In Vitro and Animal Models for SARS-CoV-2 research
2020; Elsevier BV; Volume: 41; Issue: 8 Linguagem: Inglês
10.1016/j.tips.2020.05.005
ISSN1873-3735
Autores Tópico(s)COVID-19 Clinical Research Studies
ResumoBasic research on SARS-CoV-2 is essential to understand its detailed pathophysiology and identify best drug targets. Models that can faithfully reproduce the viral life cycle and reproduce the pathology of COVID-19 are required. Here, we briefly review the cell lines, organoids, and animal models that are currently being used in COVID-19 research. Basic research on SARS-CoV-2 is essential to understand its detailed pathophysiology and identify best drug targets. Models that can faithfully reproduce the viral life cycle and reproduce the pathology of COVID-19 are required. Here, we briefly review the cell lines, organoids, and animal models that are currently being used in COVID-19 research. In December 2019, pneumonia of an unknown etiology was confirmed in China [1.Lu H. et al.Outbreak of pneumonia of unknown etiology in Wuhan China: the mystery and the miracle.J. Med. Virol. 2020; 92: 401-402Crossref PubMed Scopus (2136) Google Scholar]. The Chinese Center for Disease Control and Prevention (CCDC) identified a novel coronavirus infection as the cause of this pneumonia [2.Li Q. et al.Early transmission dynamics in Wuhan, China, of novel coronavirus–infected pneumonia.N. Engl. J. Med. 2020; 382: 1199-1207Crossref PubMed Scopus (10810) Google Scholar]. The World Health Organization (WHO) named the disease '2019-new coronavirus disease' (COVID-19)i and the International Committee on Taxonomy of Viruses named the virus 'severe acute respiratory syndrome coronavirus 2' (SARS-CoV-2)ii. The WHO soon declared that COVID-19 was a fast-evolving pandemiciii. As of 26 May 2020, it is estimated that 5 406 282 people have been infected with COVID-19 and 343 562 people have died globallyiii. Multiple clinical trials are currently underway for prevention or intervention in the disease progression [3.Lythgoe M.P. Middleton P. Ongoing clinical trials for the management of the COVID-19 pandemic.Trends Pharmacol. Sci. 2020; 41: 363-382Abstract Full Text Full Text PDF PubMed Scopus (284) Google Scholar]. In parallel, it is also equally essential to carry out basic research on SARS-CoV-2 to support the efficient development of therapeutic agents. For this, models that can faithfully reproduce the behavior of the virus and reproduce the pathology of COVID-19 are required. Here, we briefly review relevant cell lines, organoids, and animal model animals. An in vitro cell model for SARS-CoV-2 research is essential for understanding the viral life cycle, for amplifying and isolating the virus for further research, and for preclinical evaluation of therapeutic molecules. This section lays out the cell lines used to replicate and isolate SARS-CoV-2, as well as organoids that can be used to examine the effects of SARS-CoV-2 infection on specific human tissues (Table 1 and Figure 1).Table 1Cell Lines and Organoids and Animal Models Currently Being Used in COVID-19 ResearchCell lines and organoidsTypeOriginKey pointsRefsHuman airway epithelial cellsCommercially available from various vendors (Lonza, PromoCell, etc.)Human airway epithelial cells can isolate SARS-CoV-2 and mimic infected human lung cells. After SARS-CoV-2 infection, cytopathic effects were observed.[5.Zhu N. et al.A novel coronavirus from patients with pneumonia in China, 2019.N. Engl. J. Med. 2020; 382: 727-733Crossref PubMed Scopus (18869) Google Scholar]Vero E6 cellsWild type cellsIsolated from kidney epithelial cells of an African green monkeyVero E6 cells are the most widely used clone used to replicate and isolate the SARS-CoV-2.