Modulation of type I interferon responses potently inhibits SARS-CoV-2 replication and inflammation in rhesus macaques.

Type I interferons (IFN-I) are critical mediators of innate control of viral infections but also drive the recruitment of inflammatory cells to sites of infection, a key feature of severe coronavirus disease 2019. Here, IFN-I signaling was modulated in rhesus macaques (RMs) before and during acute SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection using a mutated IFN-α2 (IFN-modulator; IFNmod), which has previously been shown to reduce the binding and signaling of endogenous IFN-I. IFNmod treatment in uninfected RMs was observed to induce a modest up-regulation of only antiviral IFN-stimulated genes (ISGs); however, in SARS-CoV-2-infected RMs, IFNmod reduced both antiviral and inflammatory ISGs. IFNmod treatment resulted in a potent reduction in SARS-CoV-2 viral loads both in vitro in Calu-3 cells and in vivo in bronchoalveolar lavage (BAL), upper airways, lung, and hilar lymph nodes of RMs. Furthermore, in SARS-CoV-2-infected RMs, IFNmod treatment potently reduced inflammatory cytokines, chemokines, and CD163+ MRC1- inflammatory macrophages in BAL and expression of Siglec-1 on circulating monocytes. In the lung, IFNmod also reduced pathogenesis and attenuated pathways of inflammasome activation and stress response during acute SARS-CoV-2 infection. Using an intervention targeting both IFN-α and IFN-ß pathways, this study shows that, whereas early IFN-I restrains SARS-CoV-2 replication, uncontrolled IFN-I signaling critically contributes to SARS-CoV-2 inflammation and pathogenesis in the moderate disease model of RMs.

Polyglucosan body disease in an aged chimpanzee (Pan troglodytes).

A 57-year-old female chimpanzee presented with a brief history of increasing lethargy and rapidly progressive lower-limb weakness that culminated in loss of use. Postmortem examination revealed no significant gross lesions in the nervous system or other organ systems. Histological analysis revealed round, basophilic to amphophilic polyglucosan bodies (PGBs) in the white and gray matter of the cervical, thoracic, lumbar, and coccygeal regions of spinal cord. Only rare PGBs were observed in forebrain samples. The lesions in the spinal cord were polymorphic, and they were positively stained with hematoxylin, periodic acid Schiff, Alcian blue, toluidine blue, Bielschowsky silver, and Grocott-Gomori methenamine-silver methods, and they were negative for von Kossa and Congo Red stains. Immunohistochemical evaluation revealed reactivity with antibodies to ubiquitin, but they were negative for glial fibrillary acidic protein, neuron-specific enolase, neurofilaments, tau protein, and Aß protein. Electron microscopy revealed non-membrane-bound deposits composed of densely packed filaments within axons and in the extracellular space. Intra-axonal PGBs were associated with disruption of the axonal fine structure and disintegration of the surrounding myelin sheath. These findings are the first description of PGBs linked to neurological dysfunction in a chimpanzee. Clinicopathologically, the disorder resembled adult PGB disease in humans.

Modulation of type I interferon responses potently inhibits SARS-CoV-2 replication and inflammation in rhesus macaques.

Type-I interferons (IFN-I) are critical mediators of innate control of viral infections, but also drive recruitment of inflammatory cells to sites of infection, a key feature of severe COVID-19. Here, and for the first time, IFN-I signaling was modulated in rhesus macaques (RMs) prior to and during acute SARS-CoV-2 infection using a mutated IFNα2 (IFN-modulator; IFNmod), which has previously been shown to reduce the binding and signaling of endogenous IFN-I. In SARS-CoV-2-infected RMs, IFNmod reduced both antiviral and inflammatory ISGs. Notably, IFNmod treatment resulted in a potent reduction in (i) SARS-CoV-2 viral load in Bronchoalveolar lavage (BAL), upper airways, lung, and hilar lymph nodes; (ii) inflammatory cytokines, chemokines, and CD163+MRC1-inflammatory macrophages in BAL; and (iii) expression of Siglec-1, which enhances SARS-CoV-2 infection and predicts disease severity, on circulating monocytes. In the lung, IFNmod also reduced pathogenesis and attenuated pathways of inflammasome activation and stress response during acute SARS-CoV-2 infection. This study, using an intervention targeting both IFN-α and IFN-ß pathways, shows that excessive inflammation driven by type 1 IFN critically contributes to SARS-CoV-2 pathogenesis in RMs, and demonstrates the potential of IFNmod to limit viral replication, SARS-CoV-2 induced inflammation, and COVID-19 severity.

