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Comparison of the vibriocidal antibody response in cholera due to Vibrio cholerae O139 Bengal with the response in cholera due to Vibrio cholerae O1.

Vibrio cholerae serogroup O139, now considered to be the second organism capable of causing epidemic severe dehydrating cholera, contains a capsular polysaccharide which makes it difficult for it to be used in the conventional vibriocidal antibody assay optimized for V. cholerae O1. After modification of the procedure, which involved the use of specific bacterial strains, a lower bacterial inoculum, and increased amounts of complement, the vibriocidal antibody responses to V. cholerae O139 were measured in acute- and convalescent-phase sera from 33 V. cholerae O139-infected and 18 V. cholerae O1-infected patients and in single serum samples from 20 healthy control subjects. The responses in these individuals to V. cholerae O1 strains were also determined. Significant elevations in the homologous antibody response were found only in the convalescent-phase sera from both groups of patients with cholera. These findings may explain the basis for the lack of heterologous protection between the two serogroups of V. cholerae. Healthy controls had higher background levels of vibriocidal antibody to V. cholerae O1 than to V. cholerae O139.

Adult↗

Vibrio cholerae non-O1 serogroup associated with cholera gravis genetically and physiologically resembles O1 E1 Tor cholera strains.

Until recently, only Vibrio cholerae strains of the O1 serogroup have been associated with epidemic cholera. In December 1992, an outbreak of cholera gravis in Vellore, India, was attributed to a new serogroup of V. cholerae recently designated O139. Serogroup O139 cholera has since spread to 13 countries and has reached pandemic proportions. Serogroup O139 cholera evades immunity to O1 cholera and is not detected by the standard O1 antigen test. Understanding the origins of O139 cholera and determining the relatedness of O139 to O1 cholera are necessary to device strategies for detecting, reporting, and controlling this new pandemic. In order to determine the origins of this novel cholera serogroup, O139 was analyzed for virulence genes, for virulence proteins and their regulation, and for its genomic background. We found that O139 and O1 V. cholera strains of the E1 Tor biotype possess highly homologous virulence genes encoding cholera toxin and toxin-coregulated pili and that the regulation of virulence protein expression likewise was indistinguishable between O139 and O1. Pulsed-field gel electrophoresis (PFGE) revealed the restriction digest pattern of O139 strains to be closely related to that of O1 serogroup E1 Tor biotype cholera strains from the Indian subcontinent. However, PFGE showed minor differences among individual O139 cholera isolates, suggesting that O139 V. cholerae is evolving.

Cholera↗

Hemolytic Vibrio cholerae O1 that is sensitive to Mukerjee's cholera phage IV and the phage produced by the hemolytic vibrio lysogenized with the infection of Mukerjee's cholera phage IV.

Strains of hemolytic Vibrio cholerae O1 (El Tor vibrio) which are sensitive to Mukerjee's cholera phage group IV were isolated from cholera patients in North-East Thailand in 1986. Plaques of the phage on these hemolytic V. cholerae O1 were usually translucent but almost transparent on some strains, just like the plaques on non-hemolytic V. cholerae O1 (classical vibrio). These hemolytic V. cholerae O1 were lysogenized with the infection of cholera phage IV, and the lysogenized strains produced phage different from cholera phage IV. These hemolytic strains were classified into Cured type in prophage typing of V. cholerae O1, El Tor, because they were also lysogenized with Kappa phage and were hemolytic. When Cured-type V. cholerae O1, El Tor previously isolated in various countries were examined for the sensitivity to cholera phage IV, some of the isolates were sensitive.

Bacteriophages↗

Large epidemic of cholera-like disease in Bangladesh caused by Vibrio cholerae O139 synonym Bengal. Cholera Working Group, International Centre for Diarrhoeal Diseases Research, Bangladesh.

Epidemics of cholera caused by Vibrio cholerae O1 occur regularly in Bangladesh, but until lately V cholerae non-O1 has been associated only with sporadic cases of diarrhoeal disease in many parts of the world, including Bangladesh. We describe a large epidemic of cholera-like disease in Bangladesh that is due to a V cholerae non-O1. The epidemic began in December, 1992, in southern Bangladesh and spread throughout the country. By the end of March 107,297 cases of diarrhoea and 1473 deaths had been reported. The disease is indistinguishable from cholera in clinical features and response to treatment, but most of the cases are in adults, which suggests that the population has no previous immunological experience of the organism. At two centres 375 (40%) of 938 and 236 (48%) of 492 rectal swabs were positive for V cholerae non-O1, as were 5 of 54 surface water samples. 55 isolates of V cholerae non-O1 were studied in detail. They resembled El Tor vibrios in being resistant to polymyxin B and positive for agglutination of chicken erythrocytes. The strain did not belong to any of the 138 known V cholerae serogroups; so a new serogroup O139, with the suggested name Bengal, is proposed. All the isolates studied produced large amounts of an enterotoxin apparently identical to cholera toxin. This strain seems to have pandemic potential. It is important that other countries in southeast Asia are aware of the strain's potential to cause severe morbidity and mortality.

