HIV dynamics in seminal plasma during primary HIV infection

Viral Load Dynamics in Plasma and Semen When Antiretroviral Therapy Is Initiated During Early HIV-1 Infection

We assessed human immunodeficiency virus (HIV) load in plasma and semen during primary HIV infection using serial samples of semen and plasma during the first 24 weeks after diagnosis in untreated participants and those who started antiretroviral therapy (ART) immediately at diagnosis. In the absence of treatment, semen viral load was >1000 copies/mL in almost all specimens (83%) collected 2-10 weeks after the estimated date of HIV acquisition and remained >1000 copies/mL in 35% of untreated participants at the last observed time point. Thus, in the absence of ART, semen viral load remained at a level consistent with transmissibility throughout primary infection.

HIV-1-RNA and total HIV-1-DNA loads in the genital compartment in men receiving dolutegravir- versus darunavir-based combined ART (cART) regimens during primary HIV infection

BACKGROUND

Dolutegravir is a widespread integrase strand-transfer inhibitor (INSTI) recommended for treatment of primary HIV infection (PHI). PHI is a high-risk stage for sexual transmission because of the high viral load in semen. Yet dolutegravir concentrations in semen are lower than in blood during chronic treatment.

OBJECTIVES

To compare the kinetics of HIV-RNA and total HIV-DNA in the genital compartment in subjects receiving either tenofovir/emtricitabine/dolutegravir or tenofovir/emtricitabine/darunavir/cobicistat as a first-line combined ART (cART) at the time of PHI.

PATIENTS AND METHODS

Eighteen subjects receiving tenofovir/emtricitabine/dolutegravir and 19 receiving tenofovir/emtricitabine/darunavir/cobicistat enrolled in the ANRS169 OPTIPRIM-2 trial participated in the genital substudy.

RESULTS

Between week (W) 0 and W2 HIV-RNA in seminal plasma (SP) decreased by 1 log10 copies/mL. Undetectable SP HIV-RNA was achieved in similar proportions between the two regimens at each timepoint. Overall, eight patients still presented detectable HIV-RNA or HIV-DNA in semen at W48; 15.4% and 28.6% presented detectable HIV-RNA and 9.1% and 14.3% presented detectable HIV-DNA in dolutegravir- and darunavir-based cART groups, respectively, with no significant difference.

CONCLUSIONS

For the first time, to the best of our knowledge, we showed that a dolutegravir-based regimen initiated as soon as PHI reduces HIV-RNA and HIV-DNA with no difference compared with a control group receiving a darunavir-based regimen. Although the viral purge in semen seems longer after treatment in PHI than CHI, due to high viral loads, early dolutegravir-based treatment initiation permits a major decay of both viral particles and infected cells in semen, efficiently reducing the high risk of transmission during PHI.

Could SARS-CoV-2 affect male fertility?

We performed this systematic review to evaluate the possibility of an impact of SARS-CoV-2 infection on male fertility. SARS-CoV-2 enters the cells with the help of ACE2; therefore, testicular expression of ACE2 was analysed from transcriptome sequencing studies and our unpublished data. Literature suggested that SARS-CoV-1 (2002-2004 SARS) had a significant adverse impact on testicular architecture, suggesting a high possibility of the impact of SARS-CoV-2 as well. Out of two studies on semen samples from COVID-19 affected patients, one reported the presence of SARS-CoV-2 in the semen samples while the other denied it, raising conflict about its presence in the semen samples and the possibility of sexual transmission. Our transcriptome sequencing studies on rat testicular germ cells showed ACE expression in rat testicular germ cells. We also found ACE2 expression in transcriptome sequencing data for human spermatozoa, corroborating its presence in the testicular germ cells. Transcriptome sequencing data from literature search revealed ACE2 expression in the germ, Sertoli and Leydig cells. The presence of ACE2 on almost all testicular cells and the report of a significant impact of previous SARS coronavirus on testes suggest that SARS-CoV-2 is highly likely to affect testicular tissue, semen parameters and male fertility.

Resting-state neural signatures of depressive symptoms in acute HIV

Depressive symptoms are often elevated in acute and chronic HIV. Previous neuroimaging research identifies abnormalities in emotion-related brain regions in depression without HIV, including the anterior cingulate cortex (ACC) and amygdala. However, no studies have examined the neural signatures of depressive symptoms in acute HIV infection (AHI). Seed-based voxelwise resting-state functional connectivity (rsFC) for affective seed regions of interest (pregenual ACC, subgenual ACC [sgACC], bilateral amygdala) was computed for 74 Thai males with AHI and 30 Thai HIV-uninfected controls. Group analyses compared rsFC of ACC and amygdala seed regions between AHI and uninfected control groups. Within the AHI group, voxelwise regression analyses investigated the relationship between depressive symptoms and rsFC for these affective seed regions. Group analyses revealed alterations in rsFC of the amygdala in AHI versus uninfected controls. Depressive symptoms associated with decreased rsFC between ACC regions and posterior cingulate/precuneus, medial temporal, and lateral parietal regions in AHI. Symptoms of depression also correlated to increased rsFC between ACC regions and lateral prefrontal cortex, sgACC, and cerebellum in AHI. Similar to the ACC, depressive symptoms associated with decreased rsFC between amygdala and precuneus. Of blood biomarkers, only HIV RNA inversely correlated with rsFC between posterior sgACC and left uncus. We found that depressive symptoms in AHI associate with altered rsFC of ACC and amygdala regions previously implicated in depression. Longitudinal research in this cohort will be necessary to determine whether these early alterations in rsFC of affective network regions are related to persistent depressive symptoms after combination antiretroviral therapy.

