FIG. 8.

E2/E1 heterodimer formation. Vero cells were infected with C467A, L471A, or parental BRM34 virus. After 3 days of infection, the cells were lysed with buffer containing 1% Triton X-100. The lysates were applied to a 5 to 20% (wt/wt) sucrose gradient in TNE buffer containing 0.1% Triton X-100. After centrifugation in an SW41 rotor at 5°C and at 38,000 rpm for 28 h, the gradients were fractionated from the bottom of the tube. Samples (25 μl per fraction) were analyzed by SDS–10% PAGE under nonreducing conditions followed by immunoblotting and probing with human anti-rubella virus serum. Note that fractions 5 to 20 are shown in the figure. Sedimentation is from right to left. The capsid protein was found in the pellet fractions at the bottom of the gradient. The positions of molecular mass markers are shown on the right (in kilodaltons).