Dinoflagellate Amphiesmal Dynamics: Cell Wall Deposition with Ecdysis and Cellular Growth.

Dinoflagellates are a major aquatic protist group with amphiesma, multiple cortical membranous "cell wall" layers that contain large circum-cortical alveolar sacs (AVs). AVs undergo extensive remodeling during cell- and life-cycle transitions, including ecdysal cysts (ECs) and resting cysts that are important in some harmful algal bloom initiation-termination. AVs are large cortical vesicular compartments, within which are elaborate cellulosic thecal plates (CTPs), in thecate species, and the pellicular layer (PL). AV-CTPs provide cellular mechanical protection and are targets of vesicular transport that are replaced during EC-swarmer cell transition, or with increased deposition during the cellular growth cycle. AV-PL exhibits dynamical-replacement with vesicular trafficking that are orchestrated with amphiesmal chlortetracycline-labeled Ca2+ stores signaling, integrating cellular growth with different modes of cell division cycle/progression. We reviewed the dynamics of amphiesma during different cell division cycle modes and life cycle stages, and its multifaceted regulations, focusing on the regulatory and functional readouts, including the coral-zooxanthellae interactions.

Transcriptomic Signatures of Human Immunodeficiency Virus Post-Treatment Control.

Posttreatment controllers (PTCs) are rare HIV-infected individuals who can limit viral rebound after antiretroviral therapy interruption (ATI), but the mechanisms of this remain unclear. To investigate these mechanisms, we quantified various HIV RNA transcripts (via reverse transcription droplet digital PCR [RT-ddPCR]) and cellular transcriptomes (via RNA-seq) in blood cells from PTCs and noncontrollers (NCs) before and two time points after ATI. HIV transcription initiation did not significantly increase after ATI in PTCs or in NCs, whereas completed HIV transcripts increased at early ATI in both groups and multiply-spliced HIV transcripts increased only in NCs. Compared to NCs, PTCs showed lower levels of HIV DNA, more cell-associated HIV transcripts per total RNA at all times, no increase in multiply-spliced HIV RNA at early or late ATI, and a reduction in the ratio of completed/elongated HIV RNA after early ATI. NCs expressed higher levels of the IL-7 pathway before ATI and expressed higher levels of multiple cytokine, inflammation, HIV transcription, and cell death pathways after ATI. Compared to the baseline, the NCs upregulated interferon and cytokine (especially TNF) pathways during early and late ATI, whereas PTCs upregulated interferon and p53 pathways only at early ATI and downregulated gene translation during early and late ATI. In NCs, viral rebound after ATI is associated with increases in HIV transcriptional completion and splicing, rather than initiation. Differences in HIV and cellular transcription may contribute to posttreatment control, including an early limitation of spliced HIV RNA, a delayed reduction in completed HIV transcripts, and the differential expression of the IL-7, p53, and TNF pathways. IMPORTANCE The findings presented here provide new insights into how HIV and cellular gene expression change after stopping ART in both noncontrollers and posttreatment controllers. Posttreatment control is associated with an early ability to limit increases in multiply-spliced HIV RNA, a delayed (and presumably immune-mediated) ability to reverse an initial rise in processive/completed HIV transcripts, and multiple differences in cellular gene expression pathways. These differences may represent correlates or mechanisms of posttreatment control and may provide insight into the development and/or monitoring of therapeutic strategies that are aimed at a functional HIV cure.

A Global Trend Analysis of Kidney Cancer Incidence and Mortality and Their Associations with Smoking, Alcohol Consumption, and Metabolic Syndrome.