[11.Zhou P. et al.A pneumonia outbreak associated with a new coronavirus of probable bat origin.Nature. 2020; 579: 270-273Crossref PubMed Scopus (14613) Google Scholar]TMPRSS2-overexpressing cellsViral RNA copies in the culture supernatants of these cells were >100 times higher than those of wild type Vero E6 cells.[12.Matsuyama S. et al.Enhanced isolation of SARS-CoV-2 by TMPRSS2-expressing cells.Proc. Natl. Acad. Sci. U. S. A. 2020; 117: 7001-7003Crossref PubMed Scopus (955) Google Scholar]Caco-2 cellsIsolated from human colon adenocarcinomaSARS-CoV-2 could replicate in Caco-2 cells (data not shown).[6.Kim J-M. et al.Identification of coronavirus isolated from a patient in Korea with COVID-19.Osong Public Health Res. Perspect. 2020; 11: 3Crossref PubMed Scopus (361) Google Scholar]Calu-3 cellsIsolated from non-small cell lung cancerCompared with mock control, SARS-CoV-2 S pseudovirions showed an over 500-fold increase in luciferase activities in Calu3 cells.[7.Ou X. et al.Characterization of spike glycoprotein of SARS-CoV-2 on virus entry and its immune cross-reactivity with SARS-CoV.Nat. Commun. 2020; 11: 1-12Crossref PubMed Scopus (2258) Google Scholar]HEK293T cellsIsolated from human embryonic kidney (HEK) cells grown in tissue cultureCells showed only modest viral replication.[8.Harcourt J. et al.Isolation and characterization of SARS-CoV-2 from the first US COVID-19 patient.bioRxiv. 2020; (Published online March 3, 2020. https://doi.org/10.1101/2020.03.02.972935)PubMed Google Scholar]Huh7 cellsIsolated from hepatocyte-derived cellular carcinoma cellsCells showed about a tenfold increase in luciferase activity when transduced by SARS-CoV-2 S pseudovirions.[7.Ou X. et al.Characterization of spike glycoprotein of SARS-CoV-2 on virus entry and its immune cross-reactivity with SARS-CoV.Nat. Commun. 2020; 11: 1-12Crossref PubMed Scopus (2258) Google Scholar]Human bronchial organoidsGenerated from commercially available human bronchial epithelial cellsAfter SARS-CoV-2 infection, not only the intracellular viral genome, but also progeny virus, cytotoxicity, pyknotic cells, and moderate increases of the type I interferon signal can be observed.[17.Suzuki T. et al.Generation of human bronchial organoids for SARS-CoV-2 research.bioRxiv. 2020; (Published online May 26, 2020. https://doi.org/10.1101/2020.05.25.115600)Google Scholar]Human lung organoidsGenerated from human embryonic stem cellsThe lung organoids, particularly alveolar type II cells, are permissive to SARS-CoV-2 infection.[18.Han Y. et al.Identification of candidate COVID-19 therapeutics using hPSC-derived lung organoids.bioRxiv. 2020; (Published online May 5, 2020. https://doi.org/10.1101/2020.05.05.079095)Google Scholar]Human kidney organoidsGenerated from human embryonic stem cellsHuman kidney organoids produce infectious progeny virus.[19.Monteil V. et al.Inhibition of SARS-CoV-2 infections in engineered human tissues using clinical-grade soluble human ACE2.Cell. 2020; 181: 905-913.e7Abstract Full Text Full Text PDF PubMed Scopus (1617) Google Scholar]Human liver ductal organoidsGenerated from primary bile ducts isolated from human liver biopsiesHuman liver ductal organoids are permissive to SARS-CoV-2 infection, and SARS-CoV-2 infection impairs the bile acid transporting functions of cholangiocytes.[20.Zhao B. et al.Recapitulation of SARS-CoV-2 infection and cholangiocyte damage with human liver ductal organoids.Protein Cell. 2020; (Published online April 17, 2020. https://doi.org/10.1007/s13238-020-00718-6)Crossref Scopus (286) Google Scholar]Human intestinal organoidsGenerated from primary gut epithelial stem cellsHuman intestinal organoids were readily infected by SARS-CoV-2, as demonstrated by confocal and electron microscopy. Significant titers of infectious viral particles were detected.