Adolescent↗

Analysis of the roles of antilipopolysaccharide and anti-cholera toxin immunoglobulin A (IgA) antibodies in protection against Vibrio cholerae and cholera toxin by use of monoclonal IgA antibodies in vivo.

Secretory immunoglobulin A (IgA) antibodies (sIgA) directed against cholera toxin (CT) and surface components of Vibrio cholerae are associated with protection against cholera, but the relative importance of specific sIgAs in protection is unknown. A monoclonal IgA directed against the V. cholerae lipopolysaccharide (LPS), secreted into the intestines of neonatal mice bearing hybridoma tumors, was previously shown to provide protection against a lethal oral dose of 10(7) V. cholerae cells. We show here that a single oral dose of 5 to 50 micrograms of the monoclonal anti-LPS IgA, given within 2 h before V. cholerae challenge, protected neonatal mice against challenge. In contrast, an oral dose of 80 micrograms of monoclonal IgA directed against CT B subunit (CTB) failed to protect against V. cholerae challenge. A total of 80 micrograms of monoclonal anti-CTB IgA given orally protected neonatal mice from a lethal (5-micrograms) oral dose of CT. Secretion of the same anti-CTB IgA antibodies into the intestines of mice bearing IgA hybridoma backpack tumors, however, failed to protect against lethal oral doses of either CT (5 micrograms) or V. cholerae (10(7) cells). Furthermore, monoclonal anti-CTB IgA, either delivered orally or secreted onto mucosal surfaces in mice bearing hybridoma tumors, did not significantly enhance protection over that provided by oral anti-LPS IgA alone. These results demonstrate that anti-LPS sIgA is much more effective than anti-CT IgA in prevention of V. cholerae-induced diarrheal disease.

Administration, Oral↗

Randomized, double-blind, placebo-controlled, multicentered trial of the efficacy of a single dose of live oral cholera vaccine CVD 103-HgR in preventing cholera following challenge with Vibrio cholerae O1 El tor inaba three months after vaccination.

CVD 103-HgR is a live oral cholera vaccine strain constructed by deleting 94% of the gene for the enzymatically active A subunit of cholera toxin from classical Inaba Vibrio cholerae O1 569B; the strain also contains a mercury resistance gene as an identifying marker. This vaccine was well tolerated and immunogenic in double-blind, controlled studies and was protective in open-label studies of volunteers challenged with V. cholerae O1. A randomized, double-blind, placebo-controlled, multicenter study of vaccine efficacy was designed to test longer-term protection of CVD 103-HgR against moderate and severe El Tor cholera in U.S. volunteers. A total of 85 volunteers (50 at the University of Maryland and 35 at Children's Hospital Medical Center/University of Cincinnati) were recruited for vaccination and challenge with wild-type V. cholerae El Tor Inaba. Volunteers were randomized in a double-blind manner to receive, with buffer, a single oral dose of either CVD 103-HgR (2 x 10(8) to 8 x 10(8) CFU) or placebo (killed E. coli K-12). About 3 months after immunization, 51 of these volunteers were orally challenged with 10(5) CFU of virulent V. cholerae O1 El Tor Inaba strain N16961, prepared from a standardized frozen inoculum. Ninety-one percent of the vaccinees had a >/=4-fold rise in serum vibriocidal antibodies after vaccination. After challenge, 9 (39%) of the 23 placebo recipients and 1 (4%) of the 28 vaccinees had moderate or severe diarrhea (>/=3-liter diarrheal stool) (P < 0.01; protective efficacy, 91%). A total of 21 (91%) of 23 placebo recipients and 5 (18%) of 28 vaccinees had any diarrhea (P < 0.001; protective efficacy, 80%). Peak stool V. cholerae excretion among placebo recipients was 1.1 x 10(7) CFU/g and among vaccinees was 4.9 x 10(2) CFU/g (P < 0.001). This vaccine could therefore be a safe and effective tool to prevent cholera in travelers.

Administration, Oral↗

Cost-effectiveness of oral cholera vaccine in a stable refugee population at risk for epidemic cholera and in a population with endemic cholera.

