Studies on the Enteropathogenic Mechanism of Non-O1 Vibrio cholerae: III. Production of Enteroreactive Toxins

Cholera toxin gene and production of enteroreactive toxins were examined in 134 strains of non-O1 V. chrolerae. Results obtained were summarized as follows. Frequencies of cholera-toxin-genepositive strains were 2/58 (3.4%) from human sources and 2/76 (2.6%) from fish and environment. While, frequencies of production of hemolysin, fluid accumulating factor (FAF) related with protease, fluid accumulating factor in the suckling mouse, NAG-rTDH, NAG-ST and Vero toxin were 100, 72, 31, 2, 0 and 0%, respectively, for 58 strains from human sources, and 100, 57, 24, 0, 1.3 and 0%, respectively, for 76 strains from fish and environment. Among the 31 strains used for the injection of viable cells to the ligated rabbit ileal loop, detection frequencies of these enteroreactive toxins in the accumulated fluids were 100% for hemolysin, 3.2% for both FAF and NAG-rTDH and 0% for cholera toxin, Vero toxin or NAG-ST. Hemolysin and the fluid accumulating factor in the suckling mouse seemed to be identical in most strains. These results suggest that cholera toxin, NAG-ST, NAG-rTDH and Vero toxin may not be very important in the enteropathogenic mechanism of a great majority of non-O1 V. cholerae strains, whereas hemolysin may play an important role in the enteropathogenicity.