Mucosal effects of tenofovir 1% gel

Gene expression of tight junctions in foreskin is not affected by HIV pre-exposure prophylaxis

Introduction

Tight junctions (TJs) serve as permeability filters between the internal and external cellular environment. A large number of proteins have been identified to be localized at the TJs. Due to limitations in tissue collection, TJs in the male genital tract have been understudied.

Methods

We analysed the transcriptomics of 132 TJ genes in foreskin tissue of men requesting voluntary medical male circumcision (VMMC) and enrolled in the Combined HIV Adolescent Prevention Study (CHAPS) trial conducted in South Africa and Uganda (NCT03986970). The trial evaluated the dose requirements for event-driven HIV pre-exposure prophylaxis (PrEP) with emtricitabine-tenofovir (FTC-TDF) or emtricitabine-tenofovir alafenamide (FTC-TAF) during insertive sex. A total of 144 participants were randomized to either control arm or one of 8 PrEP arms (n=16/arm), receiving oral FTC-TDF or FTC-TAF over one or two days. Following in vivo oral PrEP dosing and VMMC, the expression level of three important TJ proteins (CLDN-1, OCN and ZO-1) was measured ex vivo in foreskin tissue by Western blot. The expression of cytokine genes implicated in TJ regulation was determined. Non-parametric Kruskal-Wallis tests were used to compare TJ gene expression and protein levels by type of PrEP received, and Spearman's correlation coefficients were calculated to assess whether TJ gene expression levels were related to cytokine gene levels or to PrEP drug concentrations and their active intracellularly phosphorylated metabolites.

Results

A high level of expression in foreskin tissue was found for 118 (of 132) TJ genes analysed; this finding contributed to create a map of TJ components within the male genital tract. Importantly, PrEP regimens tested in the CHAPS trial did not affect the expression of TJ genes and the analysed proteins in the foreskin; thus, further supporting the safety of this prevention strategy against HIV-1 transmission during insertive sex. Additionally, we identified the level of several cytokines' genes to be correlated to TJ gene expression: among them, IL-18, IL-33 and VEGF.

Discussion

TJs can limit viral entry into target cells; to affect this biological function viruses can reduce the expression of TJ proteins. Our study, on the expression and regulation of TJs in the foreskin, contribute important knowledge for PrEP safety and further design of HIV-1 prophylaxis.

Gut Microbiome Alteration in HIV/AIDS and the Role of Antiretroviral Therapy-A Scoping Review

(1) Background: The gut microbiota plays a crucial role in chronic immune activation associated with human immunodeficiency virus (HIV) infection, acquired immune deficiency syndrome (AIDS) pathogenesis, non-AIDS-related comorbidities, and mortality among people living with HIV (PLWH). The effects of antiretroviral therapy on the microbiome remain underexplored. This study aims to map the evidence of the impact of integrase strand transfer inhibitors (INSTI) and non-nucleoside reverse transcriptase inhibitors (NNRTI) on the gut microbiota of PLWH. (2) Methods: A scoping review was conducted using PubMed, Web of Science, and Embase, with reports collected following PRISMA for Scoping Reviews (PRISMA-ScR). (3) Results: Evidence suggests that INSTI-based regimes generally promote the restoration of alpha diversity, bringing it closer to that of seronegative controls, while beta diversity remains largely unchanged. INSTI-based therapies are suggested to be associated with improvements in microbiota composition and a tendency toward reduced inflammatory markers. In contrast, NNRTI-based treatments demonstrate limited recovery of alpha diversity and are linked to an increase in proinflammatory bacteria. (4) Conclusions: Based on the review of the current literature, it is indicated that INSTI-based antiretroviral therapy (ART) therapy facilitates better recovery of the gut microbiome.

A randomized clinical trial of on-demand oral pre-exposure prophylaxis does not modulate lymphoid/myeloid HIV target cell density in the foreskin

OBJECTIVES

As topical pre-exposure prophylaxis (PrEP) has been shown to cause immune modulation in rectal or cervical tissue, our aim was to examine the impact of oral PrEP on lymphoid and myeloid changes in the foreskin in response to dosing and timing of drug administration.

DESIGN

HIV-negative male individuals ( n  = 144) were recruited in South Africa and Uganda into an open-label randomized controlled trial in a 1 : 1 : 1 : 1 : 1 : 1 : 1 : 1 : 1 ratio to control arm (with no PrEP) or one of eight arms receiving emtricitabine-tenofovir disoproxil fumarate (F/TDF) or emtricitabine-tenofovir alafenamide (F/TAF) at one of two different doses, 5 or 21 h before undergoing voluntary medical male circumcision (VMMC).

METHODS

After dorsal-slit circumcision, foreskin tissue sections were embedded into Optimal Cutting Temperature media and analysed, blinded to trial allocation, to determine numbers of CD4 + CCR5 + , CD1a + cells and claudin-1 expression. Cell densities were correlated with tissue-bound drug metabolites and p24 production after ex-vivo foreskin challenge with HIV-1 bal .

RESULTS

There was no significant difference in CD4 + CCR5 + or CD1a + cell numbers in foreskins between treatment arms compared with the control arm. Claudin-1 expression was 34% higher ( P  = 0.003) in foreskin tissue from participants receiving PrEP relative to controls, but was no longer statistically significant after controlling for multiple comparisons. There was neither correlation of CD4 + CCR5 + , CD1a + cell numbers, or claudin-1 expression with tissue-bound drug metabolites, nor with p24 production after ex-vivo viral challenge.

CONCLUSION

Oral doses and timing of on-demand PrEP and in-situ drug metabolite levels in tissue have no effect on numbers or anatomical location of lymphoid or myeloid HIV target cells in foreskin tissue.

The Immunological Conundrum of Endogenous Retroelements

Our defenses against infection rely on the ability of the immune system to distinguish invading pathogens from self. This task is exceptionally challenging, if not seemingly impossible, in the case of retroviruses that have integrated almost seamlessly into the host. This review examines the limits of innate and adaptive immune responses elicited by endogenous retroviruses and other retroelements, the targets of immune recognition, and the consequences for host health and disease. Contrary to theoretical expectation, endogenous retroelements retain substantial immunogenicity, which manifests most profoundly when their epigenetic repression is compromised, contributing to autoinflammatory and autoimmune disease and age-related inflammation. Nevertheless, recent evidence suggests that regulated immune reactivity to endogenous retroelements is integral to immune system development and function, underpinning cancer immunosurveillance, resistance to infection, and responses to the microbiota. Elucidation of the interaction points with endogenous retroelements will therefore deepen our understanding of immune system function and contribution to disease.

