HIV-1 colocalizes with the recycling endocytic marker transferrin.

<p>VK2 cells were plated on glass coverslips in a 12-well plate and grown 48 h at 37°C, 5% CO₂. Native or heat-inactivated HIV-1 IIIB was then added to the cells and incubated for 4 h then subjected to confocal microscopy as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0096760#s5" target="_blank">Materials and methods</a> after removal of non-internalized virus. HIV-1 is shown in green and transferrin is shown in red. Bar graph represents the percentage cells positive for colocalization from the random counting of 162 cells exposed to native and 170 cells exposed to heat-inactivated virus. Arrows points to colocalization signals. Inset is a magnification of the signal that is inside the box.