HIV persists throughout deep tissues with repopulation from multiple anatomical sources

BACKGROUNDUnderstanding HIV dynamics across the human body is important for cure efforts. This goal has been hampered by technical difficulties and the challenge of obtaining fresh tissues.METHODSThis observational study evaluated 6 individuals with HIV (n = 4 with viral suppression using antiretroviral [ART] therapy; n = 2 with rebound viremia after stopping ART), who provided serial blood samples before death and their bodies for rapid autopsy. HIV reservoirs were characterized by digital droplet PCR, single-genome amplification, and sequencing of full-length (FL) envelope HIV. Phylogeographic methods were used to reconstruct HIV spread, and generalized linear models were tested for viral factors associated with dispersal.RESULTSAcross participants, HIV DNA levels varied from approximately 0 to 659 copies/106 cells (IQR: 22.9-126.5). A total of 605 intact FL env sequences were recovered in antemortem blood cells and across 28 tissues (IQR: 5-9). Sequence analysis showed (a) the emergence of large, identical, intact HIV RNA populations in blood after cessation of therapy, which repopulated tissues throughout the body; (b) that multiple sites acted as hubs for HIV dissemination but that blood and lymphoid tissues were the main source; (c) that viral exchanges occurred within brain areas and across the blood-brain barrier; and (d) that migration was associated with low HIV divergence between sites and greater diversity at the recipient site.CONCLUSIONHIV reservoirs persisted in all deep tissues, and blood was the main source of dispersal. This may explain why eliminating HIV susceptibility in circulating T cells via bone marrow transplants allowed some individuals with HIV to experience therapy-free remission, even though deeper tissue reservoirs were not targeted.TRIAL REGISTRATIONNot applicable.FUNDINGNIH grants P01 AI31385, P30 AI036214, AI131971-01, AI120009AI036214, HD094646, AI027763, AI134295, and AI68636.

Characterization of HIV-1 diversity in various compartments at the time of primary infection by ultradeep sequencing

We used next-generation sequencing to evaluate the quantity and genetic diversity of the HIV envelope gene in various compartments in eight patients with acute infection. Plasma (PL) and seminal fluid (SF) were available for all patients, whole blood (WB) for seven, non-spermatozoid cells (NSC) for four, and saliva (SAL) for three. Median HIV-1 RNA was 6.2 log10 copies/mL [IQR: 5.5-6.95] in PL, 4.9 log10 copies/mL [IQR: 4.25-5.29] in SF, and 4.9 log10 copies/mL [IQR: 4.46-5.09] in SAL. Median HIV-1 DNA was 4.1 log10 copies/106 PBMCs [IQR: 3.15-4.15] in WB and 2.6 log10 copies /106 Cells [IQR: 2.23-2.75] in NSC. The median overall diversity per patient varied from 0.0005 to 0.0232, suggesting very low diversity, confirmed by the clonal aspect of most of the phylogenetic trees. One single haplotype was present in all compartments for five patients in the earliest stage of infection. Evidence of higher diversity was established for two patients in PL and WB, suggesting compartmentalization. Our study shows low diversity of the env gene in the first stages of infection followed by the rapid establishment of cellular reservoirs of the virus. Such clonality could be exploited in the search for early patient-specific therapeutic solutions.

Comparisons of Human Immunodeficiency Virus Type 1 Envelope Variants in Blood and Genital Fluids near the Time of Male-to-Female Transmission

To better understand the transmission of human immunodeficiency virus type 1 (HIV-1), the genetic characteristics of blood and genital viruses from males were compared to those of the imputed founding virus population in their female partners. Initially serodiscordant heterosexual African couples with sequence-confirmed male-to-female HIV-1 transmission and blood and genital specimens collected near the time of transmission were studied. Single viral templates from blood plasma and genital tract RNA and DNA were sequenced across HIV-1 env gp160. Eight of 29 couples examined yielded viral sequences from both tissues. Analysis of these couples' sequences demonstrated, with one exception, that the women's founding viral populations arose from a single viral variant and were CCR5 tropic, even though CXCR4 variants were detected within four males. The median genetic distance of the imputed most recent common ancestor of the women's founder viruses showed that they were closer to the semen viruses than to the blood viruses of their transmitting male partner, but this finding was biased by detection of a greater number of viral clades in the blood. Using multiple assays, the blood and genital viruses were consistently found to be compartmentalized in only two of eight men. No distinct amino acid signatures in the men's viruses were found to link to the women's founders, nor did the women's env sequences have shorter variable loops or fewer N-linked glycosylation sites. The lack of selective factors, except for coreceptor tropism, is consistent with others' findings in male-to-female and high-risk transmissions. The infrequent compartmentalization between the transmitters' blood and semen viruses suggests that cell-free blood virus likely includes HIV-1 sequences representative of those of viruses in semen.IMPORTANCE Mucosal transmissions account for the majority of HIV-1 infections. Identification of the viral characteristics associated with transmission would facilitate vaccine design. This study of HIV strains from transmitting males and their seroconverting female partners found that the males' genital tract viruses were rarely distinct from the blood variants. The imputed founder viruses in women were genetically similar to both the blood and genital tract variants of their male partners, indicating a lack of evidence for genital tract-specific lineages. These findings suggest that targeting vaccine responses to variants found in blood are likely to also protect from genital tract variants.

Zika Virus Trafficking and Interactions in the Human Male Reproductive Tract

Sexual transmission of Zika virus (ZIKV) is a matter of great concern. Infectious viral particles can be shed in semen for as long as six months after infection and can be transferred to male and female sexual partners during unprotected sexual intercourse. The virus can be found inside spermatozoa and could be directly transferred to the oocyte during fertilization. Sexual transmission of ZIKV can contribute to the rise in number of infected individuals in endemic areas as well as in countries where the mosquito vector does not thrive. There is also the possibility, as has been demonstrated in mouse models, that the vaginal deposition of ZIKV particles present in semen could lead to congenital syndrome. In this paper, we review the current literature to understand ZIKV trafficking from the bloodstream to the human male reproductive tract and viral interactions with host cells in interstitial spaces, tubule walls, annexed glands and semen. We hope to highlight gaps to be filled by future research and potential routes for vaccine and antiviral development.

