Multiple independent origins of a protease inhibitor resistance mutation in salvage therapy patients

With the continuing march of the AIDS epidemic and little hope for an effective vaccine in the near future, work to develop a topical strategy to prevent HIV infection is increasingly important. This stated, the track record of large scale "microbicide" trials has been disappointing with nonspecific inhibitors either failing to protect women from infection or even increasing HIV acquisition. Newer strategies that target directly the elements needed for viral entry into cells have shown promise in non-human primate models of HIV transmission and as these agents have not yet been broadly introduced in regions of highest HIV prevalence, they are particularly attractive for prophylaxis. We review here the agents that can block HIV cellular entry and that show promise as topical strategies or "virustats" to prevent mucosal transmission of HIV infection     

Parameters of human immunodeficiency virus infection of human cervical tissue and inhibition by vaginal virucides

Heterosexual transmission of human immunodeficiency virus (HIV) is the most frequent mode of infection worldwide. However, the immediate events between exposure to infectious virus and establishment of infection are still poorly understood. This study investigates parameters of HIV infection of human female genital tissue in vitro using an explant culture model. In particular, we investigated the role of the epithelium and virucidal agents in protection against HIV infection. We have demonstrated that the major target cells of infection reside below the genital epithelium, and thus HIV must cross this barrier to establish infection. Immune activation enhanced HIV infection of such subepithelial cells. Furthermore, our data suggest that genital epithelial cells were not susceptible to HIV infection, appear to play no part in the transfer of infectious virus across the epithelium, and thus may provide a barrier to infection. In addition, experiments using a panel of virucidal agents demonstrated differential efficiency to block HIV infection of subepithelial cells from partial to complete inhibition. This is the first demonstration that virucidal agents designed for topical vaginal use block HIV infection of genital tissue. Such agents have major implications for world health, as they will provide women with a mechanism of personal and covert protection from HIV infection.     

Modulation of apoptosis by HIV protease inhibitors

Advances in treatment have transformed the Human Immunodeficiency Virus (HIV) infection from a progressive and ultimately fatal disease to one that can be managed effectively by chronic suppressive antiretroviral therapy. The drugs now used to treat HIV infection not only inhibit viral replication but also have effects on cellular metabolism and homeostasis. Of particular interest to cellular immunologists, members of the HIV Protease Inhibitor (PI) class of antiretroviral agents possess intrinsic immunomodulatory and antiapoptotic properties. This review focuses on the development and use of PI together with their impact on HIV disease, immunity, and apoptosis.     

Interrogating the promise of long-acting HIV pre-exposure prophylaxis

Oral HIV pre-exposure prophylaxis (PrEP) is a well-established product that provides a safe and highly effective way for individuals to protect themselves against HIV infection. However, hopes of a significant reduction in HIV incidence have been disappointing because of low uptake, adherence challenges to a daily pill regimen, and consistently high discontinuation rates within 6 months of initiation. Long-acting agents have been long awaited for their potential to facilitate adherence and to offer a choice between PrEP products. As the first long-acting agents enter the market, with more poised to follow, questions around how to integrate long-acting agents into oral PrEP platforms, and what the potential advantages and pitfalls of this integration will be, now need to be considered.     

The cationic properties of SEVI underlie its ability to enhance human immunodeficiency virus infection

Human semen contains peptides capable of forming amyloid fibrils termed semen-derived enhancer of viral infection (SEVI) that can greatly increase human immunodeficiency virus (HIV) infection. While SEVI appears to enhance virion attachment to target cells, its underlying mechanism of action is unknown. We now demonstrate that the intrinsic positive charges of SEVI (pI = 10.21) facilitate virion attachment to and fusion with target cells. A mutant form of SEVI in which lysines and arginines are replaced with alanines retains the ability to form amyloid fibrils but is defective in binding virions and enhancing infection. In addition, the interaction of wild-type SEVI with virions and the ability of these fibrils to increase infection are abrogated in the presence of various polyanionic compounds. These anionic polymers also decrease the enhancement of HIV infection mediated by semen. These findings suggest that SEVI enhances viral infection by serving as a polycationic bridge that neutralizes the negative charge repulsion that exists between HIV virions and target cells. Combinations of agents that neutrale SEVI action and produce HIV virucidal effects are an attractive future direction for microbicide development.     

