Inhibiting sexual transmission of HIV-1 infection

Interferon-β induced in female genital epithelium by HIV-1 glycoprotein 120 via Toll-like-receptor 2 pathway acts to protect the mucosal barrier

More than 40% of HIV infections occur via female reproductive tract (FRT) through heterosexual transmission. Epithelial cells that line the female genital mucosa are the first line of defense against HIV-1 and other sexually transmitted pathogens. These sentient cells recognize and respond to external stimuli by induction of a range of carefully balanced innate immune responses. Previously, we have shown that in response to HIV-1 gp120, the genital epithelial cells (GECs) from upper reproductive tract induce an inflammatory response that may facilitate HIV-1 translocation and infection. In this study, we report that the endometrial and endocervical GECs simultaneously induce biologically active interferon-β (IFNβ) antiviral responses following exposure to HIV-1 that act to protect the epithelial tight junction barrier. The innate antiviral response was directly induced by HIV-1 envelope glycoprotein gp120 and addition of gp120 neutralizing antibody inhibited IFNβ production. Interferon-β was induced by gp120 in upper GECs through Toll-like receptor 2 signaling and required presence of heparan sulfate on epithelial cell surface. The induction of IFNβ was dependent upon activation of transcription factor IRF3 (interferon regulatory factor 3). The IFNβ was biologically active, had a protective effect on epithelial tight junction barrier and was able to inhibit HIV-1 infection in TZM-bl indicator cells and HIV-1 replication in T cells. This is the first report that recognition of HIV-1 by upper GECs leads to induction of innate antiviral pathways. This could explain the overall low infectivity of HIV-1 in the FRT and could be exploited for HIV-1 prophylaxis.

An update of the recombinant protein expression systems of Cyanovirin-N and challenges of preclinical development

Introduction: Human immunodeficiency virus (HIV) is a debilitating challenge and concern worldwide. Accessibility to highly active antiretroviral drugs is little or none for developing countries. Production of cost-effective microbicides to prevent the infection with HIV is a requirement. Cyanovirin-N (CVN) is known as a promising cyanobacterial lectin, capable of inhibiting the HIV cell entry in a highly specific manner. Methods: This review article presents an overview of attempts conducted on different expression systems for the recombinant production of CVN. We have also assessed the potential of the final recombinant product, as an effective anti-HIV microbicide, comparing prokaryotic and eukaryotic expression systems. Results: Artificial production of CVN is a challenging task because the desirable anti-HIV activity (CVN-gp120 interaction) depends on the correct formation of disulfide bonds during recombinant production. Thus, inexpensive and functional production of rCVN requires an effective expression system which must be found among the bacteria, yeast, and transgenic plants, for the subsequent satisfying medical application. Moreover, the strong anti-HIV potential of CVN in trace concentrations (micromolar to picomolar) was reported for the in vitro and in vivo tests. Conclusion: To produce pharmaceutically effective CVN, we first need to identify the best expression system, with Escherichia coli, Pichia pastoris , Lactic acid bacteria and transgenic plants being possible candidates. For this reason, heterologous production of this valuable protein is a serious challenge. Since different obstacles influence clinical trials on microbicides in the field of HIV prevention, these items should be considered for evaluating the CVN activity in pre-clinical and clinical studies.

Localized cyclical variations in immunoproteins in the female genital tract and the implications on the design and assessment of mucosal infection and therapies

PROBLEM

Fluctuating hormones regulate reproductive processes in the female genital tract. Consequent changes in the local immunological environment are likely to affect cellular interaction with infectious agents and the assessment of therapies that target mucosal infections.

METHOD OF STUDY

We compared Softcup and Weck-Cel sampling protocols and assessed the changes in the concentrations of 39 soluble proteins with menstrual cycle progression in the mucosal and peripheral compartments.

RESULTS

We demonstrate that the mucosal immunological profile is distinct from serum with inflammatory and migratory signatures that are localized throughout the cycle. The analytes highlighted in the mucosal compartment were generally highest at the follicular phase with a tendency to fall as the cycle progressed through ovulation to the luteal phase.

CONCLUSION

Our results underscore the need to consider these localized cyclical differences in studies aimed at assessing the outcome of disease and the efficacy of mucosal vaccines and other therapies.

In vitro models for deciphering the mechanisms underlying the sexual transmission of viruses at the mucosal level

Sexually transmitted viruses infect the genital and colorectal mucosa of the partner exposed to contaminated genital secretions through a wide range of mechanisms, dictated in part by the organization of the mucosa. Because understanding the modes of entry into the organism of viruses transmitted through sexual intercourse is a necessary prerequisite to the design of treatments to block those infections, in vitro modeling of the transmission is essential. The aim of this review is to present the models and methodologies available for the in vitro study of the interactions between viruses and mucosal tissue and for the preclinical evaluation of antiviral compounds, and to point out their advantages and limitations according to the question being studied.

An update of the recombinant protein expression systems of Cyanovirin-N and challenges of preclinical development

Introduction: Human immunodeficiency virus (HIV) is a debilitating challenge and concern worldwide. Accessibility to highly active antiretroviral drugs is little or none for developing countries. Production of cost-effective microbicides to prevent the infection with HIV is a requirement. Cyanovirin-N (CVN) is known as a promising cyanobacterial lectin, capable of inhibiting the HIV cell entry in a highly specific manner.

Methods: This review article presents an overview of attempts conducted on different expression systems for the recombinant production of CVN. We have also assessed the potential of the final recombinant product, as an effective anti-HIV microbicide, comparing prokaryotic and eukaryotic expression systems.

Results: Artificial production of CVN is a challenging task because the desirable anti-HIV activity (CVN-gp120 interaction) depends on the correct formation of disulfide bonds during recombinant production. Thus, inexpensive and functional production of rCVN requires an effective expression system which must be found among the bacteria, yeast, and transgenic plants, for the subsequent satisfying medical application. Moreover, the strong anti-HIV potential of CVN in trace concentrations (micromolar to picomolar) was reported for the in vitro and in vivo tests.

Conclusion: To produce pharmaceutically effective CVN, we first need to identify the best expression system, with Escherichia coli, Pichia pastoris , Lactic acid bacteria and transgenic plants being possible candidates. For this reason, heterologous production of this valuable protein is a serious challenge. Since different obstacles influence clinical trials on microbicides in the field of HIV prevention, these items should be considered for evaluating the CVN activity in pre-clinical and clinical studies.

Higher viral load and genetic diversity of HIV-1 in seminal compartments than in blood of seven Chinese men who have sex with men and have early HIV-1 infection

To date, there have been no reports characterizing HIV-1 in the semen of Chinese men who have sex with men (MSM) with early infection. In this study, genetic diversity and viral load of HIV-1 in the seminal compartments and blood of Chinese MSM with early HIV-1 infection were examined. Viral load and genetic diversity of HIV-1 in paired samples of semen and blood were analyzed in seven MSM with early HIV-1 infection. HIV-1 RNA and DNA were quantitated by real-time PCR assays. Through sequencing the C2-V5 region of the HIV-1 env gene, the HIV-1 genotype and genetic diversity based on V3 loop amino acid sequences were determined by using Geno2pheno and PSSM programs co-receptor usage. It was found that there was more HIV-1 RNA in seminal plasma than in blood plasma and total, and more 2-LTR circular and integrated HIV-1 DNA in seminal cells than in peripheral blood mononuclear cells from all seven patients with early HIV-infection. There was also greater HIV-1 genetic diversity in seminal than in blood compartments. HIV-1 in plasma displayed higher genetic diversity than in cells from the blood and semen. In addition, V3 loop central motifs, which present some key neutralizing antibody epitopes, varied between blood and semen. Thus, virological characteristics in semen may be more representative when evaluating risk of transmission in persons with early HIV infection.