BACKGROUND: Kidney cancer is a major urological disease globally, with more than 400 000 new cases diagnosed every year. OBJECTIVE: To investigate incidence and mortality trends for kidney cancer and their associations with modifiable risk factors for kidney cancer. DESIGN, SETTING, AND PARTICIPANTS: The most up-to-date figures on kidney cancer incidence and mortality were collected from the GLOBOCAN database and the Cancer Incidence in Five Continents (CI5). Data on total alcohol consumption and the prevalence of smoking, overweight, diabetes, and hypertension were extracted from the World Health Organization Global Health Observatory data repository. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Age-standardized rates (ASRs) for incidence and mortality and their correlations with potential risk factors for kidney cancer were investigated. Multivariable linear regression analysis was also conducted. The 10-yr temporal patterns for incidence are presented as the average annual percent change with 95% confidence interval using joinpoint regression analysis. RESULTS AND LIMITATIONS: Globally, there is wide variation in kidney cancer incidence and mortality. There were positive correlations between rates of smoking, alcohol consumption, and overweight and ASRs of kidney cancer incidence and mortality. Multivariable regression analysis revealed that alcohol consumption and overweight were significant risk factors for kidney cancer incidence, while smoking and alcohol consumption were significant risk factors for kidney cancer mortality. There was an increasing trend for the incidence of kidney cancer globally, with a particularly prominent trend for European countries. Of note, increasing incidence of kidney cancer is evident even for younger individuals aged <50 yr. However, cancer registries vary by country and period and there is a lack of data regarding the severity of risk factors and disease characteristics such as the distribution of histological groups, tumor grading, and staging. CONCLUSIONS: There is an increasing trend for kidney cancer incidence globally, particularly in European countries and the younger population. Modifiable risk factors for kidney cancer incidence and mortality have been identified. The increasing incidence of kidney cancer among younger individuals is worrying and warrants early action on possible preventive measures. PATIENT SUMMARY: The incidence of kidney cancer has been increasing globally, particularly in European countries and the younger population. Risk factors include smoking, alcohol consumption, overweight, and hypertension, and these factors are all modifiable.

How to manage patients with suspected upper tract urothelial carcinoma in the pandemic of COVID-19?

BACKGROUND: The pandemic of COVID-19 has disrupted the clinical pathway for patients with suspected upper tract urothelial carcinoma (UTUC). This aims to investigate the optimal management of UTUC during the pandemic by determining 1) Whether a three-month delay of RNU leads to worsened overall survival, 2) Whether radical nephroureterectomy (RNU) can be performed without prior diagnostic ureteroscopy (URS). METHODS: Consecutive patients with RNU performed for suspected UTUC in four hospitals in Hong Kong and Taiwan were included. Patients with histologically proven UTUC and with RNU performed within one year were dichotomized into early (≤3 months) and delayed (>3 months) RNU groups. Diagnostic performances of predictive models based on pre-URS factors (gross haematuria, suspicious or malignant urine cytology, and filling defect or contrast-enhancing mass on computed tomography), with or without URS, were analysed using receiver operating characteristics and area under curve (AUC). Overall survival was analysed using Kaplan-Meier method and multivariate Cox regression analysis. RESULTS: Between 2000 and 2019, 665 patients underwent RNU, and 491 of them had prior diagnostic URS. The early RNU group had a better overall survival (P = 0.015). Early RNU was associated with a better overall survival upon multivariate analysis (HR 1.55, 95% CI 1.03-2.33, P = 0.035). Large tumour size, multi-focal tumour, T2 or above disease, and positive nodal status were associated with a poorer overall survival. A combination of any 2 out of the 3 pre-URS factors achieved a positive predictive value of 99.5 to 100%. Presence of all 3 pre-URS factors achieved an AUC of 0.851 with URS, and AUC of 0.809 without URS. CONCLUSIONS: A delay of RNU for over 3 months was associated with poorer overall survival and has to be avoided despite the current COVID-19. We can also consider direct RNU based on clinical factors alone. This also avoids URS hospitalization and expedites the clinical pathway of UTUC.

Consensus statements on the management of metastatic renal cell carcinoma from the Hong Kong Urological Association and the Hong Kong Society of Uro-Oncology 2019.

BACKGROUND: To establish a set of consensus statements for the management of metastatic renal cell carcinoma, a total of 12 urologists and clinical oncologists from two professional associations in Hong Kong formed an expert consensus panel. METHODS: Through a series of meetings and using the modified Delphi method, the panelists presented recent evidence, discussed clinical experiences, and drafted consensus statements on several areas of focus regarding the management of metastatic renal cell carcinoma. Each statement was eventually voted upon by every panelist based on the practicability of recommendation. RESULTS: A total of 46 consensus statements were ultimately accepted and established by panel voting. CONCLUSIONS: Derived from recent evidence and expert insights, these consensus statements were aimed at providing practical guidance to optimize metastatic renal cell carcinoma management and promote a higher standard of clinical care.

Gag p24 Is a Marker of Human Immunodeficiency Virus Expression in Tissues and Correlates With Immune Response.

We demonstrate that human immunodeficiency virus (HIV) gag p24 protein is more readily detected in gut and lymph node tissues than in blood CD4+ T cells and correlates better with CD4 count during antiretroviral therapy (ART). Gut p24 levels also measurably decline with ART in natural controllers. During ART, gut p24 expression is more strongly associated both with HIV-specific CD8+ T-cell frequency and plasma soluble CD14 levels than gut HIV RNA expression. This study supports using gag p24 as a marker of HIV expression in HIV+ tissues to study effects of viral persistence and to monitor efficacy of treatment in HIV-based clearance studies.

