FIG 3.

VLP formation. (A) VLPs were prepared as described in Materials and Methods. At 48 h posttransfection, the supernatants and cells were harvested. The supernatants were concentrated through a 30% sucrose cushion and then their hemagglutinin units were analyzed by using a hemagglutination assay. Data are presented as means ± SD (n = 3). **, P < 0.01 (Student's t test). (B) The concentrates and cell lysate were analyzed by SDS-PAGE followed by immunoblotting to detect viral proteins; the grayscale value of each band was measured by using ImageJ_1.50a software.