FIG 2.

HRV-A89 uncoats much more slowly than HRV-B14. (A) Time course of RNA release. Cells were incubated with HRV-A89 at 100 TCID₅₀/cell and with HRV-B14 at 300 TCID₅₀/cell at 4°C for 60 min; unbound virus was removed, and cells were transferred into infection medium. At the specified times, uncoating was halted via addition of NH₄Cl, and incubation was continued for 16 h. Infected cells were then determined in a TissueFaxs. The number of infected cells at 120 min was arbitrarily set to 100% for each virus. Data shown are the means ± standard deviations from three independent experiments, each carried out in quadruplicate. (B) Time course of loss of infectivity. Viruses as specified were allowed to bind to the cells for 1 h at 4°C. Unbound virus was removed by washing three times with cold PBS. At time zero the cells were returned to 37°C in infection medium; they were frozen at the times indicated. Virus was released by freeze-thawing, debris was removed by centrifugation, and viral titer was determined in the supernatant as the TCID₅₀ per milliliter. Values are expressed in percentages of the initial viral titer. The means ± standard deviations from two independent experiments each carried out in six replicates is shown. Note that no further decrease of infectivity was observed between 120 min and 180 min (data not shown).