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Despite suppression of human immunodeficiency virus (HIV) replication by antiretroviral therapy, reconstitution of CD4+ cells is variable and incomplete, particularly in gut-associated lymphatic tissues (GALT). We have previously shown that immune activation and inflammation in HIV-infected and simian immunodeficiency virus- infected lymph nodes results in collagen deposition and disruption of the lymphatic tissue architecture, and this damage contributes to CD4+ cell depletion before treatment and affects the extent of immune reconstitution after treatment. In the present study, we compared collagen deposition and the extent of depletion and reconstitution of total CD4+ cells and subsets in peripheral blood, lymph nodes, and inductive and effector sites in GALT. We show that CD4+ cell depletion in GALT correlates with the rapidity and greater magnitude of collagen deposition in this compartment, compared with that in peripheral lymph nodes, and that although treatment does not restore CD4+ cells to effector sites, treatment in the early stages of infection can increase CD4+ central memory cells in Peyer patches. [ABSTRACT FROM AUTHOR]

Here we report the results of an investigation into the possibility that one mechanism responsible for the establishment of persistent human immunodeficiency virus infection is an early regulatory T (Treg) cell response that blunts virus-specific responses. Using the simian immunodeficiency virus (SIV)-infected rhesus macaque model, we show that, indeed, viral replication and immune activation in lymphatic tissue drive a premature immunosuppressive response, with dramatic increases in the frequencies of CD4+CD25+FOXP3+ Treg cells, transforming growth factor-β1+ cells, interleukin-10+ cells, and indoleamine 2,3-dioxygenase+CD3+ cells. When we compared SIV infection with rhesus cytomegalovirus (RhCMV) infection, we found that the frequency of Treg cells paralleled the magnitude of immune activation during both infections but that the magnitude of immune activation and of the Treg cell response were lower and peaked much later during RhCMV infection. Importantly, the frequency of Treg cells inversely correlated with the magnitude of the SIV-specific cytotoxic T lymphocyte response. We conclude that an early Treg cell response during acute SIV infection may contribute to viral persistence by prematurely limiting the antiviral immune response before infection is cleared. [ABSTRACT FROM AUTHOR]

Coronavirus disease 2019 (COVID-19) and its associated severity have been linked to uncontrolled inflammation and may be associated with changes in the microbiome of mucosal sites including the gastrointestinal tract and oral cavity. These sites play an important role in host-microbe homeostasis, and disruption of epithelial barrier integrity during COVID-19 may potentially lead to exacerbated inflammation and immune dysfunction. Outcomes in COVID-19 are highly disparate, ranging from asymptomatic to fatal, and the impact of microbial dysbiosis on disease severity is unclear. Here, we obtained plasma, rectal swabs, oropharyngeal swabs, and nasal swabs from 86 patients hospitalized with COVID-19 and 12 healthy volunteers. We performed 16S rRNA sequencing to characterize the microbial communities in the mucosal swabs and measured concentrations of circulating cytokines, markers of gut barrier integrity, and fatty acids in the plasma samples. We compared these plasma concentrations and microbiomes between healthy volunteers and COVID-19 patients, some of whom had unfortunately died by the end of the study enrollment, and performed a correlation analysis between plasma variables and bacterial abundances. Rectal swabs of COVID-19 patients had reduced abundances of several commensal bacteria including Faecalibacterium prausnitzii and an increased abundance of the opportunistic pathogens Eggerthella lenta and Hungatella hathewayi . Furthermore, the oral pathogen Scardovia wiggsiae was more abundant in the oropharyngeal swabs of COVID-19 patients who died. The abundance of both H. hathewayi and S. wiggsiae correlated with circulating inflammatory markers including IL-6, highlighting the possible role of the microbiome in COVID-19 severity and providing potential therapeutic targets for managing COVID-19.IMPORTANCEOutcomes in coronavirus disease 2019 (COVID-19) are highly disparate and are associated with uncontrolled inflammation; however, the individual factors that lead to this uncontrolled inflammation are not fully understood. Here, we report that severe COVID-19 is associated with systemic inflammation, microbial translocation, and microbial dysbiosis. The rectal and oropharyngeal microbiomes of COVID-19 patients were characterized by a decreased abundance of commensal bacteria and an increased abundance of opportunistic pathogens, which positively correlated with markers of inflammation and microbial translocation. These microbial perturbations may, therefore, contribute to disease severity in COVID-19 and highlight the potential for microbiome-based interventions in improving COVID-19 outcomes., Competing Interests: The authors declare no conflict of interest.

