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BACKGROUND: Autism spectrum disorder (ASD) is characterized by persistent social interaction impairments and is male-biased in prevalence. We have established naturally occurring low sociality in male rhesus monkeys as a model for the social features of ASD. Low-social male monkeys exhibit reduced social interactions and increased autistic-like trait burden, with both measures highly correlated and strongly linked to low cerebrospinal fluid (CSF) arginine vasopressin (AVP) concentration. Little is known, however, about the behavioral and neurochemical profiles of female rhesus monkeys, and whether low sociality in females is a tractable model for ASD. METHODS: Social behavior assessments (ethological observations; a reverse-translated autistic trait measurement scale, the macaque Social Responsiveness Scale-Revised [mSRS-R]) were completed on N = 88 outdoor-housed female rhesus monkeys during the non-breeding season. CSF and blood samples were collected from a subset of N = 16 monkeys across the frequency distribution of non-social behavior, and AVP and oxytocin (OXT) concentrations were quantified. Data were analyzed using general linear models. RESULTS: Non-social behavior frequency and mSRS-R scores were continuously distributed across the general female monkey population, as previously found for male monkeys. However, dominance rank significantly predicted mSRS-R scores in females, with higher-ranking individuals showing fewer autistic-like traits, a relationship not previously observed in males from this colony. Females differed from males in several other respects: Social behavior frequencies were unrelated to mSRS-R scores, and AVP concentration was unrelated to any social behavior measure. Blood and CSF concentrations of AVP were positively correlated in females; no significant relationship involving any OXT measure was found. LIMITATIONS: This study sample was small, and did not consider genetic, environmental, or other neurochemical measures that may be related to female mSRS-R scores. CONCLUSIONS: Dominance rank is the most significant predictor of autistic-like traits in female rhesus monkeys, and CSF neuropeptide concentrations are unrelated to measures of female social functioning (in contrast to prior CSF AVP findings in male rhesus monkeys and male and female autistic children). Although preliminary, this evidence suggests that the strong matrilineal organization of this species may limit the usefulness of low sociality in female rhesus monkeys as a tractable model for ASD.

The injectable progestin depot-medroxyprogesterone acetate (DMPA) is a popular contraceptive choice in sub-Saharan Africa although mouse models indicate it weakens genital epithelial integrity and barrier function and increases susceptibility to genital infection. The intravaginal ring NuvaRing® is another contraceptive option that like DMPA suppresses hypothalamic pituitary ovarian (HPO) axis function with local release of progestin (etonogestrel) and estrogen (ethinyl estradiol). As we previously reported that treating mice with DMPA and estrogen averts the loss of genital epithelial integrity and barrier function induced by DMPA alone, in the current investigation we compared genital levels of the cell-cell adhesion molecule desmoglein-1 (DSG1) and genital epithelial permeability in rhesus macaques (RM) treated with DMPA or a NuvaRing®re-sized for RM (N-IVR). While these studies demonstrated comparable inhibition of the HPO axis with DMPA or N-IVR, DMPA induced significantly lower genital DSG1 levels and greater tissue permeability to intravaginally administered low molecular mass molecules. By identifying greater compromise of genital epithelial integrity and barrier function in RM administered DMPA vs. N-IVR, our results add to the growing body of evidence that indicate DMPA weakens a fundamental mechanism of anti-pathogen host defense in the female genital tract.

CD4 T follicular helper cells (Tfh) are essential for establishing serological memory and have distinct helper attributes that impact both the quantity and quality of the antibody response. Insights into Tfh subsets that promote antibody persistence and functional capacity can critically inform vaccine design. Based on the Tfh profiles evoked by the live attenuated measles virus vaccine, renowned for its ability to establish durable humoral immunity, we investigated the potential of a Tfh1/17 recall response during the boost phase to enhance persistence of HIV-1 Envelope (Env) antibodies in rhesus macaques. Using a DNA-prime encoding gp160 antigen and Tfh polarizing cytokines (interferon protein-10 (IP-10) and interleukin-6 (IL-6)), followed by a gp140 protein boost formulated in a cationic liposome-based adjuvant (CAF01), we successfully generated germinal center (GC) Tfh1/17 cells. In contrast, a similar DNA-prime (including IP-10) followed by gp140 formulated with monophosphoryl lipid A (MPLA) +QS-21 adjuvant predominantly induced GC Tfh1 cells. While the generation of GC Tfh1/17 cells with CAF01 and GC Tfh1 cells with MPLA +QS-21 induced comparable peak Env antibodies, the latter group demonstrated significantly greater antibody concentrations at week 8 after final immunization which persisted up to 30 weeks (gp140 IgG ng/ml- MPLA; 5500; CAF01, 2155; p

PurposeChoroidal vascular changes occur with normal aging and age-related macular degeneration (AMD). Here, we evaluate choroidal thickness and vascularity in aged rhesus macaques to better understand the choroid's role in this nonhuman primate model of AMD.MethodsWe analyzed optical coherence tomography (OCT) images of 244 eyes from 122 rhesus macaques (aged 4-32 years) to measure choroidal thickness (CT) and choroidal vascularity index (CVI). Drusen number, size, and volume were measured by semiautomated annotation and segmentation of OCT images. We performed regression analyses to determine any association of CT or CVI with age, sex, and axial length and to determine if the presence and volume of soft drusen impacted these choroidal parameters.ResultsIn rhesus macaques, subfoveal CT decreased with age at 3.2 µm/y (R2 = 0.481, P < 0.001), while CVI decreased at 0.66% per year (R2 = 0.257, P < 0.001). Eyes with soft drusen exhibited thicker choroid (179.9 ± 17.5 µm vs. 162.0 ± 27.9 µm, P < 0.001) and higher CVI (0.612 ± 0.051 vs. 0.577 ± 0.093, P = 0.005) than age-matched control animals. Neither CT or CVI appeared to be associated with drusen number, size, or volume in this cohort. However, some drusen in macaques were associated with underlying choroidal vessel enlargement resembling pachydrusen in human patients with AMD.ConclusionsChanges in the choroidal vasculature in rhesus macaques resemble choroidal changes in human aging, but eyes with drusen exhibit choroidal thickening, increased vascularity, and phenotypic characteristics of pachydrusen observed in some patients with AMD.

Chronic emesis (CE) is a poorly understood condition in human and nonhuman primates that negatively impacts the quality of life. Early identification of risk factors for the development of CE is likely to improve the ability to manage CE cases successfully and is, therefore, desirable. Using a case-control study, we reviewed the necropsy records of the California National Primate Research Center and identified 24 animals with recorded CE, defined as five or more incidents of emesis in 1 month. A group of 89 healthy rhesus macaques (Macaca mulatta), comparable in age and percent time housed indoors, was similarly identified. Next, we investigated the association between the occurrence of CE during later stages of life after infancy and the behavioral temperament scores attained in infancy, age, sex, birth location, rearing condition, history of self-injurious behavior (SIB), and the number of lifetime sedation events. Our analysis revealed that CE was associated with degrees of temperament constructs obtained in infancy (data was available for n = 113), such as Confidence (odds ratio (OR) = 0.45, 95% CI: 0.18, 1.08, p = 0.07), Gentleness (OR = 0.47, 95% CI: 0.23, 0.96, p = 0.03), Nervousness (OR = 2.04, 95% CI: 0.98, 4.23, p = 0.05), and Vigilance (OR = 0.36, 95% CI: 015, 0.87, p = 0.02), suggesting that CE is linked to behavioral phenomenon measured in early life, long before it becomes a medical concern. Our data suggest that CE was positively correlated with a history of SIB (OR 4.26, 95% CI: 0.98, 18.47, p = 0.04). Accurate prediction of CE can then assist behavioral and colony management professionals in making informed decisions regarding the care of animals at risk of developing CE. Moreover, the novel information we reported here could have valuable implications in human medicine, where gastrointestinal distress is a common complaint affecting a person's quality of life.

