Accelerating HIV vaccine development using non-human primate models

Cecilia Morgan and colleagues outline a two-stage nonhuman primate screening strategy for T cell-based HIV-1 vaccines.

The establishment of latent infection and poorly characterized viral reservoirs in tissues represent major obstacles to a definitive cure for HIV. Non-human primate (NHP) models of HIV infection are critical to elucidate pathogenic processes and an essential tool to test novel therapeutic strategies. Thus, the availability of novel assays to measure residual viral replication and reservoirs in NHP models may increase their utility in the search for an HIV cure. We developed a tat/rev induced limiting dilution assay to measure the frequency of CD4+ T cells that express multiply-spliced(ms)_SIV RNA in presence and absence of stimulation. We validated the assay using cell lines and cells from blood and lymph nodes of SIV infected macaques. In vitro, SIV/SHIV TILDA detects only cells expressing viral proteins. In SIV/SHIV-infected macaques, CD4+ T cells that express msSIV/SHIV RNA (TILDA data) were detected also in the setting of very low/undetectable viremia. TILDA data were significantly higher after stimulation and correlated with plasma viral load (pVL). Interestingly, TILDA data from early cART initiation correlated with peak and AUC pVL post-cART interruption. In summary, we developed an assay that may be useful in characterizing viral reservoirs and determining the effect of HIV interventions in NHP models.

T-Cell Transcriptome Analysis Reveals the Mechanisms Controlling Synergy Between Costimulation Blockade and mTOR Inhibition during Graft Versus Host Disease Prevention

Non-human primate models are widely used in research of AIDS mechanism, transmission, vaccine and drugs. Dendritic cells (DC), as antigen presenting cells linking the innate immunity and acquired immunity, play a pivotal role in AIDS progression. Studies on the change of DC subsets number, phenotype and function in AIDS non-human primate models are important for revealing some mechanism of AIDS progression. This article reviews the progress in DC subsets of non-human primate AIDS models, which will provide an avenue for further study in AIDS.

Background: Endometriosis is a painful disorder in women where endometrium-like tissue exists outside of the uterine cavity. Progress on new therapies for the disorder is dependent on physiologically relevant models. Menstruation and development of spontaneous endometriosis only occur in women and Old World nonhuman primates making nonhuman primates the most suitable animals for study. Herein we review the use of nonhuman primates for studies on endometriosis. Objective: To describe the use of nonhuman primates for studies on endometriosis. Methods: We reviewed the literature comparing the use of primate models. Results: In practice, three types of “primate” models exist; 1) studies on monkeys with spontaneous endometriosis; 2) induction of endometriosis in disease-free animals; and, 3) the engraftment of primate tissue into immunodeficient rodents. The absence of tests to identify animals with the wellcharacterized disease greatly limits the viability of studies on spontaneous endometriosis in nonhuman primates. Despite this limitation, studies of spontaneous endometriosis have elucidated risk factors associated with the etiology and pathobiology of the disease. Induced endometriosis in the baboon and macaque currently represents the prototypic and most promising primate model, producing lesions that are phenotypically similar to endometriosis in women, with a well-controlled onset, and predictable pathogenesis. The strength of using induced endometriosis models in nonhuman primates lies in the ability to document the early disease process and the exact age of lesions in the animals. However, nonhuman primates are expensive and in short supply. Xenografts of primate tissue in immunodeficient mice also allow the study of the early disease process but long-term studies are a compromise because of the immunodeficient nature of the host animals. Studies of endometriosis in rhesus and cynomolgus macaques provides an additional benefit as these are the preferred primate models for pharmacokinetic and pharmacodynamic studies in many research institutes and the pharmaceutical industry. Conclusion: Due to the physiological similarities among primates, preclinical studies of endometriosis diagnostics and therapeutics conducted in nonhuman primate models are well-positioned to lead to new clinical applications. Keywords: Nonhuman primate, animal model, induced endometriosis, baboon macaque, xenograft models, pharmacokinetic.

In utero infection with Zika virus (ZIKV) during pregnancy can lead to the development of birth defects and postnatal deficits. A nonhuman primate (NHP) model of congenital ZIKV infection can help fill the gaps in knowledge where tissue studies are required to define viral pathogenesis and identify targets for therapeutic intervention. This model system has already identified critical features of ZIKV pathogenesis in congenital infection. Before translating these NHP studies to human clinical trials, we must understand the similarities and differences between human and NHP fetal immune system development, neural development, and infant assessment tools. Because of the overall similarity between fetal and infant development in humans and NHPs, this NHP model can complement human clinical trials by defining immune correlates of protection and evaluating therapeutic interventions.

