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Tickborne Diseases The burden of tickborne diseases is growing substantially and seems likely to continue to do so. Prevention and management are hampered by suboptimal diagnostics, lack of treatment options for emerging viruses, and a paucity of vaccines.

VRC01 protects macaques from vaginal SHIV infection after a single high-dose challenge. Infusion of a simianized anti-α4β7 mAb (Rh-α4β7) just prior to, and during repeated vaginal exposures to SIVmac251 partially protected macaques from vaginal SIV infection and rescued CD4+ T cells. To investigate the impact of combining VRC01 and Rh-α4β7 on SHIV infection, 3 groups of macaques were treated with a suboptimal dosing of VRC01 alone or in combination with Rh-α4β7 or with control antibodies prior to the initiation of weekly vaginal exposures to a high dose (1000TCID50) of SHIVAD8-EO. The combination Rh-α4β7-VRC01 significantly delayed SHIVAD8-EO vaginal infection. Following infection, VRC01-Rh-α4β7-treated macaques maintained higher CD4+ T cell counts and exhibited lower rectal SIV-DNA loads compared to the controls. Interestingly, VRC01-Rh-α4β7-treated macaques had less IL-17 producing cells in the blood and the gut during the acute phase of infection. Moreover, higher T cell responses to the V2-loop of the SHIVAD8-EO envelope in the VRC01-Rh-α4β7 group inversely correlated with set point viremia. The combination of suboptimal amounts of VRC01 and Rh-α4β7 delayed infection, altered anti-viral immune responses and minimized CD4+ T cell loss. Further exploration of the effect of combining bNAbs with Rh-α4β7 on SIV/HIV infection and anti-viral immune responses is warranted and may lead to novel preventive and therapeutic strategies.Short summaryA combination of VRC01 and Rh-α4β7 significantly delayed SHIV acquisition, protected CD4 counts, decreased gut viral load and modified the immune response to the virus.

After December 17, 2014, when the US and Cuban governments announced their intent to restore relations, the two countries participated in various exchange activities in an effort to encourage cooperation in public health, health research and biomedical sciences. The conference entitled Exploring Opportunities for Arbovirus Research Collaboration, hosted at Havana's Hotel Nacional, was part of these efforts and was the first major US-Cuban scientific conference in over 50 years. Its purpose was to share information about current arbovirus research and recent findings, and to explore opportunities for future joint research. The nearly 100 participants included leading arbovirus and vector transmission experts from ten US academic institutions, NIH, CDC, FDA and the US Department of Defense. Cuban participants included researchers, clinicians and students from Cuba's Ministry of Public Health, Pedro Kourí Tropical Medicine Institute, Center for Genetic Engineering and Biotechnology, Center for State Control of Medicines and Medical Devices and other health research and regulatory organizations. Topics highlighted at the three-day meeting included surveillance, research and epidemiology; pathogenesis, immunology and virology; treatment and diagnosis; vector biology and control; vaccine development and clinical trials; and regulatory matters. Concurrent breakout discussions focused on novel vector control, nonvector transmission, community engagement, Zika in pregnancy, and workforce development. Following the conference, the Pedro Kourí Tropical Medicine Institute and the US National Institute of Allergic and Infectious Diseases have continued to explore ways to encourage and support scientists in Cuba and the USA who wish to pursue arbovirus research cooperation to advance scientific discovery to improve disease prevention and control. KEYWORDS Arboviruses, flavivirus, Zika virus, chikungunya virus, dengue virus, research, disease vectors, Cuba, USA.

Monoclonal Antibodies for Infectious Diseases Research advances could facilitate use of monoclonal antibodies for emerging infectious diseases — in treatment of infected individuals, targeted prophylaxis to protect high-risk individuals, and targeted prophylaxis to interrupt transmission in average-risk populations.

The explosive pandemic of Zika virus infection in South and Central America is the most recent of four unexpected arrivals of important arthropod-borne viral diseases in the Western Hemisphere over the past 20 years. Is this an important new disease-emergence pattern?