[22.Lamers M.M. et al.SARS-CoV-2 productively infects human gut enterocytes.Science. 2020; (Published online May 1, 2020. https://doi.org/10.1126/science.abc1669)Crossref Scopus (1173) Google Scholar,23.Zhou J. et al.Infection of bat and human intestinal organoids by SARS-CoV-2.Nat. Med. 2020; (Published online May 13, 2020. https://doi.org/10.1038/s41591-020-0912-6)Crossref Scopus (390) Google Scholar]Human blood vessel organoidsGenerated from human induced pluripotent stem cellsSARS-CoV-2 can directly infect human blood vessel organoids.[19.Monteil V. et al.Inhibition of SARS-CoV-2 infections in engineered human tissues using clinical-grade soluble human ACE2.Cell. 2020; 181: 905-913.e7Abstract Full Text Full Text PDF PubMed Scopus (1617) Google Scholar]Animal modelsAnimal speciesKey pointsRefsMiceWild type miceSARS-CoV-2 cannot invade cells through mouse Ace2.[11.Zhou P. et al.A pneumonia outbreak associated with a new coronavirus of probable bat origin.Nature. 2020; 579: 270-273Crossref PubMed Scopus (14613) Google Scholar]Human ACE2 transgenic miceAfter SARS-CoV-2 infection, the mice show weight loss, virus replication in the lungs, and interstitial pneumonia.[25.Bao L. et al.The pathogenicity of SARS-CoV-2 in hACE2 transgenic mice.Nature. 2020; (Published online May 7, 2020. https://doi.org/10.1038/s41586-020-2312-y)Crossref Scopus (814) Google Scholar]Syrian hamsterAfter SARS-CoV-2 infection, the hamsters show rapid breathing, weight loss, and diffuse alveolar damage with extensive apoptosis.[26.Chan J.F-W. et al.Simulation of the clinical and pathological manifestations of coronavirus disease 2019 (COVID-19) in golden Syrian hamster model: implications for disease pathogenesis and transmissibility.Clin. Infect. Dis. 2020; (Published online March 26, 2020. https://doi.org/10.1093/cid/ciaa325)Crossref Scopus (727) Google Scholar]FerretsAfter SARS-CoV-2 infection, acute bronchiolitis was observed in the lungs.[27.Kim Y-I. et al.Infection and rapid transmission of SARS-CoV-2 in ferrets.Cell Host Microbe. 2020; 27: 704-709.e2Abstract Full Text Full Text PDF PubMed Scopus (682) Google Scholar]CatsAfter SARS-CoV-2 infection, intra-alveolar edema and congestion in the interalveolar septa were observed. Abnormal arrangement of the epithelium with loss of cilia and lymphocytic infiltration into the lamina propria were also observed.[28.Shi J. et al.Susceptibility of ferrets, cats, dogs, and other domesticated animals to SARS–coronavirus 2.Science. 2020; (Published online April 8, 2020. https://doi.org/10.1126/science.abb7015)Crossref Scopus (1280) Google Scholar]Cynomolgus macaquesSARS-CoV-2 can infect both type I and type II pneumocytes. After SARS-CoV-2 infection, pulmonary consolidation, pneumonia, and edema fluid in alveolar lumina were observed.[29.Rockx B. et al.Comparative pathogenesis of COVID-19, MERS, and SARS in a nonhuman primate model.Science. 2020; (Published online April 17, 2020. https://doi.org/10.1126/science.abb7314)Crossref PubMed Scopus (659) Google Scholar]Rhesus macaquesInfected macaques had high viral loads in the upper and lower respiratory tract, humoral and cellular immune responses, and pathologic evidence of viral pneumonia. The therapeutic effects of adenovirus-vectored vaccine, DNA vaccine candidates expressing S protein, and remdesivir treatment could be evaluated.[30.Chandrashekar A. et al.SARS-CoV-2 infection protects against rechallenge in rhesus macaques.Science. 2020; (Published online May 20, 2020. https://doi.org/10.1126/science.abc4776)Crossref Scopus (630) Google Scholar, 31.van Doremalen N. et al.ChAdOx1 nCoV-19 vaccination prevents SARS-CoV-2 pneumonia in rhesus macaques.bioRxiv. 