Antibody response of rabbits and cystic fibrosis patients to an alginate-specific outer membrane protein of a mucoid strain of Pseudomonas aeruginosa.

The aim of this work was to study the immunogenicity of an outer membrane (OM) protein (AlgE; 54 kDa) which is produced solely by mucoid, i.e. alginate-producing strains of P. aeruginosa. The source of AlgE used for our study was the mucoid strain CF3/M1 originally isolated from sputum of a cystic fibrosis (CF) patient. The purified non-denatured protein served as antigen to raise polyclonal monospecific anti-AlgE antibodies in rabbits and to assay sera from 41 cystic fibrosis (CF) patients for anti-AlgE antibodies. According to clinical protocols the sputa of 22 CF patients were positive for P. aeruginosa, 18 were negative and one case was unknown. Our ELISA studies showed that high titers of anti-AlgE antibodies (IgG) corresponded well with the infection status of the CF patients. None of 23 control sera derived from healthy volunteers contained significant levels of anti-AlgE antibodies. Thus the ELISA should be considered as a sensitive diagnostic tool for the early detection of mucoid P. aeruginosa infections in CF patients. Furthermore, we suggest to include AlgE in a multicomponent experimental vaccine for potential protection of non-colonized CF patients from colonization with mucoid P. aeruginosa.