A serogroup of non-O1 Vibrio cholerae possessing the Inaba antigen of Vibrio cholerae O1

A serogroup of non-O1 Vibrio cholerae, tentatively named Hakata, possessing the C (Inaba) factor but not the B (Ogawa) and A factors of V. cholerae O1 is described. Strains of this serogroup were isolated from river and estuarine waters and from frozen shrimps.     

Vibrio fluvialis: a new serogroup (19) possessing the Inaba factor antigen of Vibrio cholerae O1

A serogroup of Vibrio fluvialis possessing the C (Inaba) antigen but not the B (Ogawa) nor A antigen of V. cholerae O1 is described. The O-antigen of this serogroup was identical with that of bioserogroup 1875-variant of a marine Vibrio species. As the O-antigen of this serogroup was not agglutinated by any of O-antisera for the 18 serogroups of V. fluvialis already recognized, it was designated O-serogroup 19 of this species.     

Two serogroups of Vibrio cholerae non-O1 possessing somatic antigen factors in common with Hakata serogroup of V. cholerae.

Two serogroups of Vibrio cholerae non-O1 possessing somatic antigen factors in common with Hakata serogroup of V. cholerae are described. One group was included in the Hakata serogroup and has its own antigen other than all O-antigens of the Hakata group. The other group had its own major antigen, but not factor F specific for the Hakata group.     

Distribution of Vibrio cholerae O1 antigen biosynthesis genes among O139 and other non-O1 serogroups of Vibrio cholerae

The organization and distribution of the genes responsible for O antigen biosynthesis in various serogroups of Vibrio cholerae were investigated using several DNA probes derived from various regions of the genes responsible for O1 antigen biosynthesis. Based on the reactivity pattern of the probes against the various serogroups, the cluster of genes responsible for the O1 antigen biosynthesis could be broadly divided into six groups, designated as class 1-6. The class 3 cluster of genes corresponding to gmd to wbeO, wbeT and a part of wbeU was specific for only the O1 serogroup. The other cluster of genes (class 1, 2, 4-6) reacted with other serogroups of V. cholerae. These data indicate that serotype conversion in V. cholerae does not depend on a simple mutational event but may involve horizontal gene transfer not only between V. cholerae strains but also between V. cholerae and species other than V. cholerae.     

Serological cross-reaction between intact and chemically modified lipopolysaccharides of O1 Vibrio cholerae Inaba and non-O1 V. cholerae bio-serogroup Hakata.

Serological cross-reaction of intact as well as chemically modified LPS from O1 Vibrio cholerae 569B (Inaba) with non-O1 V. cholerae Hakata LPS, which contain alpha(1-->2)-linked N-acetyl perosamine-homopolymer constituting their O polysaccharide chain, was studied by passive hemolysis test by using their LPS as antigen for sensitizing sheep red blood cells (SRBC). The N-deacylation of the alpha(1-->2)-linked linear 3-deoxy-tetronyl perosamine-homopolymer constituting the O polysaccharide chain in 569B LPS resulted in virtual elimination of their serological reactivity with both homologous Inaba and heterologous Hakata antisera. Furthermore, when the resultant NH2 groups of the N-deacylated perosamine-homopolymers in 569B LPS were N-acylated with acetyl, propionyl or butanoyl groups, they markedly recovered the serological reactivity to a marked extent, in particular, their pronounced cross-serological reactivity with heterologous Hakata antiserum. These results are believed to be compatible with the interpretation that the Inaba antigen factor C possessed by the two bacteria studied is related to the common occurrence of the N-acyl groups, regardless of what the acyl groups are, residing in the perosamine residues of the perosamine-homopolymers constituting the O polysaccharide chain of their LPS.     

Isolation and characterization of a cytolysin produced by Vibrio cholerae serogroup non-O1

A thermolabile toxin (molecular weight, 52 711; isoelectric point, 8.65) produced by a clinical isolate of Vibrio cholerae serogroup non-O1 was cytotoxic for Y-1 mouse adrenal cells and Chinese hamster ovary cells. The toxin lysed rabbit red blood cells and produced a hemorrhagic zone in rabbit skin. When injected intravenously into adult mice, the cytolysin was rapidly lethal and caused fluid accumulation in both 5- and 18-h rabbit ileal loops. Strains of V. cholerae that produced cytolysin but no cholerae enterotoxin were able to cause fluid accumulation in rabbit intestinal loops.     

A bioserogroup of marine vibrios possessing somatic antigen factors in common with Vibrio cholerae O1

A bioserogroup of halophilic vibrios, tentatively labelled bioserogroup 1875, strongly agglutinated by O1 antiserum of Vibrio cholerae is described. Cross-agglutination and agglutinin-absorption tests showed that these vibrios had antigens identical with the Ogawa and Inaba factors of V. cholerae O1, although they possessed their own specific antigen distinctive from the A factor that is the specific major antigen of the latter species. In addition, quantitative antigen variation similar to that of the Ogawa-to-Inaba type with V. cholerae O1 was recognized in this halophilic group. They were isolated from estuarine water and are considered to inhabit coastal aquatic environments. Phenotypically, however, this group is not identifiable with any of the species already recognized in the genus Vibrio .     