2020; (Published online May 13, 2020. https://doi.org/10.1101/2020.05.13.093195)Google Scholar, 32.Yu J. et al.DNA vaccine protection against SARS-CoV-2 in rhesus macaques.Science. 2020; (Published online May 20, 2020. https://doi.org/10.1126/science.abc6284)Crossref Scopus (763) Google Scholar, 33.Williamson B.N. et al.Clinical benefit of remdesivir in rhesus macaques infected with SARS-CoV-2.bioRxiv. 2020; (Published online April 22, 2020. https://doi.org/10.1101/2020.04.15.043166)Google Scholar] Open table in a new tab In humans, airway epithelial cells highly express the putative SARS-CoV-2 entry receptor, angiotensin-converting enzyme 2 (ACE2) and transmembrane serine proteinase 2 (TMPRSS2), the receptor that the virus uses to prime the S protein (spike protein of SARS-CoV-2) [4.Hoffmann M. et al.SARS-CoV-2 cell entry depends on ACE2 and TMPRSS2 and is blocked by a clinically proven protease inhibitor.Cell. 2020; 181: 271-280Abstract Full Text Full Text PDF PubMed Scopus (13672) Google Scholar]. SARS-CoV-2 infection experiments using primary human airway epithelial cells have been found to have cytopathic effects 96 h after the infection [5.Zhu N. et al.A novel coronavirus from patients with pneumonia in China, 2019.N. Engl. J. Med. 2020; 382: 727-733Crossref PubMed Scopus (18869) Google Scholar]. However, primary human airway epithelial cells are expensive and do not proliferate indefinitelyiv. Several infinitely proliferating cell lines, such as Caco-2 [6.Kim J-M. et al.Identification of coronavirus isolated from a patient in Korea with COVID-19.Osong Public Health Res. Perspect. 2020; 11: 3Crossref PubMed Scopus (361) Google Scholar], Calu-3 [7.Ou X. et al.Characterization of spike glycoprotein of SARS-CoV-2 on virus entry and its immune cross-reactivity with SARS-CoV.Nat. Commun. 2020; 11: 1-12Crossref PubMed Scopus (2258) Google Scholar], HEK293T [8.Harcourt J. et al.Isolation and characterization of SARS-CoV-2 from the first US COVID-19 patient.bioRxiv. 2020; (Published online March 3, 2020. https://doi.org/10.1101/2020.03.02.972935)PubMed Google Scholar], and Huh7 [7.Ou X. et al.Characterization of spike glycoprotein of SARS-CoV-2 on virus entry and its immune cross-reactivity with SARS-CoV.Nat. Commun. 2020; 11: 1-12Crossref PubMed Scopus (2258) Google Scholar] have been utilized in SARS-CoV-2 infection experiments. These cell lines do not accurately mimic human physiological conditions and generate low titer of infectious SARS-CoV-2 [6.Kim J-M. et al.Identification of coronavirus isolated from a patient in Korea with COVID-19.Osong Public Health Res. Perspect. 2020; 11: 3Crossref PubMed Scopus (361) Google Scholar, 7.Ou X. et al.Characterization of spike glycoprotein of SARS-CoV-2 on virus entry and its immune cross-reactivity with SARS-CoV.Nat. Commun. 2020; 11: 1-12Crossref PubMed Scopus (2258) Google Scholar, 8.Harcourt J. et al.Isolation and characterization of SARS-CoV-2 from the first US COVID-19 patient.bioRxiv. 2020; (Published online March 3, 2020. https://doi.org/10.1101/2020.03.02.972935)PubMed Google Scholar]. Despite this limitation, valuable information about the virus infection and replication can be learned from studies using these cell lines. However, Vero cells have given high titer of viral particles [8.Harcourt J. et al.Isolation and characterization of SARS-CoV-2 from the first US COVID-19 patient.bioRxiv. 2020; (Published online March 3, 2020. https://doi.org/10.1101/2020.03.02.972935)PubMed Google Scholar]. For efficient SARS-CoV-2 research, a cell line, such as Vero cells, that can easily replicate and isolate the virus is essential. These cells were isolated from the kidney epithelial cells of an African green monkey in 1963 and have been shown to not produce interferon (IFN) when infected with Newcastle disease virus, rubella virus, and other viruses [9.Desmyter J. et al.Defectiveness of interferon production and of rubella virus interference in a line of African green monkey kidney cells (Vero).J. Virol. 