Altering cell death pathways as an approach to cure HIV infection

Recent cases of successful control of human immunodeficiency virus (HIV) by bone marrow transplant in combination with suppressive antiretroviral therapy (ART) and very early initiation of ART have provided proof of concept that HIV infection might now be cured. Current efforts focusing on gene therapy, boosting HIV-specific immunity, reducing inflammation and activation of latency have all been the subject of recent excellent reviews. We now propose an additional avenue of research towards a cure for HIV: targeting HIV apoptosis regulatory pathways. The central enigma of HIV disease is that HIV infection kills most of the CD4 T cells that it infects, but those cells that are spared subsequently become a latent reservoir for HIV against which current medications are ineffective. We propose that if strategies could be devised which would favor the death of all cells which HIV infects, or if all latently infected cells that release HIV would succumb to viral-induced cytotoxicity, then these approaches combined with effective ART to prevent spreading infection, would together result in a cure for HIV. This premise is supported by observations in other viral systems where the relationship between productive infection, apoptosis resistance, and the development of latency or persistence has been established. Therefore we propose that research focused at understanding the mechanisms by which HIV induces apoptosis of infected cells, and ways that some cells escape the pro-apoptotic effects of productive HIV infection are critical to devising novel and rational approaches to cure HIV infection.     

Synthesis, gp120 binding and anti-HIV activity of fatty acid esters of 1,1-linked disaccharides

Inspired by the anti-human immunodeficiency virus (HIV) activity of analogues of β-galactosylceramide (GalCer), a set of mono- and di-saccharide fatty acid esters were designed as GalCer mimetics and their binding to the V3 loop peptide of HIV-1 and anti-HIV activity evaluated. 1,1-linked Gal-Man and Glu-Man disaccharides with an ester on the Man subunit bound the V3 loop peptide and inhibited HIV infectivity in single round infection assays with the TZM-bl cell line. IC(50)'s were in the 50 μM range with no toxicity to the cells at concentrations up to 200 μM. These compounds appear to inhibit virus entry at early steps in viral infection since they were inactive if added post viral entry. Although these compounds were found to bind to the V3 loop peptide of gp120, it is not clear that this interaction is responsible for their anti-HIV activity because the relative binding affinity of closely related analogues did not correlate with their antiviral behavior. The low cytotoxicity of these 1,1-linked disaccharide fatty acid esters, combined with the easy accessibility to structurally diverse analogues make these molecules attractive leads for new topical anti-viral agents.     

Antimicrobial peptides from amphibian skin potently inhibit human immunodeficiency virus infection and transfer of virus from dendritic cells to T cells

Topical antimicrobicides hold great promise in reducing human immunodeficiency virus (HIV) transmission. Amphibian skin provides a rich source of broad-spectrum antimicrobial peptides including some that have antiviral activity. We tested 14 peptides derived from diverse amphibian species for the capacity to inhibit HIV infection. Three peptides (caerin 1.1, caerin 1.9, and maculatin 1.1) completely inhibited HIV infection of T cells within minutes of exposure to virus at concentrations that were not toxic to target cells. These peptides also suppressed infection by murine leukemia virus but not by reovirus, a structurally unrelated nonenveloped virus. Preincubation with peptides prevented viral fusion to target cells and disrupted the HIV envelope. Remarkably, these amphibian peptides also were highly effective in inhibiting the transfer of HIV by dendritic cells (DCs) to T cells, even when DCs were transiently exposed to peptides 8 h after virus capture. These data suggest that amphibian-derived peptides can access DC-sequestered HIV and destroy the virus before it can be transferred to T cells. Thus, amphibian-derived antimicrobial peptides show promise as topical inhibitors of mucosal HIV transmission and provide novel tools to understand the complex biology of HIV capture by DCs.     

Some recent results on HIV pathogenesis with implications for therapy and vaccines.

In the third decade of AIDS research, we are still facing most of the challenges that emerged when the disease was characterized. While therapeutic approaches to control HIV infection are available in developed countries, novel principles to combat and prevent HIV infection are needed, due to the high cost and the negative effects of currently available drugs. In addition, it is now clear that this disease cannot be eliminated without a vaccine, which appears to be the only possible weapon to combat HIV in developing countries. We have focused on two approaches to fight HIV; one based on select members of a family of proteins, i.e. beta-chemokines, that we have show to interfere with HIV entry and replication, and another centered on a viral protein, HIV-1 Tat, that is crucially involved in HIV regulation and in some of the pathogenic manifestations of HIV infection. Studies from others and ourselves have shown that these two approaches are now ready to the leave experimental bench and move into clinical testing.     

The cytokine network of acute HIV infection: a promising target for vaccines and therapy to reduce viral set-point?

