Figure 7. Prior Nb Infection impairs antibody titres and vaccine efficacy following porin-immunization.

A) WT mice were infected with 5×10⁵ STm and splenic bacterial numbers were examined at day 5. Prior to infection mice were given either: i) PBS (dashed), ii) infected with 500 L3 Nb (open bar), iii) immunized with 20 µg porins (black bar) or iv) infected with 500 L3 Nb and then immunized with 20 µg porins (grey bar). B) WT mice were infected with 5×10⁵ STm opsonised with complement-inactivated serum from mice that had either been infected with STm for 35 days or primed with porins for 18 days and then boosted for 7 days. Splenic bacterial numbers were assessed 5 days post-infection. Prior to STm infection mice were either immunized with PBS or infected with 500 L3 Nb larvae for 16 days. Naïve control mice were infected with non-opsonised STm (open bar). C) Serum anti-porin IgG, IgG1 and IgG2a antibody titres were assessed by ELISA on serum isolated from mice immunized as in Figure 7A, but pre STm-infection. D) WT mice were either i) immunized with PBS (dashed bar) ii) infected with Nb for 18 days (open bar) before immunization with 20 µg porins for 18 days or iii) immunized with PBS (black bar) iv) infected with Nb for 18 days (grey bar) before immunization with 20 µg porins for 18 days followed by a second booster immunization for 7 days. Anti-porin IgG titres were then assessed by ELISA. Infections with STm and Nb were administered intraperitoneally and subcutaneously respectively. Data is representative of 4–6 mice per group and experiments were performed twice. POR = Porins. (^*P<0.05).