Cholera Caused by Vibrio cholerae O1 Induces T-Cell Responses in the Circulation

Considerable effort is being made to understand the acute and memory antibody responses in natural cholera infection, while rather less is known about the roles of cellular immune responses involving T and B lymphocytes. We studied responses in adult patients hospitalized with cholera caused by Vibrio cholerae O1. Peripheral blood mononuclear cells from patients (n = 15) were analyzed by flow cytometry after stimulation with V. cholerae O1 membrane protein (MP) or toxin-coregulated pilus antigen (TcpA). The gamma interferon (IFN-γ) and interleukin-13 (IL-13) responses in stimulated-lymphocyte supernatants were studied. The responses were compared with those of healthy controls (n = 10). Patients responded with increased frequencies of gut-homing CD4⁺ T cells (CD4⁺ β7⁺), gut-homing CD8⁺ T cells (CD8⁺ β7⁺), and gut-homing B cells (CD19⁺ β7⁺) at the early and/or late convalescent stages compared to the acute stage. After stimulation with MP or TcpA, proliferation of CD4⁺ and CD8⁺ T cells was increased at the acute stage and/or early convalescent stage compared to healthy controls. Increased IL-13 and IFN-γ responses were observed after antigenic stimulation at the acute and convalescent stages compared to healthy controls. Thus, increases in the levels of gut-homing T and B cells, as well as involvement of CD8 and CD4 Th1-mediated (IFN-γ) and CD4 Th2-mediated (IL-13) cytokine responses, take place in acute dehydrating disease caused by V. cholerae O1. Further studies are needed to determine if such responses are also stimulated after immunization with oral cholera vaccines and if these responses play a role in protection following exposure to cholera.Vibrio cholerae O1 is a common causative agent of acute watery diarrhea in children and adults in the developing world (1, 3, 10, 19). After colonizing the proximal small intestine, this bacterium produces cholera toxin, which induces a profuse secretory diarrhea. Cholera remains a key public health problem that results in epidemics in resource-poor settings.It is believed that the immune response to cholera is initiated by antigen presentation in the Peyer''s patches of the gastrointestinal mucosa, followed by migration of the stimulated antigen-specific B cells to regional lymph nodes and differentiation of these cells into specific antibody-secreting cells (28). Stimulation of the common mucosal immune system leads to production of both local and systemic antibodies (2, 15, 27) to virulence antigens of V. cholerae (25, 28).Natural cholera infection is believed to give rise to long-term protection against subsequent disease. Robust systemic and mucosal antibodies are produced to the V. cholerae lipopolysaccharide, to cholera toxin, and to colonization factors, including the major subunit of the toxin-coregulated pilus, TcpA (2, 24, 25, 28). We have recently shown that there is induction of memory B-cell responses following infection, which may play a role in longer-lasting protection (14). In addition, recent evidence suggests that an innate component of the immune system may also play a role in the host response to cholera (9, 22, 26). Studies with experimental animals have shown that the mucosal immune response to cholera toxin is T cell dependent and that CD4 T helper cells have an important role (7, 12, 13). However, not much is known about the role of the adaptive cellular immune responses in patients with cholera. The aim of the present study was to decipher the role of T- and B-cell-mediated immune responses in natural cholera infection in adults hospitalized with dehydrating illness, who were followed from the acute stage to convalescence.     

Rapid detection of Vibrio cholerae O139 Bengal from stool specimens by PCR.

In a previous study using pure bacterial cultures in a PCR assay, a primer pair corresponding to a unique chromosomal region of Vibrio cholerae O139 Bengal generated an amplicon from only V. cholerae O139 Bengal. PCR with the same primer pair was used to screen 180 diarrheal stool specimens. All the 67 V. cholerae O139 culture-positive stool specimens were positive by PCR, and the remaining specimens, which contained either other recognized enteric pathogens or no pathogens, were all negative by PCR.     

Induction of Fimbriated Vibrio cholerae O139

Several fimbriated phases of Vibrio cholerae O139 strains were selectively induced and compared immunologically and biochemically with those of V. cholerae O1. Fimbrial antigens were detected on the surfaces of vibrio cells colonizing the epithelial cells of a rabbit small intestine. Convalescent-phase sera from six individuals infected with V. cholerae O139 revealed the development of antibody against the fimbrillin. These findings suggest that the fimbriae of V. cholerae O1 and O139 are expressed in vivo during infection and that consideration must be given to the use of fimbrial antigens as components of vaccines against cholera.     

