FIG 5.

Role of cell surface sialic acid and dynamin-dependent endocytosis in MGL1-mediated infection of Lec1 cells by IAV. (A) Monolayers of parental CHO-ctrl and Lec1-MGL1 cells were mock treated or treated with 100 mU/ml bacterial sialidase (Sial) for 60 min at 37°C, followed by incubation with 5 mg/ml ASF or medium alone at 4°C for 30 min. Cells were then incubated with 10⁷ PFU of BJx109 for 1 h at 4°C to allow virus binding, washed, and incubated for a further 7 h at 37°C. (B) Monolayers of parental CHO-ctrl and Lec1-MGL1 cells were incubated with 10⁷ PFU of BJx109 alone (mock) or in the presence of 50 μM dynasore for 1 h at 37°C, washed, and incubated for a further 7 h in the presence or absence of dynasore. Cells were fixed and stained for expression of newly synthesized viral NP as described in Materials and Methods. Cells were fixed, stained, and examined by immunofluorescence as described in the text. CHO-ctrl cells incubated with 10⁶ FFU of PIV-3 in the presence or absence of dynasore were fixed and stained at 16 h postinfection. Data represent the mean percent infection (± 1 SD) and are representative of 2 independent experiments. ***, significantly different from mock-treated control cells (P ≤ 0.001; one-way ANOVA); #, significantly different from mock-treated Lec1-MGL1 cells (P ≤ 0.001; one-way ANOVA).