Fig. 1

a Replication studies of archetype JCV in COS-7 cells and in supernatants during infection. The efficiency of JCV replication during infection was assessed at selected sampling times in cells and in the supernatants collected one time a week from 4 days post infection (d.p.i.) and after 7 d.p.i., 14 d.p.i., 21 d.p.i., 28 d.p.i. until 35 d.p.i. Extra and intracellular JCV DNAs were quantified by Q-PCR of supernatants and extracted DNA from cells respectively, harvested at the indicated time points. The increase of JCV replication in COS-7 cells (diamonds) and in the supernatant (squares) during the infection experiments is shown. Data were expressed as the mean of three independent experiments, error bars represented standard deviations. For COS-7 cells data were expressed as genome equivalents (gEq) of viral DNA per cell DNA content (gEq/cell DNA content) and for supernatants as genome equivalents (gEq) of viral DNA per milliliter (gEq/ml). b Analysis of VP1 expression in COS-7 cells and in supernatants during infection. Cell protein extracts (Panel A) and supernatants (Panel C) from uninfected (U) and infected COS-7 cells were harvested at 7 d.p.i., 14 d.p.i., 21 d.p.i., 28 d.p.i. and 35 d.p.i. and analyzed by Western blot to evaluate the expression of the VP1 protein. Equal amounts of protein from supernatants and whole cell protein extracts were separated by SDS-PAGE, transferred to PVDF and probed using anti-VP1 antibody. Bars depict the expression level of VP1 protein during infection quantified by densitometry (ImageJ software), and normalized to host cell number (VP1/GAPDH) (Panel B). Data are expressed as arbitrary units and are means ± SD from at least three independent experiments