Isopropanol precipitation

Swab samples were inactivated using heat or DNA/RNA Shield as described above. 100 μL of each swab sample was mixed in 1.7 mL microcentrifuge tubes with 0.1 volumes of 3 M sodium acetate, pH 5.2, and 1 μL of 5 mg/mL linear acrylamide. Samples were then mixed with 1.1 volumes of isopropanol, incubated at -20°C for 30 min, and centrifuged at 16,000 g for 15 min at 4°C. Supernatants were aspirated, taking care not to disturb the pellets containing RNA. 1 mL of 75% ethanol was added to each sample, and samples were centrifuged again at 16,000 g for 5 min at 4°C. Supernatants were carefully but thoroughly aspirated. RNA was redissolved by adding 50 μL of water directly to each pellet and incubating for 10 min at 30°C.