In his famous 1966 New England Journal of Medicine article, Henry Beecher concluded that a critical safeguard for protecting human participants, more reliable than informed consent, was the "presence of an intelligent, informed, conscientious, compassionate, responsible investigator." This article examines Beecher's appeal to reliance on the "virtuous" investigator in light of the critical role that investigators play in research ethics and the systems of research protections that have been developed since Beecher's writing. It addresses the extent to which research ethics rely on virtuous investigators; the meaning of virtuous, as distinct from compliance with the rules and regulations that guide ethical research; the particular virtues that it might be important for investigators to have; and the impact of the existing system of human subjects protections on the virtuous investigator. The virtuous investigator who is motivated to take ethical responsibilities seriously is an essential safeguard for the protection of human research participants and an important complement to the system of oversight protections. However, since the current human subjects protection system does not promote virtue or ethical resourcefulness by investigators, attention to enhancing a culture of professional responsibility might serve to forge a synergy between the protections afforded by the current oversight system and those provided by the virtuous investigator.

Although extraordinary progress has been made in the treatment and prevention of HIV infection, the AIDS pandemic continues to rage globally with 2.1 million infections and 1.6 million AIDS-related deaths reported in 2013. Until an effective vaccine is developed, new strategies for treatment and prevention are needed. Regarding the prevention of HIV infection, a major focus of prevention research in general and vaccine research in particular involves the interaction of the HIV-1 envelope protein gp120 with cell-surface receptors, with the hope that a greater understanding of these interactions will lead to the development of novel strategies aimed at preventing and even treating HIV-1 infection. Particular attention has been directed toward gaining a more precise understanding of the early events in transmission focusing on that critical window of time when HIV first establishes infection in the host. Here we describe some of the recent findings involving HIV-1 envelope interactions with cell surface receptors that are relevant to transmission and which may represent new opportunities to develop strategies to prevent HIV infection.

The gastrointestinal (GI) mucosa is central to HIV pathogenesis, and the integrin α4β7 promotes the homing of immune cells to this site, including those that serve as viral targets. Data from simian immunodeficiency virus (SIV) animal models suggest that α4β7 blockade provides prophylactic and therapeutic benefits. We show that pre-HIV infection frequencies of α4β7+ peripheral blood CD4+ T cells, independent of other T cell phenotypes and genital inflammation, were associated with increased rates of HIV acquisition in South African women. A similar acquisition effect was observed in a Kenyan cohort and in nonhuman primates (NHPs) after intravaginal SIV challenge. This association was stronger when infection was caused by HIV strains containing V2 envelope motifs with a preference for α4β7 binding. In addition, pre-HIV α4β7+ CD4+ T cells predicted a higher set-point viral load and a greater than twofold increased rate of CD4+ T cell decline. These results were confirmed in SIV-infected NHPs. Increased frequencies of pre-HIV α4β7+ CD4+ T cells were also associated with higher postinfection expression of lipopolysaccharide binding protein, a microbial translocation marker, suggestive of more extensive gut damage. CD4+ T cells expressing α4β7 were rapidly depleted very early in HIV infection, particularly from the GI mucosa, and were not restored by early antiretroviral therapy. This study provides a link between α4β7 expression and HIV clinical outcomes in humans, in line with observations made in NHPs. Given the availability of a clinically approved anti-α4β7 monoclonal antibody for treatment of inflammatory bowel disease, these data support further evaluation of targeting α4β7 integrin as a clinical intervention during HIV infection.

Human gut associated lymphoid tissues (GALT) play a key role in the acute phase of HIV infection. The propensity of HIV to replicate in these tissues however, is not fully understood. Access and migration of naïve and memory CD4+ T cells to these sites is mediated by interactions between integrin α4β7, expressed on CD4+ T cells, and MAdCAM, expressed on high endothelial venules. We report here that MAdCAM delivers a potent costimulatory signal to naïve and memory CD4+ T cells following ligation with α4β7. Such costimulation promotes high-levels of HIV replication. An anti-α4β7 mAb that prevents mucosal transmission of SIV blocks MAdCAM signaling through α4β7 and MAdCAM-dependent viral replication. MAdCAM costimulation of memory CD4+ T cells is sufficient to drive cellular proliferation and the up-regulation of CCR5, while naïve CD4+ T cells require both MAdCAM and retinoic acid to achieve the same response. The pairing of MAdCAM and retinoic acid is unique to the GALT, leading us to propose that HIV replication in these sites is facilitated by MAdCAM-α4β7 interactions. Moreover, complete inhibition of MAdCAM signaling by an anti-α4β7 mAb, an analogue of a clinically approved therapeutic (vedolizumab), highlights the potential of such agents to control acute HIV infection.