1968; 2: 955-961Crossref PubMed Scopus (0) Google Scholar]. A homozygous ~9 Mbp deletion on chromosome 12 causes the loss of the type I interferon (IFN-I) gene cluster and of cyclin-dependent kinase inhibitor genes [10.Osada N. et al.The genome landscape of the African green monkey kidney-derived Vero cell line.DNA Res. 2014; 21: 673-683Crossref PubMed Scopus (163) Google Scholar]. The IFN deficiency allows SARS-CoV-2 to replicate in Vero cells. Among the several Vero cell clones, Vero E6 is the most widely used to replicate and isolate SARS-CoV-2 [11.Zhou P. et al.A pneumonia outbreak associated with a new coronavirus of probable bat origin.Nature. 2020; 579: 270-273Crossref PubMed Scopus (14613) Google Scholar], because these cells highly express ACE2 on the apical membrane domain. However, the expression level of TMPRSS2, the receptor that the virus uses to prime the S protein (spike protein of SARS-CoV-2) [4.Hoffmann M. et al.SARS-CoV-2 cell entry depends on ACE2 and TMPRSS2 and is blocked by a clinically proven protease inhibitor.Cell. 2020; 181: 271-280Abstract Full Text Full Text PDF PubMed Scopus (13672) Google Scholar], is quite low in this clone. To enhance the replication and isolation efficiencies of SARS-CoV-2 in Vero E6 cells, Matsuyama et al. have used TMPRSS2-overexpressing Vero E6 cells [12.Matsuyama S. et al.Enhanced isolation of SARS-CoV-2 by TMPRSS2-expressing cells.Proc. Natl. Acad. Sci. U. S. A. 2020; 117: 7001-7003Crossref PubMed Scopus (955) Google Scholar]. They reported that the viral RNA copies in the culture supernatants of these cells were >100 times higher than those of Vero E6 cells, suggesting that it would be possible to isolate higher titer virus using TMPRSS2-overexpressing Vero E6 cells. Organoids are composed of multiple cell types and model the physiological conditions of human organs. Because organoids have the ability to self-replicate, they are also suitable models for large-scale screening in drug discovery and disease research [13.Ranga A. et al.Drug discovery through stem cell-based organoid models.Adv. Drug Deliv. Rev. 2014; 69: 19-28Crossref PubMed Scopus (168) Google Scholar]. Besides the lung damage caused by pneumonia, SARS-CoV-2 affects several organs like the kidney [14.Li Z. et al.Caution on kidney dysfunctions of COVID-19 patients.medRxiv. 2020; (Published online March 27, 2020. https://doi.org/10.1101/2020.02.08.20021212)Google Scholar], liver [15.Fan Z. et al.Clinical features of COVID-19-related liver damage.Clin. Gastroenterol. Hepatol. 2020; 18: 1561-1566Abstract Full Text Full Text PDF PubMed Scopus (564) Google Scholar], and the cardiovascular system [16.Zheng Y-Y. et al.COVID-19 and the cardiovascular system.Nat. Rev. Cardiol. 2020; 17: 259-260Crossref PubMed Scopus (2293) Google Scholar]. Suzuki et al. and Han et al. generated human bronchial organoids [17.Suzuki T. et al.Generation of human bronchial organoids for SARS-CoV-2 research.bioRxiv. 2020; (Published online May 26, 2020. https://doi.org/10.1101/2020.05.25.115600)Google Scholar] or human lung organoids [18.Han Y. et al.Identification of candidate COVID-19 therapeutics using hPSC-derived lung organoids.bioRxiv. 2020; (Published online May 5, 2020. https://doi.org/10.1101/2020.05.05.079095)Google Scholar], respectively, for SARS-CoV-2 research. They showed that their organoids were permissive to the SARS-CoV-2 infection and could evaluate antiviral effects of COVID-19 candidate therapeutic compounds, including camostat [17.Suzuki T. et al.Generation of human bronchial organoids for SARS-CoV-2 research.bioRxiv. 