Donor-Recipient Identification in Para- and Poly-phyletic Trees Under Alternative HIV-1 Transmission Hypotheses Using Approximate Bayesian Computation

Diversity of the founding population of Human Immunodeficiency Virus Type 1 (HIV-1) transmissions raises many important biological, clinical, and epidemiological issues. In up to 40% of sexual infections, there is clear evidence for multiple founding variants, which can influence the efficacy of putative prevention methods, and the reconstruction of epidemiologic histories. To infer who-infected-whom, and to compute the probability of alternative transmission scenarios while explicitly taking phylogenetic uncertainty into account, we created an approximate Bayesian computation (ABC) method based on a set of statistics measuring phylogenetic topology, branch lengths, and genetic diversity. We applied our method to a suspected heterosexual transmission case involving three individuals, showing a complex monophyletic-paraphyletic-polyphyletic phylogenetic topology. We detected that seven phylogenetic lineages had been transmitted between two of the individuals based on the available samples, implying that many more unsampled lineages had also been transmitted. Testing whether the lineages had been transmitted at one time or over some length of time suggested that an ongoing superinfection process over several years was most likely. While one individual was found unlinked to the other two, surprisingly, when evaluating two competing epidemiological priors, the donor of the two that did infect each other was not identified by the host root-label, and was also not the primary suspect in that transmission. This highlights that it is important to take epidemiological information into account when analyzing support for one transmission hypothesis over another, as results may be nonintuitive and sensitive to details about sampling dates relative to possible infection dates. Our study provides a formal inference framework to include information on infection and sampling times, and to investigate ancestral node-label states, transmission direction, transmitted genetic diversity, and frequency of transmission.

Antibody gene transfer with adeno-associated viral vectors as a method for HIV prevention

Broadly neutralizing antibodies (bNAbs) against human immunodeficiency virus (HIV) show great promise in HIV prevention as they are capable of potently neutralizing a considerable breadth of genetically diverse strains. Passive transfer of monoclonal bNAb proteins can confer protection in animal models of HIV infection at modest concentrations, inspiring efforts to develop an HIV vaccine capable of eliciting bNAb responses. However, these antibodies demonstrate high degrees of somatic mutation and other unique characteristics that may hinder the ability of conventional approaches to consistently and effectively produce bNAb analogs. As an alternative strategy, we and others have proposed vector-mediated gene transfer to generate long-term, systemic production of bNAbs in the absence of immunization. Herein, we review the use of adeno-associated virus (AAV) vectors for delivery of HIV bNAbs and antibody-like proteins and summarize both the advantages and disadvantages of this strategy as a method for HIV prevention.

Broadly neutralizing antibodies suppress post-transcytosis HIV-1 infectivity

Broadly neutralizing antibodies (bNAbs) offer promising opportunities for preventing HIV-1 infection in humans. Immunoprophylaxis with potent bNAbs efficiently protects non-human primates from mucosal transmission even after repeated challenges. However, the precise mechanisms of bNAb-mediated viral inhibition in mucosal tissues are currently unknown. Here, we show that immunoglobulin (Ig)G and IgA bNAbs do not interfere with the endocytic transport of HIV-1 across epithelial cells, a process referred to as transcytosis. Instead, both viruses and antibodies are translocated to the basal pole of epithelial cells, possibly in the form of an immune complex. Importantly, as opposed to free virions, viral particles bound by bNAbs are no longer infectious after transepithelial transit. Post-transcytosis neutralization activity of bNAbs displays comparable inhibitory concentrations as those measured in classical neutralization assays. Thus, bNAbs do not block the transport of incoming HIV-1 viruses across the mucosal epithelium but rather neutralize the transcytosed virions, highlighting their efficient prophylactic and protective activity in vivo.

Colposcopic imaging using visible-light optical coherence tomography

High-resolution colposcopic optical coherence tomography (OCT) provides key anatomical measures, such as thickness and minor traumatic injury of vaginal epithelium, of the female reproductive tract noninvasively. This information can be helpful in both fundamental investigations in animal models and disease screenings in humans. We present a fiber-based visible-light OCT and two probe designs for colposcopic application. One probe conducts circular scanning using a DC motor, and the other probe is capable of three-dimensional imaging over a 4.6 × 4.6 - mm 2 area using a pair of galvo scanners. Using this colposcopic vis-OCT with both probes, we acquired high-resolution images from whole isolated macaque vaginal samples and identified biopsy lesions.

Cyanobacterial lectins characteristics and their role as antiviral agents

Lectins are ubiquitous proteins/glycoproteins of non-immune origin that bind reversibly to carbohydrates in non-covalent and highly specific manner. These lectin-glycan interactions could be exploited for establishment of novel therapeutics, targeting the adherence stage of viruses and thus helpful in eliminating wide spread viral infections. Here the review focuses on the haemagglutination activity, carbohydrate specificity and characteristics of cyanobacterial lectins. Cyanobacterial lectins exhibiting high specificity towards mannose or complex glycans have potential role as anti-viral agents. Prospective role of cyanobacterial lectins in targeting various diseases of worldwide concern such as HIV, hepatitis, herpes, influenza and ebola viruses has been discussed extensively. The review also lays emphasis on recent studies involving structural analysis of glycan-lectin interactions which in turn influence their mechanism of action. Altogether, the promising approach of these cyanobacterial lectins provides insight into their use as antiviral agents.

Immunological function of Langerhans cells in HIV infection

BACKGROUND

Langerhans cells (LCs) are one of the initial target cells for HIV following sexual exposure and they are productively infected by HIV. HIV-infected LCs migrate to the draining lymph nodes (dLNs) and transmit the virus to CD4⁺ T cells, leading to the dissemination of HIV. In contrast with the role of LCs in initial HIV acquisition, little is known about the modulation of immune responses by HIV-infected LCs.

OBJECTIVE

We aimed to elucidate the induction of HIV-specific CD8⁺ T cells and regulatory T cells (Tregs), both of which play important roles in regulating the progression of HIV infection.

METHODS

We examined the inducibility of HLA-A*0201 restricted HIV-specific CD8⁺ T cells and Tregs by HIV-primed LCs or HIV-primed dendritic cells (DCs) as a control.

RESULTS

The number of HIV-specific CD8⁺ T cells induced by HIV-primed monocyte-derived LCs (mLCs) was significantly higher than that by HIV-primed monocyte-derived DCs (mDCs). Additionally, HIV-specific CD8⁺ T cells induced by HIV-primed mLCs produced more IFN-γ than HIV-nonspecific CD8⁺ T cells. HIV-primed human epidermal LCs also induced IFN-γ-producing HIV-specific CD8⁺ T cells. As for the induction of Tregs, HIV-primed mLCs and human epidermal LCs significantly impaired the induction of FoxP3^hiCD45RA^- effector Tregs than HIV-unprimed mLCs and human epidermal LCs.

CONCLUSIONS

HIV-primed LCs trigger beneficial immune responses against HIV infection through the increased induction of HIV-specific CD8⁺ T cells and the decreased induction of effector Tregs in the initial phase of HIV infection, thereby contributing to the prolonged onset of AIDS.

Prevalence and risk factors associated with female anal sex in the context of HIV/AIDS in the selected districts of Tanzania

BACKGROUND

Female anal sex is a receptive type of sexual practice among heterosexual couples where the penis is inserted into the anus of a female partner. In the Western world, a number of studies and interventions have been carried out on anal sex among men due to its potential risks to HIV transmission. In African countries, including Tanzania, there is dearth of information on the risks inherent in practices associated with female anal sex in the general population. The objective of this study was to determine the prevalence and risk factors associated with female anal sex in fuelling HIV transmission in selected districts of Tanzania.

METHODS

This study was conducted in four districts of Tanzania of Kinondoni, Tanga Urban, Makete and Siha. Both quantitative and qualitative methods i.e. household interviews and focus group discussions were employed in data collection. Study participants included community members of aged 15 and above such as heads of the household, adolescents, bar workers and commercial sex workers.