Despite substantial clinical benefits, complete eradication of HIV has not been possible using antiretroviral therapy (ART) alone. Strategies that can either eliminate persistent viral reservoirs or boost host immunity to prevent rebound of virus from these reservoirs after discontinuation of ART are needed; one possibility is therapeutic vaccination. We report the results of a randomized, placebo-controlled trial of a therapeutic vaccine regimen in patients in whom ART was initiated during the early stage of HIV infection and whose immune system was anticipated to be relatively intact. The objectives of our study were to determine whether the vaccine was safe and could induce an immune response that would maintain suppression of plasma viremia after discontinuation of ART. Vaccinations were well tolerated with no serious adverse events but produced only modest augmentation of existing HIV-specific CD4+ T cell responses, with little augmentation of CD8+ T cell responses. Compared with placebo, the vaccination regimen had no significant effect on the kinetics or magnitude of viral rebound after interruption of ART and no impact on the size of the HIV reservoir in the CD4+ T cell compartment. Notably, 26% of subjects in the placebo arm exhibited sustained suppression of viremia (

The intestinal mucosa is a key anatomical site for HIV-1 replication and CD4+ T cell depletion. Accordingly, in vivo treatment with an antibody to the gut-homing integrin α4β7 was shown to reduce viral transmission, delay disease progression, and induce persistent virus control in macaques challenged with simian immunodeficiency virus (SIV). We show that integrin α4β7 is efficiently incorporated into the envelope of HIV-1 virions. Incorporated α4β7 is functionally active as it binds mucosal addressin cell adhesion molecule-1 (MAdCAM-1), promoting HIV-1 capture by and infection of MAdCAM-expressing cells, which in turn mediate trans-infection of bystander cells. Functional α4β7 is present in circulating virions from HIV-infected patients and SIV-infected macaques, with peak levels during the early stages of infection. In vivo homing experiments documented selective and specific uptake of α4β7+ HIV-1 virions by high endothelial venules in the intestinal mucosa. These results extend the paradigm of tissue homing to a retrovirus and are relevant for the pathogenesis, treatment, and prevention of HIV-1 infection.

Several highly potent and broadly neutralizing monoclonal antibodies against HIV have recently been isolated from B cells of infected individuals. However, the effects of these antibodies on the persistent viral reservoirs in HIV-infected individuals receiving antiretroviral therapy (ART) are unknown. We show that several HIV-specific monoclonal antibodies--in particular, PGT121, VRC01, and VRC03--potently inhibited entry into CD4(+) T cells of HIV isolated from the latent viral reservoir of infected individuals whose plasma viremia was well controlled by ART. In addition, we demonstrate that HIV replication in autologous CD4(+) T cells derived from infected individuals receiving ART was profoundly suppressed by three aforementioned and other HIV-specific monoclonal antibodies. These findings have implications for passive immunotherapy as an approach toward controlling plasma viral rebound in patients whose ART is withdrawn.

While the human immunodeficiency virus (HIV)/AIDS pandemic continues, the incidence of HIV infections has fallen because of the deployment of antiretroviral drugs and multiple prevention modalities. To achieve a durable end to the pandemic, a vaccine remains essential. Recent advances in vaccinology offer new promise for an effective HIV vaccine.

Studies proving that the benefits of prompt initiation of antiretroviral therapy for HIV infection outweigh the risks and that preexposure prophylaxis can be implemented safely and effectively will serve as critical tools in the fight to end the HIV–AIDS pandemic.

The humoral immune response after acute infection with HIV-1 is delayed and ineffective. The HIV-1 envelope protein gp120 binds to and signals through integrin α4β7 on T cells. We found that gp120 also bound to and signaled through α4β7 on naive B cells, which resulted in an abortive proliferative response. In primary B cells, signaling by gp120 through α4β7 resulted in increased expression of the immunosuppressive cytokine TGF-β1 and FcRL4, an inhibitory receptor expressed on B cells. Coculture of B cells with HIV-1-infected autologous CD4(+) T cells also increased the expression of FcRL4 by B cells. Our findings indicated that in addition to mediating chronic activation of the immune system, viral proteins contributed directly to HIV-1-associated B cell dysfunction. Our studies identify a mechanism whereby the virus may subvert the early HIV-1-specific humoral immune response.

