The HIV-1 Glycan Shield: Strategically Placed Kinks in the Armor Improve Antigen Design

Dense glycosylation on the HIV-1 envelope glycoprotein hampers the induction of broadly neutralizing antibodies against HIV-1. Zhou et al. remove key glycans to unmask sites of vulnerability and enable the induction of neutralizing antibodies

Young and Early Career Investigators: Report from a Global HIV Vaccine Enterprise Working Group

The scientific challenges facing HIV-1 vaccine development are unprecedented in the history of vaccinology. As a result, investigators, funders, and other stakeholders generally agree that “game-changing” ideas are required. While innovation can certainly arise from investigators at all career stages, young and early-career investigators, defined as those under 40 years of age or within 10 years of their final degree or clinical training, are especially key contributors of novel and transformative ideas. Young and early-career investigators bring energy, enthusiasm, and fresh perspectives that are unbiased by prevailing dogma and that are essential to scientific progress

Chronic HCV Infection Affects the NK Cell Phenotype in the Blood More than in the Liver

Although epidemiological and functional studies have implicated NK cells in protection and early clearance of HCV, the mechanism by which they may contribute to viral control is poorly understood, particularly at the site of infection, the liver. We hypothesized that a unique immunophenotypic/functional NK cell signature exists in the liver that may provide insights into the contribution of NK cells to viral control. Intrahepatic and blood NK cells were profiled from chronically infected HCV-positive and HCV-negative individuals. Baseline expression of activating and inhibitory receptors was assessed, as well as functional responses following stimulation through classic NK cell pathways. Independent of HCV infection, the liver was enriched for the immunoregulatory CD56bright NK cell population, which produced less IFNγ and CD107a but comparable levels of MIP1β, and was immunophenotypically distinct from their blood counterparts. This profile was mostly unaltered in chronic HCV infection, though different expression levels of NKp46 and NKG2D were associated with different grades of fibrosis. In contrast to the liver, chronic HCV infection associated with an enrichment of CD161lowperforinhigh NK cells in the blood correlated with increased AST and 2B4 expression. However, the association of relatively discrete changes in the NK cell phenotype in the liver with the fibrosis stage nevertheless suggests an important role for the NK response. Overall these data suggest that tissue localization has a more pervasive effect on NK cells than the presence of chronic viral infection, during which these cells might be mostly attuned to limiting immunopathology. It will be important to characterize NK cells during early HCV infection, when they should have a critical role in limiting infection

NK Cells in HIV Disease

Natural killer (NK) cells play a critical role in viral immunity. In the setting of HIV infection, epidemiologic and functional evidence support a role for NK cells in both protection from new infection and in viral control. Specifically, NK cells directly mediate immune pressure leading to virus evolution, and NK cell receptor genotypic profiles, clonal repertoires, and functional capacity have all been implicated in virus containment. In addition, indirect NK cell-mediated antibody-dependent cellular cytotoxicity has been linked to vaccine-induced protective immunity against HIV infection. With recent advances in our understanding of NK cell deficiency, development, memory-like responses, and editing of the adaptive immune system, the opportunities to direct and exploit NK cell antiviral immunity to target HIV have exponentially grown. In this review, we seek to highlight the intersections between discoveries in basic NK cell biology and the challenges of HIV chronic infection, vaccine development, and cure/eradication strategies

Correlates of protection against SARS-CoV-2 infection and COVID-19 disease

Antibodies against epitopes in S1 give the most accurate CoP against infection by the SARS-CoV-2 coronavirus. Measurement of those antibodies by neutralization or binding assays both have predictive value, with binding antibody titers giving the highest statistical correlation. However, the protective functions of antibodies are multiple. Antibodies with multiple functions other than neutralization influence efficacy. The role of cellular responses can be discerned with respect to CD4+ T cells and their augmentation of antibodies, and with respect to CD8+ cells with regard to control of viral replication, particularly in the presence of insufficient antibody. More information is needed on mucosal responses

