FIG. 5.
Biphasic induction of mRNA in aged SARS-CoV-infected mice. (A) Protein and mRNA levels of indicated cytokines and chemokines in aged SARS-CoV-infected mice on the indicated days postinfection. The data are presented for aged (A) mice on indicated days (D) 1, 2, 5, and 7 postinfection. Gene transcripts (fold change) showed biphasic responses similar to those observed with protein levels (ng of cytokine per g of lung tissue). Although Ifng did not show a biphasic protein response, the gene showed biphasic transcript. Fold changes of transcripts are the result of comparing the gene expression in the lungs of experimentally infected mice (pooled, n = 4) with the gene expression in the lungs of mock-infected mice (pooled, n = 5). Concentration of cytokines are the results of cytokine bead assays. (B) Graph showing the fold change in genes exhibiting a biphasic response on the indicated days postinfection. Each line represents an individual gene. Using the criteria of a fold change of ≥2 at day 2, a decrease in fold change at day 5, and a fold changeday 7/fold changeday 5 ratio of ≥2, 33 genes were defined as showing a biphasic response.