Elite controllers suppress human immunodeficiency virus (HIV) viremia to below the limit of detection in the absence of antiretroviral therapy (ART). However, precise frequencies of CD4(+) T cells carrying replication-competent HIV and/or the dynamics of the infectious viral reservoirs in response to initiation and discontinuation of ART in elite controllers are unknown. We show that the size of the pool of CD4(+) T cells harboring infectious HIV diminished significantly after initiation of ART and rebounded to baseline upon cessation of therapy. Our data provide compelling evidence that persistent viral replication occurs in untreated elite controllers even in the absence of detectable plasma viremia.

Human immunodeficiency virus (HIV) disease is associated with dysregulation and dysfunction involving all major lymphocyte populations, including B cells. Such perturbations occur early in the course of infection and are driven in large part by immune activation resulting from ongoing HIV replication leading to bystander effects on B cells. While most of the knowledge regarding immune cell abnormalities in HIV-infected individuals has been gained from studies conducted on the peripheral blood, it is clear that the virus is most active and most damaging in lymphoid tissues. Here, we discuss B-cell perturbations in HIV-infected individuals, focusing on the skewing of B-cell subsets that circulate in the peripheral blood and their counterparts that reside in lymphoid tissues. This review also highlights recent advances in evaluating HIV-specific B-cell responses both in the memory B-cell compartment, as well as in circulating antibody-secreting plasmablasts and the more differentiated plasma cells residing in tissues. Finally, we consider how knowledge gained by investigating B cells in HIV-infected individuals may help inform the development of an effective antibody-based HIV vaccine.

Terminal differentiation of B cells and hypergammaglobulinemia are hallmarks of B-cell hyperactivity in HIV disease. Plasmablasts are terminally differentiating B cells that circulate transiently in the blood following infection or vaccination; however, in HIV infection, they arise early and are maintained at abnormally high levels in viremic individuals. Here we show that only a small fraction of plasmablasts in the blood of viremic individuals is HIV specific. Assessment of plasmablast immunoglobulin isotype distribution revealed increased IgG + plasmablasts in early and most prominently during chronic HIV viremia, contrasting with a predominantly IgA + plasmablast profile in HIV-negative individuals or in aviremic HIV-infected individuals on treatment. Of note, IgG is the predominant immunoglobulin isotype of plasmablasts that arise transiently in the blood following parenteral immunization. Serum immunoglobulin levels were also elevated in HIV-infected viremic individuals, especially IgG, and correlated with levels of IgG + plasmablasts. Several soluble factors associated with immune activation were also increased in the sera of HIV-infected individuals, especially in viremic individuals, and correlated with serum immunoglobulin levels, particularly IgG. Thus, our data suggest that while plasmablasts in the blood may contribute to the HIV-specific immune response, the majority of these cells are not HIV specific and arise early, likely from indirect immune-activating effects of HIV replication, and reflect over time the effects of chronic antigenic stimulation. Such B-cell dysregulation may help explain why the antibody response is inadequate in HIV-infected individuals, even during early infection.

Toward the end of 2015 and well into 2016, Zika virus dominated the attention of the public as well as international and regional health authorities. The World Health Organization declared Zika virus a public health emergency of international concern. Yet as 2017 begins, public attention to Zika virus has waned considerably as incident cases have decreased in the Americas, particularly in Brazil, the most severely affected country. With this decrease in attention comes the danger of complacency and failure to appreciate the potential scope of the disease. For example, many unanswered questions remain regarding the pathogenesis of Zika virus and the acute and long-term sequelae that make accurate risk assessment and public health recommendations difficult. Therefore, it is imperative that research and public health communities continue to focus on Zika virus as the acute phase of the epidemic subsides and endemicity ensues.