Cytokines play a central role in the pathogenesis of many diseases, including HIV infection. However, the role of the cytokine network in early HIV infection is only now starting to be elucidated. A number of studies conducted in recent years have indicated that cytokines of the acute/early stages of HIV and SIV infection can impact viral set-point months later, and this is of critical importance since viral set-point during chronic HIV infection affects virus transmission and disease progression. This raises the question whether modulating the cytokine environment during acute/early HIV infection can be a target for novel approaches to develop a vaccine and therapeutics. In this review we focus on the kinetics and function of cytokines during acute HIV and SIV infection and how these may impact viral set-point. We also discuss unresolved questions that are essential for our understanding of the role of acute infection cytokines in HIV infection and that, if answered, may suggest novel therapeutic and vaccine strategies to control the worldwide HIV pandemic.     

Minocycline Down-Regulates Topical Mucosal Inflammation during the Application of Microbicide Candidates

An effective anti-human immunodeficiency virus-1 (HIV-1) microbicide should exert its action in the absence of causing aberrant activation of topical immunity that will increase the risk of HIV acquisition. In the present study, we demonstrated that the vaginal application of cellulose sulfate (CS) gel induced topical mucosal inflammatory responses; the addition of minocycline to CS gel could significantly attenuate the inflammation in a mice model. The combined gel of CS plus minocycline not only reduced the production of inflammatory cytokines in cervicovaginal lavages (CVLs), also down-regulated the activation of CD4+ T cells and the recruitment of other immune cells including HIV target cells into vaginal tissues. Furthermore, an In vitro HIV-1 pseudovirus infection inhibition assay showed that the combined gel decreased the infection efficacy of different subtypes of HIV-1 pseudoviruses compared with that of CS gel alone. These results implicate that minocycline could be integrated into microbicide formulation to suppress the aberrant activation of topical mucosal immunity and enhance the safety profile during the application of microbicides.     

Novel Antiviral Agents Targeting HIV Entry and Transmission

Studies of the mechanism of HIV entry and transmission have identified multiple new targets for drug development. A range of inhibitors have demonstrated potent antiretroviral activity by interfering with CD4-gp120 interaction,coreceptor binding or viral-cell fusion in preclinical and clinical studies. One of these agents,fusion inhibitor enfuvirtide,is already in clinical use. Here we review the progress in the development of specific entry inhibitors as novel therapeutics. The potential of entry inhibitors as topical microbicides to block HIV transmission is also discussed.     

Infection of rhesus monkeys with topical instillation of simian immunodeficiency virus (SIV)B670 into the conjunctival sac

We tested the ability of SIV to cause local and systemic infection in three rhesus monkeys after topical instillation of cell-free virus into the conjunctival cul-de-sac. Conjunctivitis or other signs of infection were monitored after inoculation. Conjunctiva were swabbed for virus culture and biopsied for PCR. Changes in lymphocyte subsets, seroconversion, antigenemia, and virus isolation from PBL were assessed systemically postinoculation. Viral DNA was detected in conjunctival biopsy by PCR in one of three animals that later developed systemic infection. The other two animals remained uninfected. These data demonstrate that the conjunctiva is a route by which SIV (and perhaps HIV) may cause systemic infection.     

Antifungal Penetration into the Nail and New Topicals for Onychomycosis

Onychomycosis is a common and difficult to treat infection, owing predominately to the limited penetration of topical drugs to the site of infection. Systemic drugs are not an option for all patients due to adverse events and drug-drug interactions. In this article, we review the nail penetration and clinical efficacy data of topical drugs, including older agents such as ciclopirox and amorolfine, as well as the newer agents, efinaconazole and tavaborole. Additionally, we describe some unresolved questions in the management of onychomycosis.     

PSC-RANTES blocks R5 human immunodeficiency virus infection of Langerhans cells isolated from individuals with a variety of CCR5 diplotypes

Topical microbicides that effectively block interactions between CCR5(+) immature Langerhans cells (LC) residing within genital epithelia and R5 human immunodeficiency virus (HIV) may decrease sexual transmission of HIV. Here, we investigated the ability of synthetic RANTES analogues (AOP-, NNY-, and PSC-RANTES) to block R5 HIV infection of human immature LC by using a skin explant model. In initial experiments using activated peripheral blood mononuclear cells, each analogue compound demonstrated marked antiviral activity against two R5 HIV isolates. Next, we found that 20-min preincubation of skin explants with each RANTES analogue blocked R5 HIV infection of LC in a dose-dependent manner (1 to 100 nM) and that PSC-RANTES was the most potent of these compounds. Similarly, preincubation of LC with each analogue was able to block LC-mediated infection of cocultured CD4(+) T cells. Competition experiments between primary R5 and X4 HIV isolates showed blocking of R5 HIV by PSC-RANTES and no evidence of increased propagation of X4 HIV, data that are consistent with the specificity of PSC-RANTES for CCR5 and the CCR5(+) CXCR4(-) phenotype of immature LC. Finally, when CCR5 genetic polymorphism data were integrated with results from the in vitro LC infection studies, PSC-RANTES was found to be equally effective in inhibiting R5 HIV in LC isolated from individuals with CCR5 diplotypes known to be associated with low, intermediate, and high cell surface levels of CCR5. In summary, PSC-RANTES is a potent inhibitor of R5 HIV infection in immature LC, suggesting that it may be useful as a topical microbicide to block sexual transmission of HIV.     

