Showing papers on "El Tor published in 1985"
TL;DR: An elevated level of IgG antitoxin was not associated with protection against colonization or disease but was the most sensitive indicator of recent symptomatic cholera and of immune response to the oral immunogen B subunit.
Abstract: In rural Bangladesh, family contacts of patients with cholera were studied prospectively to examine whether protection against colonization and disease due to Vibrio cholerae O1 was associated with circulating antibodies to V. cholerae. Family contacts (1,071) of 370 patients with cholera were visited daily for 10 days, cultured for V. cholerae, and queried about diarrhea. Sera collected on days 1 and 21 were assayed for vibriocidal antibodies, IgG and IgA antibodies to cholera toxin, and IgG antibodies to lipopolysaccharide (LPS). Vibriocidal titers of greater than or equal to 20 present in 50% of contacts by 20 years of age were associated with protection against both colonization and disease. An elevated level of IgG antitoxin was not associated with protection against colonization or disease but was the most sensitive indicator of recent symptomatic cholera and of immune response to the oral immunogen B subunit. IgG antibody to LPS and IgA antitoxin were of little value in predicting colonization or disease.
185 citations
TL;DR: Sodium bicarbonate was found to be the most important factor in toxin production by El Tor vibrios in the new medium and is recommended because of its high yield of cholera toxin and its technical simplicity.
Abstract: A new medium that stimulates in vitro production of cholera toxin by Vibrio cholerae O1 El Tor (El Tor vibrios) was developed. The medium contains 0.5% NaCl, 0.3% NaHCO3, 0.4% yeast extract, and 1.5% Bacto-Peptone. El Tor vibrios were cultured in a stationary test tube at 37 degrees C for 20 h. The culture supernatant was assayed for cholera toxin by a reversed passive latex agglutination method. Most vibrios grown in this medium produced 10 to 20 times more toxin than in traditional syncase medium. The number of live vibrios at the end of culture was about 10(8)/ml in the new medium (AKI medium) and about 10(10)/ml in the syncase medium. As a result, each individual organism in the new medium should have produced as much as 1,000 times more toxin than in syncase medium. Sodium bicarbonate was found to be the most important factor in toxin production by El Tor vibrios in the new medium. We recommend this new medium because of its high yield of cholera toxin and its technical simplicity.
154 citations
TL;DR: Zymovar analysis deals with differences which are a direct expression of the genome and seems to be unaffected by gross phenotypic changes such as smooth-rough variation and phage resistance, and is a promising tool for investigating bacteriological and epidemiological questions, in particular the significance of an environmental reservoir of cholera.
Abstract: Enzyme electrophoretic variants were studied in 49 strains of Vibrio cholerae using zymovar analysis. The following seven enzymes were selected for use: alanine dehydrogenase (ADH), isocitrate dehydrogenase (IDH), malate dehydrogenase (MDH), phosphoglucomutase (PGM), glucosephosphate isomerase (GPI), 6-phosphogluconate dehydrogenase (6PGDH) and glucose-6-phospate dehydrogenase (G6PDH). The results indicated the presence of three main groups defined chiefly by their GPI and 6PGDH variants. The first group, defined by possessing the variants GPI-2 and 6PGDH-3, contained all the 01 serovar and ElTor biovar isolates from cholera cases. The second group, defined by possessing the variants GPI-3 and 6PGDH-2, contained all the 01 serovar and classical biovar isolates; the third group was heterogeneous and included the 01 serovar isolates from environmental sources as well as isolates of other serovars (the so called NAGs, non-agglutinable with 01 antisera or NCVs). It is thus now possible to separate the epidemic strains of 01 serovar from other members of this serovar isolated from the environment. Zymovar analysis deals with differences which are a direct expression of the genome and seems to be unaffected by gross phenotypic changes such as smooth-rough variation and phage resistance. It is a promising tool for investigating bacteriological and epidemiological questions, in particular the significance of an environmental reservoir of cholera.
38 citations
TL;DR: The structural gene for the haemolysin and two accessory genes from a Vibrio cholerae O1 El Tor strain have previously been cloned in Escherichia coli K-12 to give the plasmid pPM431, which implies a high degree of homology of the ha Hemolysin of O1 and non-O1 strains.
Abstract: The structural gene for the haemolysin and two accessory genes from a Vibrio cholerae O1 El Tor strain have previously been cloned in Escherichia coli K-12 to give the plasmid pPM431. This plasmid has been used as a probe with a variety of O1 and non-O1 Vibrio cholerae strains to examine by Southern DNA hybridisations for the presence of homologous DNA. Such experiments show that the DNA homologous to that present in pPM431 is present in all of the 20 strains examined, whether they were haemolytic or non-haemolytic, implying that the genes were present but not expressed in non-haemolytic strains. Using a variety of restriction enzymes to cut the chromosomal DNA of different V. cholerae strains and probing with pPM431, it was possible to distinguish O1 and non-O1 strains, as well as haemolytic or non-haemolytic strains. This variability between hly+ and hly− may be indicative of a change in the regulatory region of the haemolysin genes. The results also imply a high degree of homology of the haemolysin of O1 and non-O1 strains.
