Gene expression profiling of patients with severe acute respiratory syndrome (SARS)

We used cDNA microarrays to systematically analyze host responses in SARS-infected individuals from onset of symptoms to discharge from hospital or death. We modeled gene expression in 60 datasets from 40 unique patients of varied clinical evolution with emphasis on correlating innate and adaptive immune responses with discrete clinical phases of the disease. Keywords: Comparative patient class comparision, SARS patients relative to healthy controls Peripheral blood was collected in 5 ml heparinized blood collection tubes from study participants upon presentation to the hospital. The median length between onset of symptoms consistent with SARS and presentation to the hospital was 2 days (range 0-7 days). Peripheral blood specimens were then collected longitudinally every five days during hospitalization and at discharge from the hospital. Whole blood RNA was stabilized and purified using Paxgene Blood Collection Tubes and Paxgene RNA kits (Qiagen, Mississauga, ON, Canada). Sufficient RNA yields were obtained after Paxgene Whole Blood RNA isolation for 70 samples from 40 unique SARS patients and 10 healthy controls (HC1-10) and amplified using MessageAmp kits (Ambion). Replicate measurements or dye swaps were not possible due to severe limitations in RNA quantity. All samples (Cy5) were hybridized against amplified reference RNA (Cy3) (Stratagene, La Jolla, CA). Longitudinal ANOVA were performed to select significantly altered genes in the pre-crisis (acute) phase of SARS (0-8 days since onset, n=22), crisis phase for non-severe SARS patients (8+ days since onset, n=15) and crisis phase for severe SARS patients (8+ days since onset, n=23).