Immuno-electron microscopy of <i>M. catarrhalis</i>.

<p>Mice were vaccinated intranasally (1 dose per week, 4 doses in total) with either the adjuvant cholera toxin alone (1 μg/dose/mouse) or the combined conjugates AB (2.5 µg of each carbohydrate per dose per mouse) plus adjuvant. Mouse sera were collected at 1 week after the final immunization. Whole cells of strain 25238 (type A, A), 26397 (type B, B), or 26404 (type C, C) were incubated with the mouse hyperimmune sera (1:400 dilution) followed by gold (5-nm diameter)-conjugated goat anti-mouse IgG. Whole cells of strain 25238 (D) incubated with the corresponding pre-immune mouse sera (1:400 dilution) were included as a control. Scale bar, 100 nm.