The G614 pandemic SARS-CoV-2 variant is not more pathogenic than the original D614 form in adult Syrian hamsters

Highlights: • Adult hamsters support SARS-CoV-2 replication in upper and lower respiratory tracts. • Adult hamsters suffer severe pneumonia and weight loss after SARS-CoV-2 infection. • Viral loads were similar for older (614D) and newer (614G) SARS-CoV-2 in hamsters. • Lung pathogenesis was similar for an older (614D) and newer (614G) clinical isolate. Dynamic tracking of variant frequencies among viruses circulating in the global pandemic has revealed the emergence and dominance of a D614G mutation in the SARS-CoV-2 spike protein. To address whether pandemic SARS-CoV-2 G614 variant has evolved to become more pathogenic, we infected adult hamsters (>10 months old) with two natural SARS-CoV-2 variants carrying either D614 or G614 spike protein to mimic infection of the adult/elderly human population. Hamsters infected by the two variants exhibited comparable viral loads and pathology in lung tissues as well as similar amounts of virus shed in nasal washes. Altogether, our study does not find that naturally circulating D614 and G614 SARS-CoV-2 variants differ significantly in pathogenicity in hamsters.