Functional responses between PMP3 small membrane proteins and membrane potential.

The Plasma Membrane Proteolipid 3 (PMP3, UPF0057 family in Uniprot) family consists of abundant small hydrophobic polypeptides with two predicted transmembrane helices. Plant homologues were upregulated in response to drought/salt-stresses and yeast deletion mutants exhibited conditional growth defects. We report here abundant expression of Group I PMP3 homologues (PMP3(i)hs) during normal vegetative growth in both prokaryotic and eukaryotic cells, at a level comparable to housekeeping genes, implicating the regular cellular functions. Expression of eukaryotic PMP3(i)hs was dramatically upregulated in response to membrane potential (Vm) variability (Vmvar ), whereas PMP3(i)hs deletion-knockdown led to Vm changes with conditional growth defects. Bacterial PMP3(i)h yqaE deletion led to a shift of salt sensitivity; Vmvar alternations with exogenous K+ addition downregulated prokaryotic PMP3(i)hs, suggesting [K+ ]-Vmvar axis being a significant feedback element in prokaryotic ionic homeostasis. Remarkably, the eukaryotic homologues functionally suppressed the conditional growth defects in bacterial deletion mutant, demonstrating the conserved cross-kingdom membrane functions by PMP3(i)hs. These data demonstrated a direct reciprocal relationship between PMP3(i)hs expression and Vm differentials in both prokaryotic and eukaryotic cells. Cumulative with PMP3(i)hs ubiquitous abundance, their lipid-binding selectivity and membrane protein colocalization, we propose [PMP3(i)hs]-Vmvar axis as a key element in membrane homeostasis.

Reaching the Hard to Reach in Thailand: Eliminating Mother-To-Child HIV Transmission.

Thailand is the first country in the Asia-Pacific region to be validated by the World Health Organization as having eliminated mother-to-child transmission (MTCT) of HIV. The Thai government made health-and specifically addressing the HIV/AIDS crisis-a political priority. The Thailand experience, from the emergence of the HIV/AIDS epidemic in the 1980s through the present, provides an important case study of successful MTCT elimination. To eliminate MTCT requires that health interventions reach those who are hardest to reach: the poorest of the poor, geographically distant and rural, and marginalized. This policy report highlights key factors for successfully reaching the hard to reach in Thailand, including the importance of national public policy as well as investments in health care infrastructure, such as access to antenatal care, the creation of effective monitoring and surveillance systems, and strengthening local health capacity. Increased availability and affordability of antiretroviral therapies was also critical to Thailand's success in addressing MTCT. The Thailand case offers important policy lessons for achieving universal health. This policy report draws on secondary research and key informant interviews in Thailand to highlight factors for success in eliminating MTCT of HIV.

Pharyngeal Dysphagia in Individuals With Cervical Spinal Cord Injury: A Prospective Observational Cohort Study.

Objectives: To identify and describe the types and time course of dysphagia following cervical spinal cord injury (SCI). Methods: This was a prospective cohort study conducted in an SCI inpatient rehabilitation unit. Seventy-six individuals with SCI were enrolled. Inclusion criteria were age 18 years or older, admitted into SCI inpatient rehabilitation unit, and medically stable for participation in bedside swallow evaluation (BSE) and videofluoroscopic swallow study (VFSS). All participants first underwent a BSE, of whom 33 completed a VFSS. A follow-up BSE was conducted on individuals who tested positive on the initial BSE and continued to show signs of dysphagia. Diagnosis and type of dysphagia as well risk factors were collected. Results: Twenty-three out of 76 individuals with cervical SCI were diagnosed with dysphagia using the BSE. All participants with positive BSE and VFSS had pharyngeal dysfunction. For participants with a positive initial BSE and persisting dysphagia (n = 14), a follow-up BSE demonstrated resolution within 34 days. Risk factors associated with dysphagia were older age, nasogastric tube, invasive mechanical ventilation, tracheostomy, and pneumonia. Posterior spinal surgery was associated with a decreased risk of dysphagia. Conclusion: Dysphagia was present in 30% of individuals based on the initial BSE. All individuals with dysphagia demonstrated pharyngeal phase dysfunction on the VFSS. No participants experiencing dysphagia were missed on the BSE as confirmed by VFSS. In the subset of individuals who received a follow-up BSE, the time course of resolution of dysphagia was at most 34 days from initial BSE.

