Reference values of hematological and biochemical parameters in young-adult cynomolgus monkey (Macaca fascicularis) and rhesus monkey (Macaca mulatta) anesthetized with ketamine hydrochloride

Fatal coinfection of blastocystosis and intestinal trichomoniasis in a rhesus macaque (Macaca mulatta)

A 3-year-old male rhesus macaque was presented at Referral Veterinary Polyclinic-Teaching Veterinary Clinical Complex, with a chief complaint of chronic diarrhoea and swelling of dependent body parts. The patient's history indicates that the monkey had been experiencing diarrhoea for the past month, with 2-3 episodes of vomiting in the last 2 days. Additionally, oedema has developed within the last 2 weeks. The clinical examination findings revealed dullness and depression, the mucus membrane appeared pale, with a temperature-102.1 °F, a respiration rate-28/min, and a heart rate-92/min. The capillary refill time was 4 s. During the physical examination, the animal exhibited oedema on the dependent part of the body and faecal staining around the perineum along with loose yellow stool. Direct saline and iodine mount faecal smear examination revealed the presence of many motile pear-shaped flagellated protozoa and round vacuolated Blastocystis organisms. Giemsa-stained faecal smear cytology confirmed the presence of Pentatrichomonas sp. and Blastocystis sp. along with many microbes. The faecal culture was negative for all pathogenic microbes. The case was diagnosed as co-infection Blastocystosis and intestinal trichomoniasis. The treatment was initiated with a combination of sulfamethoxazole + trimethoprim @ 35 mg/kg body weight and metronidazole @25 mg/kg administered orally once daily for 7 days. Supportive therapy includes hematinic injection (iron sorbitol, folic acid and vitamin B12) @ 1 ml total dose, administered intramuscularly on alternate days for four occasions as well as intravenous infusion of crystalline amino acid @ 5 ml total dose on alternate days for four occasions. To manage vomition, injection ondansetron was administered@0.5 mg/kg intramuscularly, twice daily for 3 days and H2 blockers, including injection ranitidine@2 mg/kg intramuscularly twice daily for 3 days. Electrolyte and probiotic supplementation were administered orally. After 7 days of therapy, the oedema had significantly improved and episodes of vomition were stopped but there was no significant improvement in the episode of diarrhoea and consistency of faeces. Unfortunately, on the 10th day of therapy, the animal suddenly collapsed. Understanding the virulence pattern of opportunistic protozoa in primates is crucial, and identifying suitable therapeutic candidates to prevent fatal outcomes is the need of the hour, especially considering protozoal infections as an important differential diagnosis in gastrointestinal tract-related ailments. Our study successfully demonstrated the co-occurrence of blastocystosis and intestinal trichomoniasis, both uncommon infections with potential zoonotic implications.

Potential Food Inclination of Crab-Eating Macaques in Laboratory Environments: Enhancing Positive Reinforcement Training and Health Optimization

Positive reinforcement and training for health optimization are pivotal for successful studies with monkeys. Potential food inclination is important for studies on crab-eating macaques in laboratory environments, but evaluations remain scarce. We explored crab-eating macaques' potential food inclination to establish a reward system for future behavioral assessments. Twelve male and three female monkeys underwent a food inclination assessment in which they were offered four food categories-fruits, vegetables, proteins, and nuts. The monkeys exhibited a higher inclination for plant-based foods, particularly fruits and vegetables, over animal-based proteins like chicken and tuna (p < 0.0001), with a notable inclination for nuts (eaten/provided = 100%). Additionally, the consistency of potential food inclination after repeated offerings was investigated, revealing a time-dependent increase in inclination for protein items. Food consumption ratios correlated positively with caloric intake (r = 0.59, p = 0.02), implying that individuals with a regular high caloric intake and increased body weight are more likely to accept food during positive reinforcement training. Our findings suggest fruits, vegetables, protein-rich foods, and nuts can help with health optimization. However, animal-based protein-rich foods initially had a low preference, which may increase over time. Our study can provide guidelines for positive reinforcement training and health optimization.

Evaluating the Safety and Efficacy of Capromorelin in Rhesus Macaques (Macaca mulatta)

Nonhuman primates used in biomedical research may experience clinically significant weight loss for a variety of reasons. Episodes of anorexia (complete loss of appetite) or hyporexia (decreased appetite) can result in significant weight loss, potentially altering animal welfare and scientific studies. The FDA has approved several appetite stimulants for use in domestic species, but currently none are approved for use in NHP. Treatment of inappetence and weight loss in NHP often relies on the extralabel use of these compounds. Capromorelin is a ghrelin receptor agonist. As a growth hormone secretagogue, capromorelin increases appetite, leading to weight gain. Studies in several species have shown a positive correlation between capromorelin administration and weight gain; in 2017, an oral solution of capromorelin received FDA approval for use in dogs. We tested this solution in healthy adult rhesus macaques (n = 3 males and 3 females) for its effects on body weight and insulin like growth factor-1 (IGF-1). A control group (n = 2 males and 2 females) was used for comparison. Treated macaques received a 3 mg/kg oral dose daily for 7 d. Clinical signs were observed daily. Weights were collected before, during and at the end of treatment. Blood was drawn before, during and after treatment for measurement of IGF-1 levels and standard hematology and biochemistry parameters. Baseline-adjusted mean body weights and IGF-1 levels were significantly higher in treated as compared with control monkeys after 7 d of beginning treatment (body weight of 10.5 ± 0.1 kg (mean ± SEM) and 10.1 ± 0.1 kg, respectively; IGF-1 of 758 ± 43 ng/mL and 639 ± 22 ng/mL, respectively). Capromorelin administration was not associated with appreciable changes in hematologic and biochemical values in treated macaques. These findings suggest that capromorelin may be useful for treating inappetence and weight loss in NHP, and based on blood analysis, a 7-d course of treatment does not appear to cause acute toxicity.

