DECONVOLUTION OF FULLY OVERLAPPED REFLECTIONS FROM CRYSTALS OF FOOT-AND-MOUTH-DISEASE VIRUS O-1 G67

Foot-and-mouth disease virus O-1 G67 forms crystals that appear simila r to those of the closely related viruses O1K and O1BFS, both of which belong to space group I23. Statistical disorder in the O-1 G67 crysta ls means, however, that the measured diffraction data possess higher s ymmetry consistent with point group 432. It is shown that this is due to intimate twinning, with mosaic blocks randomly distributed between the two orientations. This results in a twofold loss of information du e to the exact superimposition of non-identical reflections from the t wo orientations. A simple procedure has been devised to deconvolute th ese overlapped reflections by applying constraints in both real and re ciprocal space. This procedure works well, providing interpretable ele ctron-density maps for this virus. Other applications are discussed.