2020; (Published online May 26, 2020. https://doi.org/10.1101/2020.05.25.115600)Google Scholar]. Besides the lung damage caused by pneumonia, SARS-CoV-2 affects several organs like the kidney [14.Li Z. et al.Caution on kidney dysfunctions of COVID-19 patients.medRxiv. 2020; (Published online March 27, 2020. https://doi.org/10.1101/2020.02.08.20021212)Google Scholar], liver [15.Fan Z. et al.Clinical features of COVID-19-related liver damage.Clin. Gastroenterol. Hepatol. 2020; 18: 1561-1566Abstract Full Text Full Text PDF PubMed Scopus (564) Google Scholar], and the cardiovascular system [16.Zheng Y-Y. et al.COVID-19 and the cardiovascular system.Nat. Rev. Cardiol. 2020; 17: 259-260Crossref PubMed Scopus (2293) Google Scholar]. Monteil et al. have shown that the supernatant of SARS-CoV-2 infected kidney organoids differentiated from human embryonic stem cells can efficiently infect Vero E6 cells, showing that the kidney organoids produce infectious progeny virus [19.Monteil V. et al.Inhibition of SARS-CoV-2 infections in engineered human tissues using clinical-grade soluble human ACE2.Cell. 2020; 181: 905-913.e7Abstract Full Text Full Text PDF PubMed Scopus (1617) Google Scholar]. In addition, Zhao et al. have demonstrated that human liver ductal organoids are permissive to SARS-CoV-2 infection and support replication [20.Zhao B. et al.Recapitulation of SARS-CoV-2 infection and cholangiocyte damage with human liver ductal organoids.Protein Cell. 2020; (Published online April 17, 2020. https://doi.org/10.1007/s13238-020-00718-6)Crossref Scopus (286) Google Scholar]. Interestingly, virus infection impaired the bile acid transporting functions of cholangiocytes [20.Zhao B. et al.Recapitulation of SARS-CoV-2 infection and cholangiocyte damage with human liver ductal organoids.Protein Cell. 2020; (Published online April 17, 2020. https://doi.org/10.1007/s13238-020-00718-6)Crossref Scopus (286) Google Scholar]. This effect might be the reason for the bile acid accumulation and consequent liver damage in patients with COVID-19. Furthermore, it is expected that the intestine is another viral target organ [21.Zhou Z. et al.Effect of gastrointestinal symptoms on patients infected with COVID-19.Gastroenterology. 2020; 158: 2294-2297Abstract Full Text Full Text PDF PubMed Scopus (171) Google Scholar]. Lamers et al. and Zhou et al. have reported that human intestinal organoids, which were established from primary gut epithelial stem cells, support SARS-CoV-2 replication [22.Lamers M.M. et al.SARS-CoV-2 productively infects human gut enterocytes.Science. 2020; (Published online May 1, 2020. https://doi.org/10.1126/science.abc1669)Crossref Scopus (1173) Google Scholar,23.Zhou J. et al.Infection of bat and human intestinal organoids by SARS-CoV-2.Nat. Med. 2020; (Published online May 13, 2020. https://doi.org/10.1038/s41591-020-0912-6)Crossref Scopus (390) Google Scholar]. Moreover, Monteil et al. have also demonstrated that SARS-CoV-2 can directly infect human blood vessel organoids differentiated from human induced pluripotent stem cells [19.Monteil V. et al.Inhibition of SARS-CoV-2 infections in engineered human tissues using clinical-grade soluble human ACE2.Cell. 2020; 181: 905-913.e7Abstract Full Text Full Text PDF PubMed Scopus (1617) Google Scholar]. Consistently, Varga et al. confirmed the presence of viral elements within endothelial cells and an accumulation of inflammatory cells [24.Varga Z. et al.Endothelial cell infection and endotheliitis in COVID-19.Lancet. 