FINDINGS

A total of 903 individuals were interviewed, 60.6% of whom were females. When respondents were asked to indicate whether they had ever been tempted to practise FAS, 167 (18.5%) reported to have been tempted in the past 12 months. Of these, 44 (26.3%) respondents had at least practised FAS. Risky practices associated with FAS were forced sex, multiple partners, frequency of engaging in FAS, low use of condoms during FAS, low rates of HIV testing among partakers, poor perception of the risks to acquire HIV through FAS and use of lubricants.

CONCLUSIONS

In this population, the frequency of FAS practice was rather low. And yet, FAS practice attendant risk factors are likely to exacerbate HIV transmission. As such, there is a need for further exploratory studies to determine and document drivers of FAS. In addition, public health education should be provided with regard to the risks of contracting HIV associated with FAS practices.

Zinc reduces epithelial barrier compromise induced by human seminal plasma

Human semen has the potential to modulate the epithelial mucosal tissues it contacts, as seminal plasma (SP) is recognized to contain both pro- and anti-barrier components, yet its effects on epithelial barrier function are largely unknown. We addressed the role of human SP when exposed to the basal-lateral epithelial surface, a situation that would occur clinically with prior mechanical or disease-related injury of the human epithelial mucosal cell layers in contact with semen. The action of SP on claudins-2, -4, -5, and -7 expression, as well as on a target epithelium whose basolateral surface has been made accessible to SP, showed upregulation of claudins-4 and -5 in CACO-2 human epithelial cell layers, despite broad variance in SP-induced modulation of transepithelial electrical resistance and mannitol permeability. Upregulation of claudin-2 by SP also exhibited such variance by SP sample. We characterize individual effects on CACO-2 barrier function of nine factors known to be present abundantly in seminal plasma (zinc, EGF, citrate, spermine, fructose, urea, TGF, histone, inflammatory cytokines) to establish that zinc, spermine and fructose had significant potential to raise CACO-2 transepithelial resistance, whereas inflammatory cytokines and EGF decreased this measure of barrier function. The role of zinc as a dominant factor in determining higher levels of transepithelial resistance and lower levels of paracellular leak were confirmed by zinc chelation and exogenous zinc addition. As expected, SP presentation to the basolateral cell surface also caused a very dramatic yet transient elevation of pErk levels. Results suggest that increased zinc content in SP can compete against the barrier-compromising effect of negative modulators in SP when SP gains access to that epithelium's basolateral surface. Prophylactic elevation of zinc in an epithelial cell layer prior to contact by SP may help to protect an epithelial barrier from invasion by SP-containing STD microbial pathogens such as HPV or HIV.

5-Hydroxytyrosol inhibits HIV-1 replication in primary cells of the lower and upper female reproductive tract

We investigated the potential anti-HIV-1 activity of the candidate microbicide 5-hydroxytyrosol (5-HT) both in primary human cervical tissue explants (CTE), established from tissues of women undergoing histerectomy, and in endometrium-associated leukocytes (EAL). CTE were exposed to either the laboratory-adapted HIV-1_BaL or to primary viral isolates in the presence or absence of 5-HT or 3TC/lamivudine as control and were then monitored for 12 days in terms of HIV-1 p24 Gag antigen production in culture supernatants. HIV-1_BaL replication was also evaluated in EAL by reverse transcriptase (RT) activity. The highest nontoxic concentrations of 5-HT (200 and 100 μM for CTE and EAL, respectively) exerted a significant inhibitory effect on virus replication in both primary cell systems. 5-HT did not cause significant alterations of the activation profile of CD4⁺ and CD8⁺ T cells, in terms of CD4, CCR5, CD25, CD69 and HLA-DR expression, although it decreased the percentage of CD38⁺CD8⁺ T cells. Thus, 5-HT deserves consideration as a potential candidate microbicide for preventing HIV-1 transmission or curtailing its replication in the female reproductive tract.

Application of nanotechnology for the development of microbicides

The vaginal route is increasingly being considered for both local and systemic delivery of drugs, especially those unsuitable for oral administration. One of the opportunities offered by this route but yet to be fully utilised is the administration of microbicides. Microbicides have an unprecedented potential for mitigating the global burden from HIV infection as heterosexual contact accounts for most of the new infections occurring in sub-Saharan Africa, the region with the highest prevalent rates. Decades of efforts and massive investment of resources into developing an ideal microbicide have resulted in disappointing outcomes, as attested by several clinical trials assessing the suitability of those formulated so far. The highly complex and multi-level biochemical interactions that must occur among the virus, host cells and the drug for transmission to be halted means that a less sophisticated approach to formulating a microbicide e.g. conventional gels, etc may have to give way for a different formulation approach. Nanotechnology has been identified to offer prospects for fabricating structures with high capability of disrupting HIV transmission. In this review, predominant challenges seen in microbicide development have been highlighted and possible ways of surmounting them suggested. Furthermore, formulations utilising some of these highly promising nanostructures such as liposomes, nanofibres and nanoparticles have been discussed. A perspective on how a tripartite collaboration among governments and their agencies, the pharmaceutical industry and academic scientists to facilitate the development of an ideal microbicide in a timely manner has also been briefly deliberated.

M48U1 and Tenofovir combination synergistically inhibits HIV infection in activated PBMCs and human cervicovaginal histocultures

Microbicides are considered a promising strategy for preventing human immunodeficiency virus (HIV-1) transmission and disease. In this report, we first analyzed the antiviral activity of the miniCD4 M48U1 peptide formulated in hydroxyethylcellulose (HEC) hydrogel in activated peripheral blood mononuclear cells (PBMCs) infected with R5- and X4–tropic HIV-1 strains. The results demonstrate that M48U1 prevented infection by several HIV-1 strains including laboratory strains, and HIV-1 subtype B and C strains isolated from the activated PBMCs of patients. M48U1 also inhibited infection by two HIV-1 transmitted/founder infectious molecular clones (pREJO.c/2864 and pTHRO.c/2626). In addition, M48U1 was administered in association with tenofovir, and these two antiretroviral drugs synergistically inhibited HIV-1 infection. In the next series of experiments, we tested M48U1 alone or in combination with tenofovir in HEC hydrogel with an organ-like structure mimicking human cervicovaginal tissue. We demonstrated a strong antiviral effect in absence of significant tissue toxicity. Together, these results indicate that co-treatment with M48U1 plus tenofovir is an effective antiviral strategy that may be used as a new topical microbicide to prevent HIV-1 transmission.

Visualization of X4- and R5-Tropic HIV-1 Viruses Expressing Fluorescent Proteins in Human Endometrial Cells: Application to Tropism Study

Worldwide most HIV infections occur through heterosexual transmission, involving complex interactions of cell-free and cell-associated particles with cells of the female genital tract mucosa. The ability of HIV-1 to "infect" epithelial cells remains poorly understood. To address this question, replicative-competent chimeric constructs expressing fluorescent proteins and harboring the envelope of X4- or R5-tropic HIV-1 strains were used to "infect" endometrial HEC1-A cells. The virus-cell interactions were visualized using confocal microscopy (CM) at various times post infection. Combined with quantification of viral RNA and total HIV DNA in infected cells, the CM pictures suggest that epithelial cells do not support a complete viral replication cycle: X4-tropic viruses are imported into the nucleus in a non-productive way, whereas R5-tropic viruses transit through the cytoplasm without replication and are preferentially transmitted to susceptible activated peripheral blood mononuclear cells. Within the limit of experiments conducted in vitro on a continued cell line, these results indicate that the epithelial mucosa may participate to the selection of HIV-1 strains at the mucosal level.

Stimuli-sensitive thiolated hyaluronic acid based nanofibers: synthesis, preclinical safety and in vitro anti-HIV activity

AIM

To develop a seminal enzyme bioresponsive, mucoadhesive nanofibers (NFs) as safe and effective nanocarriers for the prevention of HIV vaginal transmission.

METHODS

A novel thiolated hyaluronic acid (HA-SH) polymer was synthesized to fabricate tenofovir (TFV)-loaded electrospun NFs (HA-SH-NFs) and characterized in vitro/in vivo.