Rhesus monkeys and humans are highly social primates, yet both species exhibit pronounced variation in social functioning, spanning a spectrum of sociality. Naturally occurring low sociality in rhesus monkeys may be a promising construct by which to model social impairments relevant to human autism spectrum disorder (ASD), particularly if low sociality is found to be stable across time and associated with diminished social motivation. Thus, to better characterize variation in sociality and social communication profiles, we performed quantitative social behavior assessments on N = 95 male rhesus macaques (Macaca mulatta) housed in large, outdoor groups. In Study 1, we determined the social classification of our subjects by rank-ordering their total frequency of nonsocial behavior. Monkeys with the greatest frequency of nonsocial behavior were classified as low-social (n = 20) and monkeys with the lowest frequency of nonsocial behavior were classified as high-social (n = 21). To assess group differences in social communication profiles, in Study 2, we quantified the rates of transient social communication signals, and whether these social signals were initiated by or directed towards the focal subject. Finally, in Study 3, we assessed the within-individual stability of sociality in a subset of monkeys (n = 11 low-social, n = 11 high-social) two years following our initial observations. Nonsocial behavior frequency significantly correlated across the two timepoints (Studies 1 and 3). Likewise, low-social versus high-social classification accurately predicted classification two years later. Low-social monkeys initiated less prosocial behavior than high-social monkeys, but groups did not differ in receipt of prosocial behavior, nor did they differ in threat behavior. These findings indicate that sociality is a stable, trait-like characteristic and that low sociality is linked to diminished initiation of prosocial behavior in rhesus macaques. This evidence also suggests that low sociality may be a useful construct for gaining mechanistic insight into the social motivational deficits often observed in people with ASD.

Recent developments in high-density neurophysiological tools now make it possible to record from hundreds of single neurons within local, highly interconnected neural networks. Among the many advantages of such recordings is that they dramatically increase the quantity of identifiable, functional interactions between neurons thereby providing an unprecedented view of local circuits. Using high-density, Neuropixels recordings from single neocortical columns of primary visual cortex in nonhuman primates, we identified 1000s of functionally interacting neuronal pairs using established crosscorrelation approaches. Our results reveal clear and systematic variations in the synchrony and strength of functional interactions within single cortical columns. Despite neurons residing within the same column, both measures of interactions depended heavily on the vertical distance separating neuronal pairs, as well as on the similarity of stimulus tuning. In addition, we leveraged the statistical power afforded by the large numbers of functionally interacting pairs to categorize interactions between neurons based on their crosscorrelation functions. These analyses identified distinct, putative classes of functional interactions within the full population. These classes of functional interactions were corroborated by their unique distributions across defined laminar compartments and were consistent with known properties of V1 cortical circuitry, such as the lead-lag relationship between simple and complex cells. Our results provide a clear proof-of-principle for the use of high-density neurophysiological recordings to assess circuit-level interactions within local neuronal networks.

We used viral intersectional tools to map the entire projectome of corticospinal neurons associated with fine distal forelimb control in Fischer 344 rats and rhesus macaques. In rats, we found an extraordinarily diverse set of collateral projections from corticospinal neurons to 23 different brain and spinal regions. Remarkably, the vast weighting of this "motor" projection was to sensory systems in both the brain and spinal cord, confirmed by optogenetic and transsynaptic viral intersectional tools. In contrast, rhesus macaques exhibited far heavier and narrower weighting of corticospinal outputs toward spinal and brainstem motor systems. Thus, corticospinal systems in macaques primarily constitute a final output system for fine motor control, whereas this projection in rats exerts a multi-modal integrative role that accesses far broader CNS regions. Unique structural-functional correlations can be achieved by mapping and quantifying a single neuronal system's total axonal output and its relative weighting across CNS targets.

Animal models are an integral part of the drug development and evaluation process. However, they are unsurprisingly imperfect reflections of humans, and the extent and nature of many immunological differences are unknown. With the rise of targeted and biological therapeutics, it is increasingly important that we understand the molecular differences in the immunological behavior of humans and model organisms. However, very few antibodies are raised against non-human primate antigens, and databases of cross-reactivity between species are incomplete. Thus, we screened 332 antibodies in five immune cell populations in blood from humans and four non-human primate species generating a comprehensive cross-reactivity catalog that includes cell type-specificity. We used this catalog to create large mass cytometry universal cross-species phenotyping and signaling panels for humans, along with three of the model organisms most similar to humans: rhesus and cynomolgus macaques and African green monkeys; and one of the mammalian models most widely used in drug development: C57BL/6 mice. As a proof-of-principle, we measured immune cell signaling responses across all five species to an array of 15 stimuli using mass cytometry. We found numerous instances of different cellular phenotypes and immune signaling events occurring within and between species, and detailed three examples (double-positive T cell frequency and signaling; granulocyte response to Bacillus anthracis antigen; and B cell subsets). We also explore the correlation of herpes simian B virus serostatus on the immune profile. Antibody panels and the full dataset generated are available online as a resource to enable future studies comparing immune responses across species during the evaluation of therapeutics.

BackgroundImmunosurveillance of the central nervous system (CNS) is vital to resolve infection and injury. However, immune activation within the CNS in the setting of chronic viral infections, such as HIV-1, is strongly linked to progressive neurodegeneration and cognitive decline. Establishment of HIV-1 in the CNS early following infection underscores the need to delineate features of acute CNS immune activation, as these early inflammatory events may mediate neurodegenerative processes. Here, we focused on elucidating molecular programs of neuroinflammation in brain regions based on vulnerability to neuroAIDS and/or neurocognitive decline. To this end, we assessed transcriptional profiles within the subcortical white matter of the pre-frontal cortex (PFCw), as well as synapse dense regions from hippocampus, superior temporal cortex, and caudate nucleus, in rhesus macaques following infection with Simian/Human Immunodeficiency Virus (SHIV.C.CH505).MethodsWe performed RNA extraction and sequenced RNA isolated from 3 mm brain punches. Viral RNA was quantified in the brain and cerebrospinal fluid by RT-qPCR assays targeting SIV Gag. Neuroinflammation was assessed by flow cytometry and multiplex ELISA assays.ResultsRNA sequencing and flow cytometry data demonstrated immune surveillance of the rhesus CNS by innate and adaptive immune cells during homeostasis. Following SHIV infection, viral entry and integration within multiple brain regions demonstrated vulnerabilities of key cognitive and motor function brain regions to HIV-1 during the acute phase of infection. SHIV-induced transcriptional alterations were concentrated to the PFCw and STS with upregulation of gene expression pathways controlling innate and T-cell inflammatory responses. Within the PFCw, gene modules regulating microglial activation and T cell differentiation were induced at 28 days post-SHIV infection, with evidence for stimulation of immune effector programs characteristic of neuroinflammation. Furthermore, enrichment of pathways regulating mitochondrial respiratory capacity, synapse assembly, and oxidative and endoplasmic reticulum stress were observed. These acute neuroinflammatory features were substantiated by increased influx of activated T cells into the CNS.ConclusionsOur data show pervasive immune surveillance of the rhesus CNS at homeostasis and reveal perturbations of important immune, neuronal, and synaptic pathways within key anatomic regions controlling cognition and motor function during acute HIV infection. These findings provide a valuable framework to understand early molecular features of HIV associated neurodegeneration.

BackgroundBoth the gut microbiota and chronic viral infections have profound effects on host immunity, but interactions between these influences have been only superficially explored. Cytomegalovirus (CMV), for example, infects approximately 80% of people globally and drives significant changes in immune cells. Similarly, certain gut-resident bacteria affect T-cell development in mice and nonhuman primates. It is unknown if changes imposed by CMV on the intestinal microbiome contribute to immunologic effects of the infection.ResultsWe show that rhesus cytomegalovirus (RhCMV) infection is associated with specific differences in gut microbiota composition, including decreased abundance of Firmicutes, and that the extent of microbial change was associated with immunologic changes including the proliferation, differentiation, and cytokine production of CD8+ T cells. Furthermore, RhCMV infection disrupted the relationship between short-chain fatty acid producers and Treg/Th17 balance observed in seronegative animals, showing that some immunologic effects of CMV are due to disruption of previously existing host-microbe relationships.ConclusionsGut microbes have an important influence on health and disease. Diet is known to shape the microbiota, but the influence of concomitant chronic viral infections is unclear. We found that CMV influences gut microbiota composition to an extent that is correlated with immunologic changes in the host. Additionally, pre-existing correlations between immunophenotypes and gut microbes can be subverted by CMV infection. Immunologic effects of CMV infection on the host may therefore be mediated by two different mechanisms involving gut microbiota. Video Abstract.

