Figure 3. Comparison of proteins shed by infected and uninfected cells.

To compare shedding from infected and mock-infected cells, gradient ultracentrifugation was used to purify virion-sized material from the growth media of bovine epithelial (MDBK) cells 48 h after either infection with WSN or mock-infection. Purifications were performed with or without a prior haemadsorption / elution step (HAd), and protein standards were added after purification to allow comparison of samples with different total protein concentrations. Purified proteins were quantified by SINQ. (a) Total abundance of purified viral and host proteins, relative to the mean total protein abundance in the infected samples (mean and s.d. of three separate experiments, not including protein standards). (b – d) The abundance of individual proteins shed by infected and mock-infected cells, and detected in at least two of three separate experiments (mean and s.d. if N=3, mean and range if N=2; not including protein standards). Proteins not detected in one condition (infected or mock-infected) were assigned the lowest abundance of any protein detected in that condition. Panels show the abundance of proteins (b) purified without HAd, (c) purified with HAd, and (d) common to the mock-infected sample without HAd and to the infected sample with HAd.