2020; 395: 1417-1418Abstract Full Text Full Text PDF PubMed Scopus (4567) Google Scholar]. Taken together, the two studies suggest that SARS-CoV-2 infection induces endotheliitis in several organs as a direct consequence of virus involvement. However, while organoids can reproduce the pathology of COVID-19 in specific tissues on which they are modeled, they cannot reproduce the systemic symptoms associated with whole body responses to the viral infection. The complex pathophysiology of the disease will only be understood by reproducing tissue-specific and systemic virus–host interactions. While cell lines and organoids are faster systems to study the virus and its interactions inside host cells, these can only reproduce the symptoms of COVID-19 in a specific cell type or organ, respectively. However, the pathology of COVID-19 can be reproduced and observed in a tissue-specific and systemic manner in animal models. Several different animals are being used to study the disease and to test candidate therapeutic compounds (Table 1 and Figure 1). One of the works that set the pace for discovery of animal models was by Zhou et al. who conducted SARS-CoV-2 infection experiments using HeLa cells that expressed ACE2 proteins taken from multiple animal species, from mice to humans [11.Zhou P. et al.A pneumonia outbreak associated with a new coronavirus of probable bat origin.Nature. 2020; 579: 270-273Crossref PubMed Scopus (14613) Google Scholar]. Interestingly, SARS-CoV-2 could use all ACE2 proteins, except for mouse ACE2. Therefore, Bao et al. used transgenic mice that express human ACE2 [25.Bao L. et al.The pathogenicity of SARS-CoV-2 in hACE2 transgenic mice.Nature. 2020; (Published online May 7, 2020. https://doi.org/10.1038/s41586-020-2312-y)Crossref Scopus (814) Google Scholar]. The team found that such mice, after SARS-CoV-2 infection, showed weight loss, virus replication in the lungs, and interstitial pneumonia [25.Bao L. et al.The pathogenicity of SARS-CoV-2 in hACE2 transgenic mice.Nature. 2020; (Published online May 7, 2020. https://doi.org/10.1038/s41586-020-2312-y)Crossref Scopus (814) Google Scholar]. In the search of alternative small animal models, molecular docking studies were performed on the binding between ACE2 of various mammals and the S protein of SARS-CoV-2, with the finding that the Syrian hamster might be suitable [26.Chan J.F-W. et al.Simulation of the clinical and pathological manifestations of coronavirus disease 2019 (COVID-19) in golden Syrian hamster model: implications for disease pathogenesis and transmissibility.Clin. Infect. Dis. 2020; (Published online March 26, 2020. https://doi.org/10.1093/cid/ciaa325)Crossref Scopus (727) Google Scholar]. After infection, these hamsters show rapid breathing, weight loss, and alveolar damage with extensive apoptosis [26.Chan J.F-W. et al.Simulation of the clinical and pathological manifestations of coronavirus disease 2019 (COVID-19) in golden Syrian hamster model: implications for disease pathogenesis and transmissibility.Clin. Infect. Dis. 2020; (Published online March 26, 2020. https://doi.org/10.1093/cid/ciaa325)Crossref Scopus (727) Google Scholar]. Small animals like mice and Syrian hamster are advantageous to study SARS-CoV-2, as they reproduce faster; however, to faithfully reproduce COVID-19 pathology in humans, larger animal models are preferred. Kim et al. reported nonlethal acute bronchiolitis in the lungs of a ferret model [27.Kim Y-I. et al.Infection and rapid transmission of SARS-CoV-2 in ferrets.Cell Host Microbe. 2020; 27: 704-709.e2Abstract Full Text Full Text PDF PubMed Scopus (682) Google Scholar]. Another study showed that SARS-CoV-2 can replicate in ferrets and cats, but not in pigs, chickens, and ducks [28.Shi J. et al.Susceptibility of ferrets, cats, dogs, and other domesticated animals to SARS–coronavirus 2.Science. 