A bioserogroup of marine vibrios possessing somatic antigen factors in common with Vibrio cholerae O1

A bioserogroup of halophilic vibrios, tentatively labelled bioserogroup 1875, strongly agglutinated by O1 antiserum of Vibrio cholerae is described. Cross-agglutination and agglutinin-absorption tests showed that these vibrios had antigens identical with the Ogawa and Inaba factors of V. cholerae O1, although they possessed their own specific antigen distinctive from the A factor that is the specific major antigen of the latter species. In addition, quantitative antigen variation similar to that of the Ogawa-to-Inaba type with V. cholerae O1 was recognized in this halophilic group. They were isolated from estuarine water and are considered to inhabit coastal aquatic environments. Phenotypically, however, this group is not identifiable with any of the species already recognized in the genus Vibrio.     

Vibrio cholerae O139 produces a protease which is indistinguishable from the haemagglutinin/protease of Vibrio cholerae O1 and non-O1

Abstract Haemaglutinin/protease (HA/P) is one of the virulence factors of Vibrio cholerae O1 and pathogenic strains of V. cholerae non-O1. In this study, we examined protease activity of a new serogroup of Vibrio cholerae recently designated as O139 synonym Bengal. The protease activity was produced by all eight isolates of V. cholerae O139 from Bangladeshi patients. Purification and partial characterization of the protease from V. cholerae O139 demonstrated the purified protease (O139-P) was indistinguishable from that previously reported for HA/P of V. cholerae non-O1 (NAG-HA/P) and V. cholerae O1 (Vc-HA/P). These results prove that V. cholerae O139 produces a protease belonging to solHA/P, and suggest that the protease is another virulence factor found in newly emerged V. cholerae O139, as in V. cholerae O1.     

Lateral gene transfer of O1 serogroup encoding genes of Vibrio cholerae

In Gram-negative bacteria, the O-antigen-encoding genes may be transferred between lineages, although mechanisms are not fully understood. To assess possible lateral gene transfer (LGT), 21 Argentinean Vibrio cholerae O-group 1 (O1) isolates were examined using multilocus sequence typing (MLST) to determine the genetic relatedness of housekeeping genes and genes from the O1 gene cluster. MSLT analysis revealed that 4.4% of the nucleotides in the seven housekeeping loci were variable, with six distinct genetic lineages identified among O1 isolates. In contrast, MLST analysis of the eight loci from the O1 serogroup region revealed that 0.24% of the 4943 nucleotides were variable. A putative breakpoint was identified in the JUMPstart sequence. Nine conserved nucleotides differed by a single nucleotide from a DNA uptake signal sequence (USS) also found in Pastuerellaceae . Our data indicate that genes in the O1 biogenesis region are closely related even in distinct genetic lineages, indicative of LGT, with a putative DNA USS identified at the defined boundary for the DNA exchange.     

Geographical variation in the distribution of phage types of Vibrio cholerae O1 and non-O1

A Vibrio cholerae O1 phage-typing scheme, developed in the USSR, has been used to type 120 strains of V. cholerae O1 isolated in Africa and Asia, and 56 non-O1 V. cholerae isolated in England and Wales from infections contracted abroad. 90.9% of V. cholerae O1 were typable. Phage type 13 predominated among African strains whereas types 11 and 15 were more common among strains from Asia. Only 14.3% of non-O1 V. cholerae reacted with the phages.     

An aberrant hemolysin of Vibrio cholerae non-O1.

An aberrant hemolysin produced by a Vibrio cholerae non-O1 strain N037 (N037-hly) was purified and characterized. N037-Hly was antigenically very similar to El Tor hemolysin but differed in molecular weight (48,000 vs. 60,000), interaction with glucose, and hemolytic activity. Of 100 V. cholerae non-O1 strains other than the N037 strain examined, none produced this aberrant hemolysin. The N-terminal amino acid sequence of N037-hly was highly homologous to that of El Tor hemolysin.     

Cholera toxin gene-positive Vibrio cholerae O1 Ogawa and Inaba strains produce the new cholera toxin

Abstract Two strains of cholera toxin (CT) gene-positive Vibrio cholerae O1, Ogawa, isolated from patients with diarrhoea and the hypertoxigenic V. cholerae O1, Inaba (569B), were found to produce the new cholera toxin that has earlier been demonstrated to be elaborated by CT gene-negative human and environmental isolates of V. cholerae O1. The CT gene-positive strains produce the new cholera toxin simultaneously with CT, indicating that they contain the gene coding for the new cholera toxin in addition to that of CT.     