Recent large epidemics of cholera with high incidence and associated mortality among refugees have raised the question of whether oral cholera vaccines should be considered as an additional preventive measure in high-risk populations. The potential impact of oral cholera vaccines on populations prone to seasonal endemic cholera has also been questioned. This article reviews the potential cost-effectiveness of B-subunit, killed whole-cell (BS-WC) oral cholera vaccine in a stable refugee population and in a population with endemic cholera. In the population at risk for endemic cholera, mass vaccination with BS-WC vaccine is the least cost-effective intervention compared with the provision of safe drinking-water and sanitation or with treatment of the disease. In a refugee population at risk for epidemic disease, the cost-effectiveness of vaccination is similar to that of providing safe drinking-water and sanitation alone, though less cost-effective than treatment alone or treatment combined with the provision of water and sanitation. The implications of these data for public health decision-makers and programme managers are discussed. There is a need for better information on the feasibility and costs of administering oral cholera vaccine in refugee populations and populations with endemic cholera.

Administration, Oral↗

Oral immunization with attenuated vaccine strains of Vibrio cholerae expressing a dodecapeptide repeat of the serine-rich Entamoeba histolytica protein fused to the cholera toxin B subunit induces systemic and mucosal antiamebic and anti-V. cholerae antibody responses in mice.

Entamoeba histolytica is a significant cause of morbidity and mortality worldwide. The serine-rich E. histolytica protein (SREHP) is a surface-expressed trophozoite protein that includes multiple hydrophilic tandem repeats. A purified fusion protein between the dodecapeptide repeat of SREHP and cholera toxin B subunit (CTB) has previously been shown to be immunogenic in mice after oral inoculation when cholera toxin is coadministered as an immunoadjuvant. We engineered a live attenuated El Tor Vibrio cholerae vaccine strain, Peru2, to express the SREHP-12-CTB fusion protein to the supernatant from either a plasmid [Peru2 (pETR5.1)] or from a chromosomal insertion (ETR3). Vector strains were administered orally to germfree mice that were subsequently housed under nongermfree conditions; mice received one (day 0) or two (days 0 and 14) inoculations. No immunoadjuvant or cholera holotoxin was administered. Mice that received two inoculations of Peru2(pETR5.1) had the most pronounced antiamebic systemic and mucosal immunologic responses. Less marked, but significant, anti-SREHP serum immunoglobulin G antibody responses were also induced in mice that received either one or two oral inoculations of strain ETR3. Anti-V. cholerae responses were also induced, as measured by the induction of serum vibriocidal antibodies and by serum and mucosal anti-CTB antibody responses. These results suggest that V. cholerae vector strains can be successful delivery vehicles for the SREHP-12-CTB fusion protein, to induce mucosal and systemic antiamebic and anti-V. cholerae immune responses. The magnitude of these responses is proportional to the amount of SREHP-12-CTB produced by the vector strain.

Administration, Oral↗

A serological survey for cholera antibodies in rural east Pakistan. 2. A comparison of antibody titres in the innunized and control populationd of a cholera-vaccine field-trial area and the relation of antibody titre to cholera case rate.

Controlled field trials of a highly antigenic cholera vaccine were held in Matlab Bazar in rural East Pakistan in 1963 and again in 1964. In July-September 1965, a serological survey for cholera antibodies was carried out on a random sample of the field-trial population. This survey revealed that it was possible to demonstrate the effect of a single injection of the cholera vaccine per head on the proportion of the population with detectable vibriocidal and agglutinating antibody 10 and 22 months after injection. More significantly, the reduction in cholera case rate caused by the vaccine could be correlated with the rise in vibriocidal antibody after vaccination, suggesting that the serological response to vaccine in man may be a useful measure of vaccine potency. The survey also indicated that in this endemic cholera area, with a high level of immunity in adults, a single injection of cholera vaccine was in fact a booster dose for the majority of the population. Thus, the results of cholera vaccine field trials in endemic areas cannot be directly extrapolated to predict the effects of the same vaccine in non-endemic areas.

Adolescent↗

Distribution of genes encoding cholera toxin, zonula occludens toxin, accessory cholera toxin, and El Tor hemolysin in Vibrio cholerae of diverse origins.

