Isolation and Partial Characterization of a Genus Common Antigen and Species Specific Antigen of Capnocytophaga

Sixteen strains of Capnocytophaga were isolated from the pocket of a localized juvenile periodontitis patient. These strains were divided into four groups on the basis of morphological and physiological traits. Strains from group I and group III were identified as C. ochracea and group II as C. sputigena. An antigen common to genus Capnocytophaga was purified utilizing immunoabsorbent chromatography from lysates obtained by sodium dodecyl sulfate treatment of C. ochracea strain S1. An antigen specific to C. ochracea was prepared by sequential gel filtration and preparative isoelectric focusing. The genus common and species specific antigens isolated were immunologically unique and pure when tested by immunoelectrophoresis and immunodiffusion against rabbit antisera prepared to Capnocytophaga and other gram-negative rods. The genus common antigen was susceptible to trypsin and pronase digestion, was soluble in chloroformmethanol, but was unaltered by ribonuclease and deoxyribonuclease treatments and periodate oxidation. Antigenicity of the species specific antigen was destroyed by periodate oxidation. The genus common antigen appeared to be lipid-associated protein, while the species specific antigen consisted mainly of carbohydrate. These specific immunological reagents would be valuable in diagnosing and monitoring diseases.