The D-6 and D-LZ mutant proteins are associated with capsids. Western blot of fractions (1, top; 18, bottom) obtained by sucrose density gradient sedimentation of capsids from cell lysates of Vero cells infected with KOS (WT), hr74 (null), or the D-6, D-LZ, or D-5 mutant. Each blot was divided into two strips and probed separately with anti-UL6 and anti-VP5 antibodies. A, B, and C represent the positions of the three types of capsids in the sucrose gradient. The last lane, CL, contained a sample of the infected-cell lysate, used as a control to monitor the expression of the mutant proteins.