Fig. 4.

Cholesterol content determination after cholesterol depletion and replenishment in cellular membranes. PAM-pCD163 and Vero cells were preincubated with various concentrations of MβCD with (+) or without (–) exogenous cholesterol and infected with PRRSV (A) and PEDV (B), respectively, in the presence or absence of MβCD and/or exogenous cholesterol as indicated. Virus-specific CPE was observed daily and photographed at 48 hpi using a fluorescent/bright-field microscope at a magnification of 200× (first panels). For immunostaining, infected cells were fixed at 48 hpi and incubated with the cholesterol-binding, fluorescing antibiotic filipin III (second panels). The cells were examined using a fluorescence microscope at 200× magnification