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Immunity conferred upon mice by anti-LPS monoclonal antibodies in murine brucellosis
J Limet1, A M Plommet, G Dubray
1Université Catholique de Louvain, International Institute of cellular and molecular pathology, Brussels.
An immune serum infused into mice prior to intravenous virulent Brucella abortus challenge may reduce initial colonization of the spleen on day 7 post-challenge and increase bacteriolysis in the spleen and liver, as evidenced on day 21. Three monoclonal antibodies (IgG1, IgG3 and IgG2a) directed toward the lipopolysaccharide-A epitope (LPS-A) of B. abortus were studied in this model and compared with three previously studied polyclonal immune sera. The three monoclonals restricted spleen infection on day 7 post-challenge and spleen and liver infections on day 21. These early and late effects were similar to those obtained with the two polyclonal sera of high anti-LPS-A titres, namely, serum from mice either infected by B. abortus or vaccinated with a cell-wall B. abortus fraction. In contrast, serum from mice vaccinated with LPS-M from B. melitensis, which had a high anti-LPS-M but a low anti-LPS-A titre, had lower activity, evidenced at day 7 only. Hence, immune serum protection was mediated by antibodies directed toward the LPS-dominant epitope of the challenge strain.
An immune serum infused into mice prior to intravenous virulent Brucella abortus challenge may reduce initial colonization of the spleen on day 7 post-challenge and increase bacteriolysis in the spleen and liver, as evidenced on day 21. Three monoclonal antibodies (IgG1, IgG3 and IgG2a) directed toward the lipopolysaccharide-A epitope (LPS-A) of B. abortus were studied in this model and compared with three previously studied polyclonal immune sera. The three monoclonals restricted spleen infection on day 7 post-challenge and spleen and liver infections on day 21. These early and late effects were similar to those obtained with the two polyclonal sera of high anti-LPS-A titres, namely, serum from mice either infected by B. abortus or vaccinated with a cell-wall B. abortus fraction. In contrast, serum from mice vaccinated with LPS-M from B. melitensis, which had a high anti-LPS-M but a low anti-LPS-A titre, had lower activity, evidenced at day 7 only. Hence, immune serum protection was mediated by antibodies directed toward the LPS-dominant epitope of the challenge strain.