Clostridium ventriculi in a cynomolgus monkey with acute gastric dilatation and rupture: A case report

Acute gastric dilatation (AGD) is one of the most prevalent and life-threatening diseases in nonhuman primates worldwide. However, the etiology of this syndrome has not been determined. Recently, sudden death occurred in a 7-year-old female cynomolgus monkey with a history of fecal microbiota transplantation using diarrheic stools. The monkey had undergone surgery previously. On necropsy, gastric dilatation and rupture demonstrated a tetrad arrangement on histopathologic examination. On 16S rRNA sequencing, a high population of Clostridium ventriculi was identified in the duodenum adjacent to stomach but not in the colon. This paper is the first report of Clostridium ventriculi infection in a cynomolgus macaque with acute gastric dilatation and rupture.

Effect of age and sex on hematological and biochemical parameters in Chinese rhesus monkeys (Macaca mulatta) anesthetized with ketamine

OBJECTIVE

Rhesus monkeys are increasingly used in biomedical research, which makes their hematological and biochemical parameters increasingly important in preclinical research. Since age and sex can influence blood parameters, establishing reference intervals for such parameters based on age and sex becomes along with identifying the effect of age and sex on those parameters.

METHODS

A total of 1385 healthy Chinese rhesus monkeys (548 males and 837 females) anesthetized with ketamine were selected and segregated by age (six groups) and sex. A total of 21 hematological and 26 biochemical parameters were measured, and the effects of age and sex were analyzed.

RESULTS

We established baseline indices for hematological and biochemical parameters based on age and sex, separately, and observed significant impacts of age, sex, and age-sex interactions on blood parameters. Among different age groups, significant differences were found in WBC, NEUT%, LYM%, EO%, LYM#, EO#, MCV, RDW-CV, PLT, MPV, PDW, PCT, TP, Alb, GLB, A/G, ALT, AST, ALP, TBIL, GGT, BUN, Cre, GLU, CK, TRIG, LDL, HCY, IL-6 FOL, Vit B12, VIT D-T, PTH, and AMH. Additionally, significant differences were observed in RBC, HGB, HCT, MPV, Alb, BUN, Cre, GLU, CHOL, TRIG, HDL, LDL, HCY, and VIT D-T between the two sexes. An age-sex interaction exerted a significant effect on WBC, NEUT#, MCV, MCHC, PDW, GLB, ALP, Cre, CHOL, TRIG, HDL, LDL, HCY, IL-6, Vit B12, VIT D-T. However, neither age, sex, and age-sex interactions exerted significant effects on MO%, MOMO#, MCH, RDW-SD, CRP, and CT.

CONCLUSION

Our study investigated the blood parameters of rhesus monkeys to provide a reference basis for rhesus monkey-related scientific experimental research.

Depletion of Bone Marrow Hematopoietic Cells in Ebolavirus-Infected Rhesus Macaques: A Possible Cause of Hematologic Abnormalities in Ebolavirus Disease

The pathophysiology of long-recognized hematologic abnormalities in Ebolavirus (EBOV) disease (EVD) is unknown. From limited human sampling (of peripheral blood), it has been postulated that emergency hematopoiesis plays a role in severe EVD, but the systematic characterization of the bone marrow (BM) has not occurred in human disease or in nonhuman primate models. In a lethal rhesus macaque model of EVD, 18 sternal BM samples exposed to the Kikwit strain of EBOV were compared to those from uninfected controls (n = 3). Immunohistochemistry, RNAscope in situ hybridization, transmission electron microscopy, and confocal microscopy showed that EBOV infects BM monocytes/macrophages and megakaryocytes. EBOV exposure was associated with severe BM hypocellularity, including depletion of myeloid, erythroid, and megakaryocyte hematopoietic cells. These depletions were negatively correlated with cell proliferation (Ki67 expression) and were not associated with BM apoptosis during disease progression. In EBOV-infected rhesus macaques with terminal disease, BM showed marked hemophagocytosis, megakaryocyte emperipolesis, and the release of immature hematopoietic cells into the sinusoids. Collectively, these data demonstrate not only direct EBOV infection of BM monocytes/macrophages and megakaryocytes but also that disease progression is associated with hematopoietic failure, notably in peripheral cytopenia. These findings inform current pathophysiologic unknowns and suggest a crucial role for BM dysfunction and/or failure, including emergency hematopoiesis, as part of the natural history of severe human disease.

Mayaro virus pathogenesis and immunity in rhesus macaques

Mayaro virus (MAYV) is a mosquito-transmitted alphavirus that causes debilitating and persistent arthritogenic disease. While MAYV was previously reported to infect non-human primates (NHP), characterization of MAYV pathogenesis is currently lacking. Therefore, in this study we characterized MAYV infection and immunity in rhesus macaques. To inform the selection of a viral strain for NHP experiments, we evaluated five MAYV strains in C57BL/6 mice and showed that MAYV strain BeAr505411 induced robust tissue dissemination and disease. Three male rhesus macaques were subcutaneously challenged with 105 plaque-forming units of this strain into the arms. Peak plasma viremia occurred at 2 days post-infection (dpi). NHPs were taken to necropsy at 10 dpi to assess viral dissemination, which included the muscles and joints, lymphoid tissues, major organs, male reproductive tissues, as well as peripheral and central nervous system tissues. Histological examination demonstrated that MAYV infection was associated with appendicular joint and muscle inflammation as well as presence of perivascular inflammation in a wide variety of tissues. One animal developed a maculopapular rash and two NHP had viral RNA detected in upper torso skin samples, which was associated with the presence of perivascular and perifollicular lymphocytic aggregation. Analysis of longitudinal peripheral blood samples indicated a robust innate and adaptive immune activation, including the presence of anti-MAYV neutralizing antibodies with activity against related Una virus and chikungunya virus. Inflammatory cytokines and monocyte activation also peaked coincident with viremia, which was well supported by our transcriptomic analysis highlighting enrichment of interferon signaling and other antiviral processes at 2 days post MAYV infection. The rhesus macaque model of MAYV infection recapitulates many of the aspects of human infection and is poised to facilitate the evaluation of novel therapies and vaccines targeting this re-emerging virus.

