FIG. 6.

K⁺ depletion does not inhibit influenza virus infection. (A) HeLa cells were shocked in a hyptonic medium for 5 min before either an influenza vRNP entry assay, a 4-h infection (1 PFU/cell), a low-MOI infection (<0.1 PFU/cell), or a transferrin (Tfn) uptake assay in a K⁺-free medium. Influenza virus infection was detected by indirect immunofluorescence with a monoclonal antibody against NP. Note that cells were not acid washed after transferrin uptake. (B) FACS analysis. HeLa cells were shocked in a hyptonic medium for 5 min before an influenza virus entry assay in a K⁺-free medium. Influenza virus was detected by a monoclonal antibody against NP. (C) FACS analysis of SFV infection in cells depleted of potassium. HeLa cells were shocked in a hypotonic medium for 5 min before 5 h of infection with SFV in a K⁺-free medium. Virus infection was detected by monoclonal antibody E1-1.