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.

Transmission of HIV-1 drug resistance mutations within partner-pairs: A cross-sectional study of a primary HIV infection cohort

BACKGROUND

Transmission of human immunodeficiency virus type 1 (HIV-1) drug resistance mutations, particularly that of minority drug-resistant variants, remains poorly understood. Population-based studies suggest that drug-resistant HIV-1 is less transmissible than drug-susceptible viruses. We compared HIV-1 drug-resistant genotypes among partner-pairs in order to assess the likelihood of transmission of drug resistance mutations and investigate the role of minority variants in HIV transmission.

METHODS AND FINDINGS

From 1992-2010, 340 persons with primary HIV-1 infection and their partners were enrolled into observational research studies at the University of Washington Primary Infection Clinic (UWPIC). Out of 50 partner-pairs enrolled, 36 (72%) transmission relationships were confirmed by phylogenetic distance analysis of HIV-1 envelope (env) sequences, and 31 partner-pairs enrolled after 1995 met criteria for this study. Drug resistance mutations in the region of the HIV-1 polymerase gene (pol) that encodes protease and reverse transcriptase were assessed by 454-pyrosequencing. In 25 partner-pairs where the transmission direction could be determined, 12 (48%) transmitters had 1-4 drug resistance mutations (23 total) detected in their HIV-1 populations at a median frequency of 6.0% (IQR 1.5%-98.7%, range 1.0%-99.6%). Of 10 major mutations detected in five transmitters at a frequency >95%, 100% (95% CI 69.2%-100%) were detected in recipients. All of these transmitters were antiretroviral (ARV)-naïve at the time of specimen collection. Fourteen mutations (eight major mutations and six accessory mutations) were detected in nine transmitters at low frequencies (1.0%-11.8%); four of these transmitters had previously received ARV therapy. Two (14% [95% CI 1.8%-42.8%]) G73S accessory mutations were detected in both transmitter and recipient. This number is not significantly different from the number expected based on the observed frequencies of drug-resistant viruses in transmitting partners. Limitations of this study include the small sample size and uncertainties in determining the timing of virus transmission and mutation history.

CONCLUSIONS

Drug-resistant majority variants appeared to be commonly transmitted by ARV-naïve participants in our analysis and may contribute significantly to transmitted drug resistance on a population level. When present at low frequency, no major mutation was observed to be shared between partner-pairs; identification of accessory mutations shared within a pair could be due to transmission, laboratory artifact, or apolipoprotein B mRNA-editing enzyme, catalytic polypeptides (APOBECs), and warrants further study.

Heterogeneity of HIV-1 Replication in Ectocervical and Vaginal Tissue Ex Vivo

In clinical trials evaluating HIV-1 prevention products, ex vivo exposure of mucosal tissue to HIV-1 is performed to inform drug levels needed to suppress viral infection. Understanding assay and participant variables that influence HIV-1 replication will help with assay implementation. Demographic and behavioral data were obtained from 61 healthy women aged 21-45. Paired cervical tissue (CT) and vaginal tissue (VT) biopsies were collected and treated with HIV-1_BaL or HIV-1_JR-CSF, washed, and cultured. On days 3, 7, and/or 11, culture supernatant was collected, and viral replication was monitored by p24 ELISA. Tissue was extracted at study end, and HIV-1 relative RNA copies were determined by polymerase chain reaction. Cumulative p24 and RNA were log-transformed and analyzed using a linear mixed model, t-test, and an intraclass correlation coefficient (ICC). HIV replication was similar between CT and VT for each virus, but HIV-1_BaL had 1.5 log₁₀ and 0.9 log₁₀ higher levels of p24 than HIV-1_JR-CSF in CT and VT, respectively (p < .001), which correlated with HIV-1 relative RNA copies. Cumulative p24 and RNA copies in both tissues demonstrated low intraperson correlation for both viruses (ICC ≤0.513 HIV-1_BaL; ICC ≤0.419 HIV-1_JR-CSF). Enrollment into previous clinical studies in which genital biopsies were collected modestly decreased the HIV-1_BaL cumulative p24 for CT, but not for VT. To improve the ex vivo challenge assay, viruses should be evaluated for replication in mucosal tissue before study implementation, baseline mucosal tissue is not needed if a placebo/no treatment group is included within the clinical trial, and previous biopsy sites should be avoided.

Impact of early cART on HIV blood and semen compartments at the time of primary infection

BACKGROUND

HIV-infected cells in semen facilitate viral transmission. We studied the establishment of HIV reservoirs in semen and blood during PHI, along with systemic immune activation and the impact of early cART.

METHODS

Patients in the ANRS-147-OPTIPRIM trial received two years of early cART. Nineteen patients of the trial were analyzed, out of which 8 had acute PHI (WB ≤1 Ab). We quantified total cell-associated (ca) HIV-DNA in blood and semen and HIV-RNA in blood and semen plasma samples, collected during PHI and at 24 months of treatment.

RESULTS

At enrollment, HIV-RNA load was higher in blood than in semen (median 5.66 vs 4.22 log10 cp/mL, p<0.0001). Semen HIV-RNA load correlated strongly with blood HIV-RNA load (r = 0.81, p = 0.02, the CD4 cell count (r = -0.98, p<0.0001), and the CD4/CD8 ratio (r = -0.85, p<0.01) in acute infection but not in later stages of PHI. Median blood and seminal cellular HIV-DNA levels were 3.59 and 0.31 log10cp/106 cells, respectively. HIV-DNA load peaked in semen later than in blood and then correlated with blood IP10 level (r = 0.62, p = 0.04). HIV-RNA was undetectable in blood and semen after two years of effective cART. Semen HIV-DNA load declined similarly, except in one patient who had persistently high IP-10 and IL-6 levels and used recreational drugs.