Knockdown of Dinoflagellate Cellulose Synthase CesA1 Resulted in Malformed Intracellular Cellulosic Thecal Plates and Severely Impeded Cyst-to-Swarmer Transition.

Cellulose synthesis (CS) is conducted by membrane-bound cellulose synthase complexes (CSCs), containing cellulose synthases (CesA), that are either arranged in hexagonal structures in higher plants or in linear arrays in most microbial organisms, including dinoflagellates. Dinoflagellates are a major phytoplankton group having linear-type CSCs and internal cellulosic thecal plates (CTPs) in large cortical vesicles. Immunological study suggested CesA1p were cortically localized to the periphery of CTPs. During cyst-to-swarmer transition (TC-S), synchronized peaks of CesA1 transcription, CesA1p expression, CS and CTP formation occurred in respective order, over 12-16 h, strategically allowing the study of CS regulation and CTP biogenesis. CesA1-knockdown resulted in 40% reduction in CesA1p level and time required for swarmer cells reappearance. CTPs were severely malformed with reduced cellulose content. As CTPs are deposited in internal organelle, the present study demonstrated dinoflagellate CesA1 ortholog was adapted for non-surface deposition; this is different to paradigm of other CesAps which require plasmamembrane for cellulose fiber deposition. This pioneer gene-knockdown study demonstrated the requirement of a gene for dinoflagellate cell wall remodeling and proper TC-S, which are prominent in dinoflagellate life-cycles.

Disruption of latent HIV in vivo during the clearance of actinic keratosis by ingenol mebutate.

Actinic keratosis (AK) is a precancerous skin lesion that is common in HIV-positive patients. Without effective treatment, AKs can progress to squamous cell carcinoma. Ingenol mebutate, a PKC agonist, is a US Food and Drug Administration-approved (FDA-approved) topical treatment for AKs. It can induce reactivation of latent HIV transcription in CD4+ T cells both in vitro and ex vivo. Although PKC agonists are known to be potent inducers of HIV expression from latency, their effects in vivo are not known because of the concerns of toxicity. Therefore, we sought to determine the effects of topical ingenol mebutate gel on the HIV transcription profile in HIV-infected individuals with AKs, specifically in the setting of suppressive antiretroviral therapy (ART). We found that AKs cleared following topical application of ingenol mebutate and detected marginal changes in immune activation in the peripheral blood and in skin biopsies. An overall increase in the level of HIV transcription initiation, elongation, and complete transcription was detected only in skin biopsies after the treatment. Our data demonstrate that application of ingenol mebutate to AKs in ART-suppressed HIV-positive patients can effectively cure AKs as well as disrupt HIV latency in the skin tissue microenvironment in vivo without causing massive immune activation.

The cardiovascular risk factors in men with lower urinary tract symptoms.

OBJECTIVE: It has been hypothesized that endothelial dysfunction and pelvic atherosclerosis may contribute to lower urinary tract symptoms (LUTS). We assessed the relationship between cardiovascular risk factors and LUTS severity in male patients presented to urology clinic. METHODS: It is a cross-sectional study on patients who presented between 2013 and 2015 with LUTS. A total of 1176 male patients were encountered, and 966 were included for analysis after excluding patients with urinary tract malignancy, urethral stricture, bladder stone and history of urinary tract surgery. Cardiovascular risk factors including components of Framingham risk score, body mass index, uroflowmetry, International Prostate Symptoms Score, fasting blood glucose and serum prostate-specific antigen (PSA) were assessed. Correlation between Framingham risk score, cardiovascular risk factors and severity of LUTS was investigated. RESULTS: Multinomial logistic regression analysis showed that severe LUTS significantly associated with Framingham score (P = 0.008) and its components of total cholesterol (OR = 1.318; P = 0.010) and age (OR = 1.032; P = 0.006) compare with mild symptoms. Framingham risk score was found to correlate with storage symptoms (CC = 0.083; P < 0.0001) but not voiding symptoms (CC = - 0.029; P = 0.185). CONCLUSIONS: Severity of LUTS and storage symptom significantly increases Framingham risk score, particularly with the components of total cholesterol level and age.

Characterization of the HIV-1 transcription profile after romidepsin administration in ART-suppressed individuals.