Cellular Therapy with Donor Mesenchymal Stem Cells Combined with Co-Stimulation Blockade Prolongs Solid Organ Allograft Survival.

BackgroundAging is a prominent risk factor for diverse diseases; therefore, an in-depth understanding of its physiological mechanisms is required. Nonhuman primates, which share the closest genetic relationship with humans, serve as an ideal model for exploring the complex aging process. However, the potential of the nonhuman primate animal model in the screening of human aging markers is still not fully exploited. Multiomics analysis of nonhuman primate peripheral blood offers a promising approach to evaluate new therapies and biomarkers. This study explores aging-related biomarker through multilayer omics, including transcriptomics (mRNA, lncRNA, and circRNA) and proteomics (serum and serum-derived exosomes) in rhesus monkeys (Macaca mulatta).ResultsOur findings reveal that, unlike mRNAs and circRNAs, highly expressed lncRNAs are abundant during the key aging period and are associated with cancer pathways. Comparative analysis highlighted exosomal proteins contain more types of proteins than serum proteins, indicating that serum-derived exosomes primarily regulate aging through metabolic pathways. Finally, eight candidate aging biomarkers were identified, which may serve as blood-based indicators for detecting age-related brain changes.ConclusionsOur results provide a comprehensive understanding of nonhuman primate blood transcriptomes and proteomes, offering novel insights into the aging mechanisms for preventing or treating age-related diseases.

Background/Objectives: Adipose tissue (AT) plays significant roles in energy storage, metabolite signaling, and immunomodulation. The understanding of its underlying mechanisms of dysregulation can provide insight into complex disease processes through analysis with histology, flow cytometry, metabolomics, and proteomics. Tissue sampling in the clinical setting has largely shifted towards minimally invasive approaches to improve factors such as patient satisfaction, post-operative recovery, and procedure length. In contrast, preclinical animal models continue to rely on more invasive methods until refined, minimally invasive techniques are developed and systematically assessed. To improve animal welfare and enhance clinical translatability, there is a critical need to reverse translate these approaches into animal models. Methods: Our study evaluated the feasibility and performance of a commercially available vacuum-assisted biopsy (VAB) device for AT sampling in a preclinical nonhuman primate (NHP) model. Six rhesus NHPs successfully underwent three serial AT biopsies with a VAB device (n = 18). Results: All animals recovered without any serious or unexpected adverse events. The amount of adipose tissue collected per biopsy (0.5–2.7 g) was proportional to the number of individual tracks. Isolation of the stromal vascular fraction (SVF) from a subset of samples (n = 6) yielded 0.41 ± 0.12 × 106 cells/g of tissue. Conclusions: The minimally invasive VAB technique is a safe and reliable method of AT collection in NHPs. This feasibility study demonstrated adequate volumes of tissue cores that are suitable for typical, downstream research applications including immunologic studies and pathology, while improving animal welfare.

Non-human primate (NHP) models are important for vaccine development and also contribute to HIV cure research. Although none of the animal models are perfect, NHPs enable the exploration of important questions about tissue viral reservoirs and the development of intervention strategies. In this review, we describe recent advances in the use of these models for HIV cure research and highlight the progress that has been made as well as limitations using these models. The main NHP models used are (i) the macaque, in which simian immunodeficiency virus (SIVmac) infection displays similar replication profiles as to HIV in humans, and (ii) the macaque infected by a recombinant virus (SHIV) consisting of SIVmac expressing the HIV envelope gene serving for studies analyzing the impact of anti-HIV Env broadly neutralizing antibodies. Lessons for HIV cure that can be learned from studying the natural host of SIV are also presented here. An overview of the most promising and less well explored HIV cure strategies tested in NHP models will be given.

BIIB059 is a novel humanized monoclonal antibody (mAb) that is currently under development for the treatment of Systemic Lupus Erythematosus and Cutaneous Lupus Erythematosus. BIIB059 is targeted against the blood dendritic cell antigen 2 (BDCA2), a receptor exclusively expressed on the surface of plasmacytoid dendritic cells (pDCs). Herein, we utilized pre-clinical pharmacokinetic (PK) and pharmacodynamic (PD) data to develop a non-human primate (NHP) model and to address whether the NHP model can be successfully scaled to predict the human PK/PD. In particular, PK data from 17 cynomolgus monkeys were utilized for PK model development, wherein BIIB059 was administered intravenously (1 and 10mg/kg single-dosing and 5mg/kg multiple-dosing) or subcutaneously (0.2 and 7.5mg/kg single-dosing). Additionally, PD data (BDCA2 receptor density on pDCs) from 6 cynomolgus monkeys were used for the development of the PD model. The developed NHP two-compartment PK model, linked with an indirect response PD model, was subsequently scaled to humans by combining traditional allometric PK scaling with sensitivity-analysis-driven scaling of the PD. The scaled PK/PD model was then used to simulate the human PK/PD for different dose levels. When clinical data from the BIIB059 Phase I study became available, they were used to evaluate the predictability of the scaled PK/PD model and the model simulations were in agreement with the clinical data. Therefore, the presented approach is suggested to be employed in scaling pre-clinical mAb models to support the selection of safe first-in-human doses and, more broadly, the prediction of PK/PD in the clinic.