We evaluated neuropathological consequences of fetal ZIKV exposure in rhesus monkeys, a translatable animal model for human neural development, by carrying out quantitative neuroanatomical analyses of the nearly full-term brains of fetuses infected with ZIKV and procedure-matched controls. For each animal, a complete cerebral hemisphere was evaluated using immunohistochemical (IHC) and neuroanatomical techniques to detect virus, identify affected cell types, and evaluate gross neuroanatomical abnormalities. IHC staining revealed the presence of ZIKV in the frontal lobe, which contained activated microglia and showed increased apoptosis of immature neurons. ZIKV-infected animals exhibited macrostructural changes within the visual pathway. Regional differences tracked with the developmental timing of the brain, suggesting inflammatory processes related to viral infiltration swept through the cortex, followed by a wave of cell death resulting in morphological changes. These findings may help explain why some infants born with normal sized heads during the ZIKV epidemic manifest developmental challenges as they age.

BackgroundRhesus monkeys (Macaca mulatta) exhibit pronounced individual differences in social traits as measured by the macaque Social Responsiveness Scale-Revised. The macaque Social Responsiveness Scale was previously adapted from the Social Responsiveness Scale, an instrument designed to assess social and autistic trait variation in humans. To better understand potential biological underpinnings of this behavioral variation, we evaluated the trait-like consistency of several biological measures previously implicated in autism (e.g., arginine vasopressin, oxytocin, and their receptors, as well as ERK1/2, PTEN, and AKT(1-3) from the RAS-MAPK and PI3K-AKT pathways). We also tested which biological measures predicted macaque Social Responsiveness Scale-Revised scores.MethodsCerebrospinal fluid and blood samples were collected from N = 76 male monkeys, which, as a sample, showed a continuous distribution on the macaque Social Responsiveness Scale-Revised. In a subset of these subjects (n = 43), samples were collected thrice over a 10-month period. The following statistical tests were used: "Case 2A" intra-class correlation coefficients of consistency, principal component analysis, and general linear modeling.ResultsAll biological measures (except AKT) showed significant test-retest reliability within individuals across time points. We next performed principal component analysis on data from monkeys with complete biological measurement sets at the first time point (n = 57), to explore potential correlations between the reliable biological measures and their relationship to macaque Social Responsiveness Scale-Revised score; a three-component solution was found. Follow-up analyses revealed that cerebrospinal fluid arginine vasopressin concentration, but no other biological measure, robustly predicted individual differences in macaque Social Responsiveness Scale-Revised scores, such that monkeys with the lowest cerebrospinal fluid arginine vasopressin concentration exhibited the greatest social impairment. Finally, we confirmed that this result held in the larger study sample (in which cerebrospinal fluid arginine vasopressin values were available from n = 75 of the subjects).ConclusionsThese findings indicate that cerebrospinal fluid arginine vasopressin concentration is a stable trait-like measure and that it is linked to quantitative social trait variation in male rhesus monkeys.

How individuals respond to and cope with stress is linked with their health and well-being. It is presumed that early stress responsiveness helps shape the health of the developing organism, but the relationship between stress responsiveness and early immune function during development is not well-known. We hypothesized that stress responsiveness may shape epigenetic regulation of immune genes in infancy. We investigated whether aspects of behavioral responsiveness and hypothalamic-pituitary adrenal stress-response were associated with epigenome-wide immune cell DNA methylation patterns in 154 infant rhesus monkeys (3-4 months old). Infants' behavioral and physiological responses were collected during a standardized biobehavioral assessment, which included temporary relocation and separation from their mother and social group. Genome-wide DNA methylation was quantified using restricted representation bisulfite sequencing (RRBS) from blood DNA collected 2-hours post-separation. Epigenome-wide analyses were conducted using simple regression, multiple regression controlling for immune cell counts, and permutation regression, all corrected for false discovery rate. Across the variables analyzed, there were 20,368 unique sites (in 9,040 genes) at which methylation was significantly associated with at least one behavioral responsiveness or cortisol measure across the three analyses. There were significant associations in 442 genes in the Immune System Process ontology category, and 94 genes in the Inflammation mediated by chemokine and cytokine signaling gene pathway. Out of 35 candidate genes that were selected for further investigation, there were 13 genes with at least one site at which methylation was significantly associated with behavioral responsiveness or cortisol, including two intron sites in the glucocorticoid receptor gene, at which methylation was negatively correlated with emotional behavior the day following the social separation (Day 2 Emotionality; β = -0.39, q

To understand susceptibility of wild California sea lions and Northern elephant seals to influenza A virus (IAV), we developed an ex vivo respiratory explant model and used it to compare infection kinetics for multiple IAV subtypes. We first established the approach using explants from colonized rhesus macaques, a model for human IAV. Trachea, bronchi, and lungs from 11 California sea lions, 2 Northern elephant seals, and 10 rhesus macaques were inoculated within 24 h postmortem with 6 strains representing 4 IAV subtypes. Explants from the 3 species showed similar IAV infection kinetics, with peak viral titers 48 to 72 h post-inoculation that increased by 2 to 4 log10 PFU/explant relative to the inoculum. Immunohistochemistry localized IAV infection to apical epithelial cells. These results demonstrate that respiratory tissue explants from wild marine mammals support IAV infection. In the absence of the ability to perform experimental infections of marine mammals, this ex vivo culture of respiratory tissues mirrors the in vivo environment and serves as a tool to study IAV susceptibility, host range, and tissue tropism. IMPORTANCE Although influenza A virus can infect marine mammals, a dearth of marine mammal cell lines and ethical and logistical challenges prohibiting experimental infections of living marine mammals mean that little is known about IAV infection kinetics in these species. We circumvented these limitations by adapting a respiratory tract explant model first to establish the approach with rhesus macaques and then for use with explants from wild marine mammals euthanized for nonrespiratory medical conditions. We observed that multiple strains representing 4 IAV subtypes infected trachea, bronchi, and lungs of macaques and marine mammals with variable peak titers and kinetics. This ex vivo model can define infection dynamics for IAV in marine mammals. Further, use of explants from animals euthanized for other reasons reduces use of animals in research.

People with autism spectrum disorder (ASD) exhibit a variety of medical morbidities at significantly higher rates than the general population. Using an established monkey model of naturally occurring low sociality, we investigated whether low-social monkeys show an increased burden of medical morbidities compared to their high-social counterparts. We systematically reviewed the medical records of N = 152 (n = 73 low-social; n = 79 high-social) rhesus macaques (Macaca mulatta) to assess the number of traumatic injury, gastrointestinal, and inflammatory events, as well as the presence of rare medical conditions. Subjects' nonsocial scores, determined by the frequency they were observed in a nonsocial state (i.e., alone), and macaque Social Responsiveness Scale-Revised (mSRS-R) scores were also used to test whether individual differences in social functioning were related to medical morbidity burden. Medical morbidity type significantly differed by group, such that low-social monkeys incurred higher rates of traumatic injury compared to high-social monkeys. Nonsocial scores and mSRS-R scores also significantly and positively predicted traumatic injury rates, indicating that monkeys with the greatest social impairment were most impacted on this health measure. These findings from low-social monkeys are consistent with well-documented evidence that people with ASD incur a greater number of traumatic injuries and receive more peer bullying than their neurotypical peers, and add to growing evidence for the face validity of this primate model. LAY SUMMARY: People with autism exhibit multiple medical problems at higher rates than the general population. We conducted a comprehensive medical record review of monkeys that naturally exhibit differences in sociality and found that low-social monkeys are more susceptible to traumatic injuries than high-social monkeys. These results are consistent with reports that people with autism also incur greater traumatic injury and peer bullying and add to growing evidence for the validity of this monkey model.

