microbicides. In addition, because most of the attempts to develop effective topical microbicides were unsuccessful, combinatorial strategies could be a valid approach when designing new microbicides. We evaluated various combinations of anionic carbosilane dendrimers with sulfated (G3-S16) and naphthyl sulfonated (G2-NF16) ended groups with different ARVs against HIV-1 infection. The G3-S16 and G2-NF16 dendrimers showed a synergistic or additive activity profile with zidovudine, efavirenz, and tenofovir in the majority of the combinations tested against the X4 and R5 tropic HIV-1 in cell lines, as well as in human primary cells. Therefore, the combination of ARVs and polyanionic carbosilane dendrimers enhances the antiviral potency of the individual compounds, and our findings support further clinical research on combinational approaches as potential microbicides to block the sexual transmission of HIV-1.