Fig. 1.

P74 is cleaved efficiently and specifically during L-ODV purification. OBs produced from S. exigua larvae were used. L-ODVs were purified under three different conditions. For the samples in lanes 1, L-OBs were dissolved in DAS at room temperature. For the samples in lanes 2, L-OBs were precooled in ice water for 40 min and dissolved with cold DAS (4°C). For the samples in lanes 3, L-OBs were heated at 80°C for 40 min and then dissolved in DAS solution. For all three treatments, L-ODVs were purified at 4°C after DAS treatment. ODV samples were separated by 10% SDS-PAGE and analyzed with P74 MAb (A) or PIF1, PIF2, and PIF3 antibodies (B, C, and D, respectively). Positions of full-length P74, P74-N, PIF1, PIF2, and PIF3 are indicated by arrows. P74-N represents the N-terminal P74 fragment after cleavage.