Few studies have longitudinally assessed the relationship between infant stress reactivity and future parenting style. Studies show that stress-induced plasma cortisol concentrations are stable over development and that they can be utilized as a marker for stress reactivity. This study investigates the relationship between stress-induced plasma cortisol concentrations in infancy and later parenting behavior in a translational nonhuman primate model. We hypothesized that higher stress-induced cortisol levels in infancy would predict impairments in maternal behaviors in adulthood. Subjects were rhesus macaque females (N = 122; Macaca mulatta), assessed as infants and again as mothers. At 3-4 months of age, subjects underwent a standardized BioBehavioral Assessment during which blood samples were obtained and they were assessed for behaviorally inhibition. Approximately 7 years later, subjects were observed as they interacted with their own offspring for four 300-s sessions. Typical rhesus monkey mother-offspring behaviors were recorded, including approaches and leaves and maternal cradling. Results showed that subjects' stress-induced cortisol concentrations and whether they exhibited behavioral inhibition as infants predicted later maternal behavior, with high cortisol concentrations and behavioral inhibition predicting high rates of offspring approaches and leaves and low rates of maternal cradling. Results also showed that higher stress-induced cortisol concentrations in infancy predicted higher scores on the Brown Index, an indication that the subjects' offspring, rather than the subject themselves, initiated changes in proximity. Taken together, these results suggest that individuals that exhibit higher stress-induced cortisol concentrations and behavioral inhibition at 3-4 months of age are at risk for engaging in less sensitive parenting behaviors as adults. To the extent that these findings generalize to humans, they suggest an important link between stress-induced cortisol concentrations and behavioral inhibition in infancy and behavior later in life, such that early-life stress reactivity can serve as a marker for later parenting behavior.

PurposeTo determine the range of normal ocular biometry and perform advanced retinal imaging and functional assessment of the rhesus macaque eye.MethodsWe performed ocular phenotyping on rhesus macaques at the California National Primate Research Center. This process consisted of anterior and posterior segment eye examination by ophthalmologists, advanced retinal imaging, and functional retinal electrophysiology.ResultsFull eye examinations were performed on 142 animals, consisting of pupillary light reflex, tonometry, external examination and photography, anterior slit lamp examination, and posterior segment examination by indirect ophthalmoscopy. Ages of the rhesus macaques ranged from 0.7 to 29 years (mean, 16.4 ± 7.5 years). Anterior segment measurements such as intraocular pressure (n = 142), corneal thickness (n = 84), lens thickness (n = 114), and axial length (n = 114) were acquired. Advanced retinal imaging in the form of fundus photography (n = 78), optical coherence tomography (n = 60), and quantitative autofluorescence (n = 44) was obtained. Electroretinography (n = 75) was used to assay retinal function. Quantitative analyses of the macular structure, retinal layer segmentation, and rod and cone photoreceptor electrical responses are reported. Quantitative assessments were made and variations between sexes were analyzed to compare with established sex changes in human eyes.ConclusionsThe rhesus macaque has an ocular structure and function very similar to that of the human eye. In particular macular structure and retinal function is very similar to humans, making this species particularly useful for the study of macular biology and development of therapies for cone photoreceptor disorders.Translational relevanceRhesus macaques are an ideal model for future vision science studies of human eye diseases.

Most primate species are highly social. Yet, within species, pronounced individual differences in social functioning are evident. In humans, the Social Responsiveness Scale (SRS) measures variation in social functioning. The SRS provides a quantitative measure of social functioning in natural social settings and can be used as a screening tool for autistic traits. The SRS was previously adapted for use in chimpanzees and recently refined for rhesus macaques, resulting in the macaque Social Responsiveness Scale-Revised (mSRS-R). Here, we performed an exploratory factor analysis on the mSRS-R in a large sample of male rhesus macaques (N = 233). We investigated the relationships of the resulting mSRS-R factors to quantitative social behavior (alone, proximity, contact, groom, and play) and to previously-established personality dimensions (Sociability, Confidence, Irritability, and Equability). Factor analysis yielded three mSRS-R factors: Poor Social Motivation, Poor Social Attractiveness, and Inappropriate Behavior. mSRS-R factors mapped closely to social behavior and personality dimensions in rhesus macaques, providing support for this instrument's convergent and discriminant validity. Animals with higher Poor Social Motivation were more likely to be observed alone and less likely to be observed in contact and grooming with conspecifics. Animals with higher Poor Social Attractiveness were less likely to be observed playing but more likely to be observed grooming with conspecifics. Inappropriate Behavior did not predict any behavioral measure. Finally, animals with higher Poor Social Motivation and higher Poor Social Attractiveness had less sociable personalities, whereas animals with more Inappropriate Behavior were more confident and more irritable. These findings suggest that the mSRS-R is a promising, psychometrically robust tool that can be deployed to better understand the psychological factors contributing to individual differences in macaque social functioning and, with relevant species-specific modification, the SRS may hold promise for investigating variation in social functioning across diverse primate taxa.

Recent studies have identified rotational dynamics in motor cortex (MC), which many assume arise from intrinsic connections in MC. However, behavioral and neurophysiological studies suggest that MC behaves like a feedback controller where continuous sensory feedback and interactions with other brain areas contribute substantially to MC processing. We investigated these apparently conflicting theories by building recurrent neural networks that controlled a model arm and received sensory feedback from the limb. Networks were trained to counteract perturbations to the limb and to reach toward spatial targets. Network activities and sensory feedback signals to the network exhibited rotational structure even when the recurrent connections were removed. Furthermore, neural recordings in monkeys performing similar tasks also exhibited rotational structure not only in MC but also in somatosensory cortex. Our results argue that rotational structure may also reflect dynamics throughout the voluntary motor system involved in online control of motor actions.

BackgroundAdeno-associated virus (AAV)-mediated gene therapies are rapidly advancing to the clinic, and AAV engineering has resulted in vectors with increased ability to deliver therapeutic genes. Although the choice of vector is critical, quantitative comparison of AAVs, especially in large animals, remains challenging.MethodsHere, we developed an efficient single-cell AAV engineering pipeline (scAAVengr) to simultaneously quantify and rank efficiency of competing AAV vectors across all cell types in the same animal.ResultsTo demonstrate proof-of-concept for the scAAVengr workflow, we quantified - with cell-type resolution - the abilities of naturally occurring and newly engineered AAVs to mediate gene expression in primate retina following intravitreal injection. A top performing variant identified using this pipeline, K912, was used to deliver SaCas9 and edit the rhodopsin gene in macaque retina, resulting in editing efficiency similar to infection rates detected by the scAAVengr workflow. scAAVengr was then used to identify top-performing AAV variants in mouse brain, heart, and liver following systemic injection.ConclusionsThese results validate scAAVengr as a powerful method for development of AAV vectors.FundingThis work was supported by funding from the Ford Foundation, NEI/NIH, Research to Prevent Blindness, Foundation Fighting Blindness, UPMC Immune Transplant and Therapy Center, and the Van Sloun fund for canine genetic research.

The nonhuman primate provides a sophisticated animal model system both to explore neurobiological mechanisms underlying complex behaviors and to facilitate preclinical research for neurodevelopmental and neuropsychiatric disease. A better understanding of evolutionarily conserved behaviors and brain processes between humans and nonhuman primates will be needed to successfully apply recently released NIMH guidelines (NOT-MH-19-053) for conducting rigorous nonhuman primate neurobehavioral research. Here, we explore the relationship between two measures of social behavior that can be used in both humans and nonhuman primates-traditional observations of social interactions with conspecifics and eye gaze detection in response to social stimuli. Infant male rhesus macaques (Macaca mulatta) serving as controls (N = 14) for an ongoing study were observed in their social rearing groups and participated in a noninvasive, longitudinal eye-tracking study. We found significant positive relationships between time spent viewing eyes of faces in an eye tracker and number of initiations made for social interactions with peers that is consistent with similar observations in human populations. Although future studies are needed to determine if this relationship represents species-typical social developmental processes, these preliminary results provide a novel framework to explore the relationship between social interactions and social attention in nonhuman primate models for neurobehavioral development.