CONCLUSIONS

HIV reservoir cells are found in semen during PHI, with gradual compartmentalization. Its size was linked to the plasma IP-10 level. Early treatment purges both the virus and infected cells, reducing the high risk of transmission during PHI.

CLINICAL TRIALS REGISTRATION

NCT01033760.

HIV Trafficking Between Blood and Semen During Early Untreated HIV Infection

BACKGROUND

Understanding the dynamics of HIV across anatomic compartments is important to design effective eradication strategies. In this study, we evaluated viral trafficking between blood and semen during primary HIV infection in 6 antiretroviral-naive men who have sex with men.

METHODS

Deep sequencing data of HIV env were generated from longitudinal blood plasma, peripheral blood mononuclear cells, and seminal plasma samples. The presence or absence of viral compartmentalization was assessed using tree-based Slatkin-Maddison and distance-based Fst methods. Phylogeographic analyses were performed using a discrete Bayesian asymmetric approach of diffusion with Markov jump count estimation to evaluate the gene flow between blood and semen during primary HIV infection. Levels of DNA from human herpesviruses and selected inflammatory cytokines were also measured on genital secretions collected at baseline to evaluate potential correlates of increased viral migration between anatomic compartments.

RESULTS

We detected varying degrees of compartmentalization in all 6 individuals evaluated. None of them maintained viral compartmentalization between blood and seminal plasma throughout the analyzed time points. Phylogeographic analyses revealed that the HIV population circulating in blood plasma populated the seminal compartment during the earliest stages of infection. In our limited data set, we found no association between local inflammation or herpesvirus shedding at baseline and viral trafficking between semen and blood.

CONCLUSIONS

The early spread of virus from blood plasma to genital tract and the complex viral interplay between these compartments suggest that viral eradication efforts will require monitoring viral subpopulations in anatomic sites and viral trafficking during the course of infection.

HIV RNA and proviral HIV DNA can be detected in semen after 6 months of antiretroviral therapy although HIV RNA is undetectable in blood

The risk of sexual transmission of HIV is strongly correlated with amounts of genital HIV RNA. Few studies have reported amounts of HIV RNA and HIV DNA in semen in HIV-infected Chinese patients undergoing antiviral treatment (ART). In this observational study, the amounts of HIV RNA and HIV DNA in semen were assessed after six months of ART in HIV-infected Chinese individuals, when HIV RNA was undetectable in blood . This study included 19 HIV-infected Chinese men undergoing ART for six months. Amounts of HIV in paired semen and blood samples were assessed using real-time PCR. The C2-V5 region of the HIV envelope (env) genes was cloned and sequenced and genotype and co-receptor usage predicted based on the sequence. It was found that HIV RNA was undetectable in the plasma of most patients (17/19), whereas HIV RNA could be detected in the semen of most patients (16/19). HIV DNA could be detected in both semen and blood. Genetic diversity of HIV between the seminal and blood compartments was identified. Thus, amounts of HIV RNA and HIV DNA remain high in semen of HIV-infected Chinese patients after six months of ART treatment, even when HIV RNA was undetectable in blood.

Cell-to-Cell Spread of HIV and Viral Pathogenesis

Human immunodeficiency virus type 1 (HIV-1) gives rise to a chronic infection that progressively depletes CD4(+) T lymphocytes. CD4(+) T lymphocytes play a central coordinating role in adaptive cellular and humoral immune responses, and to do so they migrate and interact within lymphoid compartments and at effector sites to mount immune responses. While cell-free virus serves as an excellent prognostic indicator for patient survival, interactions of infected T cells or virus-scavenging immune cells with uninfected T cells can greatly enhance viral spread. HIV can induce interactions between infected and uninfected T cells that are triggered by cell surface expression of viral Env, which serves as a cell adhesion molecule that interacts with CD4 on the target cell, before it acts as the viral membrane fusion protein. These interactions are called virological synapses and promote replication in the face of selective pressure of humoral immune responses and antiretroviral therapy. Other infection-enhancing cell-cell interactions occur between virus-concentrating antigen-presenting cells and recipient T cells, called infectious synapses. The exact roles that these cell-cell interactions play in each stage of infection, from viral acquisition, systemic dissemination, to chronic persistence are still being determined. Infection-promoting immune cell interactions are likely to contribute to viral persistence and enhance the ability of HIV-1 to evade adaptive immune responses.

Fitness-Balanced Escape Determines Resolution of Dynamic Founder Virus Escape Processes in HIV-1 Infection

To understand the interplay between host cytotoxic T-lymphocyte (CTL) responses and the mechanisms by which HIV-1 evades them, we studied viral evolutionary patterns associated with host CTL responses in six linked transmission pairs. HIV-1 sequences corresponding to full-length p17 and p24 gag were generated by 454 pyrosequencing for all pairs near the time of transmission, and seroconverting partners were followed for a median of 847 days postinfection. T-cell responses were screened by gamma interferon/interleukin-2 (IFN-γ/IL-2) FluoroSpot using autologous peptide sets reflecting any Gag variant present in at least 5% of sequence reads in the individual's viral population. While we found little evidence for the occurrence of CTL reversions, CTL escape processes were found to be highly dynamic, with multiple epitope variants emerging simultaneously. We found a correlation between epitope entropy and the number of epitope variants per response (r = 0.43; P = 0.05). In cases in which multiple escape mutations developed within a targeted epitope, a variant with no fitness cost became fixed in the viral population. When multiple mutations within an epitope achieved fitness-balanced escape, these escape mutants were each maintained in the viral population. Additional mutations found to confer escape but undetected in viral populations incurred high fitness costs, suggesting that functional constraints limit the available sites tolerable to escape mutations. These results further our understanding of the impact of CTL escape and reversion from the founder virus in HIV infection and contribute to the identification of immunogenic Gag regions most vulnerable to a targeted T-cell attack.