32 citations
TL;DR: A mass spectrometric method was applied to the B subunit of Vibrio cholerae classical biotype Inaba 569B toxin to determine its amino acid sequence and to confirm the differences in the amino acid sequences predicted from the nucleotide sequences of the genes of El Tor biotype strains 62746 and 2125 toxins.
Abstract: A mass spectrometric method was applied to the B subunit of Vibrio cholerae classical biotype Inaba 569B toxin to determine its amino acid sequence and to confirm the differences in the amino acid sequences predicted from the nucleotide sequences of the genes of El Tor biotype strains 62746 and 2125 toxins. In this method, the Staphylococcus aureus protease V8 digest of the CNBr-treated B subunit of the classical biotype toxin was examined directly by fast-atom-bombardment mass spectrometry without separation of individual peptides. The values of molecular ion signals observed in the mass spectra were compared with the amino acid sequences of the classical biotype and El Tor biotype toxins. All the observed mass values coincided with those calculated from the published sequences of the B subunit except those of the sequences at positions 12-29 and 69-79. Peptides with these sequences were isolated by high-performance liquid chromatography and analyzed by Edman degradation or by combination of mass spectrometry and enzymatic degradation. The results revealed that the amino acid residues at positions 22 and 70 were Asp instead of Asn in the published sequences of classical biotype toxin. It was also found that Asn at position 44 was partially deaminated to Asp. The amino acid sequence of the classical biotype toxin was found to be different only at positions 18 (His----Tyr), 47 (Thr----Ile) and 54 (Gly----Ser) from that of El Tor biotype toxins.
31 citations
TL;DR: Purified lipopolysaccharide from the Inaba and Ogawa serotypes, and of both the Classical and El Tor biotype of strains of V. cholerae show equal phage-inactivating capacities, has no phages inactivating capacity.
Abstract: The attachment site on the cell surface of Vibrio cholerae for the bacteriophage CP-T1 has been determined. Purified lipopolysaccharide from the Inaba and Ogawa serotypes, and of both the Classical and El Tor biotype of strains of V. cholerae show equal phage-inactivating capacities. Lipopolysaccharide extracted from a CP-T1-resistant mutant has no phage-inactivating capacity. Such mutants lack O-antigen as demonstrated by bactericidal assays utilizing a monoclonal antibody directed against O-antigen side chain of V. cholerae lipopolysaccharide. Radiolabelling of lipopolysaccharide with 33P and analysis by sodium dodecyl sulfate/polyacrylamide gel electrophoresis also revealed the absence of O-antigen in phage-resistant strains. A number of V. cholerae typing phage show cross-resistance with phage CP-T1.
28 citations
TL;DR: Results in conjunction with those for other V. cholerae extracellular proteins suggest that although E. coli K-12 can secrete these proteins into the periplasm, it lacks a specific excretion mechanism, present in V. Cholerae, for the release of soluble protein into the growth medium.
Abstract: The cellular location of the haemolysin of Vibrio cholerae El Tor strain 017 has been analyzed. This protein is found both in the periplasmic space and the extracellular medium in Vibrio cholerae. However, when the cloned gene, present on plasmid pPM431, is introduced into E. coli K-12 this protein remains localized predominantly in the periplasmic space with no activity detected in the extracellular medium. Mutants of E. coli K-12 (tolA and tolB) which leak periplasmic proteins mimic excretion and release the haemolysin into the growth medium. Secretion of haemolysin into the periplasm is independent of perA (envZ) and in fact, mutants in perA (envZ) harbouring pPM431 show hyperproduction of periplasmic haemolysin. These results in conjunction with those for other V. cholerae extracellular proteins suggest that although E. coli K-12 can secrete these proteins into the periplasm, it lacks a specific excretion mechanism, present in V. cholerae, for the release of soluble proteins into the growth medium.
26 citations
TL;DR: Analysis of purified flagellar cores from strains CA401 and N16961 showed that these two proteins, with apparent molecular weights of 47,000 and 49,000, composed the flagllar core, suggesting that, for intact cells, the flageLLar core proteins are not accessible to antibody.
