B cell immunofocusing and repriming in two HIV-1 Env immunization regimens.

Diverse and rapidly mutating viruses pose challenges to immunogen and vaccine design. In this study, we evaluated the ability of memory B-cells obtained from two independent NHP trials to cross-react with individual HIV-1 vaccine components of two different multivalent immunization strategies. We demonstrated that while an HIV-1 Env multiclade, multivalent immunization regimen resulted in a dominant memory B-cell response that converged toward shared epitopes, in a sequential immunization with clonally-related non-stabilized gp140 HIV-1 Envs followed by SOSIP-stabilized gp140 trimers, the change in immunogen format resulted in repriming of the B-cell response.

Multivariate analysis of FcR-mediated NK cell functions identifies unique clustering among humans and rhesus macaques.

Rhesus macaques (RMs) are a common pre-clinical model used to test HIV vaccine efficacy and passive immunization strategies. Yet, it remains unclear to what extent the Fc-Fc receptor (FcR) interactions impacting antiviral activities of antibodies in RMs recapitulate those in humans. Here, we evaluated the FcR-related functionality of natural killer cells (NKs) from peripheral blood of uninfected humans and RMs to identify intra- and inter-species variation.

Impact of adjuvants on the biophysical and functional characteristics of HIV vaccine-elicited antibodies in humans.

Adjuvants can alter the magnitude, characteristics, and persistence of the humoral response to protein vaccination. HIV vaccination might benefit from tailored adjuvant choice as raising a durable and protective response to vaccination has been exceptionally challenging. Analysis of trials of partially effective HIV vaccines have identified features of the immune response that correlate with decreased risk, including high titers of V1V2-binding IgG and IgG3 responses with low titers of V1V2-binding IgA responses and enhanced Fc effector functions, notably antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP).

Development of flow cytometry-based assays to assess the ability of antibodies to bind to SARS-CoV-2-infected and spike-transfected cells and mediate NK cell degranulation.

Since the beginning of the SARS-CoV-2 pandemic, antibody responses and antibody effector functions targeting SARS-CoV-2-infected cells have been understudied. Consequently, the role of these types of antibodies in SARS-CoV-2 disease (COVID-19) and immunity is still undetermined. To provide tools to study these responses, we used plasma from SARS-CoV-2-infected individuals (n = 50) and SARS-CoV-2 naive healthy controls (n = 20) to develop four specific and reproducible flow cytometry-based assays: (i) two assessing antibody binding to, and antibody-mediated NK cell degranulation against, SARS-CoV-2-infected cells and (ii) two assessing antibody binding to, and antibody-mediated NK cell degranulation against, SARS-CoV-2 Spike-transfected cells.

Structure and Fc-Effector Function of Rhesusized Variants of Human Anti-HIV-1 IgG1s.

Passive transfer of monoclonal antibodies (mAbs) of human origin into Non-Human Primates (NHPs), especially those which function predominantly by a Fc-effector mechanism, requires an preparation step, in which the human mAb is reengineered to an equivalent NHP IgG subclass. This can be achieved by changing both the Fc and Fab sequence while simultaneously maintaining the epitope specificity of the parent antibody. This Ab reengineering process, referred to as rhesusization, can be challenging because the simple grafting of the complementarity determining regions (CDRs) into an NHP IgG subclass may impact the functionality of the mAb.

Elimination of SHIV Infected Cells by Combinations of Bispecific HIVxCD3 DART Molecules.

Bispecific HIVxCD3 DART molecules that co-engage the viral envelope glycoprotein (Env) on HIV-1-infected cells and the CD3 receptor on CD3+ T cells are designed to mediate the cytolysis of HIV-1-infected, Env-expressing cells. Using a novel system with cells from rhesus macaques (RMs) infected with a chimeric Simian-Human Immunodeficiency Virus (SHIV) CH505 and maintained on ART, we tested the ability of HIVxCD3 DART molecules to mediate elimination of -reactivated CD4+ T cells in the absence or presence of autologous CD8+ T cells. HIVxCD3 DART molecules with the anti-HIV-1 Env specificities of A32 or 7B2 (non-neutralizing antibodies) or PGT145 (broadly neutralizing antibody) were evaluated individually or combined.

Functional Homology for Antibody-Dependent Phagocytosis Across Humans and Rhesus Macaques.

Analyses of human clinical HIV-1 vaccine trials and preclinical vaccine studies performed in rhesus macaque (RM) models have identified associations between non-neutralizing Fc Receptor (FcR)-dependent antibody effector functions and reduced risk of infection. Specifically, antibody-dependent phagocytosis (ADP) has emerged as a common correlate of reduced infection risk in multiple RM studies and the human HVTN505 trial. This recurrent finding suggests that antibody responses with the capability to mediate ADP are most likely a desirable component of vaccine responses aimed at protecting against HIV-1 acquisition.

Improved killing of HIV-infected cells using three neutralizing and non-neutralizing antibodies.

