THE USE OF SYNTHETIC PEPTIDES IN THE DESIGN OF A CONSENSUS SEQUENCE VACCINE FOR PSEUDOMONAS-AERUGINOSA

Pseudomonas aeruginosa employs pill to mediate adherence to epithelial cell surfaces. Research has shown that the C-terminal region of the p ilin monomer contains the epithelial cell binding domain, which is sem iconserved in seven different strains of this bacterium. Antibodies to this region of the pilin molecule are also able to block and prevent the infection process. As there is a degree of sequence and structural homology in the C-terminal region and all strains examined have been shown to bind to the same cell surface receptor, we reasoned that it s hould be possible to produce a synthetic peptide consensus sequence wh ich would provide cross-reactive antiserum from a single peptide immun ogen inhibiting the adherence of the known strains of Fl aeruginosa. I n this article we examine the cross-reactivity of five rabbit polyclon al antisera. One has been raised against the cell-surface receptor bin ding domain of native PAK strain pilin (residues 128-144) while the ot hers have been raised to analogues of this region. Analysis of the cro ss-reactivity of these antisera, using competitive ELISA assay, has sh own that it is possible to manipulate the amino acid sequence of a pep tide immunogen to generate antiserum, which exhibits enhanced cross-re activity to various strains of Fl aeruginosa. Furthermore, when this p eptide is conjugated to tetanus toroid and used to vaccinate mice it p rovided cross-reactive protection against heterologous challenge with PAO strain bacteria. The results of these experiments are analyzed, an d the applicability of our hypothesis and the implications of this app roach to the design of a strain-independent consensus vaccine for immu nization against Pseudomonas aeruginosa are discussed.