FIG. 4.

Failure to induce RANTES expression by infection with UV-irradiated MV. (A) MV was exposed to UV irradiation for 60 min. U373 monolayers were treated with UV-irradiated MV at the equivalent of an MOI of 2.5 for 24, 36, or 48 h. RANTES mRNA expression was then assessed by Northern blotting (20 μg of total RNA/lane). The mRNA bands on the autoradiogram were quantitated, and results are presented as density ratios of RANTES mRNA to β-actin mRNA. Unstim, unstimulated. (B) Binding of UV-irradiated and live MV to U373 cells. Cells were incubated on ice for 2 h with live MV or MV exposed to UV for 60 min, each at an MOI of 10. Cells were reacted with monoclonal anti-MV HA IgG or IgG isotype and then with fluorescein isothiocyanate-conjugated anti-IgG, followed by FACS analysis. The increases in specific mean fluorescence in cell-bound MV and UV-irradiated MV (UV-MV) were 60.10 and 56.77, respectively. (C) MV irradiated by UV for 2.5 to 15 min was used at an MOI of 2.5 to infect U373 cells for 48 h in 75-cm² flasks. Expression of RANTES and MV-nucleocapsid mRNAs was determined by Northern blotting (20 μg of total RNA/lane). Representative results from one of three experiments are shown as RANTES/β-actin or MV nucleocapsid/β-actin mRNA density ratios.