THE SPECIFICITY AND AFFINITY OF IMMUNOLIPOSOME TARGETING TO ORAL BACTERIA

Immunoliposomes have been prepared using antibodies raised to an antig enic determinant on the cell surface of the oral bacterium Streptococc us oralis (S. oralis) in an investigation of their potential to reduce dental plaque. The N-succinimidyl-S-acetylthioacetate (SATA) derivati ve of the antibodies were conjugated through the reactive m-maleinidob enzoyl-N-hydroxysuccinimide (MBS) derivative of dipalmitoyl-phosphatid ylethanolamine (DPPE) incorporated into liposomes. The degree of antib ody conjugation to the liposomes was controlled by the percentage of D PPEMBS incorporated into the liposomes. The chemical modification of t he antibodies did not affect the ability of the antibodies to bind to a S. oralis biofilm. However, the affinity of the immunoliposomes for S. oralis was much lower than that of the free antibody. The anti-oral is antibodies were highly specific for S. oralis. The anti-oralis immu noliposomes showed the greatest affinity for S. oralis, when targeted to a range of different oral bacterial biofilms. The immunoliposome ta rgeting affinity for S. oralis was largely unaffected by the number of antibodies conjugated to the liposomal surface or by the net charge o f the liposomal lipid bilayer. The immunoliposomes showed a greater af finity for S. oralis than 'naked' (bearing no antibody) liposomes. How ever: positively charged liposomes, incorporating stearylamine, adsorb ed to S. oralis with greater affinities than the immunoliposomes, The immunoliposomes appeared to be physically stable over a period of 18 m onths, as judged by particle-size measurements. (C) 1998 Elsevier Scie nce B.V.