Fig. 4
Early IFN-α2b treatment efficiently suppressed SARS-CoV-2 Omicron BA.1 replication and lung pathogenesis. Juvenile and aged male hamsters were intranasally inoculated with 1 × 105 PFU of SARS-CoV-2 Omicron BA.1 and then administered three doses of recombinant IFN-α2b treatment at 24, 25, and 26 h post-infection. The body weight changes of SARS-CoV-2 Omicron BA.1-infected (a) juvenile, (b) adult and (c) aged hamsters and hamsters with early IFN-α2b treatment were measured from 0 to 5 dpi (n = 4/group). All hamsters were euthanized at 5 dpi. d Gross lung images, e representative H&E staining of lung lobes and f comprehensive pathological scores are shown (for each group, 16 lung lobes collected from four hamsters were evaluated). The viral RNA loads in respiratory tract organs, including the (g) turbinates, (h) trachea and (i) lungs, were measured by RT‒PCR (n = 4/group). We analyzed the differences between the hamsters with and without early IFN-α2b treatment in each age group. Significance was calculated using an unpaired two-tailed t test (*P < 0.05; **P < 0.01; ***P < 0.001; ns nonsignificant)
