Figure 2.

Protective antigen (PA)-specific serum antibody responses in rabbits after monovalent and bivalent vaccination. Serum from rabbits immunized (a) with rAAV1/PA (group 1, monovalent immunization), or (b) with both rAAV1/PA and rAAV1/LF (group 3, bivalent immunization) was tested for anti-PA reactivity by enzyme-linked immunosorbent assay at 2, 4, 8, 12, and 16 weeks after immunization. Prebleed serum and serum from group 4 rabbits inoculated with recombinant adeno-associated virus type 1 (rAAV1) expressing enhanced green fluorescent protein were negative (<64, data not shown). Each circle represents the response of an individual rabbit and the horizontal lines represent geometric mean end-point titers. Squares represent individual rabbit antibody titers from two positive control rabbits immunized four times with soluble PA83 in an emulsion with Freund's adjuvant. LF, lethal factor.