Evaluation of the phenol-induced flagellar agglutination test for the identification of the cholera group of vibrios

Coagglutination of Vibrio cholerae, Vibrio mimicus, and Vibrio vulnificus with anti-flagellar monoclonal antibody

Monoclonal antibodies (MAbs) with serological activity for purified flagellar (H) core protein prepared from Vibrio cholerae were identified by enzyme-linked immunosorbent assay. Four of these MAbs reacted with the flagella of V. cholerae and V. mimicus exclusively, while eight MAbs reacted with at least 1 of 30 heterologous Vibrio species tested by enzyme-linked immunosorbent assay or coagglutination. It appears that V. cholerae and V. mimicus express similar, if not identical, H determinants unique to these two Vibrio species. Staphylococcus aureus cells or latex beads armed with the four species-specific MAbs coagglutinated each of 47 isolates identified bacteriologically as V. cholerae or V. mimicus from among 103 Vibrio isolates tested. One coagglutination reagent armed with anti-V. vulnificus H MAb exhibited species specificity in that only V. vulnificus cells were coagglutinated from among the 31 Vibrio species examined. This reagent coagglutinated 20 isolates identified bacteriologically as V. vulnificus in a serological survey. MAb coagglutination reagents offer a rapid, specific, and economical alternative to the classical bacteriological approach to identify the human pathogens V. cholerae, V. mimicus, and V. vulnificus.

Detection of Vibrio cholerae with monoclonal antibodies specific for serovar O1 lipopolysaccharide

Six hybridoma cell lines, each of which produced a monoclonal antibody (MAb) against Vibrio cholerae O1 lipopolysaccharide (LPS), were established. Each MAb was active serologically by both enzyme-linked immunosorbent assay (ELISA) and the slide agglutination test. In the ELISA, each MAb was tested against 7 O1 and 9 non-O1 LPS preparations. Three MAbs reacted with both Inaba and Ogawa serovars (A antigen), two MAbs reacted with the Ogawa serovars only (B antigen), and one MAb reacted with the Inaba serovars only (C antigen). Each MAb was also tested in the ELISA against whole-cell preparations of 37 O1 and 52 non-O1 V. cholerae serovars, 20 heterologous Vibrio species, and 37 heterologous bacterial species. The MAbs reacted with V. cholerae O1 cells only, except for one anti-A antigen MAb which reacted weakly with five V. cholerae non-O1 serovars and Serratia marcescens. Each anti-A antigen MAb was labeled with fluorescein isothiocyanate (FITC) and tested by direct immunofluorescence against selected O1 and non-O1 serovars. Each MAb-FITC conjugate, when tested alone, exhibited O1-specific fluorescence; however, mixtures of the MAb-FITC dramatically enhanced fluorescence intensity on O1 cells. This finding was also visualized by immunoelectron microscopy on both thin-sectioned and negatively stained O1 cells by using an anti-mouse immunoglobulin-colloidal gold conjugate. These results suggest that the A antigen can be described by more than one epitope and that a superior serotyping reagent can be prepared from a defined mixture of MAbs.

Rapid serological identification of Vibrio vulnificus by anti-H coagglutination

Staphylococcus aureus Cowan 1 cells were armed with anti-flagellar (anti-H) antibody produced in rabbits immunized with flagellar core protein prepared from Vibrio vulnificus. This reagent was assessed by coagglutination for its capacity to agglutinate and identify V. vulnificus. A species-specific H antigen is expressed in the core proteins of the polar flagella of V. vulnificus. Of 435 V. vulnificus isolates identified bacteriologically, 432 (99.3%) were agglutinated in the slide test within 2 min after the addition of the anti-V. vulnificus H coagglutination reagent. Other than Vibrio pelagius, the reagent did not agglutinate 19 heterologous Vibrio spp. tested, including 290 V. cholerae, 22 V. mimicus, 395 V. parahaemolyticus, and 16 V. fluvialis isolates recovered from seafood and the marine environment. The serological resolution of the coagglutination reaction was enhanced if the organism under test was suspended in 0.1 M Tris buffer-0.1 mM EDTA-1.0% Triton X-100 (TET) for 24 h before serological examination. The TET buffer also increased the sensitivity of the coagglutination reaction 100-fold over that for isolates suspended in 0.3% formalinized phosphate-buffered saline before testing. The anti-H coagglutination test is a rapid, serologically specific, and inexpensive procedure for identifying V. vulnificus one step beyond primary isolation.

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.