Fig. 3

Measurement of viral RNA levels and the mRNA levels of proinflammatory cytokines and type I IFN-associated genes in respiratory tract organs of SARS-CoV-2 Omicron BA.1-infected juvenile, adult, and aged hamsters. a The viral RNA loads in respiratory tract organs, including the turbinates, trachea, and lungs, were measured by RT‒PCR at 5 dpi (n = 3). The fold changes in the mRNA levels of (b) proinflammatory cytokines and (c) IFN-α-associated genes in the lung tissues collected at 5 dpi (n = 3) are shown. The mRNA levels were standardized to those of the housekeeping gene γ-actin. We compared juvenile/aged hamsters to adult hamsters. Significance was calculated using two-way ANOVA (*P < 0.05; **P < 0.01; ***P < 0.001; ns nonsignificant)