Huntley J S, Hall A C, Sathyamoorthy V, Hall R H
University Laboratory of Physiology, Oxford, United Kingdom.
Infect Immun. 1993 Oct;61(10):4326-32. doi: 10.1128/iai.61.10.4326-4332.1993.
Vibrio parahaemolyticus, an important agent of seafood-borne gastroenteritis, expresses several putative virulence factors that could account for the disease symptoms of infected humans, namely, diarrhea, nausea, and abdominal cramps. The pathogenicity of V. parahaemolyticus correlates well with the Kanagawa phenomenon (the hemolytic ability of strains grown on Wagatsuma blood agar), implicating the thermostable direct hemolysin (TDH) as the predominant toxin responsible for pathogenicity. TDH-induced hemolysis could be inhibited by the addition of the osmolyte sorbitol to the extracellular solution, supporting the hypothesis that hemolysis occurs through colloid osmosis secondary to an increase in the cation permeability of the membrane. The effect of TDH on cation permeability was investigated by measuring K+ (congener, 86Rb+) influx into human erythrocytes in which the endogenous cation transporters had been blocked (by use of ouabain, bumetanide, and nitrendipine). TDH increased K+ influx into these cells; this increase was rapid in onset and constant in magnitude, suggesting a direct action by TDH on the membrane. The kinetics of leak generation were examined; the relationship between counts accumulated and hematocrit indicated that the TDH-induced lesion is multihit in nature. TDH-induced K+ influx was sensitive to Zn2+. Time courses of hemolysis in isosmotic solutions of monovalent cation chlorides were used to obtain the selectivity series for the TDH-induced leak: Cs+ > Li+ > K+ > Rb+ > Na+. Both the Zn2+ sensitivity and this selectivity series were obtained for crude culture supernatants, suggesting that TDH is the predominant leak-inducing agent. Thus, we have identified several features of the TDH-induced leak likely to be important in the diarrhetic action of V. parahaemolyticus in the human intestine.
副溶血性弧菌是食源性肠胃炎的重要病原体，它表达多种假定的毒力因子，这些因子可能导致受感染人类出现疾病症状，即腹泻、恶心和腹部绞痛。副溶血性弧菌的致病性与神奈川现象（菌株在 Wagatsuma 血琼脂上生长的溶血能力）密切相关，这表明耐热直接溶血素（TDH）是导致致病性的主要毒素。向细胞外溶液中添加渗透剂山梨醇可抑制 TDH 诱导的溶血，这支持了溶血是通过膜阳离子通透性增加继发的胶体渗透作用发生的假说。通过测量 K⁺（同系物，⁸⁶Rb⁺）流入内源性阳离子转运体已被阻断的人红细胞（使用哇巴因、布美他尼和尼群地平）来研究 TDH 对阳离子通透性的影响。TDH 增加了 K⁺流入这些细胞；这种增加起效迅速且幅度恒定，表明 TDH 对膜有直接作用。研究了渗漏产生的动力学；累积计数与血细胞比容之间的关系表明，TDH 诱导的损伤本质上是多靶点的。TDH 诱导的 K⁺流入对 Zn²⁺敏感。使用单价阳离子氯化物等渗溶液中的溶血时间进程来获得 TDH 诱导渗漏的选择性序列：Cs⁺＞Li⁺＞K⁺＞Rb⁺＞Na⁺。从粗培养上清液中获得了 Zn²⁺敏感性和这个选择性序列，表明 TDH 是主要的渗漏诱导剂。因此，我们确定了 TDH 诱导渗漏的几个特征，这些特征可能对副溶血性弧菌在人类肠道中的腹泻作用很重要。