Productively infected cells are generally thought to arise from HIV infection of activated CD4+ T cells, and these infected activated cells are thought to be a recurring source of latently infected cells when a portion of the population transitions to a resting state. We discovered and report here that productively and latently infected cells can instead originate from direct infection of resting CD4+ T cell populations in lymphoid tissues in Fiebig I, the earliest stage of detectable HIV infection. We found that direct infection of resting CD4+ T cells was correlated with the availability of susceptible target cells in lymphoid tissues largely restricted to resting CD4+ T cells in which expression of pTEFb enabled productive infection, and we documented persistence of HIV-producing resting T cells during antiretroviral therapy (ART). Thus, we provide evidence of a mechanism by which direct infection of resting T cells in lymphoid tissues to generate productively and latently infected cells creates a mechanism by which the productively infected cells can replenish both populations and maintain two sources of virus from which HIV infection can rebound, even if ART is instituted at the earliest stage of detectable infection.

An important consequence of infection with a SARS-CoV-2 variant is protective humoral immunity against other variants. However, the basis for such cross-protection at the molecular level is incompletely understood. Here, we characterized the repertoire and epitope specificity of antibodies elicited by infection with the Beta, Gamma and WA1 ancestral variants and assessed their cross-reactivity to these and the more recent Delta and Omicron variants. We developed a method to obtain immunoglobulin sequences with concurrent rapid production and functional assessment of monoclonal antibodies from hundreds of single B cells sorted by flow cytometry. Infection with any variant elicited similar cross-binding antibody responses exhibiting a conserved hierarchy of epitope immunodominance. Furthermore, convergent V gene usage and similar public B cell clones were elicited regardless of infecting variant. These convergent responses despite antigenic variation may account for the continued efficacy of vaccines based on a single ancestral variant., (© 2022. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

Immunosuppressed patients with inflammatory bowel disease (IBD) generate lower amounts of SARS-CoV-2 spike antibodies after mRNA vaccination than healthy controls. We assessed SARS-CoV-2 spike S1 receptor binding domain-specific (S1-RBD-specific) B lymphocytes to identify the underlying cellular defects. Patients with IBD produced fewer anti-S1-RBD antibody-secreting B cells than controls after the first mRNA vaccination and lower amounts of total and neutralizing antibodies after the second. S1-RBD-specific memory B cells were generated to the same degree in IBD and control groups and were numerically stable for 5 months. However, the memory B cells in patients with IBD had a lower S1-RBD-binding capacity than those in controls, which is indicative of a defect in antibody affinity maturation. Administration of a third shot to patients with IBD elevated serum antibodies and generated memory B cells with a normal antigen-binding capacity. These results show that patients with IBD have defects in the formation of antibody-secreting B cells and affinity-matured memory B cells that are corrected by a third vaccination.

Starting antiretroviral therapy (ART) in Fiebig 1 acute HIV infection limits the size of viral reservoirs in lymphoid tissues, but does not impact time to virus rebound during a treatment interruption. To better understand why the reduced reservoir size did not increase the time to rebound we measured the frequency and location of HIV RNA+ cells in lymph nodes from participants in the RV254 acute infection cohort. HIV RNA+ cells were detected more frequently and in greater numbers when ART was initiated in Fiebig 1 compared to later Fiebig stages and were localized to the T-cell zone compared to the B-cell follicle with treatment in later Fiebig stages. Variability of virus production in people treated during acute infection suggests that the balance between virus-producing cells and the immune response to clear infected cells rapidly evolves during the earliest stages of infection. Clinical Trials Registration: NCT02919306., (© The Author(s) 2022. Published by Oxford University Press for the Infectious Diseases Society of America.)

Objective: The ability of antiretroviral drugs to penetrate and suppress viral replication in tissue reservoir sites is critical for HIV remission. We evaluated antiretroviral concentrations in lymph nodes and their impact on HIV transcription., Methods: Participants of the RV254/SEARCH010 Acute HIV Infection Cohort in Thailand were enrolled. Group 1 (n  = 6) initiated and continued antiretrovirals with two nucleoside reverse transcriptase inhibitors (NRTIs), dolutegravir (DTG) and mar- aviroc (MVC). Group 2 (n = 12) initiated antiretrovirals with two NRTIs as well as efavirenz and were switched to two NRTIs as well as DTG. Antiretroviral concentrations were measured by mass spectroscopy. HIV RNA+ and DNA+ cells were measured by in-situ hybridization., Results: All participants were MSM. At lymph node biopsy, all had plasma HIV RNA less than 20 copies/ml. Group 2 had longer durations of antiretroviral and DTG use (medians of 135 and 63 weeks, respectively) compared with Group 1 (median 44 weeks for both). TFV-DP, 3TC-TP, DTG and MVC were quantifiable in all lymph node samples from participants receiving those drugs versus carbovir-triphosphate (CBV-TP) in four out of 14. Median ratios of lymph node to peripheral blood concentrations were DTG, 0.014; MVC, 6.9; CBV-TP, 0.38; 3TC-TP, 0.32; and TFV-DP, 3.78. Median inhibitory quotients [ratios of lymph node concentrations to in-vitro inhibitory levels (IC50-or-90)] were DTG, 0.8; MVC, 38.8; CBV-TP, 0.5; 3TC- TP, 4.1; and TFV-DP, 1.8. Ongoing viral transcription was detected in lymph node of all participants. Median lymph node RNA+ cells were 71 350 versus 99 750 cells/g for Groups 1 and 2, respectively (P = 0.111)., Conclusion: MVC has enhanced lymph node penetration and thereby may contribute to more complete viral suppression in the lymph node., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