Identification of microRNAs Derived from Transposable Elements in the Macaca mulatta (Rhesus Monkey) Genome

Transposable elements (TEs) are mobile DNA entities that can move within the host genome. Over long periods of evolutionary time, TEs are typically silenced via the accumulation of mutations in the genome, ultimately resulting in their immobilization. However, they still play an important role in the host genome by acting as regulatory elements. They influence host transcription in various ways, one of which as the origin of the generation of microRNAs (miRNAs), which are so-called miRNAs derived from TEs (MDTEs). miRNAs are small non-coding RNAs that are involved in many biological processes by regulating gene expression at the post-transcriptional level. Here, we identified MDTEs in the Macaca mulatta (rhesus monkey) genome, which is phylogenetically close species to humans, based on the genome coordinates of miRNAs and TEs. The expression of 5 out of 17 MDTEs that were exclusively registered in M. mulatta from the miRBase database (v22) was examined via quantitative polymerase chain reaction (qPCR). Moreover, Gene Ontology analysis was performed to examine the functional implications of the putative target genes of the five MDTEs.

Two weeks dose range-finding and four weeks repeated dose oral toxicity study of a novel reversible monoamine oxidase B inhibitor KDS2010 in cynomolgus monkeys

A novel reversible monoamine oxidase B inhibitor, KDS2010, has been developed as a therapeutic candidate for neurodegenerative diseases. This study investigated its potential toxicity in non-human primates before human clinical trials. Daily KDS2010 doses (25, 50, or 100 mg/kg) were orally administered to cynomolgus monkeys (1 animal/sex/group, 4 males and 4 females) for 2 weeks to determine the dose range. One male was moribund, and one female was found dead in the 100 mg/kg/day group. One male was also found dead in the 50 mg/kg/day group. The death was considered an adverse effect in both sexes since distal tubules/collecting duct dilation and hypertrophy in the epithelium of the papillary duct were observed in their kidneys. Based on dose range finding results, KDS2010 (10, 20, or 40 mg/kg/day) was administered orally for 4 weeks, and animals were given 2 weeks for recovery. No significant changes were observed during daily clinical observations and macro-and microscopic examinations, including body weight, food consumption, hematology, clinical chemistry, and organ weight. And, the kidney was seen as the primary target organ of KDS2010 in the 2 weeks study, but no adverse effect was observed in the 4 weeks study. Therefore, 40 mg/kg/day is considered the no-observed-adverse-effect level in both sexes of cynomolgus monkeys.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43188-023-00182-4.

Reference Intervals and Percentiles for Hematologic and Serum Biochemical Values in Captive Bred Rhesus (Macaca mulatta) and Cynomolgus Macaques (Macaca fascicularis)

Several physiological characteristics and housing conditions are known to affect hematologic and serum biochemical values in macaques. However, the studies that have been conducted either report values calculated based on a small number of animals, were designed specifically to document the effect of a particular condition on the normal range of hematologic and serum biochemical values, or used parametric assumptions to calculate hematologic and serum biochemical reference intervals. We conducted a retrospective longitudinal cohort study to estimate reference intervals for hematologic and serum biochemical values in clinically healthy macaques based on observed percentiles without parametric assumptions. Data were obtained as part of the Biomedical Primate Research Centre (Rijswijk, The Netherlands) health monitoring program between 2018 and 2021. In total, 4009 blood samples from 1475 macaques were analyzed with a maximum of one repeat per year per animal. Data were established by species, gender, age, weight-for-height indices, pregnancy, sedation protocol, and housing conditions. Most of the parameters profoundly affected just some hematologic and serum biochemical values. A significant glucose difference was observed between the ketamine and ketamine-medetomidine sedation protocols. The results emphasize the importance of establishing uniform experimental groups with validated animal husbandry and housing conditions to improve the reproducibility of the experiments.

Suppression of flavivirus transmission from animal hosts to mosquitoes with a mosquito-delivered vaccine

Zoonotic viruses circulate in the natural reservoir and sporadically spill over into human populations, resulting in endemics or pandemics. We previously found that the Chaoyang virus (CYV), an insect-specific flavivirus (ISF), is replication-defective in vertebrate cells. Here, we develope a proof-of-concept mosquito-delivered vaccine to control the Zika virus (ZIKV) within inaccessible wildlife hosts using CYV as the vector. The vaccine is constructed by replacing the pre-membrane and envelope (prME) proteins of CYV with those of ZIKV, assigned as CYV-ZIKV. CYV-ZIKV replicates efficiently in Aedes mosquitoes and disseminates to the saliva, with no venereal or transovarial transmission observed. To reduce the risk of CYV-ZIKV leaking into the environment, mosquitoes are X-ray irradiated to ensure 100% infertility, which does not affect the titer of CYV-ZIKV in the saliva. Immunization of mice via CYV-ZIKV-carrying mosquito bites elicites robust and persistent ZIKV-specific immune responses and confers complete protection against ZIKV challenge. Correspondingly, the immunized mice could no longer transmit the challenged ZIKV to naïve mosquitoes. Therefore, immunization with an ISF-vectored vaccine via mosquito bites is feasible to induce herd immunity in wildlife hosts of ZIKV. Our study provides a future avenue for developing a mosquito-delivered vaccine to eliminate zoonotic viruses in the sylvatic cycle.

