Establishment of an African green monkey model for COVID-19

Abstract

12Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for an unprecedented global 13 pandemic of COVID-19. Animal models are urgently needed to study the pathogenesis of COVID-19 and to 14 screen candidate vaccines and treatments. Nonhuman primates (NHP) are considered the gold standard model 15 for many infectious pathogens as they usually best reflect the human condition. Here, we show that African green 16 monkeys support a high level of SARS-CoV-2 replication and develop pronounced respiratory disease that may 17 be more substantial than reported for other NHP species including cynomolgus and rhesus macaques. In 18 addition, SARS-CoV-2 was detected in mucosal samples of all animals including feces of several animals as late 19 as 15 days after virus exposure. Importantly, we show that virus replication and respiratory disease can be 20 produced in African green monkeys using a much lower and more natural dose of SARS-CoV-2 than has been 21 employed in other NHP studies. 42varying degrees of non-lethal illness when the virus was delivered into the respiratory tract of these animals [7-43 13]. While each of these models has utility in the study of COVID-19, NHPs have the closest physiological 44 resemblance to humans allowing a better comparison of host responses to infection. This genetic similarity has 45 also contributed to the increased availability of reagents to perform in-depth analyses of the immune response. 46Recently, the first studies evaluating the pathogenic potential of SARS-CoV-2 in cynomolgus and rhesus 47 macaques were performed. Rhesus macaques developed pneumonia and clinical signs whereas disease in 48 cynomolgus macaques was fairly mild indicating the former appears to better reflect more severe cases of 49 . These results suggest certain NHP species may serve as better models than others for 50 4 coronavirus infections. For SARS, the disease caused by SARS-CoV-1, African green monkeys (AGMs) were 51 found to support the highest level of viral replication, followed by cynomolgus macaques and rhesus macaques 52 when all three species were challenged in parallel [14]. Only AGMs had notable replication in the lower 53 respiratory tract following SARS-CoV-1 inoculation; necropsy of these animals indicated focal interstitial 54 mononuclear inflammatory infiltrates and edema in the lung consistent with human SARS. As SARS-CoV-1 and 55 SARS-CoV-2 share the same putative host receptor angiotensin-converting enzyme 2 (ACE2) [15, 16], we 56 reasoned that AGMs might serve as a useful model for COVID-19. 57Here, we infected AGMs with a low passage isolate of SARS-CoV-2 (SARS-CoV-2/INMI1- 58Isolate/2020/Italy) and evaluated their potential as a model for COVID-19. SARS-CoV-2/INMI1-Isolate/2020/Italy 59 was isolated from the first clinical case in Italy [17] and is the first V clade virus (GISAID) to be experimentally 60 inoculated into NHPs. We demonstrate AGMs mimic several aspects of human disease including a high degree 61 of viral replication and severe pulmonary lesions. T...

Intranasal exposure of African green monkeys to SARS-CoV-2 results in acute phase pneumonia with shedding and lung injury still present in the early convalescence phase

“…BAL uid collection was performed on days -8, 3, and 5 for all animals, as well as 7 dpi for AGM-4, AGM-5 and AGM-6. Consistent with our previous report describing the development of the combined intranasal and intratracheal SARS-CoV-2 challenge model in AGMs [10], we did not observe overt signs of clinical illness in any AGMs in this study, other than decreased appetite or brief (single day) anorexia (Supp Table 1). Temperature was longitudinally monitored in 15 minute increments for the entire study duration using surgically implanted temperature loggers; several animals (AGM-4, AGM-6) experienced brief (< 2 hours) periods of mildly elevated temperatures at 3 dpi, and two animals (AGM-2, AGM-3) exhibited an abnormal temperature cycling pattern at 3 dpi (Supp Figure 1).…”

“…however, mild to moderate prolongation of the activated partial thromboplastin time (aPTT) was also observed in all animals through the acute phase of disease, most prominently in AGM-1 and AGM-2, indicating possible disorder of the intrinsic coagulation pathway ( Figure 1H, I); this was mirrored by increased levels of circulating brinogen ( Figure 1J). We previously showed that the pathways connected to IL-6 production are activated during SARS-CoV-2 infection of AGMs [10], indicating possible mechanisms of coagulopathy in the current study.…”

“…We challenged six healthy, adult AGMs with a target dose of 3.0 x 10 6 PFU of SARS-CoV-2 (SARS-CoV-2/INMI1-Isolate/2020/Italy) via intranasal inoculation with the LMA MAD (actual delivered dose of 2.8 x 10 6 PFU). Three animals were euthanized at 5 days post-infection (dpi) which is thought to be the approximate time point of peak disease in AGMs [10], while the remaining three animals were euthanized at 34 dpi during early convalescence. Blood and mucosal swabs were sampled from all animals on days 0, 2, 3, 4, 5, and additionally on days 7, 9, 12, 15, 21, 28, and 34 for AGM-4, AGM-5, and AGM-6.…”

“…Both small animal models and nonhuman primates (NHP) may prove valuable in triaging the most promising medical countermeasures prior to use in humans. Hamsters and ferrets are currently being used as immunocompetent small animal models of COVID-19 [3][4][5] while several NHP models have been quickly developed [6][7][8][9][10][11][12]. Among the nonhuman primate models evaluated the African green monkey (AGM) appears to best recapitulate the most salient features of human COVID-19 [10][11][12].…”

K18-hACE2 mice develop respiratory disease resembling severe COVID-19

“…Although primarily a respiratory tract infection, extra-respiratory replication of SARS-CoV-2 has been observed in kidney, heart, liver and brain in fatal cases (7)(8)(9). Several experimental animal models for SARS-CoV-2 infection have been developed, including hamsters (10) ferrets (11) and non-human primate models (12)(13)(14)(15). SARS-CoV-2 pathogenicity within these animal models ranges only from mild to moderate (10)(11)(12)(13)(14)(15).…”