A vaccine targeting resistant tumours by dual T cell plus NK cell attack.

Most cancer vaccines target peptide antigens, necessitating personalization owing to the vast inter-individual diversity in major histocompatibility complex (MHC) molecules that present peptides to T cells. Furthermore, tumours frequently escape T cell-mediated immunity through mechanisms that interfere with peptide presentation1. Here we report a cancer vaccine that induces a coordinated attack by diverse T cell and natural killer (NK) cell populations. The vaccine targets the MICA and MICB (MICA/B) stress proteins expressed by many human cancers as a result of DNA damage2. MICA/B serve as ligands for the activating NKG2D receptor on T cells and NK cells, but tumours evade immune recognition by proteolytic MICA/B cleavage3,4. Vaccine-induced antibodies increase the density of MICA/B proteins on the surface of tumour cells by inhibiting proteolytic shedding, enhance presentation of tumour antigens by dendritic cells to T cells and augment the cytotoxic function of NK cells. Notably, this vaccine maintains efficacy against MHC class I-deficient tumours resistant to cytotoxic T cells through the coordinated action of NK cells and CD4+ T cells. The vaccine is also efficacious in a clinically important setting: immunization following surgical removal of primary, highly metastatic tumours inhibits the later outgrowth of metastases. This vaccine design enables protective immunity even against tumours with common escape mutations.

Dynamics and origin of rebound viremia in SHIV-infected infant macaques following interruption of long-term ART.

Understanding viral rebound in pediatric HIV-1 infection may inform the development of alternatives to lifelong antiretroviral therapy (ART) to achieve viral remission. We thus investigated viral rebound after analytical treatment interruption (ATI) in 10 infant macaques orally infected with SHIV.C.CH505 and treated with long-term ART. Rebound viremia was detected within 7 to 35 days of ATI in 9 of 10 animals, with posttreatment control of viremia seen in 5 of 5 Mamu-A*01+ macaques. Single-genome sequencing revealed that initial rebound virus was similar to viral DNA present in CD4+ T cells from blood, rectum, and lymph nodes before ATI. We assessed the earliest sites of viral reactivation immediately following ATI using ImmunoPET imaging. The largest increase in signal that preceded detectable viral RNA in plasma was found in the gastrointestinal (GI) tract, a site with relatively high SHIV RNA/DNA ratios in CD4+ T cells before ATI. Thus, the GI tract may be an initial source of rebound virus, but as ATI progresses, viral reactivation in other tissues likely contributes to the composition of plasma virus. Our study provides potentially novel insight into the features of viral rebound in pediatric infection and highlights the application of a noninvasive technique to monitor areas of HIV-1 expression in children.

A yeast expressed RBD-based SARS-CoV-2 vaccine formulated with 3M-052-alum adjuvant promotes protective efficacy in non-human primates.

Ongoing SARS-CoV-2 vaccine development is focused on identifying stable, cost-effective, and accessible candidates for global use, specifically in low and middle-income countries. Here, we report the efficacy of a rapidly scalable, novel yeast expressed SARS-CoV-2 specific receptor-binding domain (RBD) based vaccine in rhesus macaques. We formulated the RBD immunogen in alum, a licensed and an emerging alum adsorbed TLR-7/8 targeted, 3M-052-alum adjuvants. The RBD+3M-052-alum adjuvanted vaccine promoted better RBD binding and effector antibodies, higher CoV-2 neutralizing antibodies, improved Th1 biased CD4+T cell reactions, and increased CD8+ T cell responses when compared to the alum-alone adjuvanted vaccine. RBD+3M-052-alum induced a significant reduction of SARS-CoV-2 virus in respiratory tract upon challenge, accompanied by reduced lung inflammation when compared with unvaccinated controls. Anti-RBD antibody responses in vaccinated animals inversely correlated with viral load in nasal secretions and BAL. RBD+3M-052-alum blocked a post SARS-CoV-2 challenge increase in CD14+CD16++ intermediate blood monocytes, and Fractalkine, MCP-1, and TRAIL in the plasma. Decreased plasma analytes and intermediate monocyte frequencies correlated with reduced nasal and BAL viral loads. Lastly, RBD-specific plasma cells accumulated in the draining lymph nodes and not in the bone marrow, contrary to previous findings. Together, these data show that a yeast expressed, RBD-based vaccine+3M-052-alum provides robust immune responses and protection against SARS-CoV-2, making it a strong and scalable vaccine candidate.