A single-shot ChAd3-MARV vaccine confers rapid and durable protection against Marburg virus in nonhuman primates

Marburg virus (MARV) causes a severe hemorrhagic fever disease in primates with mortality rates in humans of up to 90%. MARV has been identified as a category A bioterrorism agent by the Centers for Disease Control and Prevention (CDC) and priority pathogen A by the National Institute of Allergy and Infectious Diseases (NIAID), needing urgent research and development of countermeasures because of the high public health risk it poses. The recent cases of MARV in West Africa underscore the substantial outbreak potential of this virus. The potential for cross-border spread, as had occurred during the 2014-2016 Ebola virus outbreak, illustrates the critical need for MARV vaccines. To support regulatory approval of the chimpanzee adenovirus 3 (ChAd3)-MARV vaccine that has completed phase 1 trials, we showed that the nonreplicating ChAd3 vector, which has a demonstrated safety profile in humans, protected against a uniformly lethal challenge with MARV/Ang. Protective immunity was achieved within 7 days of vaccination and was maintained through 1 year after vaccination. Antigen-specific antibodies were an immune correlate of protection in the acute challenge model, and their concentration was predictive of protection. These results demonstrate that a single-shot ChAd3-MARV vaccine generated a protective immune response that was both rapid and durable with an immune correlate of protection that will support advanced clinical development.

Monoclonal Antibody Pharmacokinetics in Cynomolgus Monkeys Following Subcutaneous Administration: Physiologically Based Model Predictions from Physiochemical Properties

An integrated physiologically based modeling framework is presented for predicting pharmacokinetics and bioavailability of subcutaneously administered monoclonal antibodies in cynomolgus monkeys, based on in silico structure-derived metrics characterizing antibody size, overall charge, local charge, and hydrophobicity. The model accounts for antibody-specific differences in pinocytosis, transcapillary transport, local lymphatic uptake, and pre-systemic degradation at the subcutaneous injection site and reliably predicts the pharmacokinetics of five different wild-type mAbs and their Fc variants following intravenous and subcutaneous administration. Significant associations were found between subcutaneous injection site degradation rate and the antibody's local positive charge of its complementarity-determining region (R = 0.56, p = 0.0012), antibody pinocytosis rate and its overall positive charge (R = 0.59, p = 0.00063), and antibody paracellular transport and its overall charge together with hydrophobicity (R = 0.63, p = 0.00096). Based on these results, population simulations were performed to predict the relationship between bioavailability and antibody local positive charge. In addition, model simulations were conducted to calculate the relative contribution of absorption pathways (lymphatic and blood), pre-systemic degradation pathways (interstitial and lysosomal), and the influence of injection site lymph flow on antibody bioavailability and pharmacokinetics. The proposed physiologically based modeling framework integrates fundamental mechanisms governing antibody subcutaneous absorption and disposition, with structured-based physiochemical properties, to predict antibody bioavailability and pharmacokinetics in vivo.

Hematological and biochemical reference intervals of wild-caught and inhouse adult Indian rhesus macaques (Macaca mulatta)

Background

Nonhuman primates are used for research purposes such as studying diseases and drug discovery and development programs. Various clinical pathology parameters are used as biomarkers of disease conditions in biomedical research. Detailed reports of these parameters are not available for Indian-origin rhesus macaques. To meet the increasing need for information, we conducted this study on 121 adult Indian rhesus macaques (57 wild-sourced and 64 inhouse animals, aged 3–7 years). A total of 18 hematology and 18 biochemistry parameters were evaluated and reported in this study. Data from these parameters were statistically evaluated for significance amongst inhouse and wild-born animals and for differences amongst sexes. The reference range was calculated according to C28-A3 guidelines for reporting reference intervals of clinical laboratory parameters.

Results

Source of the animals and sex appeared to have statistically significant effects on reference values and range. Wild-born animals reported higher WBC, platelets, neutrophils, RBC, hemoglobin, HCT, MCV, and total protein values in comparison to inhouse monkeys. Sex-based differences were observed for parameters such as RBCs, hemoglobin, HCT, creatinine, calcium, phosphorus, albumin, and total protein amongst others.

Conclusions

Through this study, we have established a comprehensive data set of reference values and intervals for certain hematological and biochemical parameters which will help researchers in planning, conducting, and interpreting various aspects of biomedical research employing Indian-origin rhesus monkeys.

Characterization of the immune system of Ellegaard Göttingen Minipigs - An important large animal model in experimental medicine

Interest in Ellegaard Göttingen Minipigs (EGMs) as a model in experimental medicine is continuously growing. The aim of this project is to increase the knowledge of the immune system of EGMs as information is still scarce. Therefore, we studied the postnatal maturation of their immune system from birth until 126 weeks of age. For the first 26 weeks of the study, animals were kept under pathogen-reduced conditions (SPF) and afterwards under conventional housing conditions. The development of the immune system was analyzed by monitoring changes in total numbers of leukocytes and lymphocytes of ten individuals and the composition of leukocyte populations by multi-color flow cytometry (FCM). We followed the presence of monocytes using monoclonal antibodies (mAbs) against CD172a+ and CD163+ and B cells based on the expression of CD79a. NK cells were distinguished as CD3-CD16+CD8α+/dim cells and further subdivided using NKp46 (CD335) expression into NKp46-, NKp46+, and NKp46high NK cells. T-cell receptor (TCR) γδ T cells were defined by the expression of TCR-γδ and different subsets were determined by their CD2 and perforin expression. TCR-αβ T cells were classified by their CD8β+ or CD4 expression. For monitoring their differentiation, expression of CD27 and perforin was investigated for CD8β++ T cells and CD8α together with CD27 for CD4+ T cells. We clearly detected a postnatal development of immune cell composition and identified phenotypes indicative of differentiation within the respective leukocyte subsets. Examination of the development of the antigen-specific immune system after transfer to different distinct housing conditions and after vaccination against common porcine pathogens such as porcine circovirus 2 (PCV2) revealed a markedly increased presence of more differentiated CD8+ and CD4+ T cells with central and effector memory T-cell phenotypes. To complement the findings, a PCV2 vaccine-specific antigen was used for in vitro restimulation experiments. We demonstrated antigen-specific proliferation of CD4+CD8α+CD27+ central and CD4+CD8α+CD27- effector memory T cells as well as antigen-specific production of TNF-α and IFN-γ. This study of postnatal immune development defines basic cellular immune parameters of EGMs and represents an important milestone for the use of EGMs for immunological questions in experimental medicine.