Short-term oral pre-exposure prophylaxis against HIV-1 modulates the transcriptome of foreskin tissue in young men in Africa

Whilst short-term oral pre-exposure prophylaxis (PrEP) with antiretroviral drugs in men who have sex with men has shown protection against HIV-1 infection, the impact of this regimen on the in vivo foreskin transcriptome is unknown. We collected foreskin tissue after voluntary medical male circumcision from 144 young men (72 from Uganda and 72 from South Africa) randomized to one to two doses of either oral tenofovir (TFV) disoproxil fumarate (FTC-TDF) or tenofovir alafenamide (FTC-TAF) or no drug (untreated controls). This novel approach allowed us to examine the impact of short-term oral PrEP on transcriptome of the male genital tract. A single dose of FTC-TDF did not affect the foreskin transcriptome in relation to control arm, however one dose of FTC-TAF induced upregulation of four genes AKAP8, KIAA0141, HSCB and METTL17. Following two doses of either FTC-TDF or FTC-TAF, there was an increase in 34 differentially expressed genes for FTC-TDF and 15 for FTC-TAF, with nine DEGs in common: KIAA0141, SAFB2, CACTIN, FXR2, AKAP8, HSCB, CLNS1A, DDX27 and DCAF15. Functional analysis of differentially expressed genes revealed modulation of biological processes related to mitochondrial stress (KIAA0141, HSCB and METTL17), anti-viral and anti-inflammatory pathways (CACTIN and AKAP8). Our results show that short-course on-demand oral PrEP in men modulates genes in foreskin tissue which are likely unfavorable to HIV acquisition and replication. We also describe an upregulated expression of genes involved in diverse mitochondria biology which may potentially result in worsened mitochondria-related. These results warrant further studies to assess the role of short-course and prolonged oral PrEP on biological processes of the foreskin mucosa.

HSV-2 Infection Enhances Zika Virus Infection of Primary Genital Epithelial Cells Independently of the Known Zika Virus Receptor AXL

Zika virus (ZIKV) is transmitted to people by bite of an infected mosquito and by sexual contact. ZIKV infects primary genital epithelial cells, the same cells targeted by herpes simplex virus 2 (HSV-2). HSV-2 seroprevalence is high in areas where ZIKV is endemic, but it is unknown whether HSV-2 increases the risk for ZIKV infection. Here, we found that pre-infecting female genital tract epithelial cells with HSV-2 leads to enhanced binding of ZIKV virions. This effect did not require active replication by HSV-2, implying that the effect results from the immune response to HSV-2 exposure or to viral genes expressed early in the HSV-2 lifecycle. Treating cells with toll-like receptor-3 ligand poly-I:C also lead to enhanced binding by ZIKV, which was inhibited by the JAK-STAT pathway inhibitor ruxolitinib. Blocking or knocking down the well-studied ZIKV receptor AXL did not prevent binding of ZIKV to epithelial cells, nor prevent enhanced binding in the presence of HSV-2 infection. Blocking the α5 integrin receptor did not prevent ZIKV binding to cells either. Overall, our results indicate that ZIKV binding to genital epithelial cells is not mediated entirely by a canonical receptor, but likely occurs through redundant pathways that may involve lectin receptors and glycosaminoglycans. Our studies may pave the way to new interventions that interrupt the synergism between herpes and Zika viruses.

Mobilization of systemic CCL4 following HIV pre-exposure prophylaxis in young men in Africa

HIV-1 pre-exposure prophylaxis (PrEP) relies on inhibition of HIV-1 replication steps. To understand how PrEP modulates the immunological environment, we derived the plasma proteomic profile of men receiving emtricitabine-tenofovir (FTC-TDF) or emtricitabine-tenofovir alafenamide (FTC-TAF) during the CHAPS trial in South Africa and Uganda (NCT03986970). The CHAPS trial randomized 144 participants to one control and 8 PrEP arms, differing by drug type, number of PrEP doses and timing from final PrEP dose to sampling. Blood was collected pre- and post-PrEP. The inflammatory profile of plasma samples was analyzed using Olink (N=92 proteins) and Luminex (N=33) and associated with plasma drug concentrations using mass spectrometry. The proteins whose levels changed most significantly from pre- to post-PrEP were CCL4, CCL3 and TNF-α; CCL4 was the key discriminator between pre- and post-PrEP samples. CCL4 and CCL3 levels were significantly increased in post-PrEP samples compared to control specimens. CCL4 was significantly correlated with FTC drug levels in plasma. Production of inflammatory chemokines CCL4 and CCL3 in response to short-term PrEP indicates the mobilization of ligands which potentially block virus attachment to CCR5 HIV-1 co-receptor. The significant correlation between CCL4 and FTC levels suggests that CCL4 increase is modulated as an inflammatory response to PrEP.

Buprenorphine Increases HIV-1 Infection In Vitro but Does Not Reactivate HIV-1 from Latency

BACKGROUND

medication-assisted treatment (MAT) with buprenorphine is now widely prescribed to treat addiction to heroin and other illicit opioids. There is some evidence that illicit opioids enhance HIV-1 replication and accelerate AIDS pathogenesis, but the effect of buprenorphine is unknown.

METHODS

we obtained peripheral blood mononuclear cells (PBMCs) from healthy volunteers and cultured them in the presence of morphine, buprenorphine, or methadone. We infected the cells with a replication-competent CCR5-tropic HIV-1 reporter virus encoding a secreted nanoluciferase gene, and measured infection by luciferase activity in the supernatants over time. We also surveyed opioid receptor expression in PBMC, genital epithelial cells and other leukocytes by qPCR and western blotting. Reactivation from latency was assessed in J-Lat 11.1 and U1 cell lines.

RESULTS

we did not detect expression of classical opioid receptors in leukocytes, but did find nociception/orphanin FQ receptor (NOP) expression in blood and vaginal lymphocytes as well as genital epithelial cells. In PBMCs, we found that at physiological doses, morphine, and methadone had a variable or no effect on HIV infection, but buprenorphine treatment significantly increased HIV-1 infectivity (median: 8.797-fold increase with 20 nM buprenorphine, eight experiments, range: 3.570-691.9, p = 0.0078). Using latently infected cell lines, we did not detect reactivation of latent HIV following treatment with any of the opioid drugs.