A large collection of 1154 strains of Vibrio cholerae of diverse origins including serogroups 01 and 0139 and those belonging to the non-01 and non-0139 (non-01:non-0139) serogroups were examined with a battery of DNA probes specific for cholera toxin (CT), zonula occludens toxin (ZOT), accessory cholera toxin (ACE) and El Tor hemolysin (HLY) to determine the distribution of genes among wild strains and to understand the importance of these factors in the pathogenesis of the disease cholera. Among the 01 clinical isolates, the majority of the strains had an intact core region (ctx, zot, ace) and also possessed the hlyA gene. Although rare, strains of 01 with natural deletions of the ctx, zot and/or ace genes were also detected. The absence of the virulence genes comprising the core region and the presence of the hlyA gene dominated the 01 environment, food isolates and the clinical and environmental non-01: non-0139 strains of V. cholerae. All the 0139 strains examined in this study possessed genes located in the core region and the hlyA gene. Among all the virulence-associated genes examined, the hlyA gene was the most conserved genetic element in V. cholerae independent of biotypes and serogroups.

Bacterial Proteins↗

Quantitative measurements of cholera enterotoxin in cultures of toxinogenic wild-type and nontoxinogenic mutant strains of Vibrio cholerae by using a sensitive and specific reversed passive hemagglutination assay for cholera enerotoxin.

A sensitive and specific reversed passive hemagglutination (RPHA) assay for cholera enterotoxin has been developed. Equine anti-choleragenoid antibodies purified by immunoadsorption were covalently coupled to formalinized sheep erythrocytes, using bis-diazotized benzidine, and the antitoxin-sensitized erythrocytes were shown to agglutinate specifically in the presence of cholera enterotoxin. In a microtiter RPHA assay system, the smallest quantity of enterotoxin that caused hemagglutination was approximately 20 pg. A sensitive assay for antibodies to enterotoxin was also developed, based on inhibition of RPHA. Using such assays, we demonstrated that several nontoxinogenic (tox-) strains of Vibrio cholerae produced small but detectable yields of enterotoxin, 4 to 16 ng/ml, under conditions where the highly toxinogenic strain 569B Inaba produced approximately 16 microgram of enterotoxin per ml. The enterotoxin produced in small quantities by these tox- strains was found to be identical to the enterotoxin from V. cholerae 569B Inaba iv its immunological and biological activities. Strains of V. cholerae that produce intermediate yields of enterotoxin have been obtained by two techniques: (i) as less toxinogenic mutants derived from highly toxinogenic strains and (ii) as more toxinogenic mutants derived from tox- strains. Thus, the yield of enterotoxin in cultures of V. cholerae grown under standardized conditions is is a genetically controlled trait that can be altered by mutation.

Antibody Specificity↗

[Research on V. cholerae anti-antibodies (agglutinating and vibriocidal) in patients affected by cholera-like gastroenteritis. Studies performed during the cholera epidemic occurred in Apulia in August-September 1973].

Agglutinating and vibriocidal antibody titers anti-V. cholerae of the serotypes Ogawa and Inaba, were determined in sera from 189 patients with cholera-like diarrheas during the epidemic of cholera occurred in August-September 1973, in Bari. Antibodies were determined in 74,2% of 70 patients, whose in the faeces and vomiting were isolated strains identified as V. cholerae, biotype El Tor, serotype Ogawa. This frequency was higher against the serotype Ogawa. The antibodies could be proved very early, 4-6 days from the beginning of symptomatology, but they disappeared as rapidly; really, at 2.3 months antibodies were determined in 7,7% only of the above mentioned subjects. As regards the other 119 patients with non-vibrio, cholera-like diarrheas, antibodies were determined in 28 subjects only; 27 of these has received cholera-vaccine some weeks before. One single case remained which was bacteriological negative, but showed signifcant agglutinating and vibriocidal antibody titers against the serotypes Ogawa and Inaba.

Agglutination Tests↗

Prevalence of Vibrio cholerae with heat-stable enterotoxin (NAG-ST) and cholera toxin genes; restriction fragment length polymorphisms of NAG-ST genes among V. cholerae O serogroups from a major shrimp production area in Thailand.

A total of 148 Vibrio cholerae isolates from a major shrimp production area in Southern Thailand were examined by colony hybridisation for genes encoding heat-stable enterotoxin (NAG-ST) and cholera toxin (CT). Only non-O1 V. cholerae strains were found to harbour NAG-ST (14 of 146) whereas no strains hybridised with the CT probe. NAG-ST-positive V. cholerae non-O1 strains were isolated from shrimp farms situated close to urban areas. Five different O serogroups were found among NAG-ST positive non-O1 strains. Southern blot and restriction endonuclease analysis of NAG-ST-positive strains revealed a high degree of genetic divergence. A total of seven classes of enterotoxin gene patterns were found with HindIII and EcoRI restriction endonucleases. Enterotoxin gene patterns correlated with O-antigen expression in 84% of isolates tested. In combination with other molecular techniques Southern blot analysis with an NAG-ST oligonucleotide probe could be useful for studying the molecular epidemiology of V. cholerae non-O1 strains.