A modified vaccinia Ankara vector-based vaccine protects macaques from SARS-CoV-2 infection, immune pathology, and dysfunction in the lungs.

A combination of vaccination approaches will likely be necessary to fully control the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Here, we show that modified vaccinia Ankara (MVA) vectors expressing membrane-anchored pre-fusion stabilized spike (MVA/S) but not secreted S1 induced strong neutralizing antibody responses against SARS-CoV-2 in mice. In macaques, the MVA/S vaccination induced strong neutralizing antibodies and CD8+ T cell responses, and conferred protection from SARS-CoV-2 infection and virus replication in the lungs as early as day 2 following intranasal and intratracheal challenge. Single-cell RNA sequencing analysis of lung cells on day 4 after infection revealed that MVA/S vaccination also protected macaques from infection-induced inflammation and B cell abnormalities and lowered induction of interferon-stimulated genes. These results demonstrate that MVA/S vaccination induces neutralizing antibodies and CD8+ T cells in the blood and lungs and is a potential vaccine candidate for SARS-CoV-2.

Baricitinib treatment resolves lower-airway macrophage inflammation and neutrophil recruitment in SARS-CoV-2-infected rhesus macaques.

SARS-CoV-2-induced hypercytokinemia and inflammation are critically associated with COVID-19 severity. Baricitinib, a clinically approved JAK1/JAK2 inhibitor, is currently being investigated in COVID-19 clinical trials. Here, we investigated the immunologic and virologic efficacy of baricitinib in a rhesus macaque model of SARS-CoV-2 infection. Viral shedding measured from nasal and throat swabs, bronchoalveolar lavages, and tissues was not reduced with baricitinib. Type I interferon (IFN) antiviral responses and SARS-CoV-2-specific T cell responses remained similar between the two groups. Animals treated with baricitinib showed reduced inflammation, decreased lung infiltration of inflammatory cells, reduced NETosis activity, and more limited lung pathology. Importantly, baricitinib-treated animals had a rapid and remarkably potent suppression of lung macrophage production of cytokines and chemokines responsible for inflammation and neutrophil recruitment. These data support a beneficial role for, and elucidate the immunological mechanisms underlying, the use of baricitinib as a frontline treatment for inflammation induced by SARS-CoV-2 infection.

Baricitinib treatment resolves lower airway inflammation and neutrophil recruitment in SARS-CoV-2-infected rhesus macaques.

Effective therapeutics aimed at mitigating COVID-19 symptoms are urgently needed. SARS-CoV-2 induced hypercytokinemia and systemic inflammation are associated with disease severity. Baricitinib, a clinically approved JAK1/2 inhibitor with potent anti-inflammatory properties is currently being investigated in COVID-19 human clinical trials. Recent reports suggest that baricitinib may also have antiviral activity in limiting viral endocytosis. Here, we investigated the immunologic and virologic efficacy of baricitinib in a rhesus macaque model of SARS-CoV-2 infection. Viral shedding measured from nasal and throat swabs, bronchoalveolar lavages and tissues was not reduced with baricitinib. Type I IFN antiviral responses and SARS-CoV-2 specific T cell responses remained similar between the two groups. Importantly, however, animals treated with baricitinib showed reduced immune activation, decreased infiltration of neutrophils into the lung, reduced NETosis activity, and more limited lung pathology. Moreover, baricitinib treated animals had a rapid and remarkably potent suppression of alveolar macrophage derived production of cytokines and chemokines responsible for inflammation and neutrophil recruitment. These data support a beneficial role for, and elucidate the immunological mechanisms underlying, the use of baricitinib as a frontline treatment for severe inflammation induced by SARS-CoV-2 infection.

Longitudinal MRI Evaluation of Ischemic Stroke in the Basal Ganglia of a Rhesus Macaque (Macaca mulatta) with Seizures.