Dynein light chain 1 peptide inhibits human immunodeficiency virus infection in eukaryotic cells

Human immunodeficiency virus (HIV) uses kinases such as Pak1 and macropinocytosis for a productive infection. Recently dynein light chain 1 (DLC1), a component of the dynein motor, was identified as a Pak1 substrate and interacted with the C-terminal region of DLC1 (aa 61-89). The dynein motor is implicated in retrograde transport, also of HIV, to the nucleus. It is known that DLC1 is important in macropinocytosis, and anti-dynein antibodies inhibit a productive HIV infection. Here, we show that in Hela-β-gal cells macropinocytosis was effectively blocked by a peptide spanning the C-terminal 19 amino acids of DLC1. We also found that the DLC1 peptide was capable of inhibiting the early entry steps of HIV, and the DLC1 peptide efficiently inhibited a productive HIV infection, and cooperated with the anti-HIV activity of CD4 antibodies. Taken together, the potentially therapeutic DLC1 peptide represents an interesting class of HIV inhibitors, targeting an essential cellular component for HIV infection. Our findings raise the possibility that the use of a DLC1 peptide in combination with currently used anti-HIV agents, might offer additional arsenal against HIV infection in human cells.     

Mechanism for HIV invasion via skin or mucosa

Sexual transmission of HIV is the most common mode of infection in the global HIV epidemic. In the absence of an effective vaccine, there is an urgent need for additional strategies to prevent new HIV infections. An emerging body of evidence now indicates that Langerhans cells (LC) are initial cellular targets in the sexual transmission of HIV, and CD4- and CCR5-mediated infection of LC plays a crucial role in virus dissemination. I focus on the recent advances regarding the cellular events that may occur during heterosexual transmission of HIV.     

The introduction of the concept of Harm Reduction in the city of Cherkassy

The introduction of the concept of Harm Reduction into the practical work of the narcological survive confidence relations with injecting drug users were established, which resulted in the possibility to carry out information and educational, as well as preventive work. In addition, there occurred changes in public opinion with respect to the problems of drug addiction (a drug addict was now regarded as a sick person) and AIDS (HIV infection was considered to be a problem, topical for wide strata of the population). The creation of a dedicated team comprising medical personnel, psychologists, representatives of the clergy, volunteers from drug addicts contributed to successes in this work. The work on the correction of negative manifestations, carried out by the organs of law protection, also contributed to the creation of balance between the strategy of Harm Reduction and the strategy of the reduction of need in narcotic drugs.     

Topical oestrogen keratinises the human foreskin and may help prevent HIV infection

With the growing incidence of HIV, there is a desperate need to develop simple, cheap and effective new ways of preventing HIV infection. Male circumcision reduces the risk of infection by about 60%, probably because of the removal of the Langerhans cells which are abundant in the inner foreskin and are the primary route by which HIV enters the penis. Langerhans cells form a vital part of the body's natural defence against HIV and only cause infection when they are exposed to high levels of HIV virions. Rather than removing this natural defence mechanism by circumcision, it may be better to enhance it by thickening the layer of keratin overlying the Langerhans cells, thereby reducing the viral load to which they are exposed. We have investigated the ability of topically administered oestrogen to induce keratinization of the epithelium of the inner foreskin. Histochemically, the whole of the foreskin is richly supplied with oestrogen receptors. The epithelium of the inner foreskin, like the vagina, responds within 24 hours to the topical administration of oestriol by keratinization, and the response persists for at least 5 days after the cessation of the treatment. Oestriol, a cheap, readily available natural oestrogen metabolite, rapidly keratinizes the inner foreskin, the site of HIV entry into the penis. This thickening of the overlying protective layer of keratin should reduce the exposure of the underlying Langerhans cells to HIV virions. This simple treatment could become an adjunct or alternative to surgical circumcision for reducing the incidence of HIV infection in men.