Fig. 2: Immunogenicity and protection of serotype 1 OspA-ferritin nanoparticles.
C3H mice were immunized intramuscularly with the molar equivalent of 1 µg of OspA-ferritin + Ribi adjuvant or 1 µg of RecombitekTM at week 0 and week 4. ELISA titers were measured 2 weeks after the 2nd immunization. A student t-test was used to determine statistical significance. Antibody titer induced by OspA-ferritin vaccine is 4.4-fold higher than that of Recombitek with 24% coefficient of variation (CV) and N = 5 per group is powered (0.8 power) to detect a 3-fold difference (p < 0.001). The mean is indicated with a horizontal line. a Homology of human LFA-1 aa 326-173 to OspA Serotype 1 (S1) (aa165-173), to OspA Serotype 2 (S2), to OspA Serotype 3 (S3) and a rational design mutant of OspA (RD). b ELISA titers 2 weeks after the 2nd immunization of the indicated mutants. c C3H mice (n = 5) were immunized intramuscularly at weeks 0 and 4 with a molar equivalent of 1 µg dose of the indicated vaccines with the Addavax adjuvant. All vaccines were composed of OspA Serotype 1 with only the LFA-1 epitope replaced with either RD, S2, or S3 sequence. The ELISA plate was coated with OspA-His serotype 1. Protective efficacy of OspA-ferritin nanoparticle vaccine (d). Mice were vaccinated with a molar equivalent of 1 µg dose of antigens at week 0 and week 4. OspA-ferritin serotype 1 with the RD epitope was used. Mice were challenged with 5–6 ticks infected with Borrelia burgdorferi N40 strain (serotype 1) for 5 days two weeks after the second immunization and sacrificed two weeks later. Tissue samples from the heart, ankle and ear were cultured in BSK media with antibiotics for B. burgdorferi for 6 wks. Negative samples were tested by PCR for the presence of B. burgdorferi. All negative cultures were also PCR-negative.
