Predictive Value of Precision-Cut Lung Slices for the Susceptibility of Three Animal Species for SARS-CoV-2 and Validation in a Refined Hamster Model

Abstract

In assessing species susceptibility for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and in the search for an appropriate animal model, multiple research groups around the world inoculated a broad range of animal species using various SARS-CoV-2 strains, doses and administration routes. Although in silico analyses based on receptor binding and diverse in vitro cell cultures were valuable, exact prediction of species susceptibility based on these tools proved challenging. Here, we assessed whether precision-cut lung slices (PCLS) could facilitate the selection of animal models, thereby reducing animal experimentation. Pig, hamster and cat PCLS were incubated with SARS-CoV-2 and virus replication was followed over time. Virus replicated efficiently in PCLS from hamsters and cats, while no evidence of replication was obtained for pig PCLS. These data corroborate the findings of many research groups that have investigated the susceptibility of hamsters, pigs and cats towards infection with SARS-CoV-2. Our findings suggest that PCLS can be used as convenient tool for the screening of different animal species for sensitivity to newly emerged viruses. To validate our results obtained in PCLS, we employed the hamster model. Hamsters were inoculated with SARS-CoV-2 via the intranasal route. Susceptibility to infection was evaluated by body weight loss, viral loads in oropharyngeal swabs and respiratory tissues and lung pathology. The broadly used hamster model was further refined by including activity tracking of the hamsters by an activity wheel as a very robust and sensitive parameter for clinical health. In addition, to facilitate the quantification of pathology in the lungs, we devised a semi-quantitative scoring system for evaluating the degree of histological changes in the lungs. The inclusion of these additional parameters refined and enriched the hamster model, allowing for the generation of more data from a single experiment.

Immune durability and protection against SARS-CoV-2 re-infection in Syrian hamsters

“…Sections (5 μm) were cut from the paraffin blocks and placed on slides. Slides were stained with haematoxylin and eosin using the Leica Autostainer XL (Leica Biosystems Inc) and scored by a board-certified veterinary pathologist using established methods [ 26 , 27 ].…”

Advances and gaps in SARS-CoV-2 infection models

“…Furthermore, the disease development may also be related to age of the used hamsters with older hamsters showing more severe disease progression [66], although others found no substantial age-related difference [67,68]. Despite the gaps of knowledge, hamsters have become the model of choice for preclinical testing of vaccines and therapeutics together with different species of NHPs [69][70][71][72].…”

Efficient direct and limited environmental transmission of SARS-CoV-2 lineage B.1.22 in domestic cats

“…Virus SARS-CoV-2/human/NL/Lelystad/2020 was isolated from a human subject early in the pandemic and used for challenge inoculation. Details can be found in Gerhards et al (2021) and the sequence is available under GenBank accession number MZ14458.…”

“…Formalin-fixed samples were embedded in paraffin, sectioned at 5μm and stained with haematoxylin and eosin (H&E) for histological examination according to general pathology principles. IHC of histological specimens was performed with an antibody directed against the SARS-CoV nucleoprotein, as previously described (Gerhards et al 2021).…”