Inhibitory activity of 3AB on PI4P biosynthesis can be overcome by 3CD but that of 3A cannot.

<p><b>(A)</b> HeLa cells expressing 3CD in the absence or presence of 3AB or 3A were immunostained for the presence of PI4P (red), 3CD (green), and 3A(B) (magenta). The nucleus is stained with DAPI (blue). <b>(B)</b> Quantification of PI4P intensity per cell was performed as described in the legend to <b><a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1007086#ppat.1007086.g001" target="_blank">Fig 1C</a></b>. The averages of the normalized values were: 1.00 ± 0.03, n = 40 (SEM) in mock cells; 2.61 ± 0.13, n = 30 (SEM) in 3CD-transfected cells; 2.37 ± 0.10, n = 30 (SEM) in 3CD and 3AB co-transfected cells; and 0.83 ± 0.03, n = 35 (SEM) in 3CD and 3A co-transfected cells. The level of PI4P induction observed in 3CD and 3AB co-transfected cells was significant when compared to mock or 3CD and 3A co-transfected cells based on a Student’s t-test, which gave a P value of <0.0001 in both instances. There was no significant difference between 3CD-transfected cells and 3AB and 3CD co-transfected cells based on a Student’s t-test, which gave a P value of 0.1490. The diminished level of PI4P observed in 3CD and 3A co-transfected cells was significant when compared to mock based on a Student’s t-test, which gave a P value of <0.0001.