Figure 1.

Guinea pig immunization protocol. Groups of six guinea pigs were immunized with each immunogen. A 25-μg sample of purified gp120_core or gp120_core W69A (or equivalent volume of phosphate-buffered saline (PBS)) was emulsified with AS02A adjuvant in a final volume of 0.5 mL and used to inoculate each animal intramuscularly. Supplemental immunizations were given 6, 10, and 14 weeks after the initial immunization. Blood samples were collected from each animal 10 days after the last immunization.