To determine antibody response to immunization, Pg extract or purified Pg fimbriae were blotted onto nitrocellulose as follows: (A) Various amount of Pg extracts was blotted onto nitrocellulose as follows: 1. 10μg, 2. 30μg, 3. 90μg. (B) Purified Pg components were blotted onto nitrocellulose as follows: 1. Lys-gingipain, 2. Gingipain R, 3. Gingipain R1, 4. Recombinant hemin/hemoglobin utilization receptor, 5. Purified Pg fimbriae (67kD + 41kD). (C) Lane 1-4, 100μg Pg extract each; (D) Lane 1-4, 1μg, 3μg, 6μg, 9μg of purified Pg fimbriae. The membrane was incubated with pooled serum (1:200) or pooled saliva (1:3.5) from rats immunized with Pg DNA (6 weeks post immunization), then with goat anti-rat IgG-HRP (1:10000). Color was developed with HRP substrate kit (BioRad).