Tolerance and Other Biological Properties of Vibrio parahaemolyticus Endotoxins

Abstract

Biological properties of endotoxins prepared from three strains of Vibrio parahaemolyticus were compared with reference to commercially prepared Salmonella typhi endotoxin. Endotoxin assays performed in rabbits included dermal Shwartzman reactivity, pyrogenicity, heat stability, and ability to induce tolerance as well as cross-tolerance.Mice were used for endotoxin LD50 determinations. Results showed V. parahaemolyticus endotoxins were similar to that of S.typhi strain 0901.Induction of tolerance to V. parahaemolyticus strain 11590 endotoxin resulted in complete cross-tolerance to S. typhi endotoxin, and vice versa. Partial cross-tolerance to S. typhi endotoxin was demonstrated with rabbits rendered tolerant to endotoxin from V. parahaemolyticus strains Sak-3 and FC 1011. Absorption spectra, nitrogen, phosphorus and carbohydrate analyses revealed additional similarities between endotoxins from V. parahaemolyticus and endotoxin from a member of the Enterobacteriaceae.Known in Japan for two decades as a causative agent of large outbreaks of seafoodassociated poisoning, Vibrio parahaemolyticus has recently been found associated with similar outbreaks in the U.S.A. [1,4,7,8,14,26,40,42,43], and other countries [2,3]. Nevertheless, the mode of pathogenesis of V. parahaemolyticus is poorly understood. Strains isolated from clinical specimens and displaying hemolysis on selected media (Kanagawa-phenomenon positive) are considered to be enteropathogenic [30,39,49], whereas nonhemolytic (Kanagawa-phenomenon negative) seafood or seawater isolates are generally considered non-enteropathogenic [19,37,38]. The problem is further complicated by the frequent isolation of several different serotypes of V. parahaemolyticus during an outbreak of food poisoning [7,8].Biologically active components (hemolysins) from selected strains of V.parahaemolyticus have been isolated which do not, however, account for the spectrum of gastroenteritis symptoms observed in clinical cases [12,17,19,25,28,29,31,36,50,51]. A single case of endotoxin shock and leg gangrene due to infections by V. parahaemolyticus following an attack of gastroenteritis has been demonstrated [36].Endotoxins from V.parahaemolyticus have not previously been studied, although some chemical analyses ofO antigens [44,45] and K antigens have been reported [32,33]. The purpose of this research was to study the biological properties of V.parahaemolyticus endotoxins and to determine if they are similar to endotoxins classically prepared from selected members of the Enterobacteriaceae, such as Salmonella typhi.

Analysis of Vibrio parahaemolyticus soluble antigens by employing passive hemagglutination

“…Also, endotoxins may contain more protein than the endotoxins of Enterobacteriaceae, but these hypotheses reported further study for verification. In our studies, however, the total Lowry nitrogen of V. parahaemolyticus endotoxins was greater than that reported for the Enterobacteriaceae (22). Aside from being less potent in lethal dosage than Salmonella typhi endotoxin, the V. parahaemolyticus endotoxins were found to be remarkably similar in biological properties (22).…”

“…(i) V. parahaemolyticus endotoxins. Endotoxins were prepared from strains 11590, FC 1011, and Sak-3 with phenol water (Phe) and trichloroacetic acid, as previously described (22).…”

“…Endotoxins prepared from strains FC 1011 and 11590 were tested for ability to act as antigens. Low passive HA titers were obtained after immunization with strain 11590, whereas good titers were obtained with strain FC 1011, an unusual phenomenon since FC 1011 endotoxin was found to be less biologically potent than the 11590 preparation (21,22). However, the antisera so obtained were not tested for ability to protect experimental animals.…”