CONCLUSIONS

our results suggest that buprenorphine, in contrast to morphine or methadone, increases the in vitro susceptibility of leukocytes to HIV-1 infection but has no effect on in vitro HIV reactivation. These findings contribute to our understanding how opioids, including those used for MAT, affect HIV infection and reactivation, and can help to inform the choice of MAT for people living with HIV or who are at risk of HIV infection.

Early Colorectal Responses to HIV-1 and Modulation by Antiretroviral Drugs

Innate responses during acute HIV infection correlate with disease progression and pathogenesis. However, limited information is available about the events occurring during the first hours of infection in the mucosal sites of transmission. With an ex vivo HIV-1 challenge model of human colorectal tissue we assessed the mucosal responses induced by R5- and X4-tropic HIV-1 isolates in the first 24 h of exposure. Microscopy studies demonstrated virus penetration of up to 39 μm into the lamina propia within 6 h of inoculation. A rapid, 6 h post-challenge, increase in the level of secretion of inflammatory cytokines, chemokines, interferon- γ (IFN-γ), and granulocyte-macrophage colony-stimulating factor (GM-CSF) was observed following exposure to R5- or X4-tropic isolates. This profile persisted at the later time point measured of 24 h. However, exposure to the X4-tropic isolate tested induced greater changes at the proteomic and transcriptomic levels than the R5-tropic. The X4-isolate induced greater levels of CCR5 ligands (RANTES, MIP-1α and MIP-1β) secretion than R5-HIV-1. Potential drugs candidates for colorectal microbicides, including entry, fusion or reverse transcriptase inhibitors demonstrated differential capacity to modulate these responses. Our findings indicate that in colorectal tissue, inflammatory responses and a Th1 cytokine profile are induced in the first 24 h following viral exposure.

Development and evaluation of mucoadhesive bigel containing tenofovir and maraviroc for HIV prophylaxis

BACKGROUND

Sexual transmission of HIV is the most common means of acquiring the disease. Topical microbicides have been investigated to prevent transmission. This study will use a specific entry inhibitor, maraviroc, and a nucleotide reverse transcriptase inhibitor (NRTI), tenofovir, a dual combination which will provide a synergist effect that can enhance the efficacy of HIV microbicides via a mucoadhesive dual compartment bigel. Bigel formulation via hydrogel organogel linkages were developed and evaluated for their physicochemical characteristics, safety, and anti-HIV efficacy. In vitro diffusion studies were performed with Franz diffusion cells having effective diffusion surface area of 1.76cm2 and receiver chamber volume of 15mL.

RESULT

The bigel formulations showed a viscosity ranging from 14179 to 14560 cPs and had a good spreadability and acidic pH in the range of 4.0 ± 0.34 to 5.2 ± 0.18. The bigel formulations showed good anti-HIV activity at a concentration of 0.1 μg/mL. The in vitro release study of maraviroc from the bigel formulations showed a release rate ranging from 2.675 to 3.838 μg/cm2/min½ while the release rate for tenofovir ranged from 3.475 to 3.825 μg/cm2/min½. The bigel formulations were non-toxic to the human vagina as there was < 1 log10 change in Lactobacilli crispatus viability.

CONCLUSION

This study successfully developed a dual compartment bigel containing maraviroc and tenofovir. BG C was found to be stable and safe towards vaginal and rectal epithelium, and it actively prevented HIV transmission. This bigel has the potential for long-term pre-exposure prophylaxis prevention of HIV transmission.

Potent Restriction of Sexual Zika Virus Infection by the Lipid Fraction of Extracellular Vesicles in Semen

Sexual Zika virus (ZIKV) transmission from men to women occurs less frequently than the often-detected high viral loads in semen would suggest, but worries that this transmission route predisposes to fetal damage in pregnant women remain. To better understand sexual ZIKV pathogenesis, we studied the permissiveness of the human female genital tract to infection and the effect of semen on this process. ZIKV replicates in vaginal tissues and primary epithelial cells from the vagina, ectocervix, and endocervix and induces an innate immune response, but also continues to replicate without cytopathic effect. Infection of genital cells and tissues is strongly inhibited by extracellular vesicles (EV) in semen at physiological vesicle-to-virus ratios. Liposomes with the same composition as semen EVs also impair infection, indicating that the EV’s lipid fraction, rather than their protein or RNA cargo, is responsible for this anti-viral effect. Thus, EVs in semen potently restrict ZIKV transmission, but the virus propagates well once infection in the recipient mucosa has been established.

Descriptive Analysis of Patients Living With HIV Affected by COVID-19

BACKGROUND

COVID-19 disease has spread globally and was declared a pandemic on March 11, 2020, by the World Health Organization. On March 10, the State of Michigan confirmed its first 2 cases of COVID-19, and the number of confirmed cases has reached 47,182 as of May 11, 2020, with 4555 deaths.

SETTING

Currently, little is known if patients living with HIV (PLWH) are at a higher risk of severe COVID-19 or if their antiretrovirals are protective. This study presents epidemiologic and clinical features of COVID-19 infected PLWH in Detroit, Michigan.

METHODS

This is a case series that included 14 PLWH with laboratory-confirmed COVID-19 infection who were evaluated at Henry Ford Hospital in Detroit, Michigan, between March 20, 2020, and April 30, 2020.

RESULTS

Fourteen PLWH were diagnosed with COVID-19. Twelve patients were men and 2 were women; 13 patients were virally suppressed. Eight patients were hospitalized, and 6 patients were told to self-quarantine at home after their diagnoses. Three patients who were admitted expired during their hospital stay. No patient required bilevel positive airway pressure or nebulizer use in the emergency department, and none developed acute respiratory distress syndrome, pulmonary embolism, deep venous thrombosis, or a cytokine storm while on therapy for COVID-19.

CONCLUSION

Although the clinical spectrum of COVID-19 among PLWH cannot be fully ascertained by this report, it adds to the data that suggest that HIV-positive patients with SARS-CoV-2 infection are not at a greater risk of severe disease or death as compared to HIV-negative patients.