FSH-blocking therapeutic for osteoporosis

Pharmacological and genetic studies over the past decade have established the follicle-stimulating hormone (FSH) as an actionable target for diseases affecting millions, namely osteoporosis, obesity, and Alzheimer's disease. Blocking FSH action prevents bone loss, fat gain, and neurodegeneration in mice. We recently developed a first-in-class, humanized, epitope-specific FSH-blocking antibody, MS-Hu6, with a KD of 7.52 nM. Using a Good Laboratory Practice (GLP)-compliant platform, we now report the efficacy of MS-Hu6 in preventing and treating osteoporosis in mice and parameters of acute safety in monkeys. Biodistribution studies using 89Zr-labeled, biotinylated or unconjugated MS-Hu6 in mice and monkeys showed localization to bone and bone marrow. The MS-Hu6 displayed a β phase t½ of 7.5 days (180 hr) in humanized Tg32 mice. We tested 217 variations of excipients using the protein thermal shift assay to generate a final formulation that rendered MS-Hu6 stable in solution upon freeze-thaw and at different temperatures, with minimal aggregation, and without self-, cross-, or hydrophobic interactions or appreciable binding to relevant human antigens. The MS-Hu6 showed the same level of "humanness" as human IgG1 in silico and was non-immunogenic in ELISpot assays for IL-2 and IFN-γ in human peripheral blood mononuclear cell cultures. We conclude that MS-Hu6 is efficacious, durable, and manufacturable, and is therefore poised for future human testing.

Chimeric Antigen by the Fusion of SARS-CoV-2 Receptor Binding Domain with the Extracellular Domain of Human CD154: A Promising Improved Vaccine Candidate

COVID-19 is a respiratory viral disease caused by a new coronavirus called SARS-CoV-2. This disease has spread rapidly worldwide with a high rate of morbidity and mortality. The receptor-binding domain (RBD) of protein spike (S) mediates the attachment of the virus to the host's cellular receptor. The RBD domain constitutes a very attractive target for subunit vaccine development due to its ability to induce a neutralizing antibody response against the virus. With the aim of boosting the immunogenicity of RBD, it was fused to the extracellular domain of CD154, an immune system modulator molecule. To obtain the chimeric protein, stable transduction of HEK-293 was carried out with recombinant lentivirus and polyclonal populations and cell clones were obtained. RBD-CD was purified from culture supernatant and further characterized by several techniques. RBD-CD immunogenicity evaluated in mice and non-human primates (NHP) indicated that recombinant protein was able to induce a specific and high IgG response after two doses. NHP sera also neutralize SARS-CoV-2 infection of Vero E6 cells. RBD-CD could improve the current vaccines against COVID-19, based in the enhancement of the host humoral and cellular response. Further experiments are necessary to confirm the utility of RBD-CD as a prophylactic vaccine and/or booster purpose.

A Case Study to Dissect Immunity to SARS-CoV-2 in a Neonate Nonhuman Primate Model

Most children are less severely affected by coronavirus-induced disease 2019 (COVID-19) than adults, and thus more difficult to study progressively. Here, we provide a neonatal nonhuman primate (NHP) deep analysis of early immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in blood and mucosal tissues. In addition, we provide a comparison with SARS-CoV-2-infected adult NHP. Infection of the neonate resulted in a mild disease compared with adult NHPs that develop, in most cases, moderate lung lesions. In concomitance with the viral RNA load increase, we observed the development of an early innate response in the blood, as demonstrated by RNA sequencing, flow cytometry, and cytokine longitudinal data analyses. This response included the presence of an antiviral type-I IFN gene signature, a persistent and lasting NKT cell population, a balanced peripheral and mucosal IFN-γ/IL-10 cytokine response, and an increase in B cells that was accompanied with anti-SARS-CoV-2 antibody response. Viral kinetics and immune responses coincided with changes in the microbiota profile composition in the pharyngeal and rectal mucosae. In the mother, viral RNA loads were close to the quantification limit, despite the very close contact with SARS-CoV-2-exposed neonate. This pilot study demonstrates that neonatal NHPs are a relevant model for pediatric SARS-CoV-2 infection, permitting insights into the early steps of anti-SARS-CoV-2 immune responses in infants.

Age- and sex-related changes in body weights and clinical pathology analytes in cynomolgus monkeys (Macaca Fascicularis) of Mauritius origin

Background

Clinical pathology and body weight information for the cynomolgus monkey in the literature is primarily derived from a small number of animals with limited age ranges, varying geographic origins, and mixed genders.

Objectives

This study aimed to summarize the age‐ and sex‐related changes in clinical pathology analytes and body weights in cynomolgus monkeys of Mauritian origin.

Methods

Pre‐study age and body weight data were reviewed in 1819 animals, and pre‐study hematologic, coagulation, and serum biochemical analytes were reviewed in 1664 animals.

