Isolation and biological activities of endotoxin from Leptospira interrogans

Endotoxins extracted with ethylenediaminetetraacetate (EDTA) from Leptospira interrogans serovars icterohaemorrhagiae and canicola and Leptospira biflexa serovar patoc were tested for various biological activities characteristic of endotoxins. The presence of lipopolysaccharide biological activity was demonstrated by the Limulus amoebocyte lysate test, pyrogenicity in rabbits, complement interaction inhibiting the erythrocyte lysis, and chicken-embryo lethality. The lipopolysaccharides did not induce the local Shwartzman reaction. The lipopolysaccharides of serovars icterohaemorrhagiae and canicola were immunogenic in rabbits and were cytotoxic to chicken-embryo fibroblasts.