Abstract: Sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis of outer membranes from a flagellated and an isogenic nonflagellated strain of Vibrio cholerae (classical, Inaba) suggested that two proteins were absent from the nonflagellated strain. Immunoblot examination of such preparations demonstrated that two proteins, present only in outer membrane from the flagellated strain, were associated with flagella. Analysis of purified flagellar cores from strains CA401 and N16961 (El Tor, Inaba) by electron microscopy, sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis, and immunoblotting showed that these two proteins, with apparent molecular weights of 47,000 and 49,000, composed the flagellar core. Antiserum specific for flagellar core proteins did not agglutinate or inhibit the motility of intact V. cholerae. These latter findings suggested that, for intact cells, the flagellar core proteins are not accessible to antibody.
20 citations
TL;DR: The persistence of Vibrio cholerae, biotype el tor, in a patient treated with trimethoprim-sulfamethoxazole was due to the acquisition of a conjugative resistance plasmid, which belonged to incompatibility group 6-C and conferred resistance to ampicillin, chloramphenicol, sulfonamide, and trimETHoprim.
Abstract: The persistence of Vibrio cholerae, biotype el tor, in a patient treated with trimethoprim-sulfamethoxazole was due to the acquisition of a conjugative resistance plasmid. The plasmid, with a molecular size of 72 megadaltons, belonged to incompatibility group 6-C and conferred resistance to ampicillin, chloramphenicol, sulfonamide, and trimethoprim.
16 citations
TL;DR: It is postulated that under the continuous culture conditions that occur in vivo, cholera toxin concentrations can accumulate to a maximum level, depending on the rate of purging by the diarrheal fluid rather than the toxigenicity of the infecting stain.
Abstract: A comparative study was carried out on the in vitro production of cholera toxin by 19 Vibrio cholerae El Tor isolates from patients with cholera in South Africa, one El Tor isolate from a patient in Malawi (a country approximately 1000 km north-northeast of South Africa), 6 El Tor and 12 classical type isolates from patients in Bangladesh, and 5 culture collection classical strains. Identical phage types and indistinguishable toxigenicities among the South African and Malawi V. cholerae, representing isolations obtained over a 10-year period, indicated that essentially a single strain was involved in the cholera of these regions. Similarly, phage typing and toxin profiles indicated that the 12 classical and 6 El Tor V. cholerae cultures in Bangladesh, all isolated in November 1983, represented just two strains. As assessed by titrations in Y-1 mouse adrenal and Chinese hamster ovary cell lines, the general order of toxigenicities was Bangladesh and culture collection classical greater than Bangladesh El Tor greater than southern African El Tor. The African isolates consistently gave rise to very low titers. Their relative reluctance to produce the toxin in vitro compared with the culture collection classical strains, particularly strain 569B, was confirmed by rocket electrophoresis. In somewhat of a contrast, maximum in vivo titers in rice water stools from cholera patients in South Africa and from both classical and El Tor type cholera patients in Bangladesh were essentially equal. It is postulated that under the continuous culture conditions that occur in vivo, cholera toxin concentrations can accumulate to a maximum level, depending on the rate of purging by the diarrheal fluid rather than the toxigenicity of the infecting stain. The relevance of these findings to the relative severities of classical and El Tor types of cholera is discussed.
14 citations
Journal Article•
TL;DR: A CAMP phenomenon was demonstrated by Vibrio cholerae biotype El Tor and B-lysin producing Staphylococcus aureus in 5% sheep red blood cells-tryptic soy agar medium and may be useful for routine use in the differentiation of V. cholerAE.
Abstract: A CAMP phenomenon was demonstrated by Vibrio cholerae biotype El Tor and B-lysin producing Staphylococcus aureus in 5% sheep red blood cells-tryptic soy agar medium. All 394 El Tor vibrio strains tested, all showed a crescent-shaped hemolysis (positive CAMP) when the cultures were incubated in a candle jar whereas 67% were CAMP positive when incubated aerobically. Only 9% of the isolates produced detectable hemolysin in a standard tube test using heart infusion broth and 72% in a tube test using heart infusion broth containing 1% glycerol. Seven classical V. cholerae tested were CAMP negative. The CAMP reaction is easy to perform and may be useful for routine use in the differentiation of V. cholerae biotype El Tor from classical V. cholerae.
TL;DR: Investigation of the effect of varying levels of extracellular protease production on the bacteriophage type of Vibrio cholerae 1621 serotype 01, biotype E1 Tor shows that the production of high levels of exoprotease can alter the apparent type of the strain by rendering it insensitive to infection by a number of bacteriaiophages.
Abstract: The effect of varying levels of extracellular protease production on the bacteriophage type of Vibrio cholerae 1621 serotype 01, biotype El Tor, has been investigated. It has been shown that the production of high levels of exoprotease can alter the apparent type of the strain by rendering it insensitive to infection by a number of bacteriophages. Prevention of a productive infection appears to be due to altered surface characteristics rather than to specific damage to the bacteriophages. Such altered surface characteristics may be due to auto-digestion. The importance of this observation to epidemiological studies of V. cholerae is noted and discussed.