IMPORTANCE

Rapid diversification of the viral population is a hallmark of HIV-1 infection, and understanding the selective forces driving the emergence of viral variants can provide critical insight into the interplay between host immune responses and viral evolution. We used deep sequencing to comprehensively follow viral evolution over time in six linked HIV transmission pairs. We then mapped T-cell responses to explore if mutations arose due to adaption to the host and found that escape processes were often highly dynamic, with multiple mutations arising within targeted epitopes. When we explored the impact of these mutations on replicative capacity, we found that dynamic escape processes only resolve with the selection of mutations that conferred escape with no fitness cost to the virus. These results provide further understanding of the complicated viral-host interactions that occur during early HIV-1 infection and may help inform the design of future vaccine immunogens.

Anogenital HIV RNA in Thai men who have sex with men in Bangkok during acute HIV infection and after randomization to standard vs. intensified antiretroviral regimens

INTRODUCTION

HIV transmission risk is highest during acute HIV infection (AHI). We evaluated HIV RNA in the anogenital compartment in men who have sex with men (MSM) during AHI and compared time to undetectable HIV RNA after three-drug versus five-drug antiretroviral therapy (ART) to understand risk for onward HIV transmission.

METHODS

MSM with AHI (n=54) had blood, seminal plasma and anal lavage collected for HIV RNA at baseline, days 3 and 7, and weeks 2, 4, 12 and 24. Data were compared between AHI stages: 1 (fourth-generation antigen-antibody combo immunoassay [IA]-, third-generation IA-, n=15), 2 (fourth-generation IA+, third-generation IA-, n=9) and 3 (fourth-generation IA+, third-generation IA+, western blot-/indeterminate, n=30) by randomization to five-drug (tenofovir+emtricitabine+efavirenz+raltegravir+maraviroc, n=18) versus three-drug (tenofovir+emtricitabine+efavirenz, n=18) regimens.

RESULTS

Mean age was 29 years and mean duration since HIV exposure was 15.4 days. Mean baseline HIV RNA was 5.5 in blood, 3.9 in seminal plasma and 2.6 log10 copies/ml in anal lavage (p<0.001). Blood and seminal plasma HIV RNA were higher in AHI Stage 3 compared to Stage 1 (p<0.01). Median time from ART initiation to HIV RNA <50 copies/ml was 60 days in blood, 15 days in seminal plasma and three days in anal lavage. Compared with the three-drug ART, the five-drug ART had a shorter time to HIV RNA <1500 copies/ml in blood (15 vs. 29 days, p=0.005) and <50 copies/ml in seminal plasma (13 vs. 24 days, p=0.048).

CONCLUSIONS

Among MSM with AHI, HIV RNA was highest in blood, followed by seminal plasma and anal lavage. ART rapidly reduced HIV RNA in all compartments, with regimen intensified by raltegravir and maraviroc showing faster HIV RNA reductions in blood and seminal plasma.

HIV reservoir dynamics in the face of highly active antiretroviral therapy

Upon discontinuation of highly active antiretroviral therapy (HAART), human immunodeficiency virus (HIV)-infected individuals experience a brisk rebound in blood plasma viremia due to the exodus of HIV from various body reservoirs. Assessment of HIV dynamics during HAART and following treatment discontinuation is essential to better understand HIV persistence. Here we will first provide a brief overview of the molecular mechanisms involved in HIV reservoir formation and persistence. After a summary of HAART-mediated HIV decay within peripheral blood, we discuss findings from clinical studies examining the effects of HAART initiation and interruption on HIV reservoir dynamics in major anatomical compartments, including lymph nodes and spleen, gut associated lymphoid tissue, reproductive organs, the central nervous system, and the lungs. Features contributing to these reservoirs as distinct compartments, including anatomical features, the presence of drug transporters, and the effect of co-infection, are also discussed.

The semen microbiome and its relationship with local immunology and viral load in HIV infection

Semen is a major vector for HIV transmission, but the semen HIV RNA viral load (VL) only correlates moderately with the blood VL. Viral shedding can be enhanced by genital infections and associated inflammation, but it can also occur in the absence of classical pathogens. Thus, we hypothesized that a dysregulated semen microbiome correlates with local HIV shedding. We analyzed semen samples from 49 men who have sex with men (MSM), including 22 HIV-uninfected and 27 HIV-infected men, at baseline and after starting antiretroviral therapy (ART) using 16S rRNA gene-based pyrosequencing and quantitative PCR. We studied the relationship of semen bacteria with HIV infection, semen cytokine levels, and semen VL by linear regression, non-metric multidimensional scaling, and goodness-of-fit test. Streptococcus, Corynebacterium, and Staphylococcus were common semen bacteria, irrespective of HIV status. While Ureaplasma was the more abundant Mollicutes in HIV-uninfected men, Mycoplasma dominated after HIV infection. HIV infection was associated with decreased semen microbiome diversity and richness, which were restored after six months of ART. In HIV-infected men, semen bacterial load correlated with seven pro-inflammatory semen cytokines, including IL-6 (p = 0.024), TNF-α (p = 0.009), and IL-1b (p = 0.002). IL-1b in particular was associated with semen VL (r² = 0.18, p = 0.02). Semen bacterial load was also directly linked to the semen HIV VL (r² = 0.15, p = 0.02). HIV infection reshapes the relationship between semen bacteria and pro-inflammatory cytokines, and both are linked to semen VL, which supports a role of the semen microbiome in HIV sexual transmission.