The gastrointestinal (GI) mucosa is central to HIV pathogenesis, and the integrin α(4)β(7) promotes the homing of immune cells to this site. Data from SIV animal models suggest that α(4)β(7) blockade provides prophylactic and therapeutic benefits. Here we show that pre-HIV infection levels of α(4)β(7)(+) peripheral blood CD4(+) T cells, independent of other T cell phenotypes and genital inflammation, were associated with increased rates of HIV acquisition in South African women. This association was stronger when infection was caused by HIV strains containing V2 Env motifs with a preference for α(4)β(7) binding. A similar acquisition effect was observed in a Kenyan cohort, and in non-human primates (NHPs) following intravaginal SIV challenge. In addition, pre-HIV α(4)β(7)(+) CD4(+) T cells predicted higher set point viral load and a >2-fold increased rate of CD4 decline. These results were confirmed in SIV-infected NHPs. Increased frequencies of pre-HIV α(4)β(7)(+) CD4(+) T cells were also associated with higher post-infection expression of LPS binding protein, a microbial translocation marker, suggestive of more extensive gut damage. CD4(+) T cells expressing α(4)β(7) were rapidly depleted very early in HIV infection, particularly from the GI mucosa, and were not restored by early antiretroviral therapy (ART). This study provides a link between α(4)β(7) expression and HIV clinical outcomes in humans, in line with observations made in NHPs. Given the availability of a clinically approved anti-α(4)β(7) monoclonal antibody for treatment of inflammatory bowel disease, these data support further evaluation of targeting α(4)β(7) integrin as a clinical intervention during HIV infection.

The discovery of potent and broadly neutralizing antibodies (bNAbs) against human immunodeficiency virus (HIV) has made passive immunization a potential strategy for the prevention and treatment of HIV infection. We sought to determine whether passive administration of VRC01, a bNAb targeting the HIV CD4-binding site, can safely prevent or delay plasma viral rebound after the discontinuation of antiretroviral therapy (ART).We conducted two open-label trials (AIDS Clinical Trials Group [ACTG] A5340 and National Institutes of Health [NIH] 15-I-0140) of the safety, side-effect profile, pharmacokinetic properties, and antiviral activity of VRC01 in persons with HIV infection who were undergoing interruption of ART.A total of 24 participants were enrolled, and one serious alcohol-related adverse event occurred. Viral rebound occurred despite plasma VRC01 concentrations greater than 50 μg per milliliter. The median time to rebound was 4 weeks in the A5340 trial and 5.6 weeks in the NIH trial. Study participants were more likely than historical controls to have viral suppression at week 4 (38% vs. 13%, P=0.04 by a two-sided Fisher's exact test in the A5340 trial; and 80% vs. 13%, P0.001 by a two-sided Fisher's exact test in the NIH trial) but the difference was not significant at week 8. Analyses of virus populations before ART as well as before and after ART interruption showed that VRC01 exerted pressure on rebounding virus, resulting in restriction of recrudescent viruses and selection for preexisting and emerging antibody neutralization-resistant virus.VRC01 slightly delayed plasma viral rebound in the trial participants, as compared with historical controls, but it did not maintain viral suppression by week 8. In the small number of participants enrolled in these trials, no safety concerns were identified with passive immunization with a single bNAb (VRC01). (Funded by the National Institute of Allergy and Infectious Diseases and others; ACTG A5340 and NIH 15-I-0140 ClinicalTrials.gov numbers, NCT02463227 and NCT02471326 .).

Antibodies sustain viral control For many infected individuals, antiretroviral therapy (ART) means that an HIV-1 diagnosis is no longer a death sentence. But the virus persists in treated individuals, and complying with the intense drug regimen to keep virus loads down can be challenging for patients. Seeking an alternative, Byrareddy et al. treated ART-suppressed monkeys with antibodies targeting α4β7 integrin. When ART was halted in the antibody-treated animals, viral loads stayed undetectable, and normal CD4 T cell counts were maintained for over 9 months—and persisted—even after stopping the antibody therapy. Science , this issue p. 197 Update: An Editorial Expression of Concern has been published here

