EN
This work describes the role of membrane bridges in the spread of ectromelia virus (ECTV) Moscow strain (ECTV-MOS) in vitro in BALB/3T3 and Vero cells. In this research, immunofluorescence techniques were used: cells were fixed, stained for the presence of viral antigens, F-actin, and DNA, and viewed under a fluorescence microscope. In both cell lines, ECTV-MOS infection induces production of two types of actin-rich protrusions: tiny actin tails or long filopodia-like structures. It appears that both types contribute to the spread of ECTV-MOS particles and may be classified as membrane bridges.