FIG 4.

Infectivity of hMPV in an integrin-deficient cell line. (A) hMPV has defects in infectivity in an integrin-deficient cell line. Confluent monolayers of GD1286 or GD25 cells in 24-well plates were incubated at 4°C for 30 min. The cells were infected with 100 PFU of hMPV per well. After incubation on ice for 1 h (with shaking every 15 min), the inoculum was removed and the cells were washed with cold DMEM 3 times. The infected cells were then incubated with fresh medium at 37°C in 5% CO₂. After 24 h, the binding capacity was determined by counting the number of immunostaining spots. Percent infectivity in GD25 cells was normalized by the infectivity of hMPV in GD1286 cells. The data shown are averages for three independent experiments. (B) hMPV forms much smaller immunospots in an integrin-deficient cell line. Confluent monolayers of GD1286 or GD25 cells were infected with hMPV. After 24 h, immunostaining assay was performed, and immunospots formed by hMPV were visualized.