Results

Body weights were statistically higher (P < 0.01) in males than females in all age groups (2–10 years). These measurements became prominent after 4 years of age and peaked at 7 to 8 years of age in both sexes. Sex‐related differences were noted in reticulocyte (RETIC) counts, creatinine, cholesterol, and triglyceride concentrations, and alkaline phosphatase (ALP) and gamma‐glutamyl transferase (GGT) activities. Age‐related differences were noted in RETIC and lymphocyte counts, creatinine, triglyceride, phosphorus, and globulin concentrations, and ALP and GGT activities. The youngest (2 to <3 year) age group had the fewest number of clinical pathologic analyte differences including ALP and GGT activity differences which occurred in all age groups from 2 to 10 years; they also had age‐related lower globulin concentrations. There were no age‐ or sex‐related differences in coagulation measurands.

Conclusions

Sexual dimorphism in body weight was apparent for all ages from 2 to 10 years of age. The only difference in clinical pathology analytes unique to the 2 to <3 years of age group were age‐related lower globulin levels.

Selected Resources for Pathology Evaluation of Nonhuman Primates in Nonclinical Safety Assessment

Humans and nonhuman primates (NHPs) share numerous anatomical and physiological characteristics, thereby explaining the importance of NHPs as essential animal models for translational medicine and nonclinical toxicity testing. Researchers, toxicologic pathologists, toxicologists, and regulatory reviewers must be familiar with normal and abnormal NHP biological traits when designing, performing, and interpreting data sets from NHP studies. The current compilation presents a list of essential books, journal articles, and websites that provide context to safety assessment and research scientists working with NHP models. The resources used most frequently by the authors have been briefly annotated to permit readers to rapidly ascertain their applicability to particular research endeavors. The references are aimed primarily for toxicologic pathologists working with cynomolgus and rhesus macaques and common marmosets in efficacy and safety assessment studies.

Seasonal Variability of Biochemical Parameters in Female Cynomolgus Macaques (Macaca fascicularis)

We study of seasonal variability of biochemical parameters of blood serum in female cynomolgus macaques (Macaca fascicularis) in the Adler nursery of the Research Institute of Medical Primatology kept under conditions of free access to the open enclosure. It was found that in the most favorable season for monkeys (from June to September) the serum levels of sodium, phosphorus, creatinine were significantly increased and cholesterol and calcium concentrations and lactate dehydrogenase activity were significantly reduced. There was no seasonal variability in the content of triglycerides, urea, potassium, activity of γ-glutamyltransferase, ALT, and AST.

Dynamic Control Balancing Cell Proliferation and Inflammation is Crucial for an Effective Immune Response to Malaria

Malaria has a complex pathology with varying manifestations and symptoms, effects on host tissues, and different degrees of severity and ultimate outcome, depending on the causative Plasmodium pathogen and host species. Previously, we compared the peripheral blood transcriptomes of two macaque species (Macaca mulatta and Macaca fascicularis) in response to acute primary infection by Plasmodium knowlesi. Although these two species are very closely related, the infection in M. mulatta is fatal, unless aggressively treated, whereas M. fascicularis develops a chronic, but tolerable infection in the blood. As a reason for this stark difference, our analysis suggests delayed pathogen detection in M. mulatta followed by extended inflammation that eventually overwhelms this monkey’s immune response. By contrast, the natural host M. fascicularis detects the pathogen earlier and controls the inflammation. Additionally, M. fascicularis limits cell proliferation pathways during the log phase of infection, presumably in an attempt to control inflammation. Subsequent cell proliferation suggests a cell-mediated adaptive immune response. Here, we focus on molecular mechanisms underlying the key differences in the host and parasite responses and their coordination. SICAvar Type 1 surface antigens are highly correlated with pattern recognition receptor signaling and important inflammatory genes for both hosts. Analysis of pathogen detection pathways reveals a similar signaling mechanism, but with important differences in the glutamate G-protein coupled receptor (GPCR) signaling pathway. Furthermore, differences in inflammasome assembly processes suggests an important role of S100 proteins in balancing inflammation and cell proliferation. Both differences point to the importance of Ca²⁺ homeostasis in inflammation. Additionally, the kynurenine-to-tryptophan ratio, a known inflammatory biomarker, emphasizes higher inflammation in M. mulatta during log phase. Transcriptomics-aided metabolic modeling provides a functional method for evaluating these changes and understanding downstream changes in NAD metabolism and aryl hydrocarbon receptor (AhR) signaling, with enhanced NAD metabolism in M. fascicularis and stronger AhR signaling in M. mulatta. AhR signaling controls important immune genes like IL6, IFNγ and IDO1. However, direct changes due to AhR signaling could not be established due to complicated regulatory feedback mechanisms associated with the AhR repressor (AhRR). A complete understanding of the exact dynamics of the immune response is difficult to achieve. Nonetheless, our comparative analysis provides clear suggestions of processes that underlie an effective immune response. Thus, our study identifies multiple points of intervention that are apparently responsible for a balanced and effective immune response and thereby paves the way toward future immune strategies for treating malaria.

Lack of Specific Regulatory T Cell Depletion and Cytoreduction Associated with Extensive Toxicity After Administration of Low and High Doses of Cyclophosphamide

Up to 93% of the human immunodeficiency virus (HIV) latent reservoir comprised defective proviruses, suggesting that a functional cure is possible through the elimination of a small population of cells containing intact virus, instead of the entire reservoir. Cyclophosphamide (Cy) is an established chemotherapeutic agent for immune cell cancers. In high doses, Cy is a nonselective cytoreductor, used in allogeneic stem-cell transplantation, while in a low dose, metronomic schedule, Cy selectively depletes regulatory T cells (Tregs). We administered low and high doses to simian immunodeficiency virus (SIV)-infected rhesus macaques (RM) to assess their effects on the SIV reservoirs. As a Treg-depleting agent, Cy unselectively depleted Treg and total lymphocytes, resulting in minimal immune activation and no viral reactivation. As a cytoreductive agent, Cy induced massive viral reactivation in elite controller RMs without ART. However, when administered with antiretroviral therapy (ART), Cy had substantial adverse effects, including mortality. Our study thus dissuades further investigation of Cy as an HIV cure agent.