BACKGROUND Data from studies in nonhuman primates suggest that the triple monoclonal antibody cocktail ZMapp is a promising immune-based treatment for Ebola virus disease (EVD). METHODS Beginning in March 2015, we conducted a randomized, controlled trial of ZMapp plus the current standard of care as compared with the current standard of care alone in patients with EVD that was diagnosed in West Africa by polymerase-chain-reaction (PCR) assay. Eligible patients of any age were randomly assigned in a 1:1 ratio to receive either the current standard of care or the current standard of care plus three intravenous infusions of ZMapp (50 mg per kilogram of body weight, administered every third day). Patients were stratified according to baseline PCR cycle-threshold value for the virus (≤22 vs. >22) and country of enrollment. Oral favipiravir was part of the current standard of care in Guinea. The primary end point was mortality at 28 days. RESULTS A total of 72 patients were enrolled at sites in Liberia, Sierra Leone, Guinea, and the United States. Of the 71 patients who could be evaluated, 21 died, representing an overall case fatality rate of 30%. Death occurred in 13 of 35 patients (37%) who received the current standard of care alone and in 8 of 36 patients (22%) who received the current standard of care plus ZMapp. The observed posterior probability that ZMapp plus the current standard of care was superior to the current standard of care alone was 91.2%, falling short of the prespecified threshold of 97.5%. Frequentist analyses yielded similar results (absolute difference in mortality with ZMapp, -15 percentage points; 95% confidence interval, -36 to 7). Baseline viral load was strongly predictive of both mortality and duration of hospitalization in all age groups. CONCLUSIONS In this randomized, controlled trial of a putative therapeutic agent for EVD, although the estimated effect of ZMapp appeared to be beneficial, the result did not meet the prespecified statistical threshold for efficacy. (Funded by the National Institute of Allergy and Infectious Diseases and others; PREVAIL II ClinicalTrials.gov number, NCT02363322 .).

Early administration of broadly neutralizing antibodies in a macaque SHIV infection model is associated with very low levels of persistent viraemia, which leads to the establishment of T-cell immunity and resultant long-term infection control. No effective vaccine has yet been developed against the human immunodeficiency virus type 1 (HIV-1), which is endemic in many areas of the world. Yoshiaki Nishimura et al. studied the effects of giving broadly neutralizing antibodies against HIV-1 to rhesus macaques shortly after beginning of exposure to low doses of the simian/human immunodeficiency virus (SHIV). This type of immunotherapy was associated with the persistence of low levels of the virus in the animals' blood, which led to the establishment of T-cell immunity and resulted in enhanced infection control. These findings could stimulate research into the mechanisms of HIV-1 control in infected humans. Highly potent and broadly neutralizing anti-HIV-1 antibodies (bNAbs) have been used to prevent and treat lentivirus infections in humanized mice, macaques, and humans1,2,3,4,5,6,7,8,9,10,11,12. In immunotherapy experiments, administration of bNAbs to chronically infected animals transiently suppresses virus replication, which invariably returns to pre-treatment levels and results in progression to clinical disease. Here we show that early administration of bNAbs in a macaque simian/human immunodeficiency virus (SHIV) model is associated with very low levels of persistent viraemia, which leads to the establishment of T-cell immunity and resultant long-term infection control. Animals challenged with SHIVAD8-EO by mucosal or intravenous routes received a single 2-week course of two potent passively transferred bNAbs (3BNC117 and 10-1074 (refs 13, 14)). Viraemia remained undetectable for 56–177 days, depending on bNAb half-life in vivo. Moreover, in the 13 treated monkeys, plasma virus loads subsequently declined to undetectable levels in 6 controller macaques. Four additional animals maintained their counts of T cells carrying the CD4 antigen (CD4+) and very low levels of viraemia persisted for over 2 years. The frequency of cells carrying replication-competent virus was less than 1 per 106 circulating CD4+ T cells in the six controller macaques. Infusion of a T-cell-depleting anti-CD8β monoclonal antibody to the controller animals led to a specific decline in levels of CD8+ T cells and the rapid reappearance of plasma viraemia. In contrast, macaques treated for 15 weeks with combination anti-retroviral therapy, beginning on day 3 after infection, experienced sustained rebound plasma viraemia when treatment was interrupted. Our results show that passive immunotherapy during acute SHIV infection differs from combination anti-retroviral therapy in that it facilitates the emergence of potent CD8+ T-cell immunity able to durably suppress virus replication.

The ultimate goal of HIV cure research is to allow HIV-infected individuals to be free of disease in the absence of antiretroviral therapy. We discuss current directions and future opportunities aimed at achieving sustained virological remission, and possibly eradication. A multidisciplinary approach to HIV cure research will be important, and ethical, social and behavioural research should be conducted in parallel with basic and clinical research.

