FIG. 1.

Modulation of antibody responses in rhesus macaques. Five groups of two rhesus macaques were immunized with 200 μg of each DNA vaccine construct at weeks 0, 6, and 12 and boosted with 500 μg of each DNA at week 28. Serum samples were collected from the immunized macaques at weeks 0, 18, and 36. Binding reactivities to recombinant HIV-1 gp120 envelope and SIV p27 Gag proteins (ImmunoDiagnostics, Inc., Bedford, Mass.) were determined by enzyme-linked immunosorbent assay as previously described (1). Specific binding (absorbance at 450 nm) was calculated by subtracting A₄₅₀ values from serum samples bound to bovine serum albumin (control) from A₄₅₀ values from serum samples bound to gp120, that is, the A₄₅₀s of experimental wells minus the A₄₅₀s of control wells. The endpoint antibody titers for immunized rhesus macaques were determined as previously described (1).