An adult rhesus macaque developed seizures after the induction of ischemic stroke. Initially, on the day of surgery, a focal ischemic lesion was present exclusively in the right caudate nucleus. By 48 h after stroke induction, the lesion had extended into the putamen, when a seizure was observed. Our report highlights the temporal changes in infarction of unilateral basal ganglia after acute stroke and the accompanying clinical symptoms. This unusual case may provide additional information regarding the involvement of the basal ganglia in seizures, given that prior case reports and studies usually have not described the temporal and spatial evolution of the lesion before clinical symptoms emerge.

Comparison of the vaginal environment in rhesus and cynomolgus macaques pre- and post-lactobacillus colonization.

BACKGROUND: Rhesus and cynomologus macaques are valuable animal models for the study of human immunodeficiency virus (HIV) prevention strategies. However, for such studies focused on the vaginal route of infection, differences in vaginal environment may have deterministic impact on the outcome of such prevention, providing the rationale for this study. METHODS: We tested the vaginal environment of rhesus and cynomolgus macaques longitudinally to characterize the normal microflora based on Nugent scores and pH. This evaluation was extended after colonization of the vaginal space with Lactobacilli in an effort to recreate NHP models representing the healthy human vaginal environment. RESULTS AND CONCLUSION: Nugent scores and pH differed significantly between species, although data from both species were suggestive of stable bacterial vaginosis. Colonization with Lactobacilli was successful in both species leading to lower Nugent score and pH, although rhesus macaques appeared better able to sustain Lactobacillus spp over time.

An evaluation of central penetration from a peripherally administered oxytocin receptor selective antagonist in nonhuman primates.

The physiology of the oxytocin receptor has increasingly become a focus of scientific investigation due to its connection with social behavior and psychiatric disorders with impairments in social funciton. Experimental utilization of small molecule and peptide antagonists for the oxytocin receptor has played a role in deciphering these biological and social behavior connections in rodents. Described herein is the evaluation of a potent and selective oxytocin receptor antagonist, ALS-I-41, and details to consider for its use in nonhuman primate behavioral pharmacology experiments utilizing intranasal or intramuscular administration. The central nervous system penetration and rate of metabolism of ALS-I-41 was investigated via mass spectroscopy analysis of cerebrospinal fluid and plasma in the rhesus macaque after intranasal and intramuscular administration. Positron emission tomography was also utilized with [18F] ALS-I-41 in a macaque to verify observed central nervous system (CNS) penetration and to further evaluate the effects of administration rate on CNS penetration of Sprague-Dawley rats in comparison to previous studies.

Germline transmission in transgenic Huntington's disease monkeys.

Transgenic nonhuman primate models are an increasingly popular model for neurologic and neurodegenerative disease because their brain functions and neural anatomies closely resemble those of humans. Transgenic Huntington's disease monkeys (HD monkeys) developed clinical features similar to those seen in HD patients, making the monkeys suitable for a preclinical study of HD. However, until HD monkey colonies can be readily expanded, their use in preclinical studies will be limited. In the present study, we confirmed germline transmission of the mutant huntingtin (mHTT) transgene in both embryonic stem cells generated from three male HD monkey founders (F0) and in second-generation offspring (F1) produced via artificial insemination by using intrauterine insemination technique. A total of five offspring were produced from 15 females that were inseminated by intrauterine insemination using semen collected from the three HD founders (5 of 15, 33%). Thus far, sperm collected from the HD founder (rHD8) has led to two F1 transgenic HD monkeys with germline transmission rate at 100% (2 of 2). mHTT expression was confirmed by quantitative real-time polymerase chain reaction using skin fibroblasts from the F1 HD monkeys and induced pluripotent stem cells established from one of the F1 HD monkeys (rHD8-2). Here, we report the stable germline transmission and expression of the mHTT transgene in HD monkeys, which suggest possible expansion of HD monkey colonies for preclinical and biomedical research studies.

Whole-body immunoPET reveals active SIV dynamics in viremic and antiretroviral therapy-treated macaques.

The detection of viral dynamics and localization in the context of controlled HIV infection remains a challenge and is limited to blood and biopsies. We developed a method to capture total-body simian immunodeficiency virus (SIV) replication using immunoPET (antibody-targeted positron emission tomography). The administration of a poly(ethylene glycol)-modified, (64)Cu-labeled SIV Gp120-specific antibody led to readily detectable signals in the gastrointestinal and respiratory tract, lymphoid tissues and reproductive organs of viremic monkeys. Viral signals were reduced in aviremic antiretroviral-treated monkeys but detectable in colon, select lymph nodes, small bowel, nasal turbinates, the genital tract and lung. In elite controllers, virus was detected primarily in foci in the small bowel, select lymphoid areas and the male reproductive tract, as confirmed by quantitative reverse-transcription PCR (qRT-PCR) and immunohistochemistry. This real-time, in vivo viral imaging method has broad applications to the study of immunodeficiency virus pathogenesis, drug and vaccine development, and the potential for clinical translation.