2020; (Published online April 8, 2020. https://doi.org/10.1126/science.abb7015)Crossref Scopus (1280) Google Scholar]. Based on these findings, it is recommended to use ferrets and cats when selecting large experimental animals rather than rodents. Another model that can be used for COVID-19 studies and is currently the closest to humans in pathophysiology, is the primate cynomolgus macaques. Rockx et al. used cynomolgus macaques to compare MERS-CoV, SARS-CoV, and SARS-CoV-2 [29.Rockx B. et al.Comparative pathogenesis of COVID-19, MERS, and SARS in a nonhuman primate model.Science. 2020; (Published online April 17, 2020. https://doi.org/10.1126/science.abb7314)Crossref PubMed Scopus (659) Google Scholar]. Although MERS-CoV mainly infected type II pneumocytes, both SARS-CoV and SARS-CoV-2 infect type I and II pneumocytes. After SARS-CoV-2 infection, damage on type I pneumocytes led to pulmonary edema and the formation of hyaline membranes. Thus, cynomolgus macaques can be infected with SARS-CoV-2 and reproduce some of the human pathologies of COVID-19. Rhesus macaques have also been used in COVID-19 studies [30.Chandrashekar A. et al.SARS-CoV-2 infection protects against rechallenge in rhesus macaques.Science. 2020; (Published online May 20, 2020. https://doi.org/10.1126/science.abc4776)Crossref Scopus (630) Google Scholar] where the therapeutic effects of adenovirus-vectored vaccine [31.van Doremalen N. et al.ChAdOx1 nCoV-19 vaccination prevents SARS-CoV-2 pneumonia in rhesus macaques.bioRxiv. 2020; (Published online May 13, 2020. https://doi.org/10.1101/2020.05.13.093195)Google Scholar], DNA vaccine candidates expressing S protein [32.Yu J. et al.DNA vaccine protection against SARS-CoV-2 in rhesus macaques.Science. 2020; (Published online May 20, 2020. https://doi.org/10.1126/science.abc6284)Crossref Scopus (763) Google Scholar], and remdesivir treatment [33.Williamson B.N. et al.Clinical benefit of remdesivir in rhesus macaques infected with SARS-CoV-2.bioRxiv. 2020; (Published online April 22, 2020. https://doi.org/10.1101/2020.04.15.043166)Google Scholar] were confirmed. While these models probably are best in replicating virus–human host interactions, a major limitation is that the reproduction rate in cynomolgus and rhesus monkeys is less and slower. Hence this can be preceded by experiments with transgenic mice and Syrian hamsters. COVID-19 has spread rapidly all over the world in the past 5 months. Even now, the number of infected people and deaths continues to rise. At this time, there are no therapeutic prevention or intervention methods available. The only ways to control the pandemic and reduce associated loss of lives has been to change peoples' behavior, like quarantine and social distancing. Therapeutic strategies for prevention and/or intervention is the need of the hour. While multiple clinical trials are currently underway, in parallel, preclinical research on in vitro and model organisms is also needed, both to understand the virus and to test therapeutic agents for safety and efficacy. We believe that this overview will help researchers select suitable cell and animal models for SARS-CoV-2 research (Table 1 and Figure 1) and help assess the advantages and disadvantages of each towards discovery of better models. We thank Dr Peter Karagiannis (Kyoto University), Dr Yoichi Miyamoto (National Institutes of Biomedical Innovation, Health and Nutrition), Dr Sachiyo Yoshio (National Center for Global Health and Medicine), Dr Kohji Moriishi (University of Yamanashi), and Dr Toru Okamoto (Osaka University) for critical reading of the manuscript. We also thank Dr Eiri Ono (Kyoto University) for creating the figure. ihttps://apps.who.int/iris/handle/10665/330893 iihttps://talk.ictvonline.org/information/w/news/1300/page iiiwww.who.int/emergencies/diseases/novel-coronavirus-2019 ivwww.fishersci.se/shop/products/human-bronchial-epithelial-cells-nhbe/13499079
Referência(s)