Differences between surface antigenic determinants of polar monotrichous flagella of Vibrio parahaemolyticus and of related species

Immunomagnetic separation and coagglutination of Vibrio parahaemolyticus with anti-flagellar protein monoclonal antibody

Mice were immunized by injection of Vibrio parahaemolyticus ATCC 17802 polar flagellin in order to produce monoclonal antibodies (mAbs). mAbs were analyzed by anti-H enzyme-linked immunosorbent assay using V. parahaemolyticus polar flagellar cores. The mAb exhibiting the highest anti-H titer was coated onto Cowan I Staphylococcus aureus cells at a concentration of 75 microg/ml cell suspension and used for slide coagglutination. Of 41 isolates identified genetically as V. parahaemolyticus, 100% coagglutinated with the anti-H mAb within 30 s, and the mAb did not react with 30 isolates identified as Vibrio vulnificus. A strong coagglutination reaction with V. parahaemolyticus ATCC 17802 was still observed when the S. aureus cells were armed with as little as 15 microg of mAb/ml S. aureus cell suspension. At this concentration, the mAb cross-reacted with three other Vibrio species, suggesting that they share an identical H antigen or antigens. The anti-H mAb was then used to optimize an immunomagnetic separation protocol which exhibited from 35% to about 45% binding of 10(2) to 10(3) V. parahaemolyticus cells in phosphate-buffered saline. The mAb would be useful for the rapid and selective isolation, concentration, and detection of V. parahaemolyticus cells from environmental sources.

Lateral flagella of vibrios: serological classification and genetical similarity

Lateral (L-) flagella-having vibrios were classified into 13 H-serogroups (flagellar antigen serogroups) by means of H-agglutination test. Vibrio parahaemolyticus was classified into 3 serogroups, HL1 to 3. V. alginolyticus and V. harveyi were classified into 5 and 3 serogroups, respectively, but 2 of those were serogroups common to the both species. V. fluvialis and V. furnissii constituted a same serogroup, HL8. Cross-reactivity between each serogroup was not observed in H-agglutination test, although some cross-reactivity was observed in gel diffusion test. Furthermore, similarity of DNA sequence of L-flagellar structure gene was demonstrated by dot blot hybridization test with a DNA probe of HL2 L-flagellar gene fragment. These results suggest conservation of DNA sequence of the L-flagellar gene of vibrios.

Presumptive identification of Vibrio species with H antiserum

Species in the genus Vibrio exhibit flagellar (H) antigens unique to the species. Thus, species-specific H antiserum could be a valuable reagent with which to screen serologically large numbers of Vibrio isolates. Antisera against V. cholerae, V. fluvialis, V. anguillarum, V. metschnikovii, V. parahaemolyticus, V. alginolyticus, and V. vulnificus H antigens was produced in rabbits by repeated injections of Formalin-preserved whole cells. Anti-O activity and anti-H activity against common H antigens was absorbed from each antiserum, V. fluvialis was shown to possess an H antigen unique to the species and also to share minor H antigens with V. cholerae, V. metschnikovii, and V. anguillarum. V. vulnificus also exhibits a species-unique H antigen. A comprehensive serological screening system based on species-specific H antiserum was developed to identify pathogenic Vibrio species one step beyond primary isolation. Vibrio species were correctly identified with accuracies ranging from 93 to 100%. Some isolates were either nonmotile or poorly so and thus did not flocculate in H antiserum.