Treatment with Commonly Used Antiretroviral Drugs Induces a Type I/III Interferon Signature in the Gut in the Absence of HIV Infection

Tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) are used for HIV treatment and prevention. Previously, we found that topical rectal tenofovir gel caused immunological changes in the mucosa. Here, we assess the effect of oral TDF/FTC in three HIV pre-exposure prophylaxis trials, two with gastrointestinal and one with cervicovaginal biopsies. TDF/FTC induces type I/III interferon-related (IFN I/III) genes in the gastrointestinal tract, but not blood, with strong correlations between the two independent rectal biopsy groups (Spearman r = 0.91) and between the rectum and duodenum (r = 0.81). Gene set testing also indicates stimulation of the type I/III pathways in the ectocervix and of cellular proliferation in the duodenum. mRNA sequencing, digital droplet PCR, proteomics, and immunofluorescence confirm IFN I/III pathway stimulation in the gastrointestinal tract. Thus, oral TDF/FTC stimulates an IFN I/III signature throughout the gut, which could increase antiviral efficacy but also cause chronic immune activation in HIV prevention and treatment settings.

Mechanisms of Endogenous HIV-1 Reactivation by Endocervical Epithelial Cells

Pharmacological HIV-1 reactivation to reverse latent infection has been extensively studied. However, HIV-1 reactivation also occurs naturally, as evidenced by occasional low-level viremia ("viral blips") during antiretroviral treatment (ART). Clarifying where blips originate from and how they happen could provide clues to stimulate latency reversal more effectively and safely or to prevent viral rebound following ART cessation. We studied HIV-1 reactivation in the female genital tract, a dynamic anatomical target for HIV-1 infection throughout all disease stages. We found that primary endocervical epithelial cells from several women reactivated HIV-1 from latently infected T cells. The endocervical cells' HIV-1 reactivation capacity further increased upon Toll-like receptor 3 stimulation with poly(I·C) double-stranded RNA or infection with herpes simplex virus 2 (HSV-2). Notably, acyclovir did not eliminate HSV-2-induced HIV-1 reactivation. While endocervical epithelial cells secreted large amounts of several cytokines and chemokines, especially tumor necrosis factor alpha (TNF-α), CCL3, CCL4, and CCL20, their HIV-1 reactivation capacity was almost completely blocked by TNF-α neutralization alone. Thus, immunosurveillance activities by columnar epithelial cells in the endocervix can cause endogenous HIV-1 reactivation, which may contribute to viral blips during ART or rebound following ART interruption.IMPORTANCE A reason that there is no universal cure for HIV-1 is that the virus can hide in the genome of infected cells in the form of latent proviral DNA. This hidden provirus is protected from antiviral drugs until it eventually reactivates to produce new virions. It is not well understood where in the body or how this reactivation occurs. We studied HIV-1 reactivation in the female genital tract, which is often the portal of HIV-1 entry and which remains a site of infection throughout the disease. We found that the columnar epithelial cells lining the endocervix, the lower part of the uterus, are particularly effective in reactivating HIV-1 from infected T cells. This activity was enhanced by certain microbial stimuli, including herpes simplex virus 2, and blocked by antibodies against the inflammatory cytokine TNF-α. Avoiding HIV-1 reactivation could be important for maintaining a functional HIV-1 cure when antiviral therapy is stopped.

Impact of Q-Griffithsin anti-HIV microbicide gel in non-human primates: In situ analyses of epithelial and immune cell markers in rectal mucosa

Natural-product derived lectins can function as potent viral inhibitors with minimal toxicity as shown in vitro and in small animal models. We here assessed the effect of rectal application of an anti-HIV lectin-based microbicide Q-Griffithsin (Q-GRFT) in rectal tissue samples from rhesus macaques. E-cadherin⁺ cells, CD4⁺ cells and total mucosal cells were assessed using in situ staining combined with a novel customized digital image analysis platform. Variations in cell numbers between baseline, placebo and Q-GRFT treated samples were analyzed using random intercept linear mixed effect models. The frequencies of rectal E-cadherin⁺ cells remained stable despite multiple tissue samplings and Q-GRFT gel (0.1%, 0.3% and 1%, respectively) treatment. Whereas single dose application of Q-GRFT did not affect the frequencies of rectal CD4⁺ cells, multi-dose Q-GRFT caused a small, but significant increase of the frequencies of intra-epithelial CD4⁺ cells (placebo: median 4%; 1% Q-GRFT: median 7%) and of the CD4⁺ lamina propria cells (placebo: median 30%; 0.1–1% Q-GRFT: median 36–39%). The resting time between sampling points were further associated with minor changes in the total and CD4⁺ rectal mucosal cell levels. The results add to general knowledge of in vivo evaluation of anti-HIV microbicide application concerning cellular effects in rectal mucosa.

TAF and TDF attenuate liver fibrosis through NS5ATP9, TGFβ1/Smad3, and NF-κB/NLRP3 inflammasome signaling pathways

BACKGROUND

This study aimed to investigate the roles and mechanisms of tenofovir alafenamide fumarate (TAF)/tenofovir disoproxil fumarate (TDF) in treating liver fibrosis.

METHODS

The effects of TAF/TDF on carbon tetrachloride (CCl₄)-induced liver fibrosis in C57BL/6 wild-type or nonstructural protein 5A transactivated protein 9 (NS5ATP9) knockout mice were studied. The differentiation, activation, and proliferation of LX-2 cells after TAF/TDF treatment were tested in vitro. The expression of NS5ATP9 and activities of transforming growth factor-β1 (TGFβ1)/Sekelsky mothers against decapentaplegic homolog 3 (Smad3) and NF-κB/NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome signaling pathways were detected in TAF/TDF-treated mice and LX-2 cells. The genes related to extracellular matrix accumulation were detected in vivo and in vitro after NS5ATP9 silencing or knockout.

RESULTS

TAF/TDF significantly inhibited CCl₄-induced liver fibrosis in mice, and regulated the differentiation, activation, and proliferation of hepatic stellate cells (HSCs). Furthermore, TAF/TDF suppressed the activities of TGFβ1/Smad3 and NF-κB/NLRP3 inflammasome signaling pathways in vivo and in vitro. NS5ATP9 inhibited liver fibrosis through TGFβ1/Smad3 and NF-κB signaling pathways. TAF/TDF upregulated the expression of NS5ATP9 in vivo and in vitro. Finally, TAF/TDF could only show marginal therapeutic effects when NS5ATP9 was silenced and knocked out in vivo and in vitro.