Association of HLA-DRB1-restricted CD4+ T cell responses with HIV immune control

The contribution of HLA class II-restricted CD4+ T cell responses to HIV immune control is poorly defined. Here, we delineated novel peptide-DRB1 restrictions in functional assays and analyzed the host genetic effects of HLA-DRB1 alleles on HIV viremia in a large cohort of HIV controllers and progressors (n=1085). We found distinct stratifications in the effect of HLA-DRB1 alleles on HIV viremia, with DRB1*15:02 significantly associated with low viremia (P=0.003, q=0.04) and DRB1*03:01 significantly associated with high viremia (P=0.004, q=0.04). Interestingly, a sub-group of HLA-DRB1 alleles linked with low viremia showed the ability to promiscuously present a larger breadth of peptides with lower functional avidity when compared to HLA-DRB1 alleles linked with high viremia (p=0.018). Our data provide systematic evidence that HLA-DRB1 allele expression significantly impacts the durable control of HIV replication, an effect that appears to be mediated primarily by the protein-specificity of HIV-specific CD4+ T cell responses to Gag and Nef

Machine Learning Methods Enable Predictive Modeling of Antibody Feature:Function Relationships in RV144 Vaccinees

The adaptive immune response to vaccination or infection can lead to the production of specific antibodies to neutralize the pathogen or recruit innate immune effector cells for help. The non-neutralizing role of antibodies in stimulating effector cell responses may have been a key mechanism of the protection observed in the RV144 HIV vaccine trial. In an extensive investigation of a rich set of data collected from RV144 vaccine recipients, we here employ machine learning methods to identify and model associations between antibody features (IgG subclass and antigen specificity) and effector function activities (antibody dependent cellular phagocytosis, cellular cytotoxicity, and cytokine release). We demonstrate via cross-validation that classification and regression approaches can effectively use the antibody features to robustly predict qualitative and quantitative functional outcomes. This integration of antibody feature and function data within a machine learning framework provides a new, objective approach to discovering and assessing multivariate immune correlates.U.S. Military HIV Research ProgramCollaboration for AIDS Vaccine Discover (OPP1032817)National Institutes of Health (U.S.) (3R01AI080289-02S1)National Institutes of Health (U.S.) (5R01AI080289-03)United States. Army Medical Research and Materiel Command (National Institute of Allergy and Infectious Diseases (U.S.) Interagency Agreement Y1-AI-2642-12)Henry M. Jackson Foundation for the Advancement of Military Medicine (U.S.) (United States. Dept. of Defense Cooperative Agreement W81XWH-07-2-0067

A robust, high-throughput assay to determine the phagocytic activity of clinical antibody samples

Phagocytosis can be induced via the engagement of Fcγ receptors by antibody-opsonized material. Furthermore, the efficiency of antibody-induced effector functions has been shown to be dramatically modulated by changes in antibody glycosylation. Because infection can modulate antibody glycans, which in turn modulate antibody functions, assays capable of determining the induction of effector functions rather than neutralization or titer provide a valuable opportunity to more fully characterize the quality of the adaptive immune response. Here we describe a robust and high-throughput flow cytometric assay to define the phagocytic activity of antigen-specific antibodies from clinical samples. This assay employs a monocytic cell line that expresses numerous Fc receptors: including inhibitory and activating, and high and low affinity receptors—allowing complex phenotypes to be studied. We demonstrate the adaptability of this high-throughput, flow-based assay to measure antigen-specific antibody-mediated phagocytosis against an array of viruses, including influenza, HIV, and dengue. The phagocytosis assay format further allows for simultaneous analysis of cytokine release, as well as determination of the role of specific Fcγ-receptor subtypes, making it a highly useful system for parsing differences in the ability of clinical and vaccine induced antibody samples to recruit this critical effector function.Neutralizing Antibody Consortium (International AIDS Vaccine Initiative)National Institute of Allergy and Infectious Diseases (U.S.)National Institutes of Health (U.S.) (AI055332)National Institutes of Health (U.S.) (AI080289)Ragon Institute of MGH, MIT and Harvar

Altered distribution of mucosal NK cells during HIV infection

The human gut mucosa is a major site of HIV infection and infection-associated pathogenesis. Increasing evidence shows that natural killer (NK) cells play an important role in control of HIV infection but the mechanism(s) by which they mediate antiviral activity in the gut is unclear. Here we show two distinct subsets of NK cells exist in the gut, one localized to intraepithelial spaces (IEL) and the other to the lamina propria (LP). The frequency of both subsets of NK cells was reduced in chronic infection, whereas IEL NK cells remained stable in spontaneous controllers with protective KIR/HLA genotypes. Both IEL and LP NK cells were significantly expanded in immunologic non-responsive (INR) patients, who incompletely recovered CD4+ T cells on HAART. These data suggest that both IEL and LP NK cells may expand in the gut in an effort to compensate for compromised CD4+ T cell recovery, but that only IEL NK cells may be involved in providing durable control of HIV in the gut