There is no cure for HIV infection, and lifelong antiretroviral therapy (ART) is required. N-803 is an IL-15 superagonist comprised of an N72D mutant IL-15 molecule attached to its alpha receptor and a human IgG1 fragment designed to increase IL-15 activity. Preclinical studies with both HIV and SIV suggest that the drug has potential to reduce virus reservoirs by activating virus from latency and enhancing effector function. We conducted a phase 1 study of N-803 ( NCT02191098 ) in people living with HIV, the primary objective of which was to assess the safety and tolerability of the drug, with an exploratory objective of assessing the impact on peripheral virus reservoirs. ART-suppressed individuals were enrolled into a dose-escalation study of N-803 in four different cohorts (0.3, 1.0, 3.0 and 6.0 mcg kg -1 ). Each cohort received three doses total, separated by at least 1 week. We enrolled 16 individuals, of whom 11 completed all three doses. The maximum tolerated dose was 6.0 mcg kg -1 . The primary clinical adverse events (AEs) reported were injection site rash and adenopathy, and four participants experienced a grade 1 or grade 2 QTc prolongation. No significant laboratory AEs attributable to N-803 were observed. In exploratory analyses, N-803 was associated with proliferation and/or activation of CD4 + and CD8 + T cells and natural killer cells that peaked at 4 d after dosing. IFN-γ, IP-10, MCP-1 and IL-15 increased during treatment. HIV transcription in memory CD4 T cells and intact proviral DNA initially increased after N-803 treatment; however, there was a small but significant decrease in the frequency of peripheral blood mononuclear cells with an inducible HIV provirus that persisted for up to 6 months after therapy. These data suggest that N-803 administration in ART-suppressed people living with HIV is safe and that larger clinical trials are needed to further investigate the effects of N-803 on HIV reservoirs., (© 2022. The Author(s), under exclusive licence to Springer Nature America, Inc.)

The impact of the microbiome on HIV disease is widely acknowledged although the mechanisms downstream of fluctuations in microbial composition remain speculative. We detected rapid, dynamic changes in translocated microbial constituents during two years after cART initiation. An unbiased systems biology approach revealed two distinct pathways driven by changes in the abundance ratio of Serratia to other bacterial genera. Increased CD4 T cell numbers over the first year were associated with high Serratia abundance, pro-inflammatory innate cytokines, and metabolites that drive Th17 gene expression signatures and restoration of mucosal integrity. Subsequently, decreased Serratia abundance and downregulation of innate cytokines allowed re-establishment of systemic T cell homeostasis promoting restoration of Th1 and Th2 gene expression signatures. Analyses of three other geographically distinct cohorts of treated HIV infection established a more generalized principle that changes in diversity and composition of translocated microbial species influence systemic inflammation and consequently CD4 T cell recovery., Competing Interests: Declaration of interests The authors declare no competing interests., (Published by Elsevier Inc.)

Background: The SARS-CoV-2 virus enters cells via Angiotensin-converting enzyme 2 (ACE2), disrupting the renin-angiotensin-aldosterone axis, potentially contributing to lung injury. Treatment with angiotensin receptor blockers (ARBs), such as losartan, may mitigate these effects, though induction of ACE2 could increase viral entry, replication, and worsen disease., Methods: This study represents a placebo-controlled blinded randomized clinical trial (RCT) to test the efficacy of losartan on outpatients with COVID-19 across three hospital systems with numerous community sites in Minnesota, U.S. Participants included symptomatic outpatients with COVID-19 not already taking ACE-inhibitors or ARBs, enrolled within 7 days of symptom onset. Patients were randomized to 1:1 losartan (25 mg orally twice daily unless estimated glomerular filtration rate, eGFR, was reduced, when dosing was reduced to once daily) versus placebo for 10 days, and all patients and outcome assesors were blinded. The primary outcome was all-cause hospitalization within 15 days. Secondary outcomes included functional status, dyspnea, temperature, and viral load. (clinicatrials.gov, NCT04311177, closed to new participants)., Findings: From April to November 2020, 117 participants were randomized 58 to losartan and 59 to placebo, and all were analyzed under intent to treat principles. The primary outcome did not differ significantly between the two arms based on Barnard's test [losartan arm: 3 events (5.2% 95% CI 1.1, 14.4%) versus placebo arm: 1 event (1.7%; 95% CI 0.0, 9.1%)]; proportion difference -3.5% (95% CI -13.2, 4.8%); p  = 0.32]. Viral loads were not statistically different between treatment groups at any time point. Adverse events per 10 patient days did not differ signifcantly [0.33 (95% CI 0.22-0.49) for losartan vs. 0.37 (95% CI 0.25-0.55) for placebo]. Due to a lower than expected hospitalization rate and low likelihood of a clinically important treatment effect, the trial was terminated early., Interpretation: In this multicenter blinded RCT for outpatients with mild symptomatic COVID-19 disease, losartan did not reduce hospitalizations, though assessment was limited by low event rate. Importantly, viral load was not statistically affected by treatment. This study does not support initiation of losartan for low-risk outpatients., Competing Interests: The authors have no financial conflicts of interest to disclose. All the authors report grants from Minnesota Partnership for Biotechnology and Medical Genomics during the conduct of the study. MAP reports also grants from Bill and Melinda Gates Foundation and grants from NHLBI, outside the submitted work., (© 2021 The Author(s).)