CONCLUSIONS

TAF/TDF prevented progression and promoted reversion of liver fibrosis through assembling TGFβ1/Smad3 and NF-κB/NLRP3 inflammasome signaling pathways via upregulating the expression of NS5ATP9. TAF/TDF also regulated the differentiation, activation, and proliferation of HSCs. The findings provided strong evidence for the role of TAF/TDF as a new promising therapeutic strategy in liver fibrosis.

Pre-exposure prophylaxis differentially alters circulating and mucosal immune cell activation in herpes simplex virus type 2 seropositive women

OBJECTIVE

Oral tenofovir-based pre-exposure prophylaxis (PrEP) is an important tool for prevention of new HIV infections, which also reduces subclinical herpes simplex virus type 2 (HSV-2) shedding and symptomatic lesions in HIV-negative, HSV-2-seropositive individuals. However, the impact of PrEP on mucosal immunity has not been examined in detail.

DESIGN

Here we evaluate paired genital tissue and systemic immune profiles to characterize the immunological effects of PrEP in HIV-negative, HSV-2-seropositive African women sexually exposed to HIV.

METHODS

We compared local and systemic innate and T-cell characteristics in samples collected during PrEP usage and 2 months after PrEP discontinuation.

RESULTS

We found that frequencies of cervical CCR5CD4 cells, regulatory T cells, and tissue macrophages were significantly reduced during PrEP use compared with after PrEP discontinuation. In contrast, peripheral blood CD4 and CD8 T cells expressing markers of activation and trafficking were increased during PrEP usage.

CONCLUSION

Together, our data are consistent with PrEP altering immunity differentially in the female genital tract compared with circulation in HSV-2+ women. Further study including comparison with HSV-2 negative women is needed to define the overall impact and mechanisms underlying these effects. These results point to the critical need to study the human mucosal compartment to characterize immune responses to mucosal infections.

Tenofovir alafenamide fumarate attenuates bleomycin-induced pulmonary fibrosis by upregulating the NS5ATP9 and TGF-β1/Smad3 signaling pathway

Background

Pulmonary fibrosis is a progressive and irreversible disease for which therapeutic options are currently limited. A recent in vivo study showed that tenofovir, a nucleotide analogue reverse transcriptase inhibitor, had direct antifibrotic effects on skin and liver fibrosis. Another study in vitro revealed that NS5ATP9 inhibited the activation of human hepatic stellate cells. Because of the similarity of fibrotic diseases, we hypothesized that tenofovir alafenamide fumarate (TAF), the prodrug of tenofovir, and NS5ATP9, is related to and plays a role in the suppression of pulmonary fibrosis.

Methods

We investigated the influence of NS5ATP9 on fibrosis in vitro. Human lung fibroblasts (HFL1) were transfected with short interfering RNAs or overexpression plasmids of NS5ATP9 before stimulation by human recombinant transforming growth factor-β1. The effect of TAF was evaluated in a bleomycin-induced fibrosis murine model. Male C57BL/6 mice were treated with bleomycin on day 0 by intratracheal injection and intragastrically administered TAF or vehicle. Left lung sections were fixed for histological analysis, while homogenates of the right lung sections and HFL1 cells were analyzed by western blotting and quantitative reverse transcription polymerase chain reaction.

Results

NS5ATP9 suppressed the activation of lung fibroblasts. Upregulation of collagen type 3 (α 1 chain) and α-smooth muscle actin was observed in HFL1 cells when NS5ATP9 was silenced, and vice-versa. TAF also showed anti-fibrotic effects in mice, as demonstrated by histological analysis of fibrosis and expression of extracellular matrix components in the lung sections. Additionally, TAF inhibited transforming growth factor-β1 and phosphorylated-Smad3 synthesis in HFL1 cells and the murine model, which was accompanied by upregulation of NS5ATP9.

Conclusions

Our results suggest that NS5ATP9 forms a negative feedback pathway in pulmonary fibrosis and TAF has anti-fibrotic properties as it upregulates the expression level of NS5ATP9. As TAF has been shown to be safe and well-tolerated in humans, TAF and NS5ATP9 may be useful for developing novel therapeutics for pulmonary fibrosis.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-1102-2) contains supplementary material, which is available to authorized users.

Tenofovir 1% vaginal gel for prevention of HIV-1 infection in women in South Africa (FACTS-001): a phase 3, randomised, double-blind, placebo-controlled trial

BACKGROUND

Young women in southern Africa have substantial risk of HIV acquisition. Female-controlled biomedical interventions are needed to mitigate this risk. We aimed to assess the safety and efficacy of a pericoitally applied tenofovir 1% gel.

METHODS

We did a phase 3, double-blind, randomised, placebo-controlled trial at nine community-based clinical trial sites in South Africa to evaluate the safety and efficacy of tenofovir 1% gel. Sexually active women who were HIV negative and aged 18-30 years were enrolled. Participants were randomly assigned (1:1) using sequential participant numbers to either tenofovir 1% gel or a placebo gel (one dose within 12 h before sex and one dose within 12 h after sex [BAT-24 regimen]), using dynamic permuted block sizes of 8 and 16 within each site. Women received monthly HIV-1 testing, risk reduction support, physical examinations, and product dispensing for up to 27 months. The primary efficacy outcome was incident HIV infection and the primary safety outcome was occurrence of grade 2-4 adverse events, both analysed in the modified intention-to-treat population. To assess the efficacy of tenofovir gel, the cumulative probability of HIV infection was calculated for each treatment using the Kaplan-Meier method. This trial is registered with ClinicalTrials.gov, number NCT01386294.

FINDINGS

From Oct 11, 2011, to Aug 29, 2014, 3844 women were screened, 2059 enrolled, and 2029 included in the primary analysis (1032 in the tenofovir group and 1027 in the placebo group); 39 (4%) in the tenofovir group and 36 (4%) in the placebo group were lost to follow-up. 123 HIV-1 infections occurred over 3036 woman-years of observation; 61 in the tenofovir group (HIV incidence 4·0 per 100 woman-years, 95% CI 3·1-5·2) and 62 in the placebo group (4·0 per 100 woman-years, 3·1-5·2; incidence rate ratio [IRR] 0·98, 95% CI 0·7-1·4). A higher incidence of grade 2 adverse events was observed in the tenofovir group than in the placebo group (IRR 1·09, 95% CI 1·0-1·2; p=0·02). The most common grade 2 or higher product-related adverse events were hypophosphataemia (n=22 for tenofovir vs n=22 for placebo), genital symptoms (n=6 for tenofovir vs n=2 for placebo), or elevated transaminases (n=2 for tenofovir vs n=2 for placebo). No product-related serious adverse events were reported, and no differences in product-related adverse events (p=0·78), grade 3 events (p=0·64), or grade 4 events (p=0·74) were observed between treatment groups.