Research-Relevant Clinical Pathology Resources: Emphasis on Mice, Rats, Rabbits, Dogs, Minipigs, and Non-Human Primates

Clinical pathology testing for investigative or biomedical research and for preclinical toxicity and safety assessment in laboratory animals is a distinct specialty requiring an understanding of species specific and other influential variables on results and interpretation. This review of clinical pathology principles and testing recommendations in laboratory animal species aims to provide a useful resource for researchers, veterinary specialists, toxicologists, and clinical or anatomic pathologists.

Reference value of hematologic, urologic, and organ weights of 2- to 4-year-old long-tailed macaques (Macaca fascicularis fascicularis) in the context of toxicological studies

BACKGROUND

The long-tailed macaque (Macaca fascicularis fascicularis) is an Old World species, which is one among the most commonly used monkeys for pharmaceutical research. However, most of the available background data are not suitable for good laboratory practice (GLP)-regulated drug safety tests because the current reverence value covers fewer indices than necessary. Therefore, in this study, historical data for preclinical safety test were collected and managed.

METHODS

Twenty-five hematology, 20 clinical chemistry, 19 urine analysis, and 16 organ weights were evaluated in a drug safety test of 228 male and 140 female 2- to 4-year-old long-tailed macaques at the Korea Institute of Toxicology under GLP regulations.

RESULTS

The absolute and relative count of lymphocyte, basophil, and large unstained cell were higher, whereas neutrophil was lower in male than in female monkeys. In serum biochemistry, IP, GGT, ALP, and TCHO of male were higher than female.

CONCLUSION

Historical data suitable for preclinical safety analysis were determined.

Blood Analysis of Laboratory Macaca mulatta Used for Neuroscience Research: Investigation of Long-Term and Cumulative Effects of Implants, Fluid Control, and Laboratory Procedures

The nonhuman primate (NHP) constitutes an extraordinarily important model in neuroscience research for understanding the neuronal underpinnings of perceptual, motor, cognitive, and executive functions of the primate brain, and to study the physiological causes, effects, and potential treatments of brain disorders. Because of their cognitive capabilities, NHPs receive special attention in animal welfare regulations around the world, and their well-being is a benchmark for the evaluation, monitoring, and refinement of experimental procedures. As a consequence, many typical neuroscientific procedures are considered only mildly severe by animal welfare boards. There is, however, an ongoing debate about possible long-term and cumulative effects. Because of a lack of longitudinal data, it is unclear whether mildly severe procedures may cause more significant harm on the long-term, and to what extent they may impact animal well-being and healthiness over time. We here make use of a database of blood samples drawn over a period of 15 years from 39 rhesus monkeys (Macaca mulatta) to address the issue of long-term, cumulative effects of neuroscientific procedures. A careful analysis of indicative primate blood markers for chronic inflammation, hydration status, and stress levels, their comparison to baseline values from both the same animals and the literature, and evaluation of additional hematologic, physiological, and behavioral parameters did not provide support for the notion of long-term, cumulative effects on the monkeys’ healthiness and well-being. The results may serve the community as a reference for the severity assessment of neuroscientific experiments involving NHPs.

Point-of-Care Assessment of DCD Livers During Normothermic Machine Perfusion in a Nonhuman Primate Model

Normothermic machine perfusion (NMP) provides clinicians an opportunity to assess marginal livers before transplantation. However, objective criteria and point-of-care (POC) biomarkers to predict risk and guide decision making are lacking. In this investigation, we characterized trends in POC biomarkers during NMP and compared primate donation after circulatory death (DCD) livers with short and prolonged warm ischemic injury. Following asystole, livers were subjected to either 5 minutes (DCD-5min, n = 4) or 45 minutes (DCD-45min, n = 4) of warm ischemia time. Livers were flushed with heparinized UW solution, and preserved in cold storage before NMP. During flow-controlled NMP, circulating perfusate and tissue biopsies were collected at 0, 2, 4, 6, and 8 hours for analysis. DCD-45min livers had greater terminal portal vein pressure (8.5 vs. 13.3 mm Hg, P = 0.027) and terminal portal vein resistance (16.3 vs. 32.4 Wood units, P = 0.005). During perfusion, DCD-45min livers had equivalent terminal lactate clearance (93% vs. 96%, P = 0.344), greater terminal alanine aminotransferase (163 vs. 883 U/L, P = 0.002), and greater terminal perfusate gamma glutamyltransferase (GGT) (5.0 vs. 31.7 U/L, P = 0.002). DCD-45min livers had higher circulating levels of flavin mononucleotide (FMN) at hours 2 and 4 of perfusion (136 vs. 250 ng/mL, P = 0.029; and 158 vs. 293 ng/mL, P = 0.003; respectively). DCD-5min livers produced more bile and demonstrated progressive decline in bile lactate dehydrogenase, whereas DCD-45min livers did not. On blinded histologic evaluation, DCD-45min livers demonstrated greater injury and necrosis at late stages of perfusion, indicative of nonviability. Conclusion: Objective criteria are needed to define graft viability during NMP. Perfusate lactate clearance does not discriminate between viable and nonviable livers during NMP. Perfusate GGT and FMN may represent POC biomarkers predictive of liver injury during NMP.