Background: HIV is produced in lymphoid tissues (LT) and stored on the follicular dendritic cell network in LT. When antiretroviral therapy is started, plasma viremia decays in 2 phases; the first within days of starting therapy and the second over weeks. Raltegravir (RAL), an integrase inhibitor, has been associated with only a single rapid phase of decay, and we speculated this may be due to higher intracellular concentration (IC) of RAL in LT. We have previously measured suboptimal ICs of antiretroviral therapy agents in LT, which were associated with slower decay of both vRNA+ cells and the follicular dendritic cell network pool., Setting: Outpatient clinic at the Joint Clinical Research Center in Kampala, Uganda., Methods: We compared the rate of decay in LT in people starting RAL with those starting efavirenz (EFV)., Results: There was no difference in the rate of virus decay in LT. The ratio of the ICs of RAL and EFV in lymph node to the concentration of drug that inhibits 95% of virus in blood was 1 log lower in lymph node for EFV and >3 logs lower for RAL., Conclusion: These data further highlight the challenges of drug delivery to LT in HIV infection and demonstrate that RAL is not superior to EFV as judged by direct measurements of the source of virus in LT.

Analytical antiretroviral treatment interruption (ATI) is an important feature of HIV research, seeking to achieve sustained viral suppression in the absence of antiretroviral therapy (ART) when the goal is to measure effects of novel therapeutic interventions on time to viral load rebound or altered viral setpoint. Trials with ATIs also intend to determine host, virological, and immunological markers that are predictive of sustained viral control off ART. Although ATI is increasingly incorporated into proof-of-concept trials, no consensus has been reached on strategies to maximise its utility and minimise its risks. In addition, differences in ATI trial designs hinder the ability to compare efficacy and safety of interventions across trials. Therefore, we held a meeting of stakeholders from many interest groups, including scientists, clinicians, ethicists, social scientists, regulators, people living with HIV, and advocacy groups, to discuss the main challenges concerning ATI studies and to formulate recommendations with an emphasis on strategies for risk mitigation and monitoring, ART resumption criteria, and ethical considerations. In this Review, we present the major points of discussion and consensus views achieved with the goal of informing the conduct of ATIs to maximise the knowledge gained and minimise the risk to participants in clinical HIV research., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Introduction: Latent HIV reservoirs are rapidly established in lymphoid tissues during acute HIV infection (AHI). Sampling these tissues provides important information about HIV pathogenesis. This period is associated with viral replication and immune activation that may affect procedure-related adverse events (AEs). We examined the safety and tolerability of inguinal lymph node (LN) biopsy in research participants with AHI in Bangkok, Thailand., Methods: Between 2013 and 2016, 67 AHI participants in the RV254/SEARCH010 study underwent at least one optional inguinal LN biopsy during AHI at the baseline visit and/or after antiretroviral therapy (median 48 weeks after antiretroviral therapy). Biopsy-related AEs were graded according to NIH Division of AIDS guidelines. Poisson regression was used to calculate incidence rate ratios and 95% confidence intervals to evaluate associations of demographic and HIV characteristics, procedure timing, and repetition with AE incidence., Results: Of the 67 participants, 97% were male with a median age of 26. Among 78 LN biopsies (39 at baseline and 39 at follow-up), 10 (12.8%) AEs were reported: 6 (7.7%) grade 1 and 4 (5.1%) grade 2. The AEs were biopsy-site discomfort (n = 8, 10.2%) and hematoma (n = 2, 2.6%). No factors were significantly associated with AE incidence. All biopsy-related AEs were transient and self-limited., Conclusions: Inguinal LN biopsies were safe and well tolerated in mostly Thai men with AHI. As LN biopsies become an integral part of HIV research, this study provides information to participants, researchers, and institutional review boards that these samples can be safely obtained.

