Isocage n bio containment system

Housing and experimental infections of hamsters have been described [15] (link), [16] (link), [17] (link). In brief, 6 to 8 weeks old female Syrian hamsters (Mesocricetus auratus) were sourced from Janvier Laboratories and kept per two in individually ventilated isolator cages (IsoCage N Bio-containment System, Tecniplast) at 21 °C, 55% humidity and 12:12 day/night cycles. Animals had ad libitum access to food and water, and a wooden gnawing block and extra bedding material was provided as cage enrichment. All hamsters had SPF status at arrival and manipulations were performed under a laminar flow cabinet. Animals were anesthetized with ketamine/xylazine/atropine and intranasally infected with 50 µL of virus stock containing approximately 1 × 10⁵ TCID₅₀ (25 µL in each nostril), and euthanized 4 days post infection (dpi) for sampling of the lungs and further analysis by i.p. injection of 500 μL Dolethal (200 mg/mL sodium pentobarbital).

Female, 4-10 weeks old C57BL/6JOlaHsd (BL6) mice were purchased from Envigo RMS GmbH and were housed under pathogen-free conditions at the animal facility of the University of Veterinary Medicine Hannover, Foundation, in individually ventilated cages type Sealsafe Plus GM500 or IsoCage N Biocontainment system (Tecniplast) for the entire duration of the experiment. All mice were subjected to two weeks of habituation and acclimatization before they were taken into the experiments. Sterilized food pellets and water were provided ad libitum.

The hamster infection model of SARS-CoV-2 has been described before^{23 (link),24 (link)}. Female Syrian hamsters (Mesocricetus auratus) were purchased from Janvier Laboratories and kept per two in individually ventilated isolator cages (IsoCage N Bio-containment System, Tecniplast) at 21 °C, 55% humidity and 12:12 day/night cycles. Housing conditions and experimental procedures were approved by the ethics committee of animal experimentation of KU Leuven (license P065-2020). For infection, two groups of index female hamsters of 6-8 weeks old were anesthetized with ketamine/xylazine/atropine and inoculated intranasally with 50 µL containing 1×10⁴ TCID₅₀ of either SARS-CoV-2 WT virus or the 3CLpro^res virus(day 0). In the morning of day 1 post-infection (pi), each index hamster was co-housed with a contact (sentinel) hamster (non-infected hamsters) in one cage and the co-housing continued until the sacrifice day i.e. 3 days after start of exposure. On day 4 pi, animals were euthanized by intraperitoneal injection of 500 μL Dolethal (200 mg/mL sodium pentobarbital) and lungs were collected for further analysis. Two independent studies were performed each with a total of n = 12 per group.