INTERPRETATION

Overall, pericoital tenofovir gel did not prevent HIV-1 acquisition in this population of young women at risk of HIV infection in South Africa. Alternate safe and effective products that are less user dependent than this product or do not require high adherence are needed.

FUNDING

The US Agency for International Development (USAID), the Bill & Melinda Gates Foundation, and the South African Department of Science and Technology and Department of Health.

Repeated rectal application of a hyperosmolar lubricant is associated with microbiota shifts but does not affect PrEP drug concentrations: results from a randomized trial in men who have sex with men

INTRODUCTION

Oral pre-exposure prophylaxis (PrEP) with tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) is highly effective in preventing HIV infection among men who have sex with men (MSM). The effects of consistent personal lubricant use in the rectum on tissue PrEP drug concentrations and the rectal microbiota are unknown. We investigated rectal PrEP drug concentrations and the microbiota in MSM before and after repeated rectal application of a hyperosmolar lubricant.

METHODS

We randomized 60 HIV-negative MSM to apply 4 mL of hyperosmolar rectal lubricant daily (n = 20), take daily oral TDF/FTC (n = 19), or both (n = 21) for seven days. Blood, rectal biopsies and rectal secretions were collected via rigid sigmoidoscopy before and on day 8 after product use. Tenofovir (TFV) and FTC as well as their intracellular metabolites tenofovir-diphosphate (TFV-DP), FTC-triphosphate (FTC-TP) were measured by HPLC-mass spectrometry. Rectal mucosal microbiota was sequenced with 16S rRNA sequencing using Illumina MiSeq.

RESULTS

Seven days of lubricant application was not associated with differences in PrEP drug concentrations in rectal tissue or secretions. Lubricant use was associated with a decrease in the relative abundance of the Bacteroides genus (p = 0.01) and a non-significant increase in the Prevotella genus (p = 0.09) in the rectum. PrEP drug concentrations in rectal tissue and secretions were not associated with microbiota composition or diversity either before or after lubricant use.

CONCLUSIONS

Repeated rectal application of a hyperosmolar lubricant does not affect mucosal PrEP drug concentrations but is associated with changes in the rectal microbiome.

Sex Differences in HIV Infection: Mystique Versus Machismo

Biological sex is a determinant of both susceptibility to and pathogenesis of multiple infections, including HIV. These differences have effects on the spectrum of HIV disease from acquisition to eradication, with diverse mechanisms including distinct chromosomal complements, variation in microbiota composition, hormonal effects on transcriptional profiles, and expression of different immunoregulatory elements. With a comparative biology approach, these sex differences can be used to highlight protective and detrimental immune activation pathways, to identify strategies for effective prevention, treatment, and curative interventions.

The Antiviral Drug Arbidol Inhibits Zika Virus

There are many emerging and re-emerging globally prevalent viruses for which there are no licensed vaccines or antiviral medicines. Arbidol (ARB, umifenovir), used clinically for decades in several countries as an anti-influenza virus drug, inhibits many other viruses. In the current study, we show that ARB inhibits six different isolates of Zika virus (ZIKV), including African and Asian lineage viruses in multiple cell lines and primary human vaginal and cervical epithelial cells. ARB protects against ZIKV-induced cytopathic effects. Time of addition studies indicate that ARB is most effective at suppressing ZIKV when added to cells prior to infection. Moreover, ARB inhibits pseudoviruses expressing the ZIKV Envelope glycoprotein. Thus, ARB, a broadly acting anti-viral agent with a well-established safety profile, inhibits ZIKV, likely by blocking viral entry.

Sex Differences in HIV Infection

PURPOSE OF REVIEW

This review will outline the multilevel effects of biological sex on HIV acquisition, pathogenesis, treatment response, and prospects for cure. Potential mechanisms will be discussed along with future research directions.

RECENT FINDINGS

HIV acquisition risk is modified by sex hormones and the vaginal microbiome, with the latter acting through both inflammation and local metabolism of pre-exposure prophylaxis drugs. Female sex associates with enhanced risk for non-AIDS morbidities including cardiovascular and cerebrovascular disease, suggesting different inflammatory profiles in men and women. Data from research on HIV cure points to sex differences in viral reservoir dynamics and a direct role for sex hormones in latency maintenance. Biological sex remains an important variable in determining the risk of HIV infection and subsequent viral pathogenesis, and emerging data suggest sex differences relevant to curative interventions. Recruitment of women in HIV clinical research is a pathway to both optimize care for women and to identify novel therapeutics for use in both men and women.

Enrichment of herpes simplex virus type 2 (HSV-2) reactive mucosal T cells in the human female genital tract

Local mucosal cellular immunity is critical in providing protection from HSV-2. To characterize and quantify HSV-2-reactive mucosal T cells, lymphocytes were isolated from endocervical cytobrush and biopsy specimens from 17 HSV-2-infected women and examined ex vivo for the expression of markers associated with maturation and tissue residency and for functional T-cell responses to HSV-2. Compared with their circulating counterparts, cervix-derived CD4+ and CD8+ T cells were predominantly effector memory T cells (CCR7-/CD45RA-) and the majority expressed CD69, a marker of tissue residency. Co-expression of CD103, another marker of tissue residency, was highest on cervix-derived CD8+ T cells. Functional HSV-2 reactive CD4+ and CD8+ T-cell responses were detected in cervical samples and a median of 17% co-expressed CD103. HSV-2-reactive CD4+ T cells co-expressed IL-2 and were significantly enriched in the cervix compared with blood. This first direct ex vivo documentation of local enrichment of HSV-2-reactive T cells in the human female genital mucosa is consistent with the presence of antigen-specific tissue-resident memory T cells. Ex vivo analysis of these T cells may uncover tissue-specific mechanisms of local control of HSV-2 to assist the development of vaccine strategies that target protective T cells to sites of HSV-2 infection.

