Amphipathic Antigens of Oral Microorganisms — Immunogenicity and Other Biological Properties

Abstract

Amphipathic antigens are characterized by possessing both hydrophilic and hydrophobic regions in their molecular structure. These dual features dictate their physicochemical properties and, in turn, play a determinative role in their biological properties. The most well known examples of such antigens are the lipopoly-saccharides of Gram-negative bacteria and the lipoteichoic acids found in many genera of Gram-positive bacteria. Both types of amphophile are membrane associated through hydrophobic interaction of their lipid moieties with phospholipid bilayer; in the case of lipopolysaccharides with the outer cell membrane of the cell envelope and with lipoteichoic acids the plasma cell membrane of the Gram-positive bacterial cell (1,2,3). More recently examples of another class of amphipathic molecule have been reported (4,5), the lipomannans of Micrococcus spp. Like lipoteichoic acids, lipomannans are membrane associated. All three classes of amphophile are known to be immunogenic and can act as surface antigens (3,4). In the case of lipopolysaccharides a surface location is perhaps obvious from the association with the outer cell membrane.