The binding of Ad5 to erythrocytes can be visualized by cryo-electron microscopy. Erythrocyte ghosts were exposed to Ad5 for 30 minutes before fixation and imaging. (A) Gallery of 6 images of Ad5 interacting peripherally with human erythrocyte ghost membranes in PBS. In each case, the tubular density visible for the pentagonal vertex fiber is boxed in red, with a series of points marking the flexible path of the fiber from the Ad5 surface above to the membrane below. (B) Images of Ad5 and ghost membranes in close association in PBS. (C) Central image shows a reconstruction of the close interaction of Ad5 with the human ghost membrane. The planar membrane (blue density mesh) forms the top part of the image, and the curved pentagonal vertex of the Ad5 (gray density surface) the bottom portion. They are linked by a crown of obliquely oriented features. The Ad5 portion of the image is superimposed with the equivalent portion of a whole-Ad5 reconstruction, for comparison.21 The whole Ad5 is shown to the left (gray density), in the same orientation as in the middle panel, with equivalent portions in the 2 boxed in red. A closeup of one connection is shown to the right, and equivalent portions of it and the central image are boxed in magenta.
