Immunochemistry of extracts from Leptospira interrogans serotype hardjo

Antigens from Leptospira interrogans serotype hardjo grown in modified Korthof's medium were obtained by ethanol and alkaline extraction procedures and their chemical and serological properties were compared. The protein to polysaccharide ratio in the ethanol extract was 1:1-8 and in the alkali extract was 1-7:1. The lipid content of the latter was twice that of the former (8-5%, w/w). There was an inverse relationship of the protein and carbohydrate contents of the two preparations, the total reducing sugar being higher in the ethanol extract whereas protein was higher in the alkali extract. Both preparations contained arabinose, rhamnose, fucose, xylose, mannose, galactose, glucose and galacturonic acid but in different amounts. No muramic acid or 2-keto-3-deoxyoctonate was detected. Both extracts contained erythrocyte sensitizing substances which, in the passive haemagglutination absorption test, appeared to be closely related antigenically but not identical. In the electron microscope, thin sections of the ethanol extract showed trilaminar outer envelope-like material.