Immunological study of antisera to to artificial O-antigen of Pseudomonas aeruginosa.

O-sera were obtained by immunizing rabbits with artificial antigens: polysaccharide extracted from the lipopolysaccharide of P. aeruginosa (strain No. 868; 03a, 3d, 3e), or the high-molecular-weight or low-molecular-weight fraction of this polysaccharide, complexed with a natural protein (human IgG or rabbit globulin). The antisera to these antigenic complexes were highly O-specific. Antisera to the complexes of polysaccharide-protein and high-molecular-weight fraction-protein were more active in the passive haemagglutination reaction, slide agglutination test and immunodiffusion test in agar gel than was antiserum to the low-molecular-weight fraction-protein complex. The artificial antigens prepared and employed in the study are apt to be used for the preparation of monospecific immune sera.