Mitogenicity and adjuvanticity of a marine bacterium, Vibrio anguillarum, in mice

Biological activities and endotoxic activities of protective antigens (PAgs) of Leptospira interrogans

The biological and endotoxic activities of protective antigens (PAgs) prepared by the chloroform-methanol-water method from Leptospira interrogans serovars lai, copenhageni and canicola were examined. The PAg preparations did not show a local Shwartzman reaction in the rabbits at doses of 100 micrograms and 50 micrograms/site and lethal toxicity to galactosamine-sensitized mice at the dose of 12.5 micrograms to 50 micrograms/mouse. PAgs exhibited a weak cytotoxic action on peritoneal exudate macrophages of C3H/HeJ and C3H/HeN mice at the dose of 500 micrograms/ml in vitro, but did not show cytotoxicity for BHK-21 cells kidney cells of the Syrian hamster, CHO-K1, ovary cells of the Chinese hamster, and CHL, lung cells of the Chinese hamster, at doses of 5 and 500 micrograms/ml. Gelation activity in the Limulus test was only observed at PAg concentrations over 100 ng/ml, which dose was 10,000 times that of lipopolysaccharide (LPS) of Escherichia coli O55:B5. Furthermore, an adjuvant activity of PAgs was not observed in the production of anti-sheep red blood cell antibody in mice. Mitotic conversion of spleen cells from C3H/HeJ and C3H/HeN mice was observed by the addition of PAgs in vitro. These results indicated that the biological properties of PAgs were different from those of LPS prepared from gram-negative enterobacteria, that PAgs had no endotoxic activity and that the biological safety of PAgs as vaccine was proved.

Biological activities of chemically synthesized 2-keto-3-deoxyoctonic acid-(alpha 2----6)-D-glucosamine analogs of lipid A

The mitogenicity, lethal toxicity, and Shwartzman reaction of three derivatives of chemically synthesized 2-keto-3-deoxyoctonic acid-linked 2,3-diacyloxyacylglucosamine-4-phosphate (KDO-GlcN-4-P) were determined. The compounds, A-301 (with di-3-hexadecanoyloxytetradecanoyl at the C-2 and C-3 positions), A-303 (di-3-tetradecanoyloxytetradecanoyl), and A-305 (3-dodecanoyloxytetradecanoyl and 3-tetradecanoyloxytetradecanoyl), induced a significant incorporation of [3H]thymidine into splenocytes of C57BL/6 mice. The compounds A-301 and A-303 showed lethality at a high dose of 50 micrograms per mouse in C57BL/6 mice sensitized with D-galactosamine, whereas A-305 caused toxicity even at a dose of 10 micrograms per mouse. However, the three compounds did not elicit the local Shwartzman reaction in rabbits. These findings indicate that the addition of 2-keto-3-deoxyoctonic acid enhances the mitogenic activity of 2,3-diacyloxyacylglucosamine-4-phosphate but does not affect the lethal toxicity and the induction of Shwartzman reaction.

Biological activities of lipopolysaccharide-like substance (LLS) extracted from Leptospira interrogans serovar canicola strain Moulton

The biological activities of lipopolysaccharide-like substance (LLS) extracted from Leptospira interrogans serovar canicola strain Moulton by the hot phenol-water method were studied in mice. The addition of 12.5 micrograms/ml or more of LLS fraction increased the incorporation of [3H]thymidine into in vitro cultured spleen cells of C57BL/6 mice, while the activity of the LLS fraction was about 20 times weaker than that of Salmonella typhimurium lipopolysaccharide (LPS). Pretreatment of murine spleen cells with rabbit anti-mouse thymocyte antiserum did not diminish the mitogenic activity of leptospiral LLS, and the LLS could not increase the incorporation of [3H]thymidine into thymocytes, suggesting that LLS acts on a B-lymphocyte population of lymphocytes. When sheep erythrocytes and LLS fraction were injected intraperitoneally into BALB/c mice, LLS exhibited an enhancing effect on antibody response in vivo. However, lethal toxicity of the LLS fraction was about 500 times lower than that of LPS in C57BL/6 mice loaded with galactosamine. No antitumor activity of leptospiral LLS (250-1,000 micrograms/mouse) against the ascites form of Ehrlich carcinoma in ddY mice was observed. The biological activities of the LLS fraction from the organism were weaker than those of gram-negative bacterial LPS, suggesting that Leptospira possesses no typical LPS.