R plasmids in environmental Vibrio cholerae non-O1 strains

The occurrence of drug resistance and its plasmid-mediated transferability was investigated in 140 environmental strains of Vibrio cholerae non-O1 and 6 strains of Vibrio cholerae, both O1 and non-O1, of clinical origin. Of the 146 strains tested, 93% were resistant to at least one drug and 74% were resistant to two or more antibiotics. The O1 strains were susceptible to all antibiotics used. A total of 26 of 28 selected resistant wild strains carried R plasmids that were transferable by intraspecific and intergeneric matings. The most common transmissible R factor determined resistance to ampicillin, amoxicillin, and sulfanilamide (30%), followed by resistance to ampicillin and amoxicillin (13%) and resistance to ampicillin, amoxicillin, phosphomycin, and sulfanilamide (9%). Comparison of the three methods of plasmid analysis showed that the method of Birnboim and Doly (Nucleic Acids Res. 7:1513-1523, 1979) without EDTA and lysozyme was optimal for isolation of both large and small plasmids in environmental V. cholerae strains. Most strains harbored more than one plasmid, and the molecular sizes ranged from 1.1 to 74.8 megadaltons. The plasmids of high molecular size (around 74 megadaltons) were responsible for the resistance pattern transferred and were maintained with high stability in the hosts.     

The occurrence of alpha (1----2) linked N-acetylperosamine--homopolymer in lipopolysaccharides of non-O1 Vibrio cholerae possessing an antigenic factor in common with O1 V. cholerae

Chemical analysis was carried out on lipopolysaccharides from Vibrio cholerae bio-serogroup Hakata 487-85. The O-specific chain of the phenol-soluble lipopolysaccharides was demonstrated by 13C-NMR spectroscopy and methylation analysis to contain a linear homopolymer of alpha(1----2) linked N-acetylperosamine (4-acetamido-4,6-dideoxy-D-mannopyranose), which was closely similar to but not identical to a linear alpha(1----2) linked N-3-deoxy-L-glycerotetronyl (S-2,4-dihydroxybutyryl) perosamine-homopolymer constituting that of O1 Vibrio cholerae lipopolysaccharides.     

Differentiation among the Vibrio cholerae serotypes O1, O139, O141 and non-O1, non-O139, non-O141 using specific monoclonal antibodies with dot blotting

Seven different monoclonal antibodies (MAbs) specific to only Vibrio cholerae were produced using a combination of five representative serotypes of V. cholerae for immunization. The first three MAbs (VC-93, VC-82 and VC-223) were specific to the V. cholerae serogroup O1 with different avidity for the serotypes O1 Inaba and O1 Ogawa. The fourth and the fifth MAbs were specific to V. cholerae O139 (VC-812) or O141 (VC-191) serogroups, respectively. The sixth MAb (VC-26) bound to all three serogroups of V. cholerae. The seventh MAb (VC-63) bound to all twenty five isolates of V. cholerae used in this study. None of the seven MAbs showed cross-reactivity with other Vibrio spp. or closely-related V. cholerae species, V. mimicus or other gram-negative bacteria. The eighth MAbs (VC-201) specific to almost all Vibrio spp. was also obtained. In dot blotting, these MAbs can be used to detect a diluted pure culture of V. cholerae in solution with a sensitivity range of from 10⁵ to 10⁷ CFU ml^− 1. However, the detection capability could be improved equivalent to that of PCR technique after preincubation of samples in alkaline peptone water (APW). Thus, these MAbs constitute convenient immunological tools that can be used for simple, rapid and simultaneous direct detection and differentiation of the individual serotypes of V. cholerae in complex samples, such as food and infected animals, without the requirement for bacterial isolation or biochemical characterization.     

Immunogenicity of synthetic saccharide fragments of Vibrio cholerae O1 (Ogawa and Inaba) bound to Exotoxin A

Recombinant exotoxin A (rEPA) from Pseudomonas aeruginosa conjugated to Vibrio cholerae O1 serotype-specific polysaccharides (mono-, di- and hexasaccharide) were immunogenic in mice. Monosaccharide conjugates boosted the humoral responses to the hexasaccharide conjugates. Prior exposure to purified Ogawa lipopolysaccharide (LPS) enabled contra-serotype hexasaccharide conjugates to boost the vibriocidal response, but Inaba LPS did not prime for an enhanced vibriocidal response by a contra-serotype conjugate. Prior exposure to the carrier, and priming B cells with the LPS of either serotype, resulted in enhanced vibriocidal titers if the Ogawa hexasaccharides were used, but a diminished response to the Inaba LPS. These studies demonstrate that the 'functional' B cell epitopes on the LPS differ from those of the neoglycoconjugates and that the order of immunization and the serotype of the boosting conjugate can influence the epitope specificity and function of the antisera.