New anionic carbosilane dendrons functionalized with a DO3A ligand at the focal point for the prevention of HIV-1 infection

Novel third-generation polyanionic carbosilane dendrons with sulfonate or carboxylate end-groups and functionalized with a DO3A ligand at the focal point, and their corresponding copper complexes, have been prepared as antiviral compounds to prevent HIV-1 infection. The topology enables the compound to have an excellent chelating agent, DO3A, while keeping anionic peripheral groups for a therapeutic action. In this study, the cytotoxicity and anti-HIV-1 abilities of carboxylate- (5) or sulfonate-terminated (6) dendrons containing DO3A and their copper complexes (7 or 8) were evaluated. All compounds showed low cytotoxicity and demonstrated potent and broad-spectrum anti-HIV-1 activity in vitro. We also assessed the mode of antiviral action on the inhibition of HIV-1 through a panel of different in vitro antiviral assays. Our results show that copper-free dendron 6 protects the epithelial monolayer from short-term cell disruption. Copper-free dendrons 5 and 6 exert anti-HIV-1 activity at an early stage of the HIV-1 lifecycle by binding to the envelope glycoproteins of HIV-1 and by interacting with the CD4 cell receptor and blocking the binding of gp120 to CD4, and consequently HIV-1 entry. These findings show that copper-free dendrons 5 and 6 have a high potency against HIV-1 infection, confirming their non-specific ability and suggesting that these compounds deserve further study as potential candidate microbicides to prevent HIV-1 transmission.

Anti-proliferative therapy for HIV cure: a compound interest approach

In the era of antiretroviral therapy (ART), HIV-1 infection is no longer tantamount to early death. Yet the benefits of treatment are available only to those who can access, afford, and tolerate taking daily pills. True cure is challenged by HIV latency, the ability of chromosomally integrated virus to persist within memory CD4⁺ T cells in a non-replicative state and activate when ART is discontinued. Using a mathematical model of HIV dynamics, we demonstrate that treatment strategies offering modest but continual enhancement of reservoir clearance rates result in faster cure than abrupt, one-time reductions in reservoir size. We frame this concept in terms of compounding interest: small changes in interest rate drastically improve returns over time. On ART, latent cell proliferation rates are orders of magnitude larger than activation and new infection rates. Contingent on subtypes of cells that may make up the reservoir and their respective proliferation rates, our model predicts that coupling clinically available, anti-proliferative therapies with ART could result in functional cure within 2–10 years rather than several decades on ART alone.

Historical development of vaginal microbicides to prevent sexual transmission of HIV in women: from past failures to future hopes

Infection with human immunodeficiency virus (HIV) remains a global public health concern and is particularly serious in low- and middle-income countries. Widespread sexual violence and poverty, among other factors, increase the risk of infection in women, while currently available prevention methods are outside the control of most. This has driven the study of vaginal microbicides to prevent sexual transmission of HIV from men to women in recent decades. The first microbicides evaluated were formulated as gels for daily use and contained different substances such as surfactants, acidifiers and monoclonal antibodies, which failed to demonstrate efficacy in clinical trials. A gel containing the reverse transcriptase inhibitor tenofovir showed protective efficacy in women. However, the lack of adherence by patients led to the search for dosage forms capable of releasing the active principle for longer periods, and hence to the emergence of the vaginal ring loaded with dapivirine, which requires a monthly application and is able to reduce the sexual transmission of HIV. The future of vaginal microbicides will feature the use of alternative dosage forms, nanosystems for drug release and probiotics, which have emerged as potential microbicides but are still in the early stages of development. Protecting women with vaginal microbicide formulations would, therefore, be a valuable tool for avoiding sexual transmission of HIV.

Tenofovir Inhibits Wound Healing of Epithelial Cells and Fibroblasts from the Upper and Lower Human Female Reproductive Tract

Disruption of the epithelium in the female reproductive tract (FRT) is hypothesized to increase HIV infection risk by interfering with barrier protection and facilitating HIV-target cell recruitment. Here we determined whether Tenofovir (TFV), used vaginally in HIV prevention trials, and Tenofovir alafenamide (TAF), an improved prodrug of TFV, interfere with wound healing in the human FRT. TFV treatment of primary epithelial cells and fibroblasts from the endometrium (EM), endocervix (CX) and ectocervix (ECX) significantly delayed wound closure. Reestablishment of tight junctions was compromised in EM and CX epithelial cells even after wound closure occurred. In contrast, TAF had no inhibitory effect on wound closure or tight junction formation following injury. TAF accumulated inside genital epithelial cells as TFV-DP, the active drug form. At elevated levels of TAF treatment to match TFV intracellular TFV-DP concentrations, both equally impaired barrier function, while wound closure was more sensitive to TFV. Furthermore, TFV but not TAF increased elafin and MIP3a secretion following injury, molecules known to be chemotactic for HIV-target cells. Our results highlight the need of evaluating antiretroviral effects on genital wound healing in future clinical trials. A possible link between delayed wound healing and increased risk of HIV acquisition deserves further investigation.

Replication Capacity of Viruses from Acute Infection Drives HIV-1 Disease Progression

The viral genotype has been shown to play an important role in HIV pathogenesis following transmission. However, the viral phenotypic properties that contribute to disease progression remain unclear. Most studies have been limited to the evaluation of Gag function in the context of a recombinant virus backbone. Using this approach, important biological information may be lost, making the evaluation of viruses obtained during acute infection, representing the transmitted virus, a more biologically relevant model. Here, we evaluate the roles of viral infectivity and the replication capacity of viruses from acute infection in disease progression in women who seroconverted in the CAPRISA 004 tenofovir microbicide trial. We show that viral replication capacity, but not viral infectivity, correlates with the set point viral load (Spearman r = 0.346; P = 0.045) and that replication capacity (hazard ratio [HR] = 4.52; P = 0.01) can predict CD4 decline independently of the viral load (HR = 2.9; P = 0.004) or protective HLA alleles (HR = 0.61; P = 0.36). We further demonstrate that Gag-Pro is not the main driver of this association, suggesting that additional properties of the transmitted virus play a role in disease progression. Finally, we find that although viruses from the tenofovir arm were 2-fold less infectious, they replicated at rates similar to those of viruses from the placebo arm. This indicates that the use of tenofovir gel did not select for viral variants with higher replication capacity. Overall, this study supports a strong influence of the replication capacity in acute infection on disease progression, potentially driven by interaction of multiple genes rather than a dominant role of the major structural gene gagIMPORTANCE HIV disease progression is known to differ between individuals, and defining which fraction of this variation can be attributed to the virus is important both clinically and epidemiologically. In this study, we show that the replication capacity of viruses isolated during acute infection predicts subsequent disease progression and drives CD4 decline independently of the viral load. This provides further support for the hypothesis that the replication capacity of the transmitted virus determines the initial damage to the immune system, setting the pace for later disease progression. However, we did not find evidence that the major structural gene gag drives this correlation, highlighting the importance of other genes in determining disease progression.