Animals↗

A controlled field trial of the effectiveness of cholera and cholera El Tor vaccines in the Philippines. Preliminary report; Philippines Cholera Committee.

In a controlled field trial on some 584 000 people in an endemic cholera El Tor area in the Philippines, it was demonstrated that cholera vaccines gave moderate protection of short duration. Injection of a single dose of vaccine prepared from either Vibrio cholerae or Vibrio El Tor gave over 50% protection for the first two months. The immunity conferred by the V. cholerae vaccine rapidly declined after three to four months. The V. El Tor vaccine gave protection for six months, but its effectiveness declined. An oil-adjuvant vaccine prepared from V. cholerae conferred an increasing degree of protection of long duration, but, owing to severe vaccination reactions, its use could not be recommended.

Adolescent↗

Isolation of a new variant of Vibrio cholerae O1: V. cholerae O1 ribotype B27 toxinogenotype TB31 during the last cholera epidemic in Senegal.

A total of 205 Vibrio cholerae O1 isolates from recent cholera epidemic in Senegal were analyzed by conventional methods, polymerase chain reaction (PCR) for genes encoding cholera toxin (ctx A), zonula occludens toxin (zot) and accessory cholera enterotoxin (ace), ribotyping and toxinogenotyping. Ribotyping after Bg1 I digestion of total DNA revealed that ribotype B5a, the predominant ribotype of the seventh pandemic in Africa and Asia, was not isolated. A new ribotype designated B27 in our database is predominant and was associated with a new toxinogenotype designated TB31.

Cholera↗

Coleridge's choleras: cholera morbus, Asiatic cholera, and dysentery in early nineteenth-century England.

Samuel Taylor Coleridge suffered from a variety of bowel disorders throughout his life; though a large part of his ailment was caused by his famous opium habit, he continuously sought an organic origin, and on at least two separate occasions, in 1804 and 1831-32, he ascribed his disorders to attacks of "cholera." With Asiatic cholera apparently first reaching England in late 1831, there was considerable argument among both physicians and the general public as to whether it was a distinctly new disease, or merely a severer variation of traditional English cholera, known as "cholera morbus." Coleridge took a particular interest in these discussions. In this paper, we attempt to establish the exact nature of his attacks of illness, and point to the complexities of describing and framing new diseases and bowel disorders in the early nineteenth century.

Cholera↗

Neutralisation of the new cholera toxin by antiserum against crude enterotoxin of cholera toxin gene-positive Vibrio cholerae 01 in rabbit ileal loop model.

The enterotoxicity of the new cholera toxin (NCT) prepared from cholera toxin gene-negative (CT-) V. cholerae 01 strains isolated from human diarrhoeal and environmental sources was assayed in rabbit ileal loops and the toxin unit was calculated to be 24 micrograms of protein. The enterotoxicity of the NCT preparations were completely neutralised by the antiserum raised against the enterotoxin preparation from the CT+ V. cholerae 01 strain 569B at 1 in 16 dilution in ileal loops. The antiserum contained 1 unit of antitoxin in 85 x 10(-4) ml amount. The data indicate that the antiserum prepared against the enterotoxin of CT+ strain contains antibody against the NCT and can neutralise the toxin in vivo. The observations also suggest that CT+ strains liberate the NCT simultaneously with CT and the latter gets eliminated during the process of purification.

Animals↗

The study of intestinal immunity against V. cholerae: purification of V. cholerae El Tor haemagglutinin and the protective role of its antibody in experimental cholera.

V. cholerae El Tor Ogawa strain O17SR grown on trypticase soy agar were extracted with 0.05 M cyclohexylamino propane sulfonic acid (CAPS) pH 9.5 at 37 degrees C for 1 hour. The bacteria were then removed by centrifugation and millipore filtration. The filtered fluid, after being dialysed against many changes of cold distilled water, was concentrated and passed through Sephadex G200 column. Three protein profiles were eluted out with 0.05 M Tris buffer pH 8.6. The haemagglutinin and the bacterial lipopolysaccharide (LPS) were confined to the first profile. They were subsequently separated by agarose gel electrophoresis. The haemagglutinin was found to be more anodic than the LPS. After homogenization of the gel strips containing the haemagglutinin followed by centrifugation at 9,000 g pure haemagglutinin was obtained in the supernatant. Rabbit aniserum against pure haemagglutinin contained protective antibodies against V. cholerae infection in the baby mouse model. Specific antibodies prepared from this antiserum was as protective as the antibodies directed against whole V. cholerae and heat stable somatic antigens of V. cholerae upon the same weight unit.

Agglutinins↗