ABSTRACT
Cellular immunity plays an important role in the pathogenesis and formation of protective immune defense against the SARS-CoV-2 virus. The aim of the work was to study the cellular immunity of rhesus monkeys applying flow cytometry after experimental infection with the SARS-CoV-2 virus. Materials and methods. Male rhesus monkeys were intranasally inoculated with the SARS-CoV-2 virus, Isolate B strain and hCoV-19/Russia/SP48-1226/2020 strain (abbreviated name U-2), at a dose of 5.0 lg PFU. Using flow cytometry, the levels of 21 populations/subpopulations of mononuclear cells in the peripheral blood of animals were determined before experimental infection with the pathogen and on day 14 after infection. SARS-CoV-2 coronavirus RNA was assessed using real-time polymerase chain reaction. Determination of the titer of virus-neutralizing antibodies to the SARS-CoV-2 virus in the blood sera of animals was conducted through neutralization test evaluating the ability to suppress negative colonies. Results and discussion. Infection with Isolate B strain culture has led to an increase in the relative content of total T-lymphocytes (p<0.2), cytotoxic T-lymphocytes (p<0.1), as well as monocytes expressing the early activation marker CD25 (p<0.2). The decrease in levels has been observed for total B-lymphocytes (p<0.2) and T-helper cells (p<0.1). Infection with the U-2 strain culture revealed an increase in the relative content of monocytes expressing the early activation marker CD25 (p<0.2). Thus, for the first time in the Russian Federation, flow cytometry was used to study the cellular immunity of rhesus monkeys before and after experimental infection with the SARS-CoV-2 virus. The obtained information can be used for studying the pathogenesis of SARS-CoV-2 infection, course, and outcome of the disease, and developing strategies for vaccination and treatment. © 2022 Russian Research Anti-Plague Institute. All rights reserved.
ABSTRACT
OBJECTIVE To find out whether 2811 will cause toxic reactions in animals, and determine the safe dose of without any toxic reactions and the relationship between the dose, time of administration and results of the toxicity test. METHODS Thirty healthy rhesus monkeys were selected and randomly divided into 3 groups, 1 O in each group (half males and half females), namely, the solvent control group, 2811 100 and 400 mg* kg-1 groups, respectively. The solvent control group was iv given 0.9% sodium chloride injection, while the experimental groups were iv given 2811 100 and 400 mg* kg-1 , respectively, once every 6 days, 3 times in 2 weeks, and allowed to recover for 9 weeks after drug withdrawal. During the test, the body weight, food intakes, body temperatures, ophthalmology, blood pressure, electrocardiograms, blood routine, anticoagulation, blood biochemistry, electrolytes, urine, systemic anatomy, organ weight and coefficient were observed, while histopathology and immunology tests were performed. At the same time, the anti-drug antibody (ADA) and plasma concentrations were determined, and toxikinetic parameters were analyzed. RESULTS During the experiment, the observation of general symptoms, body mass, food intakes, body temperatures, ophthalmology, blood pressure, electrocardiograms, blood routine, anticoagulation, blood biochemistry, electrolytes, urine, organ weight and coefficient, histopathology and immunology of animals in each dose group showed no significant changes related to the tested animals. ADA was not detected in any of the groups. Plasma drug concentrations in 2B11 100 and 400 mg* kg-1 groups were basically consistent and proportional to the dose, so was the ratio of peak concentration and exposure. 2B11 injection showed linear kinetics in vivo. CONCLUSION Under the conditions set in this test, the 2-week repeated administration toxicity test of 2B11 in rhesus monkeys is safe, and no clinical adverse reactions are observed at the dose level of 400 mg*kg-1, which provides reference for the follow-up clinical study of 2B11. Copyright © 2022 Chinese Journal of Pharmacology and Toxicology. All rights reserved.
ABSTRACT
Macaques are a commonly used model for studying immunity to human viruses, including for studies of SARS-CoV-2 infection and vaccination. However, it is unknown whether macaque antibody responses resemble the response in humans. To answer this question, we employed a phage-based deep mutational scanning approach (Phage-DMS) to compare which linear epitopes are targeted on the SARS-CoV-2 Spike protein in convalescent humans, convalescent (re-infected) rhesus macaques, mRNA-vaccinated humans, and repRNA-vaccinated pigtail macaques. We also used Phage-DMS to determine antibody escape pathways within each epitope, enabling a granular comparison of antibody binding specificities at the locus level. Overall, we identified some common epitope targets in both macaques and humans, including in the fusion peptide (FP) and stem helix-heptad repeat 2 (SH-H) regions. Differences between groups included a response to epitopes in the N-terminal domain (NTD) and C-terminal domain (CTD) in vaccinated humans but not vaccinated macaques, as well as recognition of a CTD epitope and epitopes flanking the FP in convalescent macaques but not convalescent humans. There was also considerable variability in the escape pathways among individuals within each group. Sera from convalescent macaques showed the least variability in escape overall and converged on a common response with vaccinated humans in the SH-H epitope region, suggesting highly similar antibodies were elicited. Collectively, these findings suggest that the antibody response to SARS-CoV-2 in macaques shares many features with humans, but with substantial differences in the recognition of certain epitopes and considerable individual variability in antibody escape profiles, suggesting a diverse repertoire of antibodies that can respond to major epitopes in both humans and macaques. Differences in macaque species and exposure type may also contribute to these findings.