The correlation of HIV-specific antibody-dependent cellular cytotoxicity (ADCC) responses with protection from and delayed progression of HIV-1 infection provides a rationale to leverage ADCC-mediating antibodies for treatment purposes. We evaluated ADCC mediated by different combinations of 2 to 6 neutralizing and non-neutralizing anti-HIV-1 Envelope (Env) mAbs, using concentrations ≤ 1 μg/mL, to identify combinations effective at targeting latent reservoir HIV-1 viruses from 10 individuals. We found that within 2 hours, combinations of 3 mAbs mediated more than 30% killing of HIV-infected primary CD4+ T cells in the presence of autologous NK cells, with the combination of A32 (C1C2), DH511.

Redirection of Cord Blood T Cells and Natural Killer Cells for Elimination of Autologous HIV-1-Infected Target Cells Using Bispecific DART® Molecules.

Mother-to-child transmission of HIV-1 remains a major global health challenge. Currently, HIV-1-infected infants require strict lifelong adherence to antiretroviral therapy to prevent replication of virus from reservoirs of infected cells, and to halt progression of disease. There is a critical need for immune interventions that can be deployed shortly after infection to eliminate HIV-1-infected cells in order to promote long-term remission of viremia, or to potentially cure pediatric HIV-1-infection.

Boosting with AIDSVAX B/E Enhances Env Constant Region 1 and 2 Antibody-Dependent Cellular Cytotoxicity Breadth and Potency.

Induction of protective antibodies is a critical goal of HIV-1 vaccine development. One strategy is to induce nonneutralizing antibodies (NNAbs) that kill virus-infected cells, as these antibody specificities have been implicated in slowing HIV-1 disease progression and in protection. HIV-1 Env constant region 1 and 2 (C1C2) monoclonal antibodies (MAbs) frequently mediate potent antibody-dependent cellular cytotoxicity (ADCC), making them an important vaccine target.

Bridging Vaccine-Induced HIV-1 Neutralizing and Effector Antibody Responses in Rabbit and Rhesus Macaque Animal Models.

Studies in animal models are essential prerequisites for clinical trials of candidate HIV vaccines. Small animals, such as rabbits, are used to evaluate promising strategies prior to further immunogenicity and efficacy testing in nonhuman primates. Our goal was to determine how HIV-specific vaccine-elicited antibody responses, epitope specificity, and Fc-mediated functions in the rabbit model can predict those in the rhesus macaque (RM) model.

Impact of prior local therapy on overall survival in men with metastatic castration-resistant prostate cancer: Results from Shared Equal Access Regional Cancer Hospital.

Objectives: To evaluate the impact of previous local treatment on survival in men with newly diagnosed metastatic castration-resistant prostate cancer.

Methods: We carried out a retrospective study of patients newly diagnosed with metastatic castration-resistant prostate cancer in the year 2000 or later from eight Veterans Affairs Medical Centers. Patients were categorized based on prior local therapy (none, prostatectomy ± radiation or radiation alone).

Receptor-dependent and receptor-independent endocannabinoid signaling: a therapeutic target for regulation of cancer growth.

The endocannabinoid system comprises the G-protein coupled CB1 cannabinoid receptor (CB1R) and CB2 cannabinoid receptor (CB2R), their endogenous ligands (endocannabinoids), and the enzymes responsible for their synthesis and catabolism. Recent works have revealed several important interactions between the endocannabinoid system and cancer. Moreover, it is now well established that synthetic small molecule cannabinoid receptor agonist acting on either CB1R or CB2R or both exerts anti-cancer effects on a variety of tumor cells.

Evaluating the therapeutic potential of a non-natural nucleotide that inhibits human ribonucleotide reductase.

Human ribonucleotide reductase (hRR) is the key enzyme involved in de novo dNTP synthesis and thus represents an important therapeutic target against hyperproliferative diseases, most notably cancer. The purpose of this study was to evaluate the ability of non-natural indolyl-2'-deoxynucleoside triphosphates to inhibit the activity of hRR. The structural similarities of these analogues with dATP predicted that they would inhibit hRR activity by binding to its allosteric sites.

Structural basis for allosteric regulation of human ribonucleotide reductase by nucleotide-induced oligomerization.

Ribonucleotide reductase (RR) is an α(n)β(n) (RR1-RR2) complex that maintains balanced dNTP pools by reducing NDPs to dNDPs. RR1 is the catalytic subunit, and RR2 houses the free radical required for catalysis. RR is allosterically regulated by its activator ATP and its inhibitor dATP, which regulate RR activity by inducing oligomerization of RR1.

Naringin, a grapefruit flavanone, protects V79 cells against the bleomycin-induced genotoxicity and decline in survival.

The effect of naringin, a grapefruit flavonone was studied on bleomycin-induced genomic damage and alteration in the survival of cultured V79 cells. Exposure of V79 cells to bleomycin induced a concentration dependent elevation in the frequency of binucleate cells bearing micronuclei (MNBNC) and a maximum number of MNBNCs were observed in the cells treated with 50 microg ml(-1) bleomycin, the highest concentration evaluated. This genotoxic effect of bleomycin was reflected in the cell survival, where a concentration dependent decline was observed in the cells treated with different concentrations of bleomycin.