Human Coronavirus 229E Remains Infectious on Common Touch Surface Materials

Warnes, Sarah L.; Little, Zoë R.; Keevil, C. William

Infectivity assay for HuCoV-229E exposed to surfaces. Infected cell lysate preparations of HuCoV-229E were spread over coupons of the test surface and incubated at room temperature. The virus was removed from the coupons at various times and assayed for infectious virus by a plaque assay which was a modification of the murine norovirus 1 (MNV-1) assay described previously (26) . Briefly, coupons inoculated with virus and incubated for various times at room temperature were added to a tube containing 5 ml growth medium and 2-mm-diameter glass beads and subjected to vortex mixing for 15 s. Dilutions were prepared in growth medium, and 1-ml aliquots were plated onto confluent monolayers of MRC-5 cells that had been prepared 24 h earlier in 6-well trays. The inoculum was removed after 90 min and replaced with agarose overlays, and plates were incubated at 37°C and 5% CO 2 for 4 to 7 days until CPE was evident. The monolayers were stained with vital stain and neutral red, and plaques in the monolayer were enumerated. Triplicate samples were processed for each time point.