Vaccine responses vary by geographic location. We have previously described how HIV-associated inflammation leads to fibrosis of secondary lymph nodes (LNs) and T cell depletion. We hypothesized that other infections may cause LN inflammation and fibrosis, in a process similar to that seen in HIV infection, which may lead to T cell depletion and affect vaccine responses. We studied LNs of individuals from Kampala, Uganda, before and after yellow fever vaccination (YFV) and found fibrosis in LNs that was similar to that seen in HIV infection. We found blunted antibody responses to YFV that correlated to the amount of LN fibrosis and loss of T cells, including T follicular helper cells. These data suggest that LN fibrosis is not limited to HIV infection and may be associated with impaired immunologic responses to vaccines. This may have an impact on vaccine development, especially for infectious diseases prevalent in the developing world.

Background: Allogeneic hematopoietic cell transplantation (allo-HCT) in a CCR5∆32 homozygous donor resulted in HIV cure. Understanding how allo-HCT impacts the HIV reservoir will inform cure strategies., Methods: A 12-year-old with perinatally acquired, CCR5-tropic HIV and acute lymphoblastic leukemia underwent myeloablative conditioning and umbilical cord blood (UCB) transplantation from a CCR5∆32 homozygous donor. Peripheral blood mononuclear cells (PBMCs) and the rectum were sampled pre- and post-transplant. The brain, lung, lymph node (LN), stomach, duodenum, ileum, and colon were sampled 73 days after transplantation (day +73), when the patient died from graft-vs-host disease. Droplet digital polymerase chain reaction (ddPCR) and in situ hybridization (ISH) were used detect the HIV reservoir in tissues. CCR5 and CD3 expression in the LN was assessed using immunohistochemistry (IHC)., Results: HIV DNA (vDNA) was detected in PBMCs by ddPCR pretransplant but not post-transplant. vDNA was detected by ISH in the rectum at days -8 and +22, and in the LN, colon, lung, and brain day +73. vDNA was also detected in the lung by ddPCR. IHC revealed CCR5+CD3+ cells in the LN postmortem., Conclusions: HIV was detected in multiple tissues 73 days after CCR5∆32 homozygous UCB allo-HCT despite myeloablative conditioning and complete donor marrow engraftment. These results highlight the importance of analyzing tissue during HIV cure interventions and inform the choice of assay used to detect HIV in tissue reservoirs.

In the quest for a functional cure or the eradication of HIV infection, it is necessary to know the sizes of the reservoirs from which infection rebounds after treatment interruption. Thus, we quantified SIV and HIV tissue burdens in tissues of infected nonhuman primates and lymphoid tissue (LT) biopsies from infected humans. Before antiretroviral therapy (ART), LTs contained >98% of the SIV RNA + and DNA + cells. With ART, the numbers of virus (v) RNA+ cells substantially decreased but remained detectable, and their persistence was associated with relatively lower drug concentrations in LT than in peripheral blood. Prolonged ART also decreased the levels of SIV- and HIV-DNA + cells, but the estimated size of the residual tissue burden of 10 8 vDNA + cells potentially containing replication-competent proviruses, along with evidence of continuing virus production in LT despite ART, indicated two important sources for rebound following treatment interruption. The large sizes of these tissue reservoirs underscore challenges in developing 'HIV cure' strategies targeting multiple sources of virus production.

Allogeneic hematopoietic stem cell transplantation is hampered by chronic graft-versus-host disease (cGVHD), resulting in multiorgan fibrosis and diminished function. Fibrosis in lung and skin leads to progressive bronchiolitis obliterans (BO) and scleroderma, respectively, for which new treatments are needed. We evaluated pirfenidone, a Food and Drug Administration (FDA)-approved drug for idiopathic pulmonary fibrosis, for its therapeutic effect in cGVHD mouse models with distinct pathophysiology. In a full major histocompatibility complex (MHC)-mismatched, multiorgan system model with BO, donor T-cell responses that support pathogenic antibody production are required for cGVHD development. Pirfenidone treatment beginning one month post-transplant restored pulmonary function and reversed lung fibrosis, which was associated with reduced macrophage infiltration and transforming growth factor-β production. Pirfenidone dampened splenic germinal center B-cell and T-follicular helper cell frequencies that collaborate to produce antibody. In both a minor histocompatibility antigen-mismatched as well as a MHC-haploidentical model of sclerodermatous cGVHD, pirfenidone significantly reduced macrophages in the skin, although clinical improvement of scleroderma was only seen in one model. In vitro chemotaxis assays demonstrated that pirfenidone impaired macrophage migration to monocyte chemoattractant protein-1 (MCP-1) as well as IL-17A, which has been linked to cGVHD generation. Taken together, our data suggest that pirfenidone is a potential therapeutic agent to ameliorate fibrosis in cGVHD., (© 2017 by The American Society of Hematology.)

