Figure 5
Protective immunity experiments in guinea pigs vaccinated with 2 immunizations of various SterneΔhtrA spore doses.
(a) A schematic representation of the double-immunization experiments is shown. (b) The Kaplan-Meier survival profiles of the guinea pigs (at least 10 guinea pigs/group) immunized with the indicated doses of SterneΔhtrA spores is shown. The animals were challenged 5 weeks after the second immunization (boost) with 100 × LD50 of the fully virulent Vollum spores (pXO1+; pXO2+) by SC infection (104 spores/animal, upper panel) or IN exposure (106 spores/animal, lower panel). See Fig. 6 for the pre-challenge anti-PA, anti-bacterial antigens and neutralizing antibody titres.