Rectal 1% Tenofovir Gel Use Associates with Altered Epidermal Protein Expression

Rectal use of a 1% tenofovir (TFV) gel is currently being evaluated for HIV prevention. While careful assessment of mucosal safety of candidate microbicides is a primary concern, tools to assess mucosal toxicity are limited. Mass spectrometry-based proteomics is a sensitive and high-throughput technique that can provide in-depth information on inflammation processes in biological systems. In this study, we utilized a proteomics approach to characterize mucosal responses in study participants involved in a phase 1 clinical trial of a rectal TFV-based gel. Project Gel was a phase 1 randomized (1:1), double-blind, multisite, placebo-controlled trial in which 24 participants received rectal TFV or a universal placebo [hydroxyethyl cellulose (HEC)] over a course of 8 daily doses. Rectal mucosal swabs were collected after 0, 1, and 8 doses and were analyzed by label-free tandem mass spectrometry. Differential protein expression was evaluated using a combination of paired (time-effects) and unpaired (across study arm) t-tests, and multivariate [least absolute shrinkage and selection operator (LASSO)] modeling. Within the TFV arm, 7% (17/249, p < .05) and 10% (25/249, p < .05) of total proteins changed after 1 and 8 daily applications of TFV gel, respectively, compared to 3% (7/249, p < .05) and 6% (16/249, p < .05) in the HEC arm. Biofunctional analysis associated TFV use with a decrease in epidermal barrier proteins (adj. p = 1.21 × 10⁻¹⁰). Multivariate modeling identified 13 proteins that confidently separated TFV gel users (100% calibration and 96% cross-validation accuracy), including the epithelial integrity factors (FLMNB, CRNN, CALM), serpins (SPB13, SPB5), and cytoskeletal proteins (VILI, VIME, WRD1). This study suggested that daily rectal applications of a 1% TFV gel may be associated with mucosal proteome changes involving epidermal development. Further assessment of more extended use of TFV-gel is recommended to validate these initial associations.

Antiretroviral pre-exposure prophylaxis preferences among men who have sex with men in Vietnam: results from a nationwide cross-sectional survey

Background: The HIV/AIDS epidemic in Vietnam is concentrated in subgroups of the population, including men who have sex with men (MSM). Pre-exposure prophylaxis (PrEP) is a viable strategy for HIV prevention, but knowledge about and preferences for PrEP delivery among Vietnamese MSM are not well understood. Methods: In 2015, an online survey was conducted with recruitment via social networking websites for MSM and peer recruitment. A description of daily oral, long-acting injectable, and rectal microbicide formulations of PrEP was provided to participants. Participants were asked about their prior awareness of and interest in PrEP, and ranked their most preferred PrEP modality. Multivariable logistic regression models were used to assess factors associated with having heard of PrEP and preference for each PrEP modality. Results: Of 548 participants who answered demographic and PrEP-related questions, 26.8% had previously heard of PrEP and most (65.7%) endorsed rectal microbicides as their most preferred PrEP delivery modality. Commonly-cited perceived barriers to uptake of PrEP included concern about side-effects, perception about being HIV positive, and family or friends finding out about their sexual behaviour. In multivariable models, older participants less often endorsed rectal microbicides (adjusted odds ratio (AOR) 0.95 per year, 95% confidence interval (CI) 0.91-0.99) and more often endorsed long-acting injectables (AOR 1.08 per year, 95% CI 1.03 to 1.14) as their preferred PrEP modality. Participants who were willing to pay more for PrEP less often endorsed rectal microbicides (AOR 0.81, 95% CI 0.72-0.92) and more often endorsed long-acting injectables (AOR 1.17, 95% CI 1.01-1.35) and daily oral pills (AOR 1.16, 95% CI 1.00-1.35) as their preferred form of PrEP. Conclusions: A variety of PrEP modalities were acceptable to MSM in Vietnam, but low knowledge of PrEP may be a barrier to implementation.

Rationale and Safety Assessment of a Novel Intravaginal Drug-Delivery System with Sustained DL-Lactic Acid Release, Intended for Long-Term Protection of the Vaginal Microbiome

Bacterial vaginosis is a prevalent state of dysbiosis of the vaginal microbiota with wide-ranging impact on human reproductive health. Based on recent insights in community ecology of the vaginal microbiome, we hypothesize that sustained vaginal DL-lactic acid enrichment will enhance the recruitment of lactobacilli, while counteracting bacterial vaginosis-associated bacteria. We therefore aimed to develop an intravaginal device that would be easy to insert and remove, while providing sustained DL-lactic acid release into the vaginal lumen. The final prototype selected is a vaginal ring matrix system consisting of a mixture of ethylene vinyl acetate and methacrylic acid-methyl methacrylate copolymer loaded with 150 mg DL-lactic acid with an L/D-lactic acid ratio of 1:1. Preclinical safety assessment was performed by use of the Slug Mucosal Irritation test, a non-vertebrate assay to evaluate vaginal mucosal irritation, which revealed no irritation. Clinical safety was evaluated in a phase I trial with six healthy nulliparous premenopausal volunteering women, with the investigational drug left in place for 7 days. Colposcopic monitoring according to the WHO/CONRAD guidelines for the evaluation of vaginal products, revealed no visible cervicovaginal mucosal changes. No adverse events related to the investigational product occurred. Total release from the intravaginal ring over 7 days was estimated through high performance liquid chromatography at 37.1 (standard deviation 0.9) mg DL-lactic acid. Semisolid lactic acid formulations have been studied to a limited extent in the past and typically consist of a large volume of excipients and very high doses of lactic acid, which is of major concern to mucosal safety. We have documented the feasability of enriching the vaginal environment with pure DL-lactic acid with a prototype intravaginal ring. Though the efficacy of this platform remains to be established possibly requiring further development, this approach may offer a novel avenue to modulate and protect the vaginal microbiota.

A new hypothesis on HIV cure

In this opinion article, I provide the rationale for my hypothesis that nucleoside reverse transcriptase inhibitors (NRTIs) may prevent human immunodeficiency virus (HIV) cure by promoting the survival of cells with integrated provirus. If correct, we may be closer to a cure than we realize.