Alternatives to animal models and their application in the discovery of species susceptibility to SARS-CoV-2 and other respiratory infectious pathogens: A review

Abstract

The emergence of the coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) inspired rapid research efforts targeting the host range, pathogenesis and transmission mechanisms, and the development of antiviral strategies. Genetically modified mice, rhesus macaques, ferrets, and Syrian golden hamsters have been frequently used in studies of pathogenesis and efficacy of antiviral compounds and vaccines. However, alternatives to in vivo experiments, such as immortalized cell lines, primary respiratory epithelial cells cultured at an air–liquid interface, stem/progenitor cell-derived organoids, or tissue explants, have also been used for isolation of SARS-CoV-2, investigation of cytopathic effects, and pathogen–host interactions. Moreover, initial proof-of-concept studies for testing therapeutic agents can be performed with these tools, showing that animal-sparing cell culture methods could significantly reduce the need for animal models in the future, following the 3R principles of replace, reduce, and refine. So far, only few studies using animal-derived primary cells or tissues have been conducted in SARS-CoV-2 research, although natural infection has been shown to occur in several animal species. Therefore, the need for in-depth investigations on possible interspecies transmission routes and differences in susceptibility to SARS-CoV-2 is urgent. This review gives an overview of studies employing alternative culture systems like primary cell cultures, tissue explants, or organoids for investigations of the pathophysiology and reverse zoonotic potential of SARS-CoV-2 in animals. In addition, future possibilities of SARS-CoV-2 research in animals, including previously neglected methods like the use of precision-cut lung slices, will be outlined.

Ferrets are valuable models for SARS-CoV-2 research

“…infection of primary mucosal explants derived from different regions of the nasal cavity. 47 Histological lesions associated with SARS-CoV-2 infection in young ferrets are usually mild and gross lesions are generally absent (Supplemental Table S9). In most cases, mild rhinitis with epithelial necrosis, mild bronchopneumonia, and mild interstitial pneumonia with BALT and type II pneumocyte hyperplasia and perivascular and peribronchiolar cuffing have been described.…”

“… 44 This hypothesis could be substantiated by further experiments, for instance by infection of primary mucosal explants derived from different regions of the nasal cavity. 47 …”

An Overview of Epithelial-to-Mesenchymal Transition and Mesenchymal-to-Epithelial Transition in Canine Tumors: How Far Have We Come?

“…Another study suggested that the SARS-CoV-2 M protein induces motility, proliferation, stemness, and in vivo metastasis of triple-negative breast cancer [ 111 ]. Despite studies reporting that SARS-CoV-2 could also infect felids [ 113 ], dogs [ 114 ], and many other domestic species [ 115 ], reports on dogs or other pets exhibiting a SARS-CoV-2-induced EMT process are still lacking.…”

A comparative study of COVID-19 transcriptional signatures between clinical samples and preclinical cell models in the search for disease master regulators and drug repositioning candidates

“…The emergence and rapid worldwide spread of SARS-CoV-2 has motivated a surge of in vitro model development for application on COVID-19 research, with cell lines derived from both humans and several other species, such as nonhuman primates. These models have been widely used for the isolation of SARS-CoV-2, the study of virus infection etiopathogenesis and the identification of potential drugs for efficient therapeutic interventions ( Runft et al, 2022 ). Up to this date, several drugs have been evaluated as potential COVID-19 therapeutic alternatives, mainly proposed as candidates based on two different strategies: empirical drug repositioning, and in vitro experiment with hypothetical or known antiviral compounds ( Izda et al, 2021 ; WHO Solidarity Trial Consortium et al, 2021 ).…”