A recombinant spike protein subunit vaccine confers protective immunity against SARS-CoV-2 infection and transmission in hamsters

Multiple safe and effective vaccines that elicit immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are necessary to respond to the ongoing coronavirus disease 2019 (COVID-19) pandemic. Here, we developed a protein subunit vaccine composed of spike ectodomain protein (StriFK) plus a nitrogen bisphosphonate-modified zinc-aluminum hybrid adjuvant (FH002C). StriFK-FH002C generated substantially higher neutralizing antibody titers in mice, hamsters, and cynomolgus monkeys than those observed in plasma isolated from COVID-19 convalescent individuals. StriFK-FH002C also induced both TH1- and TH2-polarized helper T cell responses in mice. In hamsters, StriFK-FH002C immunization protected animals against SARS-CoV-2 challenge, as shown by the absence of virus-induced weight loss, fewer symptoms of disease, and reduced lung pathology. Vaccination of hamsters with StriFK-FH002C also reduced within-cage virus transmission to unvaccinated, cohoused hamsters. In summary, StriFK-FH002C represents an effective, protein subunit-based SARS-CoV-2 vaccine candidate.

Trained Immunity-Promoting Nanobiologic Therapy Suppresses Tumor Growth and Potentiates Checkpoint Inhibition

Trained immunity, a functional state of myeloid cells, has been proposed as a compelling immune-oncological target. Its efficient induction requires direct engagement of myeloid progenitors in the bone marrow. For this purpose, we developed a bone marrow-avid nanobiologic platform designed specifically to induce trained immunity. We established the potent anti-tumor capabilities of our lead candidate MTP₁₀-HDL in a B16F10 mouse melanoma model. These anti-tumor effects result from trained immunity-induced myelopoiesis caused by epigenetic rewiring of multipotent progenitors in the bone marrow, which overcomes the immunosuppressive tumor microenvironment. Furthermore, MTP₁₀-HDL nanotherapy potentiates checkpoint inhibition in this melanoma model refractory to anti-PD-1 and anti-CTLA-4 therapy. Finally, we determined MTP₁₀-HDL's favorable biodistribution and safety profile in non-human primates. In conclusion, we show that rationally designed nanobiologics can promote trained immunity and elicit a durable anti-tumor response either as a monotherapy or in combination with checkpoint inhibitor drugs.

A modular approach toward producing nanotherapeutics targeting the innate immune system

Immunotherapies controlling the adaptive immune system are firmly established, but regulating the innate immune system remains much less explored. The intrinsic interactions between nanoparticles and phagocytic myeloid cells make these materials especially suited for engaging the innate immune system. However, developing nanotherapeutics is an elaborate process. Here, we demonstrate a modular approach that facilitates efficiently incorporating a broad variety of drugs in a nanobiologic platform. Using a microfluidic formulation strategy, we produced apolipoprotein A1-based nanobiologics with favorable innate immune system-engaging properties as evaluated by in vivo screening. Subsequently, rapamycin and three small-molecule inhibitors were derivatized with lipophilic promoieties, ensuring their seamless incorporation and efficient retention in nanobiologics. A short regimen of intravenously administered rapamycin-loaded nanobiologics (mTORi-NBs) significantly prolonged allograft survival in a heart transplantation mouse model. Last, we studied mTORi-NB biodistribution in nonhuman primates by PET/MR imaging and evaluated its safety, paving the way for clinical translation.

Nutrient bioavailability of white lupine in complete feed for non-human primates

The article is devoted to the current world problem of vegetable protein deficiency, the solution of which can be white lupine. Particular attention is paid to assessing the bioavailability of nutrients from white lupine (Lupinus albus) in the body of non-human primates M. Mulatta. Because primates are phylogenetically closer to humans than other laboratory animals, which is very convenient for modeling and studying the digestibility of nutrients in diets. The purpose of the article is to study the digestibility of nutrients in lupine in the structure of complete feed and its effect on the biochemical parameters of the blood. As a result of the research, it was found that the inclusion of white lupine in the structure of the diet allows to improve the bioavailability of nutrients of complete feed, when included in the structure of the diet of white lupine in an amount of 10%, it made it possible to improve the digestibility of crude protein in relation to the control group by 5.5%, crude fat by 0.99%, crude fiber by 1.84%, BEV by 7.99%, crude ash by 4.67%, calcium (Ca) and phosphorus (P) by 6.99%, and 1.02 %. With the inclusion of 20% white lupine in the structure of the diet, it made it possible to improve the digestibility of crude protein in relation to the control group by 9.28%, crude fat by 6.5%, crude fiber by 5.98%, BEV by 2, 78%, crude ash by 11.28%, and absorption of calcium (Ca) and phosphorus (P) by 9.93% and 8.68%. At the same time, the results of hematological analyzes generally indicate the safety of consuming white lupine for 35 days.

Correlations of serum biochemistry profile with ultrasonic histogram of liver, gallbladder, and kidneys and morphometry of rescued long-tailed macaques (Macaca fascicularis)

BACKGROUND

Serum biochemistry and ultrasonography can be useful diagnostic tools in evaluating the general health condition of long-tailed macaques in rescue and rehabilitation centers.

METHODS

This study was conducted to determine and correlate the serum biochemistry profile of 24 apparently healthy male and female rescued long-tailed macaques (LTM) with the body weight, crown-rump length, and ultrasonic histogram of liver parenchyma, gallbladder lumen, and renal cortices.

RESULTS

There were no sex-related differences in serum biochemistry values of aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase, blood urea nitrogen, total cholesterol, and total protein. Creatinine was positively correlated with body weights and crown-rump length. Multiple weak positive and negative correlations of organ-specific serum parameters and mean ultrasonic histogram of liver, gallbladder, and kidneys were observed.

CONCLUSION

This study established the correlations of serum biochemistry profile with ultrasonic histogram of liver, gallbladder, and kidneys and morphometry of rescued LTM.