RESULTS

A triggered drug release (87% w/w) from the engineered HA-SH-NFs (mean diameter ∼75 nm) occured within 1 h under the influence of seminal hyaluronidase enzyme. HA-SH-NFs were noncytotoxic, induced no damage on the C57BL/6 mice genital-tract and other organs. No significant CD45 cell-infiltration and changes in cytokines level in cervicovaginal tissues were observed. HA-SH-NFs significantly enhanced both TFV retention and bioavailability in vaginal tissue compared with the 1% TFV-gel. The anti-HIV activity of TFV (on pseudotyped virus followed by luciferase assay) was not adversely affected by the electrospinning process.

CONCLUSION

HA-SH-NFs developed in this study could potentially serve as a safe nanotemplate for topical intravaginal delivery of HIV/AIDS microbicides.

Enhanced binding of antibodies generated during chronic HIV infection to mucus component MUC16

Transmission of HIV across mucosal barriers accounts for the majority of HIV infections worldwide. Thus, efforts aimed at enhancing protective immunity at these sites are a top priority, including increasing virus-specific antibodies (Abs) and antiviral activity at mucosal sites. Mucin proteins, including the largest cell-associated mucin, mucin 16 (MUC16), help form mucus to provide a physical barrier to incoming pathogens. Here, we describe a natural interaction between Abs and MUC16 that is enhanced in specific disease settings such as chronic HIV infection. Binding to MUC16 was independent of IgG subclass, but strongly associated with shorter Ab glycan profiles, with agalactosylated (G0) Abs demonstrating the highest binding to MUC16. Binding of Abs to epithelial cells was diminished following MUC16 knockdown, and the MUC16 N-linked glycans were critical for binding. Further, agalactosylated VRC01 captured HIV more efficiently in MUC16. These data point to a novel opportunity to enrich Abs at mucosal sites by targeting Abs to MUC16 through changes in Fc glycosylation, potentially blocking viral movement and sequestering the virus far from the epithelial border. Thus, next-generation vaccines or monoclonal therapeutics may enhance protective immunity by tuning Ab glycosylation to promote the enrichment of Abs at mucosal barriers.

CD4-mimetic sulfopeptide conjugates display sub-nanomolar anti-HIV-1 activity and protect macaques against a SHIV162P3 vaginal challenge

The CD4 and the cryptic coreceptor binding sites of the HIV-1 envelope glycoprotein are key to viral attachment and entry. We developed new molecules comprising a CD4 mimetic peptide linked to anionic compounds (mCD4.1-HS₁₂ and mCD4.1-PS1), that block the CD4-gp120 interaction and simultaneously induce the exposure of the cryptic coreceptor binding site, rendering it accessible to HS₁₂- or PS1- mediated inhibition. Using a cynomolgus macaque model of vaginal challenge with SHIV162P3, we report that mCD4.1-PS1, formulated into a hydroxyethyl-cellulose gel provides 83% protection (5/6 animals). We next engineered the mCD4 moiety of the compound, giving rise to mCD4.2 and mCD4.3 that, when conjugated to PS1, inhibited cell-free and cell-associated HIV-1 with particularly low IC₅₀, in the nM to pM range, including some viral strains that were resistant to the parent molecule mCD4.1. These chemically defined molecules, which target major sites of vulnerability of gp120, are stable for at least 48 hours in conditions replicating the vaginal milieu (37 °C, pH 4.5). They efficiently mimic several large gp120 ligands, including CD4, coreceptor or neutralizing antibodies, to which their efficacy compares very favorably, despite a molecular mass reduced to 5500 Da. Together, these results support the development of such molecules as potential microbicides.

New Biomedical Technologies and Strategies for Prevention of HIV and Other Sexually Transmitted Infections

Sexually transmitted infections remain to be of public health concern in many developing countries. Their control is important, considering the high incidence of acute infections, complications and sequelae, and their socioeconomic impact. This article discusses the new biomedical technologies and strategies for the prevention of HIV and other sexually transmitted infections.

Relationship of Estimated SHIV Acquisition Time Points During the Menstrual Cycle and Thinning of Vaginal Epithelial Layers in Pigtail Macaques

BACKGROUND

HIV acquisition in the female genital tract remains incompletely understood. Quantitative data on biological HIV risk factors, the influence of reproductive hormones, and infection risk are lacking. We evaluated vaginal epithelial thickness during the menstrual cycle in pigtail macaques (Macaca nemestrina). This model previously revealed increased susceptibility to vaginal infection during and after progesterone-dominated periods in the menstrual cycle.

METHODS

Nucleated and nonnucleated (superficial) epithelial layers were quantitated throughout the menstrual cycle of 16 macaques. We examined the relationship with previously estimated vaginal SHIVSF162P3 acquisition time points in the cycle of 43 different animals repeatedly exposed to low virus doses.

RESULTS

In the luteal phase (days 17 to cycle end), the mean vaginal epithelium thinned to 66% of mean follicular thickness (days 1-16; P = 0.007, Mann-Whitney test). Analyzing 4-day segments, the epithelium was thickest on days 9 to 12 and thinned to 31% thereof on days 29 to 32, with reductions of nucleated and nonnucleated layers to 36% and 15% of their previous thickness, respectively. The proportion of animals with estimated SHIV acquisition in each cycle segment correlated with nonnucleated layer thinning (Pearson r = 0.7, P < 0.05, linear regression analysis), but not nucleated layer thinning (Pearson r = 0.6, P = 0.15).

CONCLUSIONS

These data provide a detailed picture of dynamic cycle-related changes in the vaginal epithelium of pigtail macaques. Substantial thinning occurred in the superficial, nonnucleated layer, which maintains the vaginal microbiome. The findings support vaginal tissue architecture as susceptibility factor for infection and contribute to our understanding of innate resistance to SHIV infection.

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.

Role and modulation of drug transporters in HIV-1 therapy

Current treatment of human immunodeficiency virus type-1 (HIV-1) infection involves a combination of antiretroviral drugs (ARVs) that target different stages of the HIV-1 life cycle. This strategy is commonly referred to as highly active antiretroviral therapy (HAART) or combined antiretroviral therapy (cART). Membrane-associated drug transporters expressed ubiquitously in mammalian systems play a crucial role in modulating ARV disposition during HIV-1 infection. Members of the ATP-binding cassette (ABC) and solute carrier (SLC) transporter superfamilies have been shown to interact with ARVs, including those that are used as part of first-line treatment regimens. As a result, the functional expression of drug transporters can influence the distribution of ARVs at specific sites of infection. In addition, pathological factors related to HIV-1 infection and/or ARV therapy itself can alter transporter expression and activity, thus further contributing to changes in ARV disposition and the effectiveness of HAART. This review summarizes current knowledge on the role of drug transporters in regulating ARV transport in the context of HIV-1 infection.

Progress and Perspectives on HIV-1 microbicide development

The majority of HIV-1 infections occur via sexual intercourse. Women are the most affected by the epidemic, particularly in developing countries, due to their socio-economic dependence on men and the fact that they are often victims of gender based sexual violence. Despite significant efforts that resulted in the reduction of infection rates in some countries, there is still need for effective prevention methods against the virus. One of these methods for preventing sexual transmission in women is the use of microbicides. In this review we provide a summary of the progress made toward the discovery of affordable and effective HIV-1 microbicides and suggest future directions. We show that there is a wide range of compounds that have been proposed as potential microbicides. Although most of them have so far failed to show protection in humans, there are many promising ones currently in pre-clinical studies and in clinical trials.

