The post-acute phase of SARS-CoV-2 infection in two macaques species is associated with signs of ongoing virus replication and pathology in pulmonary and extrapulmonary tissues

Abstract

SARS-CoV-2 is a coronavirus that sparked the current COVID-19 pandemic. To stop the shattering effect of COVID-19, effective and safe vaccines, and antiviral therapies are urgently needed. To facilitate the preclinical evaluation of intervention approaches, relevant animal models need to be developed and validated. Rhesus macaques (Macaca mulatta) and cynomolgus macaques (Macaca fascicularis) are widely used in biomedical research and serve as models for SARS-CoV-2 infection. However, differences in study design make it difficult to compare and understand potential species-related differences. Here, we directly compared the course of SARS-CoV-2 infection in the two genetically closely-related macaque species. After inoculation with a low passage SARS-CoV-2 isolate, clinical, virological, and immunological characteristics were monitored. Both species showed slightly elevated body temperatures in the first days after exposure while a decrease in physical activity was only observed in the rhesus macaques and not in cynomolgus macaques. The virus was quantified in tracheal, nasal, and anal swabs, and in blood samples by qRT-PCR, and showed high similarity between the two species. Immunoglobulins were detected by various enzyme-linked immunosorbent assays (ELISAs) and showed seroconversion in all animals by day 10 post-infection. The cytokine responses were highly comparable between species and computed tomography (CT) imaging revealed pulmonary lesions in all animals. Consequently, we concluded that both rhesus and cynomolgus macaques represent valid models for evaluation of COVID-19 vaccine and antiviral candidates in a preclinical setting.

Bronchoalveolar lavage affects thorax computed tomography of healthy and SARS-CoV-2 infected rhesus macaques (Macaca mulatta)

“…A semi-quantitative scoring system for thorax CT evaluation was used to estimate SARS-CoV-2-induced lung disease (7, 13). Quantification of the opacities on the CTs was performed independently by two experienced imaging scientists based on the sum of the lobar scores.…”

SARS-CoV-2 causes brain inflammation and induces Lewy body formation in macaques

“…No viral RNA was detected in samples collected from the pituitary gland or olfactory bulb, substantia nigra, medulla oblongata, pons, nucleus caudatus, and putamen. Of interest, other tissues collected from macaque C3, including tracheobronchial lymph nodes, heart, liver, spleen, and kidney, also tested positive in the RT-qPCR, with comparable (lymph nodes, heart), or lower (kidney, liver, spleen) viral RNA loads (13) . Subgenomic messenger RNA analysis did not show evidence for active virus replication in the brains at the time point of euthanasia.…”

“…To address this issue, a study was performed in two macaques species, rhesus macaques (Macaca mulatta) and cynomolgus macaques (Macaca fascicularis) (Table 1), both well-accepted animal models for COVID-19 (12) . Four male rhesus and four male cynomolgus macaques were inoculated with 10 5 TCID 50 of SARS-CoV-2 strain BetaCoV/BavPat1/2020 via a combined intratracheal and intranasal route (13, 14) . Following infection, SARS-CoV-2 genomic material was detected in tracheal and nasal swabs up to ten days, and based on clinical signs and thorax CTs, all animals showed mild to moderate disease symptoms (13, 15) .…”

Aerosolized Exposure to H5N1 Influenza Virus Causes Less Severe Disease Than Infection via Combined Intrabronchial, Oral, and Nasal Inoculation in Cynomolgus Macaques

“…At the end of the procedure, atipamezol hydrochloride, 0.5 mg/kg (sedastop, ASTFarma B.V., Oudewater, The Netherlands) was used for faster recovery of the animals. The CTs of the lungs were evaluated blindly by two imaging experts and scored using a semiquantitative scoring system as described for coronavirus disease [ 35 , 36 , 37 ]. In brief, each of seven lung lobes were scored as follows: grade 0, normal image; grade 1, less than 5% of area affected; grade 2, 5–24% affected; grade 3, 25–49% affected; grade 4, 50–74% affected; grade 5, more than 75% affected.…”