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

The effects of whole cells of three different O serotypes of Vibrio anguillarum on the murine immune response were studied. The addition of different doses (1-100 microgram/ml) of V. anguillarum cells, as well as Salmonella typhimurium lipopolysaccharide, markedly increased the incorporation of [3H]thymidine into in vitro cultured spleen cells of C57BL/6 mice. All three serotype strains of V. anguillarum were able to induce the mitogenic effect at 10 microgram /ml and 100 microgram/ml, but serotype I strains were more potent than the others. Since pretreatment of spleen cells with rabbit anti-mouse thymocyte antiserum did not affect the mitogenic activity of V. anguillarum, Vibrio cells may be a B-lymphocyte mitogen. When sheep or horse erythrocytes and Vibrio cells were injected intraperitoneally into ddY mice, Vibrio cells exhibited an enhancing effect on antibody response in vivo, regardless of the different serotypes. Vibrio cells, when injected intraperitoneally into mice before the antigen, markedly suppressed the antibody response. Several days after the injection of Vibrio cells, these mice showed an enhanced carbon clearance activity. Acid phosphatase activity in their peritoneal cells was also augmented, suggesting that Vibrio cells activated macrophages in the mice.