The classical paradigm of HIV infectivity centers on the blood HIV RNA viral load. However, while other fluid compartments such as semen and cerebrospinal fluid can have distinct viral loads from blood, the causes of localized HIV shedding are not fully understood. Since the semen viral load is an independent predictor of HIV transmission risk, it is critical to understand the local factors that trigger increased semen viral shedding in order to develop novel preventative strategies. Here, we evaluated the semen microbiome, bacterial load, and cytokine levels in 22 HIV-uninfected men who have sex with men (MSM) and in 27 HIV-infected MSM before and after initiation of antiretroviral therapy (ART). We found that HIV infection reduces semen microbiome biodiversity, which is restored with ART and immune reconstitution. We also found that semen bacterial load in untreated, HIV-infected men is associated with the levels of seven semen cytokines, relationships not seen in the uninfected controls. In particular, the cytokine IL-1b was uniquely correlated with both semen bacterial and viral load. Our findings support the interaction between semen microbiome and local immunology, and suggest that IL-1b could be a mechanism for semen microbiome to trigger semen viral shedding.

Increased sequence coverage through combined targeting of variant and conserved epitopes correlates with control of HIV replication

A major challenge in the development of an HIV vaccine is that of contending with the extensive sequence variability found in circulating viruses. Induction of HIV-specific T-cell responses targeting conserved regions and induction of HIV-specific T-cell responses recognizing a high number of epitope variants have both been proposed as strategies to overcome this challenge. We addressed the ability of cytotoxic T lymphocytes from 30 untreated HIV-infected subjects with and without control of virus replication to recognize all clade B Gag sequence variants encoded by at least 5% of the sequences in the Los Alamos National Laboratory HIV database (1,300 peptides) using gamma interferon and interleukin-2 (IFN-γ/IL-2) FluoroSpot analysis. While targeting of conserved regions was similar in the two groups (P = 0.47), we found that subjects with control of virus replication demonstrated marginally lower recognition of Gag epitope variants than subjects with normal progression (P = 0.05). In viremic controllers and progressors, we found variant recognition to be associated with viral load (r = 0.62, P = 0.001). Interestingly, we show that increased overall sequence coverage, defined as the overall proportion of HIV database sequences targeted through the Gag-specific repertoire, is inversely associated with viral load (r = -0.38, P = 0.03). Furthermore, we found that sequence coverage, but not variant recognition, correlated with increased recognition of a panel of clade B HIV founder viruses (r = 0.50, P = 0.004). We propose sequence coverage by HIV Gag-specific immune responses as a possible correlate of protection that may contribute to control of virus replication. Additionally, sequence coverage serves as a valuable measure by which to evaluate the protective potential of future vaccination strategies.

Efficiency of cell-free and cell-associated virus in mucosal transmission of human immunodeficiency virus type 1 and simian immunodeficiency virus

Effective strategies are needed to block mucosal transmission of human immunodeficiency virus type 1 (HIV-1). Here, we address a crucial question in HIV-1 pathogenesis: whether infected donor mononuclear cells or cell-free virus plays the more important role in initiating mucosal infection by HIV-1. This distinction is critical, as effective strategies for blocking cell-free and cell-associated virus transmission may be different. We describe a novel ex vivo model system that utilizes sealed human colonic mucosa explants and demonstrate in both the ex vivo model and in vivo using the rectal challenge model in rhesus monkeys that HIV-1-infected lymphocytes can transmit infection across the mucosa more efficiently than cell-free virus. These findings may have significant implications for our understanding of the pathogenesis of mucosal transmission of HIV-1 and for the development of strategies to prevent HIV-1 transmission.

Compartmentalization and antiviral effect of efavirenz metabolites in blood plasma, seminal plasma, and cerebrospinal fluid

Efavirenz (EFV) is one of the most commonly prescribed antiretrovirals for use in the treatment of human immunodeficiency virus (HIV) infection. EFV is extensively metabolized by cytochrome P450 to a number of oxygenated products; however, the pharmacologic activity and distribution of these metabolites in anatomic compartments have yet to be explored. The systemic distribution of EFV oxidative metabolites was examined in blood plasma, seminal plasma, and cerebrospinal fluid from subjects on an EFV-based regimen. The 8-hydroxy EFV metabolite was detected in blood plasma, seminal plasma, and cerebrospinal fluid, with median concentrations of 314.5 ng/ml, 358.5 ng/ml, and 3.37 ng/ml, respectively. In contrast, 7-hydroxy and 8,14-hydroxy EFV were only detected in blood plasma and seminal plasma with median concentrations of 8.84 ng/ml and 10.23 ng/ml, and 5.63 ng/ml and 5.43 ng/ml, respectively. Interestingly, protein-free concentrations of metabolites were only detectable in seminal plasma, where a novel dihdyroxylated metabolite of EFV was also detected. This accumulation of protein-free EFV metabolites was demonstrated to be the result of differential protein binding in seminal plasma compared with that of blood plasma. In addition, the oxidative metabolites of EFV did not present with any significant pharmacologic activity toward HIV-1 as measured using an HIV green fluorescent protein single-round infectivity assay. This study is the first to report the physiologic distribution of metabolites of an antiretroviral into biologic compartments that the virus is known to distribute and to examine their anti-HIV activity. These data suggest that the male genital tract may be a novel compartment that should be considered in the evaluation of drug metabolite exposure.

Are there benefits to starting antiretroviral therapy during primary HIV infection? Conclusions from the Seattle Primary Infection Cohort vary by control group

It is controversial whether starting combination antiretroviral therapy (cART) during primary HIV infection (PHI) is beneficial. Subjects in this observational cohort began cART <30 days (group 1: acute treatment, n = 40), 31-180 days (group 2: early treatment, n = 82) or >180 days (group 3: delayed treatment, n = 35) after HIV infection, and were compared with 27 historical and 60 contemporary controls. Time to HIV-related diagnoses did not differ for group 1 (adjusted hazard ratio [aHR] 1.44, P = 0.3) or group 2 (aHR 1.17, P = 0.5) compared with contemporary controls, but it was delayed for both treated groups (aHR 0.38 for group 1, P = 0.01; and aHR 0.28 for group 2, P < 0.0001) compared with historical controls. Although rates of HIV-related diagnoses were similar in acutely treated subjects and contemporary controls, results were confounded by associations between higher CD4 counts, lower HIV RNA levels and delayed disease progression as reasons for deferring treatment. Randomized trials are needed to address benefits of cART during PHI.