Naturally low-social rhesus macaques exhibit social impairments with direct relevance to autism spectrum disorder (ASD). To more efficiently identify low-social individuals in a large colony, we exploited, refined, and psychometrically assessed the macaque Social Responsiveness Scale (mSRS), an instrument previously derived from the human ASD screening tool. We performed quantitative social behavior assessments and mSRS ratings on a total of N = 349 rhesus macaques (Macaca mulatta) housed in large, outdoor corrals. In one cohort (N = 116), we conducted inter-rater and test-retest reliabilities, and in a second cohort (N = 233), we evaluated the convergent construct and predictive validity of the mSRS-Revised (mSRS-R). Only 17 of the original 36 items demonstrated inter-rater and test-retest reliability, resulting in the 17-item mSRS-R. The mSRS-R showed strong validity: mSRS-R scores robustly predicted monkeys' social behavior frequencies in home corrals. Monkeys that scored 1.5 standard deviations from the mean on nonsocial behavior likewise exhibited significantly more autistic-like traits, and mSRS-R scores predicted individuals' social classification (low-social vs. high-social) with 96% accuracy (likelihood ratio chi-square = 25.07; P

PurposeTo employ quantitative fundus autofluorescence (qAF) imaging in rhesus macaques to noninvasively assess retinal pigment epithelial (RPE) lipofuscin in nonhuman primates (NHPs) as a model of aging and age-related macular degeneration (AMD).MethodsThe qAF imaging was performed on eyes of 26 rhesus macaques (mean age 18.8 ± 8.2 years, range 4-27 years) with normal-appearing fundus or with age-related soft drusen using a confocal scanning laser ophthalmoscope with 488 nm excitation and an internal fluorescence reference. Eyes with soft drusen also underwent spectral-domain optical coherence tomography imaging to measure drusen volume and height of individual drusen lesions. The qAF levels were measured from the perifoveal annular ring (quantitative autofluorescence 8 [qAF8]) using the Delori grid, as well as focally over individual drusen lesions in this region. The association between qAF levels and age, sex, and drusen presence and volume were determined using multivariable regression analysis.ResultsMean qAF levels increased with age (P < 0.001) and were higher in females (P = 0.047). Eyes with soft drusen exhibited reduced mean qAF compared with age-matched normal eyes (P = 0.003), with greater drusen volume showing a trend toward decreased qAF levels. However, qAF levels are focally increased over most individual drusen (P < 0.001), with larger drusen appearing more hyperautofluorescent (R2 = 0.391, P < 0.001).ConclusionsIn rhesus macaques, qAF levels are increased with age and female sex, but decreased in eyes with soft drusen, similar to human AMD. However, drusen lesions appear hyperautofluorescent unlike those in humans, suggesting similarities and differences in RPE lipofuscin between humans and NHPs that may provide insight into drusen biogenesis and AMD pathogenesis.

The typical developmental trajectory of brain structure among nonhuman primates (NHPs) remains poorly understood. In this study, we characterized the normative trajectory of developmental change among a cohort of rhesus monkeys (n = 28), ranging in age from 2 to 22 months, using structural MRI datasets that were longitudinally acquired every 3-4 months. We hypothesized that NHP-specific transient intracranial volume decreases reported during late infancy would be part of the typical developmental process, which is driven by volumetric contraction of gray matter in primary functional areas. To this end, we performed multiscale analyses from the whole brain to voxel level, characterizing regional heterogeneity, hemispheric asymmetry, and sexual dimorphism in developmental patterns. The longitudinal trajectory of brain development was explained by three different regional volumetric growth patterns (exponentially decreasing, undulating, and linearly increasing), which resulted in developmental brain volume curves with transient brain volumetric decreases. White matter (WM) fractional anisotropy increased with age, corresponding to WM volume increases, while mean diffusivity (MD) showed biphasic patterns. The longitudinal trajectory of brain development in young rhesus monkeys follows typical maturation patterns seen in humans, but regional volumetric and MD changes are more dynamic in rhesus monkeys compared with humans, with marked decreases followed by "rebound-like" increases.

While tuberculosis (TB) is a risk factor in HIV-1-infected individuals, the mechanisms by which Mycobacterium tuberculosis (Mtb) worsens HIV-1 pathogenesis remain scarce. We showed that HIV-1 infection is exacerbated in macrophages exposed to TB-associated microenvironments due to tunneling nanotube (TNT) formation. To identify molecular factors associated with TNT function, we performed a transcriptomic analysis in these macrophages, and revealed the up-regulation of Siglec-1 receptor. Siglec-1 expression depends on Mtb-induced production of type I interferon (IFN-I). In co-infected non-human primates, Siglec-1 is highly expressed by alveolar macrophages, whose abundance correlates with pathology and activation of IFN-I/STAT1 pathway. Siglec-1 localizes mainly on microtubule-containing TNT that are long and carry HIV-1 cargo. Siglec-1 depletion decreases TNT length, diminishes HIV-1 capture and cell-to-cell transfer, and abrogates the exacerbation of HIV-1 infection induced by Mtb. Altogether, we uncover a deleterious role for Siglec-1 in TB-HIV-1 co-infection and open new avenues to understand TNT biology.

The prevalence and societal impact of neurodevelopmental disorders (NDDs) continue to increase despite years of research in both patient populations and animal models. There remains an urgent need for translational efforts between clinical and preclinical research to (i) identify and evaluate putative causes of NDD, (ii) determine their underlying neurobiological mechanisms, (iii) develop and test novel therapeutic approaches, and (iv) translate basic research into safe and effective clinical practices. Given the complexity behind potential causes and behaviors affected by NDDs, modeling these uniquely human brain disorders in animals will require that we capitalize on unique advantages of a diverse array of species. While much NDD research has been conducted in more traditional animal models such as the mouse, ultimately, we may benefit from creating animal models with species that have a more sophisticated social behavior repertoire such as the rat (Rattus norvegicus) or species that more closely related to humans, such as the rhesus macaque (Macaca mulatta). Here, we highlight the rat and rhesus macaque models for their role in previous psychological research discoveries, current efforts to understand the neurobiology of NDDs, and focus on the convergence of behavior outcome measures that parallel features of human NDDs.

The effects of early stress may not be limited to the exposed generation, but are sometimes passed on to subsequent generations. Such non-genetic transgenerational inheritance is a potentially important developmental and evolutionary force. We compared the transgenerational effects of maternal and paternal line early stress on anxiety- and health-related traits in three non-exposed generations (F1, F2 and F3) of semi-naturalistically raised rhesus macaques. As infants, F0 macaques were exposed to nursery rearing (NR) or semi-naturalistic social conditions (CONTROL). Three hundred forty non-exposed F1-F3 descendants were CONTROL reared and physiological and behavioral measures were collected during standardized assessment at 3-4 months of age. Paternal line NR was significantly associated with greater nervousness in F1-F3 and lower immune cell counts in F1-F2. Maternal-line NR effects were not observed. This study suggests that acquired stress-related traits may be "inherited" across generations in primates, through complex social or germ-line mechanisms.

Brain stimulation modulates the excitability of neural circuits and drives neuroplasticity. While the local effects of stimulation have been an active area of investigation, the effects on large-scale networks remain largely unexplored. We studied stimulation-induced changes in network dynamics in two macaques. A large-scale optogenetic interface enabled simultaneous stimulation of excitatory neurons and electrocorticographic recording across primary somatosensory (S1) and motor (M1) cortex (Yazdan-Shahmorad et al., 2016). We tracked two measures of network connectivity, the network response to focal stimulation and the baseline coherence between pairs of electrodes; these were strongly correlated before stimulation. Within minutes, stimulation in S1 or M1 significantly strengthened the gross functional connectivity between these areas. At a finer scale, stimulation led to heterogeneous connectivity changes across the network. These changes reflected the correlations introduced by stimulation-evoked activity, consistent with Hebbian plasticity models. This work extends Hebbian plasticity models to large-scale circuits, with significant implications for stimulation-based neurorehabilitation.