Rhizosecretion improves the production of Cyanovirin-N in Nicotiana tabacum through simplified downstream processing

Rhizosecretion has many advantages for the production of recombinant pharmaceuticals, notably facile downstream processing from hydroponic medium. The aim of this study was to increase yields of the HIV microbicide candidate, Cyanovirin-N (CV-N), obtained using this production platform and to develop a simplified methodology for its downstream processing from hydroponic medium. Placing hydroponic cultures on an orbital shaker more than doubled the concentration of CV-N in the hydroponic medium compared to plants which remained stationary, reaching a maximum of approximately 20μg/ml in one week, which is more than 3 times higher than previously reported yields. The protein composition of the hydroponic medium, the rhizosecretome, was characterised in plants cultured with or without the plant growth regulator alpha-napthaleneacetic acid by LC-ESI-MS/MS, and CV-N was the most abundant protein. The issue of large volumes in the rhizosecretion system was addressed by using ion exchange chromatography to concentrate CV-N and partially remove impurities. The semi-purified CV-N was demonstrated to bind to HIV gp120 in an ELISA and to neutralise HIVBa-L with an IC50 of 6nM in a cell-based assay. Rhizosecretion is therefore a practicable and inexpensive method for the production of functional CV-N.

In Vitro Pre- and Post-Exposure Prophylaxis Using HIV Inhibitors as Microbicides Against Cell-Free or Cell-Associated HIV-1 Infection

Several classes of microbicides are being evaluated for the prevention of sexual HIV transmission. In vivo, the infectious dose and viral source involved in transmission remain uncertain and it is likely that women will use microbicides both before and after high-risk HIV exposure. Therefore, we evaluated HIV entry inhibitors (EIs) and reverse transcriptase inhibitors (RTIs) for their ability to block cell-free and cell-associated HIV-1 infection in co-cultures of monocyte-derived dendritic cells (MO-DC) and CD4+T-cells using settings of pre- and post-exposure prophylaxis. In the pre-exposure assay, where compound was present before, during and 24 h after infection, all tested EIs (BMS806, TAK779 and T20) and RTIs (PMPA, TMC120 and UC781) blocked infection with 10−4multiplicity of infection (MOI) of cell-free virus at a dose between 100 and 10,000 nM, dependent on the compound used. At 10−3MOI, however, only T20 and the RTIs completely blocked infection. Furthermore, in experiments with cell-associated virus, EIs were ineffective, whereas RTIs actively blocked infection with similar potency as in the experiments with cell-free virus. In the post-exposure assay, where compound was added 2 h after infection and remained present for 24 h, EIs were inactive whereas RTIs blocked cell-free and cell-associated viral infections equally efficiently. Moreover, post-exposure prophylaxis initiated 24 h after infection with cell-free or cell-associated HIV-1 was still effective with 1,000 nM of TMC120. Both EIs and RTIs were non-cytotoxic at any tested concentration for MO-DC and CD4+T-cells in co-culture. Our study shows that RTIs are potent inhibitors of cell-free and cell-associated virus used either in pre- or post-exposure settings. It highlights that parameters such as viral input, viral source, the time of compound addition and the target cells should be considered in microbicides evaluation.

Does HIV Exploit the Inflammatory Milieu of the Male Genital Tract for Successful Infection?

In many parts of the World, medical male circumcision (MMC) is used as standard prevention of care against HIV infection. This is based on seminal reports made over 10 years ago that removal of the foreskin provides up to 60% protection against HIV infection in males and seems currently the best antiretroviral-free prevention strategy yet against the global epidemic. We explore the potential mechanisms by which MMC protects against HIV-1 acquisition and that one of the oldest, albeit re-invented, rituals of removing a foreskin underscores the exploitative nature of HIV on the anatomy and tissue of the uncircumcised penis. Furthermore, foreskin removal also reveals how males acquire HIV, and in reality, the underlying mechanisms of MMC are not known. We argue that the normal sequelae of inflammation in the male genital tract (MGT) for protection from sexually transmitted infections (STI)-induced pathology represents a perfect immune and microbial ecosystem for HIV acquisition. The accumulation of HIV-1 target cells in foreskin tissue and within the urethra in response to STIs, both during and after resolution of infection, suggests that acquisition of HIV-1, through sexual contact, makes use of the natural immune milieu of the MGT. Understanding immunity in the MGT, the movement of HIV-1 target cells to the urethra and foreskin tissue upon encounter with microbial signals would provide more insight into viral acquisition and lay the foundation for further prevention strategies in males that would be critical to curb the epidemic in all sexual partners at risk of infection. The global female-centric focus of HIV-1 transmission and acquisition research has tended to leave gaps in our knowledge of what determines HIV-1 acquisition in men and such understanding would provide a more balanced and complete view of viral acquisition.

Cyanovirin-N produced in rice endosperm offers effective pre-exposure prophylaxis against HIV-1BaL infection in vitro

Cyanovirin-N produced in rice endosperm provides efficient pre-exposure prophylaxis against HIV-1 BaL infection in vitro. Cyanovirin-N (CV-N) is a lectin with potent antiviral activity that has been proposed as a component of microbicides for the prevention of infection with Human immunodeficiency virus (HIV). The production of protein-based microbicide components requires a platform that is sufficiently economical and scalable to meet the demands of the large at-risk population, particularly in resource poor developing countries. We, therefore, expressed CV-N in rice endosperm, because the dried seed is ideal for storage and transport and crude extracts could be prepared locally and used as a microbicide component without further purification. We found that crude extracts from rice seeds expressing up to 10 µg CV-N per gram dry seed weight showed dose-dependent gp120 binding activity, confirming that the protein was soluble, correctly folded and active. The recombinant lectin ((OS)CV-N) reduced the infectivity of HIV-1BaL (an R5 virus strain representing the majority of transmitted infections) by ~90 % but showed only weak neutralization activity against HIV-1RF (representative of X4 virus, rarely associated with transmission), suggesting it would be highly effective for pre-exposure prophylaxis against the vast majority of transmitted strains. Crude extracts expressing (OS)CV-N showed no toxicity towards human cells at working dilutions indicating that microbicide components produced in rice endosperm are safe for direct application as topical microbicides in humans.

Antiviral molecules correlate with vitamin D pathway genes and are associated with natural resistance to HIV-1 infection

The relationship between the immunomodulatory effects of Vitamin D (VitD) and the expression of anti-HIV-1 molecules has not been explored in HIV-1-exposed seronegative individuals (HESNs). Higher mRNA levels of cathelicidin and HAD-4 in oral-mucosa and peripheral-blood, along with higher CYP24A1 mRNA in vaginal-mucosa and lower TLR2 mRNA in endocervical-mucosa were found in HESNs compared to non-exposed controls. Furthermore, the mRNA of anti-HIV molecules Elafin, TRIM5, Cathelicidin, HAD-4 and RNase7, previously associated with natural resistance to HIV-1 infection, positively correlated with the mRNA expression of VDR in HESNs, suggesting the potential participation of VitD in natural resistance to HIV-1.

Vectored antibody gene delivery for the prevention or treatment of HIV infection

PURPOSE OF REVIEW

To discuss recent progress in the use of vectors to produce antibodies in vivo as an alternative form of HIV prophylaxis or therapy. Instead of passive transfer of monoclonal antibody proteins, a transgene encoding an antibody is delivered to cells by the vector, resulting in expression and secretion by the host cell. This review will emphasize adeno-associated virus (AAV)-based strategies and summarize the evidence in support of this strategy as an alternative to traditional vaccines. We will highlight the major findings in the field and discuss the impact that this approach could have on the prevention, treatment and possibly eradication of HIV in patients.

RECENT FINDINGS

In this emerging field, the emphasis has been on the use of vectors delivering antibodies as an alternative to the development of an HIV vaccine. However, recent findings suggest that AAV-delivered broadly neutralizing antibodies can suppress HIV replication. As such, a single injection of AAV could mediate long-term antibody expression to act as a long-lived therapeutic in the absence of antiretroviral drugs.

SUMMARY

Vector-mediated antibody expression can both prevent transmission and inhibit the replication of established HIV infections. As such, it offers an alternative to immunogen-based vaccine design and a novel therapeutic intervention by enabling precise manipulation of humoral immunity. Success may enable not only the development of effective prevention against HIV but may also provide an alternative to a lifetime of antiretroviral drugs taken by those who are already infected.