Almost 4 years ago, one of us (F.S.C.) wrote an Editorial ([ 1 ][1]) affirming the continued importance of basic research to the National Institutes of Health (NIH) mission. The Editorial emphasized that basic scientific discovery is the engine that powers the biomedical enterprise, and NIH

Despite the rare appearance of potent HIV-neutralizing mAbs in infected individuals requiring prolonged affinity maturation, little is known regarding this process in the majority of viremic individuals. HIV-infected individuals with chronic HIV viremia have elevated numbers of nonconventional tissue-like memory (TLM) B cells that predominate in blood over conventional resting memory (RM) B cells. Accordingly, we investigated affinity maturation in these 2 memory B cell populations. Analysis of IgG-expressing TLM B cells revealed a higher number of cell divisions compared with RM B cells; however, TLM B cells paradoxically displayed significantly lower frequencies of somatic hypermutation (SHM). To assess Ab reactivity in TLM and RM B cells, single-cell cloning was performed on HIV envelope CD4–binding site–sorted (CD4bs-sorted) B cells from 3 individuals with chronic HIV viremia. Several clonal families were present among the 127 cloned recombinant mAbs, with evidence of crosstalk between TLM and RM B cell populations that was largely restricted to non-VH4 families. Despite evidence of common origins, SHM frequencies were significantly decreased in TLM-derived mAbs compared with SHM frequencies in RM-derived mAbs. However, both cell populations had lower frequencies of SHMs than did broadly neutralizing CD4bs–specific mAbs. There was a significant correlation between SHM frequencies and the HIV-neutralizing capacities of the mAbs. Furthermore, HIV neutralization was significantly higher in the RM-derived mAbs compared with that seen in the TLM-derived mAbs, and both SHM frequencies and neutralizing capacity were lowest in TLM-derived mAbs with high polyreactivity. Thus, deficiencies in memory B cells that arise during chronic HIV viremia provide insight into the inadequacy of the Ab response in viremic individuals.

The extraordinary scientific advances made in the past three decades to understand, treat, and prevent HIV infection have contributed to the hope that a world free of AIDS is achievable. The growing armamentarium of scientifically proven interventions-including the use of antiretroviral medications to treat and prevent HIV infection, voluntary medical male circumcision, education and counseling about HIV risk and behavior change, condom use, drug and alcohol treatment, and needle exchange programs for injection drug users-offers an unprecedented opportunity to make major gains in the fight against HIV/AIDS. Combining and implementing these interventions as effectively as possible has the potential to dramatically change the trajectory of the HIV/AIDS pandemic. Substantive challenges remain, especially obtaining sufficient funding for HIV-related interventions and developing the operational capacity to deliver them cost-effectively to all in need. If these challenges can be met, the world will have a clear path toward an "AIDS-free generation" in which new HIV infections, as well as illness and death due to AIDS, are increasingly rare.

The ultimate goal of HIV cure research is to allow HIV-infected individuals to be free of disease in the absence of antiretroviral therapy. We discuss current directions and future opportunities aimed at achieving sustained virological remission, and possibly eradication. A multidisciplinary approach to HIV cure research will be important, and ethical, social and behavioural research should be conducted in parallel with basic and clinical research.

Until recently, few potent and broadly neutralizing HIV-specific antibodies had been identified, but recent findings have inspired optimism that an effective HIV vaccine can finally be developed. Here we review these studies, which used state-of-the-art high-throughput techniques to collectively describe hundreds of new potent and broad HIV-neutralizing antibodies isolated from HIV-infected individuals.

Residual plasma viremia (50 copies/mL) persists in certain human immunodeficiency virus (HIV)-infected individuals receiving antiretroviral therapy (ART); however, the relationship between the degree of residual plasma viremia, the size of HIV reservoirs, and the level of immune activation has not been delineated. Here, we demonstrate that residual plasma viremia correlates with the size of the CD4(+) T cell viral reservoir, but not with markers of immune activation, suggesting that reactivation of the latent viral reservoir may not be the sole source of residual plasma viremia. Novel therapeutic strategies aimed at targeting the source of residual viremia may be necessary to achieve viral eradication.