Lower HIV prevalence among Asian/Pacific Islander men who have sex with men: a critical review for possible reasons

We conducted a critical literature review for possible reasons that may explain the lower HIV prevalence observed among API MSM compared to MSM of other races/ethnicities. Trends emerging from the literature suggest that traditional individual-level factors-unprotected anal intercourse, substance use, STD prevalence, rates and frequency of HIV testing, and utilization of HIV prevention services-do not appear to be related to the lower HIV prevalence among API MSM. Some evidence suggests that socio-cultural and structural factors might be the more critical forces in determining racial/ethnic disparities of HIV among MSM. For API MSM, these factors include structures of sexual networks, access to and reception of medical care and treatment among HIV-positive MSM, and influences of different levels and types of acculturation. Moreover, emerging risk reduction strategies, such as seroadaptive behaviors, could play a role. Future research should address these factors in intervention design. In addition, better theories of resilience and measurement of strengths and protective factors are needed to enhance the efficacy of HIV interventions.

Feasibility of Repurposing the Polyanionic Microbicide, PPCM, for Prophylaxis against HIV Transmission during ART

HIV-serodiscordant couples wishing to conceive often seek assisted reproduction, during which spermatozoa from infected men are washed to minimize the risk of HIV transmission to partner and fetus. We sought to improve this method by adding a microbicide, PPCM, as an HIV prophylactic. HIV-1 (BaL) inhibition by PPCM appears irreversible and independent of added Ca²⁺. Without added Ca²⁺, PPCM (≤10 mg/mL, ≤90 min), a stimulus of Ca²⁺-dependent acrosomal loss, has no effect on sperm motility, forward progression, or acrosomal status. PPCM-treated (10 mg/mL) sperm retain their ability to acrosome react when Ca²⁺ is added. Sperm DNA integrity/function is unaffected by PPCM (≤10 mg/mL). Adding PPCM (5 mg/mL, 30 min) to washing media reduces infectivity (viral antigen p24 and RNA) of ex-vivo HIV-infected semen by 3-4 Logs compared with washing alone. Sperm washing with appropriate extracellular Ca²⁺ levels and PPCM is significantly more effective than washing alone at reducing HIV infectivity.

Virus-specific CD8+ T-cell responses better define HIV disease progression than HLA genotype

HLA alleles B57/58, B27, and B35 have the strongest genetic associations with HIV-1 disease progression. The mechanisms of these relationships may be host control of HIV-1 infection via CD8(+) T-cell responses. We examined these immune responses in subjects from the Seattle Primary Infection Cohort with these alleles. CD8(+) T-cell responses to conserved HIV epitopes within B57/58 alleles (TW10 and KF11) and B27 alleles (KK10 and FY10) delayed declines in CD4(+) T-cell counts (4 to 8 times longer), while responses to variable epitopes presented by B35 alleles (DL9 and IL9) resulted in more rapid progression. The plasma viral load was higher in B57/58(+) and B27(+) subjects lacking the conserved B57/58- and B27-restricted responses. The presence of certain B57/58-, B27-, and B35-restricted HIV-specific CD8(+) T-cell responses after primary HIV-1 infection better defined disease progression than the HLA genotype alone, suggesting that it is the HIV-specific CD8(+) T cells and not the presence of a particular HLA allele that determine disease progression. Further, the most effective host CD8(+) T-cell responses to HIV-1 were prevalent within an HLA allele, represented a high total allele fraction of the host CD8(+) T-cell response, and targeted conserved regions of HIV-1. These data suggest that vaccine immunogens should contain only conserved regions of HIV-1.

Strategies used in the detection of acute/early HIV infections. The NIMH Multisite Acute HIV Infection Study: I

Acute/early HIV infection plays a critical role in onward HIV transmission. Detection of HIV infections during this period provides an important early opportunity to offer interventions which may prevent further transmission. In six US cities, persons with acute/early HIV infection were identified using either HIV RNA testing of pooled sera from persons screened HIV antibody negative or through clinical referral of persons with acute or early infections. Fifty-one cases were identified and 34 (68%) were enrolled into the study; 28 (82%) were acute infections and 6 (18%) were early infections. Of those enrolled, 13 (38%) were identified through HIV pooled testing of 7,633 HIV antibody negative sera and 21 (62%) through referral. Both strategies identified cases that would have been missed under current HIV testing and counseling protocols. Efforts to identify newly infected persons should target specific populations and geographic areas based on knowledge of the local epidemiology of incident infections.

Conserved HIV-1 epitopes continuously elicit subdominant cytotoxic T-lymphocyte responses

BACKGROUND

The epitope specificities and antiviral activities of class I HLA-restricted CD8(+) T cells, especially those induced during human immunodeficiency virus type 1 (HIV-1) primary infection, are important considerations in designing HIV-1 vaccines. Conserved epitopes may be more commonly and persistently recognized than variable epitopes, as they may be more likely to be present in infecting viruses. However, some studies have shown preferential or similar targeting of variable versus conserved epitopes during primary infection.

METHODS

We analyzed cytotoxic T-lymphocyte (CTL) responses toward predefined conserved and variable epitopes in 45 subjects during primary (n = 34) and/or chronic infection (n = 16).

RESULTS

Conserved and variable CTL epitopes were recognized with similar probabilities, whereas conserved epitopes generally elicited subdominant responses during both primary and chronic infection. During primary infection, CTL responses against Gag versus responses against Env and variable epitopes tended to be associated with lower and higher viral loads, respectively. During chronic infection, Env-specific responses tended to be associated with lower CD4(+) cell counts.