Short Communication: Investigating a Chain of HIV Transmission Events Due to Homosexual Exposure and Blood Transfusion Based on a Next Generation Sequencing Method

This study investigates a chain of HIV transmission events due to homosexual exposure and blood transfusion in China. The MiSeq platform, a next generation sequencing (NGS) system, was used to obtain genetic details of the HIV-1 env region (336 base pairs). Evolutionary analysis combined with epidemiologic evidence suggests a transmission chain from patient T3 to T2 through homosexual exposure and subsequently to T1 through blood transfusion. More importantly, a phylogenetic study suggested a likely genetic bottleneck for HIV in homosexual transmission from T3 to T2, while T1 inherited the majority of variants from T2. The result from the MiSeq platform is consistent with findings from the epidemiologic survey. The MiSeq platform is a powerful tool for tracing HIV transmissions and intrapersonal evolution.

Nanoparticle-Based ARV Drug Combinations for Synergistic Inhibition of Cell-Free and Cell-Cell HIV Transmission

Nanocarrier-based drug delivery systems are playing an emerging role in human immunodeficiency virus (HIV) chemoprophylaxis and treatment due to their ability to alter the pharmacokinetics and improve the therapeutic index of various antiretroviral (ARV) drug compounds used alone and in combination. Although several nanocarriers have been described for combination delivery of ARV drugs, measurement of drug-drug activities facilitated by the use of these nanotechnology platforms has not been fully investigated for topical prevention. Here, we show that physicochemically diverse ARV drugs can be encapsulated within polymeric nanoparticles to deliver multidrug combinations that provide potent HIV chemoprophylaxis in relevant models of cell-free, cell-cell, and mucosal tissue infection. In contrast to existing approaches that coformulate ARV drug combinations together in a single nanocarrier, we prepared single-drug-loaded nanoparticles that were subsequently combined upon administration. ARV drug-nanoparticles were prepared using emulsion-solvent evaporation techniques to incorporate maraviroc (MVC), etravirine (ETR), and raltegravir (RAL) into poly(lactic-co-glycolic acid) (PLGA) nanoparticles. We compared the antiviral potency of the free and formulated drug combinations for all pairwise and triple drug combinations against both cell-free and cell-associated HIV-1 infection in vitro. The efficacy of ARV-drug nanoparticle combinations was also assessed in a macaque cervicovaginal explant model using a chimeric simian-human immunodeficiency virus (SHIV) containing the reverse transcriptase (RT) of HIV-1. We observed that our ARV-NPs maintained potent HIV inhibition and were more effective when used in combinations. In particular, ARV-NP combinations involving ETR-NP exhibited significantly higher antiviral potency and dose-reduction against both cell-free and cell-associated HIV-1 BaL infection in vitro. Furthermore, ARV-NP combinations that showed large dose-reduction were identified to be synergistic, whereas the equivalent free-drug combinations were observed to be strictly additive. Higher intracellular drug concentration was measured for cells dosed with the triple ARV-NP combination compared to the equivalent unformulated drugs. Finally, as a first step toward evaluating challenge studies in animal models, we also show that our ARV-NP combinations inhibit RT-SHIV virus propagation in macaque cervicovaginal tissue and block virus transmission by migratory cells emigrating from the tissue. Our results demonstrate that ARV-NP combinations control HIV-1 transmission more efficiently than free-drug combinations. These studies provide a rationale to better understand the role of nanocarrier systems in facilitating multidrug effects in relevant cells and tissues associated with HIV infection.

Short Communication: Exploring Antibody Potential as Prophylactic/Therapeutic Strategies for Prevention of Early Mucosal HIV-1 Infection

Mucosal tissues are the predominant sites for genital HIV-1 transmission. We investigated the mechanisms by which broadly neutralizing antibodies (bNAbs) inhibit HIV-1 replication in a coculture model including primary mucosal dendritic cells (DCs), such as Langerhans cells, interstitial dendritic cells, and CD4(+) T lymphocytes. We show that bNAbs efficiently prevent HIV-1 infection by inhibiting HIV-1 transmission to CD4(+) T lymphocytes. This inhibition of cell-to-cell transmission was observed with equal potency as the inhibition of cell-free infection of primary CD4(+) T lymphocytes. In addition, a decrease in HIV-1 replication in DCs and the induction of DC maturation were detected. This additional inhibition was Fc mediated as it was blocked by the use of specific anti-FcγR monoclonal Abs. The DC maturation by bNAbs during HIV transmission may contribute to mucosal protection. Therefore, multiple antibody-mediated inhibitory functions should be combined for the improvement of future preventive/therapeutic strategies to cure HIV.

Regulatory approval and a first-in-human phase I clinical trial of a monoclonal antibody produced in transgenic tobacco plants

Although plant biotechnology has been widely investigated for the production of clinical-grade monoclonal antibodies, no antibody products derived from transgenic plants have yet been approved by pharmaceutical regulators for clinical testing. In the Pharma-Planta project, the HIV-neutralizing human monoclonal antibody 2G12 was expressed in transgenic tobacco (Nicotiana tabacum). The scientific, technical and regulatory demands of good manufacturing practice (GMP) were addressed by comprehensive molecular characterization of the transgene locus, confirmation of genetic and phenotypic stability over several generations of transgenic plants, and by establishing standard operating procedures for the creation of a master seed bank, plant cultivation, harvest, initial processing, downstream processing and purification. The project developed specifications for the plant-derived antibody (P2G12) as an active pharmaceutical ingredient (API) based on (i) the guidelines for the manufacture of monoclonal antibodies in cell culture systems; (ii) the draft European Medicines Agency Points to Consider document on quality requirements for APIs produced in transgenic plants; and (iii) de novo guidelines developed with European national regulators. From the resulting process, a GMP manufacturing authorization was issued by the competent authority in Germany for transgenic plant-derived monoclonal antibodies for use in a phase I clinical evaluation. Following preclinical evaluation and ethical approval, a clinical trial application was accepted by the UK national pharmaceutical regulator. A first-in-human, double-blind, placebo-controlled, randomized, dose-escalation phase I safety study of a single vaginal administration of P2G12 was carried out in healthy female subjects. The successful completion of the clinical trial marks a significant milestone in the commercial development of plant-derived pharmaceutical proteins.

Development of water-soluble polyanionic carbosilane dendrimers as novel and highly potent topical anti-HIV-2 microbicides

The development of topical microbicide formulations for vaginal delivery to prevent HIV-2 sexual transmission is urgently needed. Second- and third-generation polyanionic carbosilane dendrimers with a silicon atom core and 16 sulfonate (G2-S16), napthylsulfonate (G2-NS16) and sulphate (G3-Sh16) end-groups have shown potent and broad-spectrum anti-HIV-1 activity. However, their antiviral activity against HIV-2 and mode of action have not been probed. Cytotoxicity, anti-HIV-2, anti-sperm and antimicrobial activities of dendrimers were determined. Analysis of combined effects of triple combinations with tenofovir and raltegravir was performed by using CalcuSyn software. We also assessed the mode of antiviral action on the inhibition of HIV-2 infection through a panel of different in vitro antiviral assays: attachment, internalization in PBMCs, inactivation and cell-based fusion. Vaginal irritation and histological analysis in female BALB/c mice were evaluated. Our results suggest that G2-S16, G2-NS16 and G3-Sh16 exert anti-HIV-2 activity at an early stage of viral replication inactivating the virus, inhibiting cell-to-cell HIV-2 transmission, and blocking the binding of gp120 to CD4, and the HIV-2 entry. Triple combinations with tenofovir and raltegravir increased the anti-HIV-2 activity, consistent with synergistic interactions (CIwt: 0.33-0.66). No vaginal irritation was detected in BALB/c mice after two consecutive applications for 2 days with 3% G2-S16. Our results have clearly shown that G2-S16, G2-NS16 and G3-Sh16 have high potency against HIV-2 infection. The modes of action confirm their multifactorial and non-specific ability, suggesting that these dendrimers deserve further studies as potential candidate microbicides to prevent vaginal/rectal HIV-1/HIV-2 transmission in humans.