Targeted HIV cure strategies require definition of the mechanisms that maintain the virus. Here, we tracked HIV replication and the persistence of infected CD4 T cells in individuals with natural virologic control by sequencing viruses, T cell receptor genes, HIV integration sites, and cellular transcriptomes. Our results revealed three mechanisms of HIV persistence operating within distinct anatomic and functional compartments. In lymph node, we detected viruses with genetic and transcriptional attributes of active replication in both T follicular helper (TFH) cells and non-TFH memory cells. In blood, we detected inducible proviruses of archival origin among highly differentiated, clonally expanded cells. Linking the lymph node and blood was a small population of circulating cells harboring inducible proviruses of recent origin. Thus, HIV replication in lymphoid tissue, clonal expansion of infected cells, and recirculation of recently infected cells act together to maintain the virus in HIV controllers despite effective antiviral immunity., (Published by Elsevier Inc.)

Early after HIV infection there is substantial depletion of CD4 + T cells in the gastrointestinal (GI) tract lamina propria (LP), with associated epithelial barrier damage, leading to microbial translocation and systemic inflammation and immune activation. In this study, we analyzed these early events in the GI tract in a cohort of Thai acute HIV-infected patients and determined the effect of early combination antiretroviral treatment (cART). HIV-uninfected and chronically and acutely HIV-infected patients at different Fiebig stages (I-V) underwent colonic biopsies and then received cART. Immunohistochemistry and quantitative image analysis were performed on cross-sectional and longitudinal colon biopsy specimens (day 0 to week 96) to measure GI tract damage (infiltration of polymorphonuclear cells), inflammation (M×1, TNF-α), immune activation (Ki-67), and the CD4 + T cell population in the LP. The magnitude of GI tract damage, immune activation, and inflammation was significantly increased, with significantly depleted CD4 + T cells in the LP in all acutely infected groups prior to cART compared with HIV-uninfected control participants. While most patients treated during acute infection resolved GI tract inflammation and immune activation back to baseline levels after 24 weeks of cART, most acutely infected participants did not restore their CD4 + T cells after 96 weeks of cART.

With the advent and stunning success of combination antiretroviral therapy (ART) to prolong and improve quality of life for persons with HIV infection, HIV research has been afforded the opportunity to pivot towards studies aimed at finding "a cure." The mere idea that cure of HIV might be possible has energized researchers and the community towards achieving this goal. Funding agencies, both governmental and private, have targeted HIV cure as a high priority; many in the field have responded to these initiatives and the cure research agenda is robust. In this "salon" two editors of Pathogens and Immunity , Michael Lederman and Daniel Douek ask whether curing HIV is a realistic, scalable objective. We start with an overview perspective and have asked a number of prominent HIV researchers to add to the discussion.

Lymphoid tissue is a key reservoir established by HIV-1 during acute infection. It is a site associated with viral production, storage of viral particles in immune complexes, and viral persistence. Although combinations of antiretroviral drugs usually suppress viral replication and reduce viral RNA to undetectable levels in blood, it is unclear whether treatment fully suppresses viral replication in lymphoid tissue reservoirs. Here we show that virus evolution and trafficking between tissue compartments continues in patients with undetectable levels of virus in their bloodstream. We present a spatial and dynamic model of persistent viral replication and spread that indicates why the development of drug resistance is not a foregone conclusion under conditions in which drug concentrations are insufficient to completely block virus replication. These data provide new insights into the evolutionary and infection dynamics of the virus population within the host, revealing that HIV-1 can continue to replicate and replenish the viral reservoir despite potent antiretroviral therapy.

Antiretroviral therapy (ART) suppresses HIV replication in most individuals but cannot eradicate latently infected cells established before ART was initiated. Thus, infection rebounds when treatment is interrupted by reactivation of virus production from this reservoir. Currently, one or a few latently infected resting memory CD4 T cells are thought be the principal source of recrudescent infection, but this estimate is based on peripheral blood rather than lymphoid tissues (LTs), the principal sites of virus production and persistence before initiating ART. We, therefore, examined lymph node (LN) and gut-associated lymphoid tissue (GALT) biopsies from fully suppressed subjects, interrupted therapy, monitored plasma viral load (pVL), and repeated biopsies on 12 individuals as soon as pVL became detectable. Isolated HIV RNA-positive (vRNA+) cells were detected by in situ hybridization in LTs obtained before interruption in several patients. After interruption, multiple foci of vRNA+ cells were detected in 6 of 12 individuals as soon as pVL was measureable and in some subjects, in more than one anatomic site. Minimal estimates of the number of rebounding/founder (R/F) variants were determined by single-gene amplification and sequencing of viral RNA or DNA from peripheral blood mononuclear cells and plasma obtained at or just before viral recrudescence. Sequence analysis revealed a large number of R/F viruses representing recrudescent viremia from multiple sources. Together, these findings are consistent with the origins of recrudescent infection by reactivation from many latently infected cells at multiple sites. The inferred large pool of cells and sites to rekindle recrudescent infection highlights the challenges in eradicating HIV.