Extensive vascular mineralization in the brain of a chimpanzee (Pan troglodytes).

Spontaneous vascular mineralization (deposition of iron or calcium salts) has been observed in marble brain syndrome, mineralizing microangiopathy, hypothyroidism, Fahr syndrome, Sturge-Weber syndrome, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, and calciphylaxis in humans and as an aging or idiopathic lesion in the brains of horses, cats, nonhuman primates, mice, rats, cattle, white-tailed deer, and dogs. Here we present a 27-y-old, adult male chimpanzee (Pan troglodytes) with spontaneous, extensive vascular mineralization localized solely to the brain. The chimpanzee exhibited tremors and weakness of the limbs, which progressed to paralysis before euthanasia. Magnetic resonance brain imaging in 2002 and 2010 (immediately before euthanasia) revealed multiple hypointense foci, suggestive of iron- and calcium-rich deposits. At necropsy, the brain parenchyma had occasional petechial hemorrhage, and microscopically, the cerebral, cerebellar and brain stem, gray and white matter had moderate to severe mural aggregates of a granular, basophilic material (mineral) in the blood vessels. In addition, these regions often had moderate to severe medial to transmural deposition of mature collagen in the blood vessels. We ruled out common causes of brain mineralization in humans and animals, but an etiology for the mineralization could not be determined. To our knowledge, mineralization in brain has been reported only once to occur in a chimpanzee, but its chronicity in our case makes it particularly interesting.

Aerosolized oxytocin increases cerebrospinal fluid oxytocin in rhesus macaques.

Intranasal (IN) administration is a widely used method for examining the effect of oxytocin (OT) on social behavior and cognition in healthy subjects and psychiatric populations. IN-OT in humans enhances trust, emotional perception, and empathetic behavior and is under investigation as a potential pharmacotherapy to enhance social functioning in a variety of neuropsychiatric disorders, including autism spectrum disorders (ASD). Nonhuman primates (NHP) are an important model for understanding the effect of OT on social cognition, its neural mechanisms, and the development of IN-OT as a pharmacotherapy for treating social deficits in humans. However, NHP and even some human populations, such as very young infants and children, cannot easily follow the detailed self-administration protocol used in the majority of human IN-OT studies. Therefore, we evaluated the efficacy of several OT-administration routes for elevating central OT concentrations in rhesus macaques. First, we examined the effect of IN and intravenous (IV) routes of OT administration on concentrations of OT and vasopressin (AVP) in plasma and lumbar CSF. Second, we examined these same measures in monkeys after an aerosolized (AE) OT delivery route. All three administration routes significantly increased plasma OT concentrations, but only the AE-OT route significantly increased concentrations of CSF OT. No route affected concentrations of AVP in plasma or CSF. This study confirms that the AE route is the most effective method for increasing central OT concentrations in monkeys, and may also be an effective route, alternative to IN, for administering OT to some human populations.

Osteochondromatosis in a Rhesus macaque (Macaca mulatta).

A 5-y-old, male, rhesus macaque (Macaca mulatta) presented with a prominent mass slightly anteriomedial to the right stifle. On exam, multiple radiopaque masses were identified protruding from the mid- and distal femur. Lateral and anteroposterior radiographs of the right stifle region revealed multiple exophytic masses arising from the femur, with mild bony reaction of the proximal tibia. Histologic examination of biopsy tissue revealed woven and lamellar bone with granulation tissue and skeletal muscle. Because the macaque was exhibiting no lameness or signs of pain, we decided to monitor the progression of the masses. Minimal change was noted during the time prior to study termination at 6.5 y of age. Necropsy revealed that the bony masses were cartilage-capped lesions arising near the growth plate of the distal femur and midshaft of the femur and tibia. Histologic examination revealed chondro-osseous exophytic growths that blended imperceptibly with the cortex and spongiosa of the femur, consistent with a final diagnosis of multiple osteochondromas.