Nonhuman primates are important preclinical models of retinal diseases because they uniquely possess a macula similar to humans. Ocular imaging technologies such as spectral-domain optical coherence tomography (SD-OCT) allow noninvasive, in vivo measurements of chorioretinal layers with near-histological resolution. However, the boundaries are based on differences in reflectivity, and detailed correlations with histological tissue layers have not been explored in rhesus macaques, which are widely used for biomedical research. Here, we compare the macular anatomy and thickness measurements of chorioretinal layers in rhesus macaque eyes using SD-OCT and high-resolution histological sections. Images were obtained from methylmethacrylate-embedded histological sections of 6 healthy adult rhesus macaques, and compared with SD-OCT images from 6 age-matched animals. Thicknesses of chorioretinal layers were measured across the central 3 mm macular region using custom semi-automated or manual software segmentation, and compared between the two modalities. We found that histological sections provide better distinction between the ganglion cell layer (GCL) and inner plexiform layer (IPL) than SD-OCT imaging. The first hyperreflective band between the external limiting membrane (ELM) and retinal pigment epithelium (RPE) appears wider on SD-OCT than the junction between photoreceptor inner and outer segments seen on histology. SD-OCT poorly distinguishes Henle nerve fibers from the outer nuclear layer (ONL), while histology correctly identifies these fibers as part of the outer plexiform layer (OPL). Overall, the GCL, inner nuclear layer (INL), and OPL are significantly thicker on histology, especially at the fovea; while the ONL, choriocapillaris (CC), and outer choroid (OC) are thicker on SD-OCT. Our results show that both SD-OCT and high-resolution histological sections allow reliable measurements of chorioretinal layers in rhesus macaques, with distinct advantages for different sublayers. These findings demonstrate the effects of tissue processing on chorioretinal anatomy, and provide normative values for chorioretinal thickness measurements on SD-OCT for future studies of disease models in these nonhuman primates.

HIV vaccine development is focused on designing immunogens and delivery methods that elicit protective immunity. We evaluated a combination of adenovirus (Ad) vectors expressing HIV 1086.C (clade C) envelope glycoprotein (Env), SIV Gag p55, and human pegivirus GBV-C E2 glycoprotein. We compared replicating simian (SAd7) with nonreplicating human (Ad4) adenovirus-vectored vaccines paired with recombinant proteins in a novel prime-boost regimen in rhesus macaques, with the goal of eliciting protective immunity against SHIV challenge. In both vaccine groups, plasma and buccal Env-specific IgG, tier 1 heterologous neutralizing antibodies, and antibody-dependent cell-mediated viral inhibition were readily generated. High Env-specific T cell responses elicited in all vaccinees were significantly greater than responses targeting Gag. After three intrarectal exposures to heterologous tier 1 clade C SHIV, all 10 sham-vaccinated controls were infected, whereas 4/10 SAd7- and 3/10 Ad4-vaccinated macaques remained uninfected or maintained tightly controlled plasma viremia. Time to infection was significantly delayed in SAd7-vaccinated macaques compared to the controls. Cell-associated and plasma virus levels were significantly lower in each group of vaccinated macaques compared to controls; the lowest plasma viral burden was found in animals vaccinated with the SAd7 vectors, suggesting superior immunity conferred by the replicating simian vectors. Furthermore, higher V1V2-specific binding antibody titers correlated with viral control in the SAd7 vaccine group. Thus, recombinant Ad plus protein vaccines generated humoral and cellular immunity that was effective in either protecting from SHIV acquisition or significantly reducing viremia in animals that became infected, consequently supporting additional development of replicating Ad vectors as HIV vaccines.IMPORTANCE There is a well-acknowledged need for an effective AIDS vaccine that protects against HIV infection and limits in vivo viral replication and associated pathogenesis. Although replicating virus vectors have been advanced as HIV vaccine platforms, there have not been any direct comparisons of the replicating to the nonreplicating format. The present study directly compared the replicating SAd7 to nonreplicating Ad4 vectors in macaques and demonstrated that in the SAd7 vaccine group, the time to infection was significantly delayed compared to the control group, and V1V2 Env-specific binding antibodies correlated with viral outcomes. Viral control was significantly enhanced in vaccinated macaques compared to controls, and in infected SAd7-vaccinated macaques compared to Ad4-vaccinated macaques, suggesting that this vector may have conferred more effective immunity. Because blocking infection is so difficult with current vaccines, development of a vaccine that can limit viremia if infection occurs would be valuable. These data support further development of replicating adenovirus vectors.

Obesity and its multiple metabolic sequelae, including type 2 diabetes, cardiovascular disease, and fatty liver disease, are becoming increasingly widespread in both the developed and developing world. There is an urgent need to identify new approaches for the prevention and treatment of these costly and prevalent metabolic conditions. Accomplishing this will require the use of appropriate animal models for preclinical and translational investigations in metabolic disease research. Although studies in rodent models are often useful for target/pathway identification and testing hypotheses, there are important differences in metabolic physiology between rodents and primates, and experimental findings in rodent models have often failed to be successfully translated into new, clinically useful therapeutic modalities in humans. Nonhuman primates represent a valuable and physiologically relevant model that serve as a critical translational bridge between basic studies performed in rodent models and clinical studies in humans. The purpose of this review is to evaluate the evidence, including a number of specific examples, in support of the use of nonhuman primate models in metabolic disease research, as well as some of the disadvantages and limitations involved in the use of nonhuman primates. The evidence taken as a whole indicates that nonhuman primates are and will remain an indispensable resource for evaluating the efficacy and safety of novel therapeutic strategies targeting clinically important metabolic diseases, including dyslipidemia and atherosclerosis, type 2 diabetes, hepatic steatosis, steatohepatitis, and hepatic fibrosis, and potentially the cognitive decline and dementia associated with metabolic dysfunction, prior to taking these therapies into clinical trials in humans.

The development of a vaccine to prevent congenital human cytomegalovirus (HCMV) disease is a public health priority. We tested rhesus CMV (RhCMV) prototypes of HCMV vaccine candidates in a seronegative macaque oral challenge model. Immunogens included a recombinant pentameric complex (PC; gH/gL/pUL128/pUL130/pUL131A), a postfusion gB ectodomain, and a DNA plasmid that encodes pp65-2. Immunization with QS21-adjuvanted PC alone or with the other immunogens elicited neutralizing titers comparable to those elicited by RhCMV infection. Similarly, immunization with all 3 immunogens elicited pp65-specific cytotoxic T-cell responses comparable to those elicited by RhCMV infection. RhCMV readily infected immunized animals and was detected in saliva, blood, and urine after challenge in quantities similar to those in placebo-immunized animals. If HCMV evades vaccine-elicited immunity in humans as RhCMV evaded immunity in macaques, a HCMV vaccine must elicit immunity superior to, or different from, that elicited by the prototype RhCMV vaccine to block horizontal transmission. [ABSTRACT FROM AUTHOR]

Many characteristics associated with Ebola virus disease remain to be fully understood. It is known that direct contact with infected bodily fluids is an associated risk factor, but few studies have investigated parameters associated with transmission between individuals, such as the dose of virus required to facilitate spread and route of infection. Therefore, we sought to characterize the impact by route of infection, viremia, and viral shedding through various mucosae, with regards to intraspecies transmission of Ebola virus in a nonhuman primate model. Here, challenge via the esophagus or aerosol to the face did not result in clinical disease, although seroconversion of both challenged and contact animals was observed in the latter. Subsequent intramuscular or intratracheal challenges suggest that viral loads determine transmission likelihood to naive animals in an intramuscular-challenge model, which is greatly facilitated in an intratracheal-challenge model where transmission from challenged to direct contact animal was observed consistently. [ABSTRACT FROM AUTHOR]

Calcium (Ca2+) plays an important role in the function and health of neurons. In vertebrate cone photoreceptors, Ca2+ controls photoresponse sensitivity, kinetics, and light adaptation. Despite the critical role of Ca2+ in supporting the function and survival of cones, the mechanism for its extrusion from cone outer segments is not well understood. Here, we show that the Na+/Ca2+, K+ exchanger NCKX4 is expressed in zebrafish, mouse, and primate cones. Functional analysis of NCKX4-deficient mouse cones revealed that this exchanger is essential for the wide operating range and high temporal resolution of cone-mediated vision. We show that NCKX4 shapes the cone photoresponse together with the cone-specific NCKX2: NCKX4 acts early to limit response amplitude, while NCKX2 acts late to further accelerate response recovery. The regulation of Ca2+ by NCKX4 in cones is a novel mechanism that supports their ability to function as daytime photoreceptors and promotes their survival.