CONCLUSIONS

Subdominant CTL recognition of conserved HIV-1 epitopes commonly occurs from the primary through chronic stages of HIV-1 infection. These findings underscore the challenge in designing T cell-based vaccines that can induce immunodominant CTL responses to conserved HIV-1 regions.

Polymorphisms in toll-like receptor 4 and toll-like receptor 9 influence viral load in a seroincident cohort of HIV-1-infected individuals

OBJECTIVES

Toll-like receptors (TLRs) are innate immune sensors that are integral to resisting chronic and opportunistic infections. Mounting evidence implicates TLR polymorphisms in susceptibilities to various infectious diseases, including HIV-1. We investigated the impact of TLR single nucleotide polymorphisms (SNPs) on clinical outcome in a seroincident cohort of HIV-1-infected volunteers.

DESIGN

We analyzed TLR SNPs in 201 antiretroviral treatment-naive HIV-1-infected volunteers from a longitudinal seroincident cohort with regular follow-up intervals (median follow-up 4.2 years, interquartile range 4.4). Participants were stratified into two groups according to either disease progression, defined as peripheral blood CD4(+) T-cell decline over time, or peak and setpoint viral load.

METHODS

Haplotype tagging SNPs from TLR2, TLR3, TLR4, and TLR9 were detected by mass array genotyping, and CD4(+) T-cell counts and viral load measurements were determined prior to antiretroviral therapy initiation. The association of TLR haplotypes with viral load and rapid progression was assessed by multivariate regression models using age and sex as covariates.

RESULTS

Two TLR4 SNPs in strong linkage disequilibrium [1063 A/G (D299G) and 1363 C/T (T399I)] were more frequent among individuals with high peak viral load compared with low/moderate peak viral load (odds ratio 6.65, 95% confidence interval 2.19-20.46, P < 0.001; adjusted P = 0.002 for 1063 A/G). In addition, a TLR9 SNP previously associated with slow progression was found less frequently among individuals with high viral setpoint compared with low/moderate setpoint (odds ratio 0.29, 95% confidence interval 0.13-0.65, P = 0.003, adjusted P = 0.04).

CONCLUSION

This study suggests a potentially new role for TLR4 polymorphisms in HIV-1 peak viral load and confirms a role for TLR9 polymorphisms in disease progression.

Monkeying around with HIV vaccines: using rhesus macaques to define 'gatekeepers' for clinical trials

Rhesus macaques are an important animal model for the study of human disease and the development of vaccines against HIV and AIDS. HIV vaccines have been benchmarked in rhesus macaque preclinical challenge studies using chimeric viruses made up of parts of HIV and simian immunodeficiency viruses. However, the lack of efficacy in a recent clinical trial calls for a re-evaluation of the scientific assumptions regarding the predictive value of using data generated from rhesus macaques as a 'gatekeeper' for the advancement of candidate vaccines into the clinic. In this context, there is significant consensus among HIV vaccinologists that next-generation HIV vaccines must generate 'better' immunity in rhesus macaques than clinically unsuccessful vaccines generated using validated assays. Defining better immunity is the core challenge of HIV vaccine development in this system and is the focus of this Review.

Transport theory for HIV diffusion through in vivo distributions of topical microbicide gels

Topical microbicide products are being developed for the prevention of sexually transmitted infections. These include vaginally-applied gels that deliver anti-HIV molecules. Gels may also provide partial barriers that slow virion diffusion from semen to vulnerable epithelium, increasing the time during which anti-HIV molecules can act. To explore the barrier function of microbicide gels, we developed a deterministic mathematical model for HIV diffusion through realistic gel distributions. We applied the model to experimental data for in vivo coating distributions of two vaginal gels in women. Time required for a threshold number of virions to reach the tissue surface was used as a metric for comparing different scenarios. Results delineated how time to threshold increased with increasing gel layer thickness and with decreasing diffusion coefficient. We note that for gel layers with average thickness > approximately 100 microm, the fractional area coated, rather than the gel layer thickness, was the primary determinant of time to threshold. For gel layers < approximately 100 microm, time to threshold was brief, regardless of fractional area coated. Application of the model to vaginal coating data showed little difference in time to threshold between the two gels tested. However, the protocol after gel application (i.e., with or without simulated coitus) had a much more significant effect. This study suggests that gel distribution in layers of thickness >100 microm and fractional area coated >0.8 is critical in determining the ability of the gel to serve as a barrier to HIV diffusion.

Potential impact of early antiretroviral therapy on transmission

PURPOSE OF REVIEW

In this review, we will discuss the potential of early highly active antiretroviral therapy (HAART) to reduce the sexual transmission of HIV on an individual and population level. We will focus on the biological plausibility and behavioural factors associated with HAART use and interventions that might influence such a strategy.

RECENT FINDINGS

Empiric and phylogenetic studies support the view that recent HIV infection is a highly infectious disease stage. Evidence increasingly demonstrates that individuals on fully suppressive HAART are significantly less likely to transmit HIV to sexual partners and some even suggest that such individuals cannot transmit HIV. Changes in risk behaviour are associated with the availability of HAART but behavioural studies offer contradictory observations regarding the direction and magnitude of these changes. This in turn makes the intricate assumptions and therefore outcomes of many complex mathematical modelling studies less secure. Furthermore, there is evidence that it is those individuals with undiagnosed HIV infection who contribute significantly to onward sexual transmission.

SUMMARY

At an individual level, HAART will reduce viral load and, therefore, infectiousness, although whether to zero or not remains controversial. At a population level, if recent infection and undiagnosed infections continue to drive onward transmission, earlier treatment will only alter the pandemic if accompanied by an improvement in diagnosing the undiagnosed and recognizing recent infection.