Recent advances on anti-HIV vaginal delivery systems development

A review of the recent outcomes regarding technologies to prevent vaginal transmission of HIV, mainly by using antiretroviral (ARV) drugs formulated as microbicides. An introduction about the HIV transmission mechanisms by the vaginal route is included, together with the recent challenges faced for development of successful microbicide products. The outcomes of clinical evaluations are mentioned, and the different formulation strategies studied to-date, with the requirements, advantages, disadvantages and limitations of each dosage-form type, are presented. Finally, the recent attempts to apply various types of nanotechnologies in order to develop advanced microbicide-products and overcome existing limitations, are discussed.

A molecular tweezer antagonizes seminal amyloids and HIV infection

Semen is the main vector for HIV transmission and contains amyloid fibrils that enhance viral infection. Available microbicides that target viral components have proven largely ineffective in preventing sexual virus transmission. In this study, we establish that CLR01, a ‘molecular tweezer’ specific for lysine and arginine residues, inhibits the formation of infectivity-enhancing seminal amyloids and remodels preformed fibrils. Moreover, CLR01 abrogates semen-mediated enhancement of viral infection by preventing the formation of virion–amyloid complexes and by directly disrupting the membrane integrity of HIV and other enveloped viruses. We establish that CLR01 acts by binding to the target lysine and arginine residues rather than by a non-specific, colloidal mechanism. CLR01 counteracts both host factors that may be important for HIV transmission and the pathogen itself. These combined anti-amyloid and antiviral activities make CLR01 a promising topical microbicide for blocking infection by HIV and other sexually transmitted viruses.

DOI:http://dx.doi.org/10.7554/eLife.05397.001

Human Immunodeficiency Virus (HIV) is a sexually transmitted virus that can cause a serious disease that weakens the immune system. The virus is most commonly transmitted between individuals in semen, the male reproductive fluid. Semen contains deposits of protein fragments called amyloid fibrils, which can increase the transmission of HIV by trapping viral particles. This helps the virus to attach to the membranes surrounding human cells, which increases the risk of infection. Therefore, therapies that reduce the levels of amyloid fibrils in semen might be able to reduce the transmission of HIV.

Drugs that prevent amyloid formation are already being developed because structurally similar fibrils can also form in the brains of individuals with neurodegenerative diseases. One such molecule—called CLR01—works by binding to particular sites on the proteins that form fibrils in the brain. This inhibits fibril formation and slowly disassembles the fibrils that have already formed. CLR01 physically interacts with these residues in a way that resembles a tweezer.

The peptides in the amyloid fibrils in semen also have these sites, which suggests that CLR01 might also disrupt amyloid fibrils from forming in semen. Here Lump and Castellano et al. show that CLR01 can both disrupt fibril formation and remodel fibrils that have already formed. In addition, CLR01 prevents HIV particles from interacting with these fibrils and can displace the virus particles that have already bound to the fibrils. In the presence of CLR01, human cells exposed to semen that contained HIV were less likely to become infected with the virus.

Unexpectedly, CLR01 also directly destroys HIV and other enveloped viruses such as HCV or HSV particles by disrupting the membranes that surround the virus. Therefore, Lump and Castellano et al.'s findings reveal that CLR01 has considerable potential to be used as an agent for reducing the transmission of HIV and other sexually transmitted viral diseases.

DOI:http://dx.doi.org/10.7554/eLife.05397.002

Gene Expression Profiling of Human Vaginal Cells In Vitro Discriminates Compounds with Pro-Inflammatory and Mucosa-Altering Properties: Novel Biomarkers for Preclinical Testing of HIV Microbicide Candidates

BACKGROUND

Inflammation and immune activation of the cervicovaginal mucosa are considered factors that increase susceptibility to HIV infection. Therefore, it is essential to screen candidate anti-HIV microbicides for potential mucosal immunomodulatory/inflammatory effects prior to further clinical development. The goal of this study was to develop an in vitro method for preclinical evaluation of the inflammatory potential of new candidate microbicides using a microarray gene expression profiling strategy.

METHODS

To this end, we compared transcriptomes of human vaginal cells (Vk2/E6E7) treated with well-characterized pro-inflammatory (PIC) and non-inflammatory (NIC) compounds. PICs included compounds with different mechanisms of action. Gene expression was analyzed using Affymetrix U133 Plus 2 arrays. Data processing was performed using GeneSpring 11.5 (Agilent Technologies, Santa Clara, CA).

RESULTS

Microarraray comparative analysis allowed us to generate a panel of 20 genes that were consistently deregulated by PICs compared to NICs, thus distinguishing between these two groups. Functional analysis mapped 14 of these genes to immune and inflammatory responses. This was confirmed by the fact that PICs induced NFkB pathway activation in Vk2 cells. By testing microbicide candidates previously characterized in clinical trials we demonstrated that the selected PIC-associated genes properly identified compounds with mucosa-altering effects. The discriminatory power of these genes was further demonstrated after culturing vaginal cells with vaginal bacteria. Prevotella bivia, prevalent bacteria in the disturbed microbiota of bacterial vaginosis, induced strong upregulation of seven selected PIC-associated genes, while a commensal Lactobacillus gasseri associated to vaginal health did not cause any changes.

CONCLUSIONS

In vitro evaluation of the immunoinflammatory potential of microbicides using the PIC-associated genes defined in this study could help in the initial screening of candidates prior to entering clinical trials. Additional characterization of these genes can provide further insight into the cervicovaginal immunoinflammatory and mucosal-altering processes that facilitate or limit HIV transmission with implications for the design of prevention strategies.

Engineering a degradable polyurethane intravaginal ring for sustained delivery of dapivirine

We describe the engineering of a degradable intravaginal ring (IVR) for the delivery of the potent HIV-1 reverse transcriptase inhibitor dapivirine. The degradable polymer used in fabricating the device incorporated poly(caprolactone) ester blocks in a poly(tetramethylene ether) glycol ABA type polyurethane backbone. The polymer was designed to maintain its structure for 1 month during usage and then degrade in the environment post-disposal. In vitro release of dapivirine showed zero-order kinetics for up to 1 month and significant levels of drug release into engineered vaginal tissue. The mechanical properties of the degradable IVR were comparable to those of a widely used contraceptive intravaginal ring upon exposure to simulated vaginal conditions. Incubation under simulated vaginal conditions for a month caused minimal degradation with minimal effect on the mechanical properties of the ring and polymer. The cytotoxicity evaluation of the drug-loaded IVRs against Vk2/E6E7 human vaginal epithelial cells, Lactobacillus jensenii, and engineered vaginal tissue constructs showed the degradable polyurethane to be non-toxic. In vitro evaluation of inflammatory potential monitored through the levels of inflammatory cytokines IL-8, IL-1α, IL-6, IL-1β, and MIP-3α when engineered EpiVaginal™ tissue was incubated with the polyurethanes suggested that the degradable polyurethane was comparable to commercial medical grade polyurethane. These results are encouraging for further development of this degradable IVR for topical vaginal delivery of microbicides.

Imaging endocervical mucus anatomy and dynamics in macaque female reproductive track using optical coherence tomography

BACKGROUND

Endocervical mucus acts as an important barrier to block human immunodeficiency virus (HIV) infection and other sexually transmitted diseases (STDs). Disruption of the mucus layer increases the risk of infection for females. An effective method to image the mucus properties can serve as a pre-screening step to risk-stratify the susceptible population.

METHODS

We proposed to use optical coherence tomography (OCT) to quantitatively measure the thickness of endocervical mucus. We used a home-built bench-top OCT system to monitor the dynamic change in mucus thickness of a cultivated sample. We also fabricated a prototype endoscopic OCT probe to demonstrate potential in situ applications.

