Hamster and ferret experimental infection with intranasal low dose of a single strain of SARS-CoV-2.

Understanding the pathogenesis of the SARS-CoV-2 infection is key to developing preventive and therapeutic strategies against COVID-19, in the case of severe illness but also when the disease is mild. The use of appropriate experimental animal models remains central in the in vivo exploration of the physiopathology of infection and antiviral strategies. This study describes SARS-CoV-2 intranasal infection in ferrets and hamsters with low doses of low-passage SARS-CoV-2 clinical French isolate UCN19, describing infection levels, excretion, immune responses and pathological patterns in both animal species. Individual infection with 103 p.f.u. SARS-CoV-2 induced a more severe disease in hamsters than in ferrets. Viral RNA was detected in the lungs of hamsters but not of ferrets and in the brain (olfactory bulb and/or medulla oblongata) of both species. Overall, the clinical disease remained mild, with serological responses detected from 7 days and 10 days post-inoculation in hamsters and ferrets respectively. The virus became undetectable and pathology resolved within 14 days. The kinetics and levels of infection can be used in ferrets and hamsters as experimental models for understanding the pathogenicity of SARS-CoV-2, and testing the protective effect of drugs.