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The protease from Vibrio cholerae nicks arginine at position 192 from the N-terminus of the heat-labile enterotoxin a subunit from enterotoxigenic Escherichia coli

It was examined where a protease purified from Vibrio cholerae might nick the heat-labile enterotoxin (LT) A subunit from enterotoxigenicEscherichia coli.LT was digested by the protease and contained a fragment which had the same mobility on SDS-PAGE as that of the Al fragment of LT digested by trypsin. The biological activity of LT by this protease was also identical to that of LT by trypsin. The amino acid sequence of the N-terminus of the A2-like fragment was Thr-Ser-Thr-Gly, which corresponded to the sequence from 193 to 196 of the A subunit.These data suggest that this protease, like trypsin, nicks arginine at position 192 from the N-terminus of the A subunit and that the biological activation of LT by this protease is similar to that by trypsin.

Studies on Novel Pili from Shigella flexneri

Pili were detected using electron microscopy in clinical isolates of Shigella flexneri which had been continuously subcultivated in liquid media. Morphologically, the pili appeared as thin, flexible, cylindrical structures of up to 2–5 μm in length and about 3–5 nm in diameter. Two strains showed mannose‐resistant (MR) hemagglutination to fresh fowl erythrocytes (type 4), and one to tannic acid‐treated horse erythrocyte (type 3) pili. These pili are novel and different from the mannose‐sensitive (MS) type 1 pili described by Duguid and Gillies.

Detection and Quantitative Assessment of a Vibrio cholerae O1 Species in Several Foods by a Novel Enzyme Immunoassay

A selected antibody enzyme immunoassay (SAEIA) for the general detection of Vibrio cholerae O1 species has been developed using the immunological reagents of a rabbit antiserum specific for V. cholerae O1 classical Inaba 569B and immobilized cell fragments of V. cholerae O1 E1 Tor 85P6, and β‐D‐galactosidase‐labeled goat anti‐rabbit immunoglobulin G as tracer. The SAEIA was specific for V. cholerae O1 species and showed low cross‐reaction values to other microorganism species tested including Vibrio parahaemolyticus. The detection limit of the SAEIA was 4,500 cells per assay for all the 13 strains of V. cholerae O1 examined. Quantitative comparison on the growth of the E1 Tor 85P4 in several foods cultured for 24 hr were studied using the SAEIA. Preceding the experiments, little inhibition of every food homogenate for the measurement of the SAEIA was first demonstrated and then the homogenate was directly used for an assay sample. The interaction of the growth of Escherichia coli to that of V. cholerae O1 in a food was also found to be little under the mixed culturing of both bacteria using the SAEIA.