Brucellosis vaccine protects against liver and spleen infection, but not lung infection.(Brief Article)

2002 SEP 4 - (NewsRx.com & NewsRx.net) -- by Maria G. Essig, MS, ELS, senior medical writer - Mice immunized intranasally with a vaccine composed of lipopolysaccharide from Brucella combined with a membrane protein of Neisseria received some protection against brucellosis infection of the liver and spleen, but not of the lungs.

Apurba K. Bhattacharjee and colleagues at the Walter Reed Army Institute of Research in Washington, DC, formulated a vaccine containing purified Brucella melitensis lipopolysaccharide (LPS) combined noncovalently with the group B outer membrane protein (GBOMP) of Neisseria meningitidis.

Mice immunized with the vaccine demonstrated high titers of LPS-specific immunoglobulin (IgG) antibodies and a robust humoral response in the mucosa. The antibody response was dominated by the IgG1 subtype, but also included the IgG2a, IgG2b, and IgG3 subtypes. The humoral response remained strong for 16 weeks after immunization (Protection of mice against brucellosis by intranasal immunization with Brucella melitensis lipopolysaccharide as a noncovalent complex with Neisseria meningitidis group B outer membrane. Infection and Immunity, 2002;70(7):3324-3329).

Four weeks after the second vaccination, the vaccinated and control mice were challenged with a virulent strain (16 M) of B. melitensis (10[superscript]4 colony-forming units, CFU). The lungs, liver, and spleen were examined for bacterial infection 3 days, 9 days, and 8 weeks after the challenge.

On day 3, all of the mice had B. melitensis infection in the lungs but none had spleen or liver infections. However, by day 9, the spleens and livers of 40% of the mice were infected.

By 8 weeks post-immunization, significant differences existed in spleen and liver infections between immunized and control mice. Of the 62 immunized mice, 25 (40%) had infected spleens, compared with 61 of the 62 control ...