There is intense interest in developing curative interventions for HIV. How such a cure will be quantified and defined is not known. We applied a series of measurements of HIV persistence to the study of an HIV-infected adult who has exhibited evidence of cure after allogeneic hematopoietic stem cell transplant from a homozygous CCR5Δ32 donor. Samples from blood, spinal fluid, lymph node, and gut were analyzed in multiple laboratories using different approaches. No HIV DNA or RNA was detected in peripheral blood mononuclear cells (PBMC), spinal fluid, lymph node, or terminal ileum, and no replication-competent virus could be cultured from PBMCs. However, HIV RNA was detected in plasma (2 laboratories) and HIV DNA was detected in the rectum (1 laboratory) at levels considerably lower than those expected in ART-suppressed patients. It was not possible to obtain sequence data from plasma or gut, while an X4 sequence from PBMC did not match the pre-transplant sequence. HIV antibody levels were readily detectable but declined over time; T cell responses were largely absent. The occasional, low-level PCR signals raise the possibility that some HIV nucleic acid might persist, although they could also be false positives. Since HIV levels in well-treated individuals are near the limits of detection of current assays, more sensitive assays need to be developed and validated. The absence of recrudescent HIV replication and waning HIV-specific immune responses five years after withdrawal of treatment provide proof of a clinical cure.

Microbial translocation from the gastrointestinal tract has been implicated in chronic activation of the immune system during progressive HIV-1 infection by ill-defined mechanisms. We recently identified a gene encoding syndecan-1 (SYN1) in microarray studies of HIV-1 infection in lymphatic tissues and show here that increased expression of SYN1 in the gut of HIV-1-infected individuals is associated with increased microbial translocation. We further show that: (1) microbial access to SYN1 in the intestinal epithelium could be mediated by compromised barrier function through the upregulation of claudin-2; (2) increases in SYN1 and microbial translocation are associated with systemic immune activation; and (3) SYN1 expression and microbial translocation are inversely correlated with peripheral blood CD4 T-cell counts. We thus propose a new mechanism in which claudin-2 and SYN1 work in concert to enhance microbial translocation across the intestinal epithelial barrier to contribute to chronic immune activation and CD4 T-cell depletion.

Background: Pathogenesis studies show that naive CD4 cells are preferentially depleted in lymphoid tissues during HIV infection, and studies of advanced patients suggest levels of naive CD4 cells in blood correlate to total CD4 cells after starting antiretroviral therapy (ARV). We hypothesized that measuring naive CD4 cells in blood in people at earlier stages of disease would identify those at highest risk for poor CD4 reconstitution who may benefit from earlier initiation of ARV., Methods and Findings: We identified 348 patients from multiple AIDS Clinical Trials Group studies who were ARV naive, had a CD4 count between 200 and 500 cells per microliter, a measure of pretreatment-naive CD4 percent, and serial follow-up measures of CD4 count and plasma HIV RNA after starting ARV. We used logistic regression to model the ability of naive CD4 percent to predict 100 and 200 CD4 cell increases after 24 months of therapy. After controlling for baseline viral load and demographic variables, baseline naive but not total CD4 cell count strongly predicted CD4 cell increases. Lower baseline naive CD4 percent was associated with greater time spent at lower CD4 T-cell counts after initiating ARV., Conclusions: Measurement of naive CD4 percent in patients can identify those least likely to reconstitute immunity, who may benefit from earlier ARV treatment.

T cell receptors (TCRs) on T lymphocytes in an individual bind foreign peptides bound to major histocompatibility complex (MHC) molecules expressed in that individual (designated MHC(A)). Results from radiation bone marrow chimeras and TCR transgenic mice indicate that this complex form of antigen recognition is the result of positive selection of clones with low affinity for self peptide:MHC(A) complexes during development. Here we used a sensitive peptide:MHC tetramer enrichment method to quantify the role of positive selection in the generation of the preimmune polyclonal T cell repertoire in normal individuals. We made the surprising observation that mouse and human naive T cells capable of binding to foreign peptide:MHC(A) were present at the same frequency in hosts that expressed MHC(A) or a different MHC isoform (MHC(B)). However, most of the clones in MHC(B) hosts also recognized self peptide:MHC(A) complexes. When these "alloreactive" T cells were removed from the MHC(B) repertoire via negative selection in an MHC(A) host, the number of foreign peptide:MHC(A)-binding T cells was reduced to one fifth and many of the remaining cells did not respond to the peptide. Therefore, although positive selection on MHC(A) was not required to produce foreign peptide:MHC(A)-binding clones, it had a large effect on selecting responsive clones.