While it is now well known that social deprivation during early development permanently perturbs affective responding, accumulating evidence suggests that less severe restriction of the early social environment may also have deleterious effects. In the present report, we evaluate the affective responding of rhesus macaque (Macaca mulatta) infants raised by their mothers in restricted social environments or by their mothers in large social groups by indexing autonomic nervous system activity. Following a 25-hr evaluation of biobehavioral organization, electrocardiogram, and an index of respiration were recorded for 10 min. This allowed for an evaluation of both heart rate and respiratory sinus arrhythmia (RSA), an index of parasympathetic activity, during a challenging situation. Three- to four-month-old infants raised in restricted social environments had significantly higher heart rates and lower RSA as compared to infants raised in unrestricted social environments, consistent with a more potent stress response to the procedure. These results are consistent with mounting evidence that the environment in which individuals are raised has important consequences for affective processing.

The present report details the final phase of a longitudinal evaluation of the social behavior in a cohort of adult rhesus monkeys that received bilateral neurotoxic lesions of the amygdala or hippocampus, or sham operations at 2 weeks of age. Results were compared to previous studies in which adult animals received amygdala lesions and were tested in a similar fashion. Social testing with four novel interaction partners occurred when the animals were between 7 and 8 years of age. Experimental animals interacted with two male and two female partners in two conditions - one in which physical access was restricted (the constrained social access condition) and a second in which physical access was unrestricted (the unconstrained social access condition). Across conditions and interaction partners, there were no significant effects of lesion condition on the frequency or duration of social interactions. As a group, the hippocampus-lesioned animals generated the greatest number of communicative signals during the constrained social access condition. Amygdala-lesioned animals generated more frequent stress-related behaviors and were less exploratory. Amygdala and hippocampus-lesioned animals demonstrated greater numbers of stereotypies than control animals. Subtle, lesion-based differences in the sequencing of behaviors were observed. These findings suggest that alterations of adult social behavior are much less prominent when damage to the amygdala occurs early in life rather than in adulthood.

This study continues a longitudinal analysis of rhesus macaque social behavior following bilateral neonatal ibotenic acid lesions of the amygdala or hippocampus, or sham operations. The social behavior of female subjects was evaluated at a critical developmental time point-the transition to adulthood. At approximately 4 years of age, female subjects were housed in small groups with other female subjects and reproductively viable adult males. As compared with neurologically intact control animals and animals with early amygdala damage, animals with early hippocampal damage were more social with their female peers. In contrast, as compared with control animals, animals with early amygdala damage spent less time with the males, engaged less frequently in behaviors typical of reproductive consortships, had higher frequencies of self-directed stereotypies, and became pregnant later. Males also generated fewer communicative signals toward animals with early amygdala damage than to control animals and animals with early hippocampus damage. Rates of sexual behavior were generally low for all animals, and there were no lesion-based differences in their frequencies. Discriminant function analyses demonstrated that patterns of affiliative social behaviors differed across the 3 experimental groups, both in terms of the social behaviors directed to the males, and the social behaviors generated by the males toward the females. In 4 of the 5 social groups, amygdala-lesioned animals were lowest ranked, potentially contributing to reduced sociability interactions with males. Other potential mechanisms and the experiments needed to elucidate them are discussed. (PsycINFO Database Record

Previous research has shown that adverse social conditions may promote a conserved transcriptional response to adversity (CTRA) involving up-regulation of proinflammatory gene expression and down-regulation of Type I interferon anti-viral genes in circulating blood cells. However, the impact of social conditions on lymphoid tissue gene regulation remains largely unexplored. This project assessed how social instability in adult male rhesus macaques (N=10, 5 in unstable, and 5 in stable social conditions) might regulate gene expression within secondary lymphoid tissue (lymph nodes; LN). Unstable social conditions down-regulated axillary LN expression of genes involved in Type I interferon anti-viral responses. Transcript origin analyses implicated monocytes and B cells as cellular mediators of these effects, and promoter-based bioinformatics analyses indicated reduced activity of AP-1, NF-κB, IRF, and CREB transcription factors within the axillary LN microenvironment. Although the current study is limited in sample size, these results suggest that social influences on immune cell gene regulation extend beyond the circulating leukocyte pool to alter generalized transcriptome profiles in secondary lymphoid tissue, and they do so in a regulatory program that resembles the pattern of antiviral inhibition previously observed in circulating leukocytes.

Psychosocial stressors appear to promote the onset of depressive illness through activation and sensitization of inflammatory mechanisms. Here, adult male rhesus monkeys brought from large outdoor social groups to indoor housing for 8 days reliably exhibited a hunched, depressive-like posture. When rehoused indoors a second 8 days about 2 weeks later, monkeys housed alone, but not those with an affiliative partner, showed sensitization of the depressive-like hunched posture. Housing indoors also affected circulating pro-inflammatory cytokines: IL-1β showed increased responsiveness to immune challenge, and IL-1β and TNF-α showed reduced suppression by dexamethasone. Sensitivity of the anti-inflammatory cytokine IL-10 to immune challenge exhibited a relative increase from the first to the second round of indoor housing in animals housed in pairs, and a relative decrease in animals housed alone. Cytokine levels during indoor housing were positively correlated with duration of depressive-like behavior. Plasma cortisol levels increased but did not differentiate housing conditions or rounds. Results demonstrate a rapid induction and sensitization of depressive-like behavior to indoor individual housing, social buffering of sensitization, and associated inflammatory responses. This paradigm may provide a practical nonhuman primate model for examining inflammatory-mediated consequences of psychosocial stressors on depression and possible social buffering of these effects.

Oxytocin (OT) is a neuropeptide that mediates a variety of complex social behaviors in animals and humans. Intranasal OT has been used as an experimental therapeutic for human conditions characterized by deficits in social functioning, especially autism spectrum disorder and schizophrenia. However, it is currently under intense debate whether intranasal delivery of OT reaches the central nervous system. In this study, four female rhesus macaques were implanted with chronic intrathecal catheters and used to investigate the pharmacokinetic profile of OT in the central nervous system and the peripheral vasculature following intravenous (IV) and intranasal (IN) administration of OT. In a randomized, crossover design, OT was given to four awake monkeys at three different doses based on body weight (0.1 IU/kg; 1 IU/kg; 5 IU/kg). A time course of concurrent cerebrospinal fluid (CSF) and plasma samples were taken following administration. We found a dose-dependent effect of IV OT treatment on plasma OT levels, which peaked at 5 min post-dose and gradually returned to baseline by 120 min. In contrast, a change in CSF OT was only observed at the highest IV dose (5 IU/kg) at 15 min post-dose and gradually returned to baseline by 120 min. After IN administration, there was no significant change in plasma OT at any of the three doses. However, at the highest dose level, we found a significant increase in CSF OT at 15-30 min post- dose. The results of this study in light of recent, similar publications highlight the importance of methodological consistency across studies. This study also establishes a non-human primate model that can provide a stable platform for carrying out serial sampling from the central nervous system and peripheral vasculature concurrently.

