Fig. 1.

Propagation of SFV devoid of capsid in different cell lines. a SFV RNA genomes devoid of capsid (SFV-enh-spike or SFV-spike, abbreviated in the diagram as SFV-ΔC) were packaged into VPs by co-electroporation of BHK cells with a helper RNA able to provide the SFV capsid in trans (SFV-helper-C-S219A, abbreviated as SFV-helper-C). SFV-LacZ VPs were generated by co-electroporation of BHK cells with SFV-LacZ RNA and two helper RNAs providing the SFV capsid and envelope proteins in trans, respectively [22] (not shown in the diagram). VPs were collected at 24 h post-electroporation and used to infect monolayers of BHK cells (b) or the indicated cell lines (c) at MOI 0.05. Cells were fixed at the indicated times and analysed by immunofluorescence (IF) with a polyclonal antiserum specific for the nsP2 subunit of SFV Rep (α-nsp2) (b), or with a polyclonal antiserum specific for SFV envelope proteins (α-spikes) (c). Images correspond to a representative experiment from at least two independent experiments performed in triplicate with similar results. Magnification of images: ×200 (except for images of C6/36 cells that were taken at ×400). Scale bar in all images: 50 μm