Fig 1: Age-associated delay in viral clearance in olfactory mucosaa, Representative images showing CD45 and Iba1 co-staining in olfactory mucosa. Mock or maSARS-Cov2 infected wildtype mice were examined at 6dpi.b, Co-immunostaining shows Iba1+ macrophages engulfing NP+ debris in hamster olfactory mucosa at 4dpi.c, Representative image of Iba1 and cleaved caspase-3 co-staining in hamster at 4dpi. Arrowheads highlight the Iba1+ macrophages undergoing apoptosis.d, Representative images showing Iba1 or NP staining in serial sections. Each panel combines 6 40x images acquired under tile scan mode. Young or old hamsters’ olfactory tissues were examined at 6dpi.e,f, Quantification of Iba1+ (e) or NP+ (f) cells in hamster nasal olfactory lumen at 6dpi. Serial sections (d) from 4 different levels were quantified.g, Violin plots showing the differentially expressed Clec4n (Dectin2) or Fpr2 in young and old macrophage/dendritic lineage.h, Confocal images of Iba1 and Dectin2 co-staining in mouse olfactory mucosa.Each data point represents an individual hamster sample. Statistical significance was determined by unpaired two-tailed t-test. The white dotted line in (a-c) indicates the basement membrane. Scale bars, 20 µm (a-c, h); 50 µm (d).