Early infant diet has significant impacts on the gut microbiota and developing immune system. We previously showed that breast-fed and formula-fed rhesus macaques develop significantly different gut microbial communities, which in turn are associated with different immune systems in infancy. Breast-fed animals manifested greater T cell activation and proliferation and harbored robust pools of T helper 17 (TH17) cells. These differences were sustained throughout the first year of life. Here we examine groups of juvenile macaques (approximately 3 to 5 y old), which were breast-fed or formula-fed in infancy. We demonstrate that juveniles breast-fed in infancy maintain immunologic differences into the fifth year of life, principally in CD8(+) memory T cell activation. Additionally, long-term correlation networks show that breast-fed animals maintain persistent relationships between immune subsets that are not seen in formula-fed animals. These findings demonstrate that infant feeding practices have continued influence on immunity for up to 3 to 5 y after birth and also reveal mechanisms for microbial modulation of the immune system.

Neurons expressing the calcium binding proteins (CaBPs) parvalbumin (PV) and calbindin (CB) have shown age-related density changes throughout the ascending auditory system of both rodents and macaque monkeys. In the cerebral cortex, neurons expressing these CaBPs express markers of γ-aminobutyric acidergic neurotransmission, such as GAD67, and have well-understood physiological response properties. Recent evidence suggests that, in the rodent auditory brainstem, CaBP-containing cells do not express GAD67. It is unknown whether PV- and CB-containing cells in subcortical auditory structures of macaques similarly do not express GAD67, and a better understanding of the neurotransmission of neurons expressing these proteins is necessary for understanding the age-related changes in their density throughout the macaque auditory system. This was investigated with immunofluorescent double-labeling techniques to coregister PV- and CB-expressing neurons with GAD67 in the superior olivary complex and the inferior colliculus of young and aged rhesus macaques. The proportions of GAD67-expressing PV- and CB-positive neurons were computed with unbiased sampling techniques. Our results indicate that between 42% and 62% of PV- and CB-positive neurons in the auditory brainstem and midbrain express GAD67, which is significantly less than in the cerebrum. In general, fewer PV(+) neurons and more CB(+) neurons expressed GAD67 as a function of age. These results demonstrate that the inhibitory molecular profile of PV- and CB-expressing neurons can change with age in subcortical auditory structures and that these neurons are distinct from the well-described inhibitory interneurons that express these proteins in the cerebral cortex.

BackgroundAnxious temperament (AT) is identifiable early in life and predicts the later development of anxiety disorders and depression. Neuropeptide Y (NPY) is a putative endogenous anxiolytic neurotransmitter that adaptively regulates responses to stress and might confer resilience to stress-related psychopathology. With a well-validated nonhuman primate model of AT, we examined expression of the NPY system in the central nucleus (Ce) of the amygdala, a critical neural substrate for extreme anxiety.MethodsIn 24 young rhesus monkeys, we measured Ce messenger RNA (mRNA) levels of all members of the NPY system that are detectable in the Ce with quantitative real time polymerase chain reaction. We then examined the relationship between these mRNA levels and both AT expression and brain metabolism.ResultsLower mRNA levels of neuropeptide Y receptor 1 (NPY1R) and NPY5R but not NPY or NPY2R in the Ce predicted elevated AT; mRNA levels for NPY1R and NPY5R in the motor cortex were not related to AT. In situ hybridization analysis provided for the first time a detailed description of NPY1R and NPY5R mRNA distribution in the rhesus amygdala and associated regions. Lastly, mRNA levels for these two receptors in the Ce predicted metabolic activity in several regions that have the capacity to regulate the Ce.ConclusionsDecreased NPY signaling in the Ce might contribute to the altered metabolic activity that is a component of the neural substrate underlying AT. This suggests that enhancement of NPY signaling might reduce the risk to develop psychopathology.

Nonhuman primates are widely used models to investigate the neural substrates of human behavior, including the development of higher cognitive and affective function. Due to their neuroanatomical and behavioral homologies with humans, the rhesus macaque monkey (Macaca mulatta) provides an excellent animal model in which to characterize the maturation of brain structures from birth through adulthood and into senescence. To evaluate hippocampal development in rhesus macaques, structural magnetic resonance imaging scans were obtained longitudinally at 9 time points between 1 week and 260 weeks (5 years) of age on 24 rhesus macaque monkeys (12 males, 12 females). In our sample, the hippocampus reaches 50% of its adult volume by 13 weeks of age and reaches an adult volume by 52 weeks in both males and females. The hippocampus appears to be slightly larger at 3 years than at 5 years of age. Male rhesus macaques have larger hippocampi than females from 8 weeks onward by approximately 5%. Interestingly, there was increased variability in hemispheric asymmetry for hippocampus volumes at younger ages than at later ages. These data provide a comprehensive evaluation of the longitudinal development of male and female rhesus macaque hippocampus across development from 1 week to 5 years of age.

Dexamethasone has well-described effects to induce insulin resistance and increase insulin secretion. Herein, we examined potential contributors to the effect of dexamethasone to increase insulin secretion in rhesus macaques. Six male rhesus macaques received daily injections of either saline or dexamethasone (0.25 mg/kg i.m. for 7 days) in random order with 3 weeks between treatments. At the end of the treatment period, animals were fasted overnight and underwent a feeding study the next day, during which blood samples were taken before and for 60 min after a meal in order to assess islet hormone and incretin secretion. Dexamethasone induced marked increases in fasting plasma insulin, glucagon, leptin, and adiponectin concentrations (P

Medial temporal lobe brain structures, such as the amygdala, play an important role in the normal perception and generation of emotional behavior. Little research, however, has assessed the role of such structures across the neurodevelopmental trajectory. We assessed emotional behavioral responses of rhesus macaques that received bilateral ibotenic acid lesions of the amygdala or hippocampus at 2 weeks of age and sham-operated controls. At 9 and 18 months of age, animals interacted with novel objects that varied in visual complexity as a means of varying emotional salience. All animals behaved differently in the presence of visually simple, as compared to complex, objects, suggesting that they were sensitive to variation in emotional salience. Across both experiments, amygdala-lesioned animals appeared to be less behaviorally inhibited insofar as they explored all objects most readily. Interestingly, hippocampus-lesioned animals' propensity for exploration mirrored that of control animals in some contexts but that of amygdala-lesioned animals in other contexts. At 18 months of age, both amygdala-lesioned and hippocampus-lesioned animals were judged to be less fearful than controls during the testing procedure. Implications for understanding the neurobiology of emotional behavior are discussed.

Abstract Recombinant antibodies serve as therapeutic molecules for a broad range of applications. High affinity antibodies are typically isolated following an active and effective immunization. Human-like antibodies may be obtained from immunized nonhuman primates (NHP), such as rhesus macaque, when immunized human origin is not available. For the isolation of such antibodies, strategies like phage and yeast display, are employed. These strategies are primarily based on the amplification of the rearranged variable (V) regions coded by mRNA, obtained from lymphatic source of immunized animals. To amplify these genomic sequences, designated set of primers are required, ideally covering the immune animal V-gene repertoire. Such primer sets are commonly designed based on the germline repertoire of specific animals according to immunoglobulin databases. However, In case of rhesus macaque, however, the known immunoglobulin germline V-gene database is still limited. The emergence and continuous improvements in high-throughput sequencing (HTS) technologies now enable the profiling of an immune repertoire for both basic and applicative studies, among which is the identification and expression of novel alleles. We report here on the profiling of non-immunized rhesus macaque (Macaca mulatta) expressed antibody repertoire, using HTS and advanced tailored bioinformatics tools. This analysis resulted in 32,480 and 73,354 complete heavy and light variable gene (V H and V L) sequences, respectively. Further analysis of these sequences, using the IgDiscover tool, resulted in the identification of 102, 214 and 48 inferred V H , V κ and V λ germline sequences, respectively, of which over 50% are novel alleles. This dataset, together with other recently published datasets, enabled the design of a comprehensive primer set (v2018), which demonstrated the broadest coverage of rhesus macaque germline genes identified up to date. The newly designed primer set was confirmed for its extent of coverage of the V-genes in various datasets of rhesus macaque germlines as well as the expressed repertoire mapped in this study. Among other things, an improvement of 28% and 50% in the coverage of the VH and VL expressed repertoire was demonstrated in comparison to a primer set we have previously designed. This primer set can be further used for various applications that require the complete coverage of the NHP V-gene repertoire. [ABSTRACT FROM AUTHOR]