Fig. 7.

Homologous and heterologous protection for mice immunized with killed NTHi bacteria. (A) Jbo/+ mice immunized three times subcutaneously with 10⁸ killed NTHi 162 (but not 176 or 375) had a significantly lower ME infection rate when inoculated with 10⁶ CFU of NTHi 162sr compared with PBS-immunized controls. (B) Jbo/+ mice immunized with killed NTHi 162, 176 or 375 had significantly lower ME titres than PBS-immunized controls. n=14-15 mice per cohort for NTHi 176- and 375-immunized mice and n=30 for NTHi 162- and PBS-immunized mice; data are represented as mean±95% CI. (A) Fisher’s exact tests comparing infection rates for each NTHi strain with the PBS control. (B) t-tests comparing titres for each NTHi strain with the PBS control. NS, not significant; **P<0.01; ***P<0.001.