OBJECTIVES: Reversing HIV-1 latency has been suggested as a strategy to eradicate HIV-1. We investigated the effect of romidepsin on the HIV transcription profile in participants from the REDUC part B clinical trial. DESIGN: Seventeen participants on suppressive antiretroviral therapy were vaccinated with six doses of the therapeutic vaccine Vacc-4x followed by treatment with three doses of romidepsin. Samples from nine study participants were available for HIV transcription profile analysis. METHODS: Read-through, total (TAR), elongated (longLTR), polyadenylated (polyA) and multiply-spliced (Tat-Rev) HIV transcripts and total HIV DNA were quantified at baseline (visit 1) and 4 h after the second (visit 10b) and third (visit 11b) romidepsin infusions. RESULTS: Read-through, total, elongated, and polyadenylated HIV transcripts increased after romidepsin infusion (P = 0.020, P = 0.0078, P = 0.0039, P = 0.027, respectively), but no changes were observed in multiply-spliced HIV RNA or HIV DNA. No change was observed in the ratio of read-through/total HIV transcripts. The ratio of elongated/total HIV RNA increased after romidepsin (P = 0.016), whereas the ratio of polyadenylated/elongated HIV decreased. Both elongated HIV transcripts and total HIV DNA correlated negatively with the time to viral rebound after interruption of ART. CONCLUSIONS: In these patients, romidepsin increased early events in HIV transcription (initiation and especially elongation), but had less effect on later stages (completion, multiple splicing) that may be required for comprehensive latency reversal and cell killing. Without cell death, increased HIV transcription before or after latency reversal may hasten viral rebound after therapy interruption.

Comparison of the prognostic value of non-ischaemic fractional flow reserve using intracoronary versus intravenous adenosine.

AIMS: Intracoronary adenosine (ICA) yields similar fractional flow reserve (FFR) results to the "gold standard" of intravenous adenosine (IVA). Whether they have similar prognostic significance is unknown. We therefore sought to study the prognostic value of the route of adenosine administration for the measurement of FFR in deferred coronary lesions in a large, real-world cohort. METHODS AND RESULTS: Five hundred and seventy-six patients with 787 lesions in whom PCI was deferred based on FFR >0.75 were studied. The primary outcome was the first major adverse cardiovascular event (MACE; defined as death, myocardial infarction [MI], or target vessel revascularisation [TVR]), and the secondary outcome was a composite of MI and target vessel failure (TVF). FFR was measured with ICA in 426 lesions and IVA in 361 lesions. Median follow-up duration was 3.2 years (interquartile range: 1.7- 4.6). Propensity-matched cohorts of ICA and IVA were well matched for baseline clinical, angiographic and haemodynamic characteristics. In the propensity-matched cohort, MACE occurred in 23.5% of the ICA group and in 22.3% of the IVA group (p=0.29). On multivariate analysis, acute coronary syndrome, FFR and prior MI/revascularisation were independent predictors of MACE and MI/TVF. The route of adenosine administration was not predictive of MACE or MI/TVF. CONCLUSIONS: ICA and IVA yield similar FFR values and show comparable long-term prognostic utility in a deferred population. These findings provide confirmation that non-ischaemic FFR using a simpler ICA protocol provides prognostic data similar to the gold standard IVA.

Impact of Allogeneic Hematopoietic Stem Cell Transplantation on the HIV Reservoir and Immune Response in 3 HIV-Infected Individuals.

BACKGROUND: Allogeneic hematopoietic stem cell transplantation (HSCT) can lead to significant changes to the HIV reservoir and HIV immune responses, indicating that further characterization of HIV-infected patients undergoing HSCT is warranted. METHODS: We studied 3 patients who underwent HSCT after either reduced intensity conditioning or myeloablative conditioning regimen. We measured HIV antigens and antibodies (Ag/Ab), HIV-specific CD4 T-cell responses, HIV RNA, and DNA in plasma, peripheral blood mononuclear cells, isolated CD4 T cells from peripheral blood, and lymph node cells. The patients remained on antiretroviral therapy throughout the follow-up period. RESULTS: All patients have been in continued remission for 4-6 years post-HSCT. Analyses of HIV RNA and DNA levels showed substantial reductions in HIV reservoir-related measurements in all 3 patients, changes in immune response varied with pronounced reductions in 2 patients and a less dramatic reduction in 1 patient. One patient experienced unexpected viral rebound 4 years after HSCT. CONCLUSIONS: These 3 cases highlight the substantial changes to the HIV reservoir and the HIV immune response in patients undergoing allogeneic HSCT. The viral rebound observed in 1 patient indicates that replication competent HIV can re-emerge several years after HSCT despite these marked changes.