Intra-uterine growth restriction (IUGR) is a common cause of fetal/neonatal morbidity and mortality and is associated with increased offspring predisposition for cardiovascular disease (CVD) development. Mitochondria are essential organelles in maintaining cardiac function, and thus, fetal cardiac mitochondria could be responsive to the IUGR environment. In this study, we investigated whether in utero fetal cardiac mitochondrial programming can be detectable in an early stage of IUGR pregnancy. Using a well-established nonhuman IUGR primate model, we induced IUGR by reducing by 30% the maternal diet (MNR), both in males (MNR-M) and in female (MNR-F) fetuses. Fetal cardiac left ventricle (LV) tissue and blood were collected at 90 days of gestation (0.5 gestation, 0.5 G). Blood biochemical parameters were determined and heart LV mitochondrial biology assessed. MNR fetus biochemical blood parameters confirm an early fetal response to MNR. In addition, we show that in utero cardiac mitochondrial MNR adaptations are already detectable at this early stage, in a sex-divergent way. MNR induced alterations in the cardiac gene expression of oxidative phosphorylation (OXPHOS) subunits (mostly for complex-I, III, and ATP synthase), along with increased protein content for complex-I, -III, and -IV subunits only for MNR-M in comparison with male controls, highlight the fetal cardiac sex-divergent response to MNR. At this fetal stage, no major alterations were detected in mitochondrial DNA copy number nor markers for oxidative stress. This study shows that in 90-day nonhuman primate fetuses, a 30% decrease in maternal nutrition generated early in utero adaptations in fetal blood biochemical parameters and sex-specific alterations in cardiac left ventricle gene and protein expression profiles, affecting predominantly OXPHOS subunits. Since the OXPHOS system is determinant for energy production in mitochondria, our findings suggest that these early IUGR-induced mitochondrial adaptations play a role in offspring’s mitochondrial dysfunction and can increase predisposition to CVD in a sex-specific way.

Despite the critical importance of emerging infectious disease research, the underlying immune responses to risk group 4 pathogens remain largely understudied relative to many other pathogens. Spectral flow cytometry has dramatically increased the capacity of fluorescence-based cell analyses, allowing for the development of comprehensive panels across a variety of cell types. We have developed a 33-color phenotypic panel that incorporates a plethora of markers to simultaneously identify numerous distinct cellular populations within circulation and in tissue with a deliberate and extensive characterization of monocytes, dendritic cells, and tissue-resident T cells. This panel utilizes multiple approaches to accurately identify appropriate cell markers that can be easily distinguished with minimal to no compensation, despite containing fluorochromes with similar excitation and emission spectra. Importantly, this high-complexity panel was implemented on both fresh and frozen samples of whole blood, peripheral blood mononuclear cells (PBMCs), and cells isolated from multiple peripheral tissues across several nonhuman primate (NHP) models and on frozen human PBMCs, making this a broad cross-reactive panel enabling direct comparisons among NHP species and with humans. This new phenotypic flow panel allows for broad insight into underlying immune responses to infections across species while remaining amenable to additional potential markers of interest.

Aging and certain viral infections can negatively impact humoral responses in humans. To further develop the nonhuman primate (NHP) model for investigating B cell dynamics in human aging and infectious disease, a flow cytometric panel was developed to characterize circulating rhesus B cell subsets. Significant differences between human and macaque B cells included the proportions of cells within IgD+ and switched memory populations and a prominent CD21-CD27+ unswitched memory population detected only in macaques. We then utilized the expanded panel to analyze B cell alterations associated with aging and acute simian immunodeficiency virus (SIV) infection in the NHP model. In the aging study, distinct patterns of B cell subset frequencies were observed for macaques aged one to five years compared to those between ages 5 and 30 years. In the SIV infection study, B cell frequencies and absolute number were dramatically reduced following acute infection, but recovered within four weeks of infection. Thereafter, the frequencies of activated memory B cells progressively increased; these were significantly correlated with the magnitude of SIV-specific IgG responses, and coincided with impaired maturation of anti-SIV antibody avidity, as previously reported for HIV-1 infection. These observations further validate the NHP model for investigation of mechanisms responsible for B cells alterations associated with immunosenescence and infectious disease.

Is an HIV vaccine possible?