Most human immunodeficiency virus (HIV)-infected individuals experience increases in peripheral CD4(+) T cell counts with suppressive antiretroviral therapy (ART) that achieves plasma HIV RNA levels that are less than the limit of detection. However, some individuals experience decreasing CD4(+) T cell counts despite suppression of plasma viremia. We evaluated 4 patients with a history of CD4(+) T cell decline despite successfully suppressive ART, from a median of 719 cells/mm(3) (range, 360-1141 cells/mm(3)) to 227 cells/mm(3) (range, 174-311 cells/mm(3)) over a period of 18-24 months; 3 of the patients were receiving tenofovir and didanosine, which may have contributed to this decrease. There was no evidence of HIV replication, nor of antiretroviral drug resistance in the blood or lymphoid tissue, or increased proliferation or decreased thymic production of naive CD4(+) T cells. All 4 patients had significant fibrosis of the T cell zone of lymphoid tissue, which appeared to be an important factor in the failure to reconstitute T cells.

The prevalence of herpes genitalis (genital herpes) has increased markedly over the past three decades. The most common cause is infection with the herpes simplex virus type 2 (HSV-2), but it can also occur as a result of HSV-1 infection. Herpes genitalis can cause substantial psychosexual as well as physical morbidity and, in immunocompromised individuals, such as those who are HIV-positive, HSV infection can result in severe disease with progressive and extensive lesions. The natural history of herpes genitalis and the pathways of infection are now well known; however, the factors associated with reactivation have yet to be fully defined. A number of management approaches with antiviral medications are commonly used, including episodic and suppressive treatments. For episodic therapy, the duration of both lesions and symptoms, as well as the proportion of aborted episodes, are the most important measures of efficacy. For suppressive therapy, the time to first recurrence and frequency of recurrences over time are the most important clinical measures of antiviral benefit. Regarding the duration of episodic regimens, comparisons of 1-, 2- and 3-day antiviral courses with standard 5-day regimens show similar benefits on healing and relief of symptoms, with the obvious improvement in convenience, economy and compliance. In HIV-positive patients, antiherpes therapy has proved effective in speeding healing of lesions and reducing subclinical shedding, and can be used to treat genital HSV-2 infections in this group. Suppressive antiviral therapy has been shown to decrease the risk of HSV transmission in heterosexual couples. New approaches to the prevention of HSV infection, including vaccines and topical microbicides, are under investigation.

The organized structure of lymphatic tissues (LTs) constitutes a microenvironment referred to as a niche that plays a critical role in immune system homeostasis by promoting cellular interactions and providing access to cytokines and growth factors on which cells are dependent for survival, proliferation, and differentiation. In chronic human immunodeficiency virus type 1 (HIV-1) infection, immune activation and inflammation result in collagen deposition and disruption of this LT niche. We have previously shown that these fibrotic changes correlate with a reduction in the size of the total population of CD4+ T cells. We now show that this reduction is most substantial within the naïve CD4+ T-cell population and is in proportion to the extent of LT collagen deposition in HIV-1 infection. Thus, the previously documented depletion of naïve CD4+ T cells in LTs in HIV-1 infection may be a consequence not only of a decreased supply of thymic emigrants or chronic immune activation but also of the decreased ability of those cells to survive in a scarred LT niche. We speculate that LT collagen deposition might therefore limit repopulation of naïve CD4+ T cells with highly active antiretroviral therapy, and thus, additional treatments directed to limiting or reversing inflammatory damage to the LT niche could potentially improve immune reconstitution.

Dendritic cells (DCs), because they orchestrate the immune response to microbes, represent an ideal target for pathogens attempting to evade the immune system. We hypothesized that interactions between human immunodeficiency virus (HIV) and DCs lead to the development of a semimature state, in which DCs migrate to lymph nodes but induce tolerance in T cells, rather than immunity. We found that lymph nodes from untreated HIV-infected subjects contained an abundance of semimature DCs, the disappearance of which correlated with the initiation of highly active antiretroviral therapy (HAART). Such lymph nodes also contained an abundance of T cells that had a regulatory phenotype and that persisted after HAART. Lymph node DCs from untreated HIV-infected subjects cultured with normal allogeneic T cells induced these T cells to adopt the phenotype of regulatory T cells, an ability that was lost after HAART. We conclude that HIV infection correlates with the presence of semimature DCs that stimulate T cell tolerance rather than immunity. These regulatory T cells may contribute to the lack of effective HIV immune responses.

Osteopontin is a multifunctional protein with known roles in bone remodeling, wound healing, and normal and pathological immune responses. We showed in microarray studies that osteopontin gene expression is increased in human immunodeficiency virus type 1 (HIV-1)-infected lymphatic tissues after treatment, and we undertook mapping experiments to study osteopontin's possible functions in this context. We discovered species-specific colocalization of osteopontin with the follicular dendritic cell (FDC) network in lymphatic tissues in HIV-1 and simian immunodeficiency virus infections, and we found that changes in FDC-associated osteopontin covary with changes in lymphoid follicles during acute and late stages of infection and in response to treatment. We propose that this localization normally facilitates antibody production and plays a role in B cell abnormalities in infection and in the reconstitution of lymphoid follicles with treatment and that mapping genes identified in microarray studies is a useful experimental approach to gaining a better understanding of function in the context of a particular tissue and disease.