RESULTS

We observed a 200% increase in the endocervical mucus thickness after cultivating in 37 °C phosphate buffered saline solution for 30 minutes. During mucus hydrolysis, we found that mucus layer thickness decreased to about 60% of its original value after applying neuraminidase. Three dimensional volumetric image of intact macaque inner vaginal wall was also acquired.

CONCLUSIONS

We demonstrated that OCT can quantitatively measure the endocervical mucus thickness and its dynamics in ex vivo experiments. Endoscopic OCT has the potential to resolve fine structures inside macaque female reproductive track (FRT) for in vivo applications.

Progesterone-based intrauterine device use is associated with a thinner apical layer of the human ectocervical epithelium and a lower ZO-1 mRNA expression

Currently, whether hormonal contraceptives affect male to female human immunodeficiency virus (HIV) transmission is being debated. In this study, we investigated whether the use of progesterone-based intrauterine devices (pIUDs) is associated with a thinning effect on the ectocervical squamous epithelium, down-regulation of epithelial junction proteins, and/or alteration of HIV target cell distribution in the human ectocervix. Ectocervical tissue biopsies from healthy premenopausal volunteers using pIUDs were collected and compared to biopsies obtained from two control groups, namely women using combined oral contraceptives (COCs) or who do not use hormonal contraceptives. In situ staining and image analysis were used to measure epithelial thickness and the presence of HIV receptors in tissue biopsies. Messenger RNA levels of epithelial junction markers were measured by quantitative PCR. The epithelial thickness displayed by women in the pIUD group was similar to those in the COC group, but significantly thinner as compared to women in the no hormonal contraceptive group. The thinner epithelial layer of the pIUD group was specific to the apical layer of the ectocervix. Furthermore, the pIUD group expressed significantly lower levels of the tight junction marker ZO-1 within the epithelium as compared to the COC group. Similar expression levels of HIV receptors and coreceptors CD4, CCR5, DC-SIGN, and Langerin were observed in the three study groups. Thus, women using pIUD displayed a thinner apical layer of the ectocervical epithelium and reduced ZO-1 expression as compared to control groups. These data suggest that pIUD use may weaken the ectocervical epithelial barrier against invading pathogens, including HIV.

Passive Immunization

Whereas active immunity refers to the process of exposing the individual to an antigen to generate an adaptive immune response, passive immunity refers to the transfer of antibodies from one individual to another. Passive immunity provides immediate but short-lived protection, lasting several weeks up to 3 or 4 months. Passive immunity can occur naturally, when maternal antibodies are transferred to the fetus through the placenta or from breast milk to the gut of the infant. It can also be produced artificially, when antibody preparations derived from sera or secretions of immunized donors or, more recently, different antibody producing platforms are transferred via systemic or mucosal route to nonimmune individuals. Passive immunization has recently become an attractive approach because of the emergence of new and drug-resistant microorganisms, diseases that are unresponsive to drug therapy and individuals with an impaired immune system who are unable to respond to conventional vaccines. This chapter addresses the contributions of natural and artificial acquired passive immunity in understanding the concept of passive immunization. We will mainly focus on administration of antibodies for protection against various infectious agents entering through mucosal surfaces.

The role of dendritic cells in driving genital tract inflammation and HIV transmission risk: are there opportunities to intervene?

Effective prevention of new HIV infections will require an understanding of the mechanisms involved in HIV acquisition. HIV transmission across the female genital tract is the major mode of new HIV infections in sub-Saharan Africa and involves complex processes, including cell activation, inflammation and recruitment of HIV target cells. Activated CD4(+) T-cells, dendritic cells (DC) and macrophages have been described as targets for HIV at the genital mucosa. Activation of these cells may occur in the presence of sexually-transmitted infections, disturbances of commensal flora and other inflammatory processes. In this review, we discuss causes and consequences of inflammation in the female genital tract, with a focus on DC. We describe the central role these cells may play in facilitating or preventing HIV transmission across the genital mucosa, and in the initial recognition of HIV and other pathogens, allowing activation of an adaptive immune response to infection. We discuss studies that investigate interventions to limit DC activation, inflammation and HIV transmission. This knowledge is essential in the development of novel strategies for effective HIV control, including microbicides and pre-exposure prophylaxis.

Assessing the implementation effectiveness and safety of 1% tenofovir gel provision through family planning services in KwaZulu-Natal, South Africa: study protocol for an open-label randomized controlled trial

BACKGROUND

The Centre for the AIDS Programme of Research in South Africa (CAPRISA) 004 trial demonstrated a 39% reduction in HIV infection, with a 54% HIV reduction in women who used tenofovir gel consistently. A confirmatory trial is expected to report results in early 2015. In the interim, we have a unique window of opportunity to prepare for and devise effective strategies for the future policy and programmatic scale-up of tenofovir gel provision. One approach is to integrate tenofovir gel provision into family planning (FP) services. The CAPRISA 008 implementation trial provides an opportunity to provide post-trial access to tenofovir gel while generating empiric evidence to assess whether integrating tenofovir gel provision into routine FP services can achieve similar levels of adherence as the CAPRISA 004 trial.

METHODS/DESIGN

This is a two-arm, open-label, randomized controlled non-inferiority trial. A maximum of 700 sexually active, HIV-uninfected women aged 18 years and older who previously participated in an antiretroviral prevention study will be enrolled from an urban and rural site in KwaZulu-Natal, South Africa. The anticipated study duration is 30 months, with active accrual requiring approximately 12 months (following which an open cohort will be maintained) and follow-up continuing for approximately 18 months. At each of the two sites, eligible participants will be randomly assigned to receive tenofovir gel through either FP services (intervention arm) or through the CAPRISA research clinics (control arm). As part of the study intervention, a quality improvement approach will be used to assist the FP services to expand their current services to include tenofovir gel provision.

DISCUSSION

This protocol aims to address an important implementation question on whether FP services are able to effectively incorporate tenofovir gel provision for this at-risk group of women in South Africa. Provision of tenofovir gel to the women from the CAPRISA 004 trial meets the ethical obligation for post-trial access, and helps identify a potential avenue for future scale-up of microbicides within the public health system of South Africa.

TRIAL REGISTRATION

This trial was registered with the South Africa Department of Health (reference: DOH-27-0812-4129) and ClinicalTrials.gov (reference: NCT01691768) on 05 July 2012.

Transient antibody-mucin interactions produce a dynamic molecular shield against viral invasion

Given the difficulty in finding a cure for HIV/AIDS, a promising prevention strategy to reduce HIV transmission is to directly block infection at the portal of entry. The recent Thai RV144 trial offered the first evidence that an antibody-based vaccine may block heterosexual HIV transmission. Unfortunately, the underlying mechanism(s) for protection remain unclear. Here we theoretically examine a hypothesis that builds on our recent laboratory observation: virus-specific antibodies (Ab) can trap individual virions in cervicovaginal mucus (CVM), thereby reducing infection in vivo. Ab are known to have a weak-previously considered inconsequential-binding affinity with the mucin fibers that constitute CVM. However, multiple Ab can bind to the same virion at the same time, which markedly increases the overall Ab-mucin binding avidity, and creates an inheritable virion-mucin affinity. Our model takes into account biologically relevant length and timescales, while incorporating known HIV-Ab affinity and the respective diffusivities of viruses and Ab in semen and CVM. The model predicts that HIV-specific Ab in CVM leads to rapid formation and persistence of an HIV concentration front near the semen/CVM interface, far from the vaginal epithelium. Such an HIV concentration front minimizes the flux of HIV virions reaching target cells, and maximizes their elimination upon drainage of genital secretions. The robustness of the result implies that even exceedingly weak Ab-mucin affinity can markedly reduce the flux of virions reaching target cells. Beyond this specific application, the model developed here is adaptable to other pathogens, mucosal barriers, and geometries, as well as kinetic and diffusional effects, providing a tool for hypothesis testing and producing quantitative insights into the dynamics of immune-mediated protection.