Number of regulated genes in different functional categories following primary infection and reinfection.

<p>Number of regulated genes in different functional categories with at least 1.5-fold change and a significant t-test of p<0.05 (↑ upregulated, ↓ downregulated).</p

Expression of selected significantly changed genes over time in SARS-CoV infected–reinfected ferret lungs.

a<p>Mean gene expression ratios (log2) for selected genes is relative to the mock-infected ferret gene expression at 2 DPI.</p>b<p>Statistical significance of gene expression differences over time is determined by EDGE analysis as described in the Methods.</p>c<p><i>Canis familiaris</i> UniGene Build #11 (April, 2005) identifiers as per the Affymetrix GeneChip Canine Genome 2.0 Array probe library.</p

Mean levels of serum neutralizing antibody to SARS-CoV.

<p>Neutralizing antibody levels in serum were determined as outlined in the materials and methods section. Inverse neutralization titre is represented on the y-axis vs. day of study on the x-axis. Note that ferrets were infected on study day 1 and reinfected ferrets were also innoculated on study day 30. Mock infected animals received an intranasal instillation of serum-free media on study day 1 and had undetectable titres. Values shown represent group mean of 3–4 ferrets per group, and error bars show standard deviation.</p

Viral burden in lung tissue.

<p>Viral burdens in sections of lung were determined by the TCID₅₀ method, as outlined in the materials and methods section. Log10 virus titres are shown on the vertical axis vs. study day on the horizontal axis. Note that ferrets were infected on study day 1, and reinfected ferrets were also inoculated on study day 30. Mock infected animals received an intranasal instillation of serum-free media on study day 1 and had undetectable virus. Values shown represent group means of 3–4 ferrets per group, and error bars show standard deviation.</p

IFN responses in SARS-CoV infected-reinfected ferret lungs.

<p>(A) Fifty IRGs selected by pathway analysis are shown in a one-way hierarchical cluster. (B) IPA canonical IFN-signaling pathway analysis at 3 DPI and 3 DPR. All genes are significantly differently expressed (EDGE analysis: ≥2-fold change in at least one time point, p≤0.05, and q≤0.1).</p

Lung histopathology to SARS-CoV challenge following reinfection.

<p>Histological lung sections (5 µm) were obtained from multiple lung lobes at 7 d postchallenge and stained by hematoxylin and eosin. Representative micrographs from uninfected (A), SARS infected alone (B), or SARS infected and re-infected (C and D) are shown. Primary SARS-CoV infection produced inflammation and the appearance of lung immune cells primarily surrounding small-to-medium bronchial airways at 7 days following challenge (B). Ferrets that received infection-reinfection were largely protected from lung histopathology (C).</p