Protection conferred on mice by monoclonal antibodies directed against outer-membrane-protein antigens of Brucella

Abstract

Summary. Twenty-six monoclonal antibodies (MAbs) directed against seven brucella outer-membrane proteins (OMPs) of 10, 16.5, 19, 25–27, 31–34, 36–38 and 89 Kda were screened for passive protection of mice; three MAbs (directed against 16.5, 25–27 and 36–38 Kda) reduced significantly the initial colonisation of the spleen measured 7 days after challenge. Although significant, the reduction in numbers of Brucella organisms in the spleen was low compared with that conferred by MAbs against lipopolysaccharide of smooth specificity (S-LPS). The three most protective MAbs belonged to two isotypes (IgG1 and IgG2a) and were specific for three different OMPs. No relationship between protection and binding of MAbs to the challenge S strain or its rough mutant was observed in the mouse model. The humoral protection depended mainly on antibodies directed against S-LPS, although some MAbs against OMPs had weak protective activity.