FIG 1.
Expression of langerin by SIA-deficient Lec2 cells results in permissiveness to IAV infection. (A) (i) Langerin expression histograms showing cell surface expression of human langerin on Lec2-Lg, Lec2-ctrl, and CHO-ctrl cells. (ii) Western blot confirming expression of langerin in cell lysates from Lec2-Lg cells but not CHO-ctrl and Lec2-ctrl cells. (B and C) Monolayers of CHO-ctrl, Lec2-ctrl, and Lec2-Lg cells were infected with 107 PFU of BJx109 at 37°C for 1 h, washed, and incubated as described in Materials and Methods. (B) At 2 h and 8 h, supernatants were removed and total RNA was extracted from cell monolayers and used for qRT-PCR measurements of vRNA (panel i) and mRNA (panel ii) levels of the IAV M gene. The amount of RNA at 2 h and 8 h postinfection is shown on the left panel, while the fold increase in copy number between 2 h and 8 h postinfection is shown on the right. Data represent the mean (±1 SD) from triplicate samples and are representative of two independent experiments. (C) (i) At 2 h and 8 h postinfection, cells were fixed and stained for expression of viral NP. Representative images show NP (FITC, green) and nucleic acid (PI, red). (ii) Data show the mean percent infection (±1 SD) and are representative of five independent experiments. The detection limit is indicated by a horizontal dotted line. (D) FACS histograms showing HA and NP expression 15 min and 8 h postinfection of Lec2-Lg (black filled histogram), CHO-ctrl (gray filled histogram), Lec2-ctrl (gray unfilled histogram), and uninfected (dotted lines) cells. For data in panels B and C, statistical significance was assessed using Student's t test to compare two sets of data and a one-way ANOVA to compare multiple data sets. *, P < 0.05; **, P < 0.01; ***, P < 0.001.