FIG. 3.

Neutralizing antibody response in peptide-immunized animals before and after challenge with either SHIV-89.6P or SHIV-89.6. Animals were inoculated with either C4/scbl-V3 or C4/89.6P-V3 at weeks 0, 6, 12, 18, 24, and 31 and were challenged with either SHIV-89.6P or SHIV-89.6 at week 33. Neutralizing antibodies to SHIV-89.6 (A) and SHIV-89.6P (B) were measured in MT-2 cells at multiple times throughout the immunization schedule and postchallenge. Peptide inoculations were made at the times indicated (∧). Arrow, day of challenge. The lowest serum dilution tested was 1:20 for SHIV-89.6 and 1:5 for SHIV-89.6P (negative results were given values of 20 and 5, respectively, for presentation).