Percutaneous Needle Tenotomy for the Treatment of Lateral Epicondylitis: A Systematic Review of the Literature.

OBJECTIVE: To analyze the literature to determine whether controlled studies on percutaneous tenotomy have been published, and if so, to systematically assess the efficacy of percutaneous tenotomy for the treatment of tendinosis at the lateral epicondyle of the elbow. DESIGN: Systematic review of the available literature. METHODS: Cochrane Controlled Trials Register (CENTRAL), MEDLINE, EMBASE, CINAHL, and Web of Science databases were searched in November 2015, unrestricted by date. After the initial search, we excluded conference proceedings, theses, reviews, expert opinions, and publications written in languages other than English. Next, 2 independent reviewers screened all of the remaining records with regard to their titles and abstracts, and subsequently, the full texts of identified publications potentially relevant to the present study. RESULTS: Six articles focused on percutaneous tenotomy, none of which were controlled against a placebo or conservative treatment group. The absence of true randomized controlled trials created a great deal of heterogeneity between the studies; thus we could not include any of our studies in the intended final quantitative analysis with meta-analysis tools. We describe all 6 studies identified by this systematic review with a detailed analysis of the procedural methods, outcome measures, and conclusions of each study. CONCLUSIONS: Percutaneous tenotomy presents an alternative to surgical release of the common extensor tendon for the treatment of chronic tendinosis at the lateral epicondyle of the elbow. Current research supporting the efficacy of this procedure, however, is of low quality (level II to level IV). LEVEL OF EVIDENCE: III.

Stimulating the RIG-I pathway to kill cells in the latent HIV reservoir following viral reactivation.

The persistence of latent HIV proviruses in long-lived CD4(+) T cells despite antiretroviral therapy (ART) is a major obstacle to viral eradication. Because current candidate latency-reversing agents (LRAs) induce HIV transcription, but fail to clear these cellular reservoirs, new approaches for killing these reactivated latent HIV reservoir cells are urgently needed. HIV latency depends upon the transcriptional quiescence of the integrated provirus and the circumvention of immune defense mechanisms. These defenses include cell-intrinsic innate responses that use pattern-recognition receptors (PRRs) to detect viral pathogens, and that subsequently induce apoptosis of the infected cell. Retinoic acid (RA)-inducible gene I (RIG-I, encoded by DDX58) forms one class of PRRs that mediates apoptosis and the elimination of infected cells after recognition of viral RNA. Here we show that acitretin, an RA derivative approved by the US Food and Drug Administration (FDA), enhances RIG-I signaling ex vivo, increases HIV transcription, and induces preferential apoptosis of HIV-infected cells. These effects are abrogated by DDX58 knockdown. Acitretin also decreases proviral DNA levels in CD4(+) T cells from HIV-positive subjects on suppressive ART, an effect that is amplified when combined with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor. Pharmacological enhancement of an innate cellular-defense network could provide a means by which to eliminate reactivated cells in the latent HIV reservoir.

Tissue reservoirs of HIV.

PURPOSE OF REVIEW: Tissue reservoirs of HIV may promote the persistent immunopathology responsible for non-AIDS morbidity and data support multifocal reactivation from tissues as the source of viral rebound during antiretroviral therapy (ART) interruption. The heterogeneity of tissue reservoirs and incomplete knowledge about their composition are obstacles to an HIV cure. RECENT FINDINGS: In addition to the higher concentration of infected CD4 T cells found in both central lymphoid tissues and gut, specific subsets of CD4 T cells appear to play a disproportionate role in HIV persistence. Recently, a subset of central memory T cells enriched in lymph node germinal centers called T-follicular helper cells has been identified that expresses more viral RNA and occupies an anatomic niche inaccessible to cytotoxic T lymphocyte killing. Additional observations suggest that antiretroviral drug (ARV) concentrations may be lower in some tissues, raising the possibility for localized, low-level viral replication. Finally, some recent data implicate the persistence of infected, non-CD4 T-cell types in tissues during ART. SUMMARY: The retention of infected cells in a wide variety of tissues, often with distinct viral and cellular characteristics, underscores the importance of studying tissue reservoirs in the development and assessment of cure strategies. Both inhibitory ARVs and latency-reversing drugs must reach these sites, and novel strategies may be needed to attack virus in cells as variable as T-follicular helper cells and macrophages.