Phagocytosis of Vibrio cholerae O139 Bengal by human polymorphonuclear leukocytes

Capsulated bacteria exhibit serum (complement) resistance and resistance to phagocytosis, which result in disseminated infections. Vibrio cholerae O139 strains possess a thin capsule and have been found to be partially serum resistant in a previous study. In the present study, compared to a standard capsulated Klebsiella pneumoniae strain, which showed total resistance to killing by phagocytosis, V. cholerae O139 strains were shown to be only partially resistant, with most strains showing <40% survival. These findings may explain the relative rarity of V. cholerae O139 bacteremia in cholera caused by this organism.     

Phagocytosis of Vibrio cholerae O139 Bengal by Human Polymorphonuclear Leukocytes

Capsulated bacteria exhibit serum (complement) resistance and resistance to phagocytosis, which result in disseminated infections. Vibrio cholerae O139 strains possess a thin capsule and have been found to be partially serum resistant in a previous study. In the present study, compared to a standard capsulated Klebsiella pneumoniae strain, which showed total resistance to killing by phagocytosis, V. cholerae O139 strains were shown to be only partially resistant, with most strains showing <40% survival. These findings may explain the relative rarity of V. cholerae O139 bacteremia in cholera caused by this organism.     

Resurgent Vibrio cholerae O139: Rearrangement of Cholera Toxin Genetic Elements and Amplification of rrn Operon

The unprecedented genesis of a novel non-O1 Vibrio cholerae strain belonging to serogroup O139, which caused an epidemic in late 1992 in the Indian subcontinent, and its subsequent displacement by El Tor O1 vibrios after 18 months initiated a renewed investigation of the aspects of the organism that are related to pathogenesis. The reappearance of V. cholerae O139 with altered antibiotic sensitivity compared to O139 Bengal (O139B) in late 1996 has complicated the epidemiological scenario of V. cholerae and has necessitated an examination of possible rearrangements in the genome underlying such rapid changes in the phenotypic traits. With a view to investigating whether the phenotypic changes that have occurred are associated with alteration in the genome, the genome of the resurgent V. cholerae O139 (O139R) strains were examined. Pulsed-field gel electrophoresis analysis of NotI- and SfiI-digested genomic DNA of O139R isolates showed restriction fragment length polymorphism including in the cholera toxin (CTX) genetic element locus and with O139B isolates. Analyses of the organization of the CTX genetic elements in O139R strains showed that in contrast to two copies of the elements connected by two direct-repeat sequences (RS) in most of the genomes of O139B isolates, the genomes of all O139R strains examined, except strain AS192, have three such elements connected by a single RS. While the RS present in the upstream of the CTX genetic elements in the genome of O139R is of O139B origin, the RS connecting the cores of the elements has several new restriction sites and has lost the BglII site which is supposed to be conserved in all O1 strains and O139B. The endonuclease I-CeuI, which has sites only in the rrn operons in the genomes of all organisms examined so far, has 10 sites in the genomes of O139R strains, compared to 9 in the genomes of O139B strains. The recent isolates of V. cholerae O139 have thus gained one rrn operon. This variation in the number of rrn operons within a serogroup has not been reported for any other organism. The results presented in this report suggest that like the pathogenic El Tor O1 strains, the genomes of O139 strains are undergoing rapid alterations.     

Rapid screening method for identification of cholera toxin-producing Vibrio cholerae O1 and O139.

A novel method of identifying cholera enterotoxin (CT)-producing Vibrio cholerae serogroups O1 and O139 was developed. The method uses degradation of NAD as a specific biochemical marker for the CT-producing strains. The substrate NAD at a concentration of 100 mumol/liter was markedly degraded when it was incubated at 37 degrees C for 2 h with the CT-producing stains at a final cell density equivalent to that of a twofold dilution of a McFarland no. 1 standard. NAD degradation was monitored by an enzyme-amplified color development assay. Subsequent tests conducted with a total of 119 strains of V. cholerae, including both clinical and environmental isolates, confirmed a significant correlation between NAD degradation and CT production for all V. cholerae strains belonging to serogroups O1 and O139. Since 2 of 11 non-O1, non-O139 V. cholerae strains not carrying the CT gene degraded NAD, serotyping of the strains prior to the test is recommended.     

Phage specific for Vibrio cholerae O139 Bengal.

From the stool of a Vibrio cholerae O139 Bengal-infected patient, a phage that specifically lysed capsulated V. cholerae O139 strains only was isolated. The phage is useful for the confirmatory diagnosis of V. cholerae O139 infection and for the differentiation of variants that lack the capsule.     

霍乱弧菌O139菌毛提取及其疫苗的试制

目的　 寻求Ｏ１３９ 型霍乱弧菌菌毛提取纯化的最适方法和其疫苗研制。方法　ＳＤＳＰＡＧＥ,斑点酶免疫（ＤＢＩ） 检测和ＢＡＥＬＩＳＡ 法。采用ＰＥＬＡ 材料包封菌毛,成为缓释微球疫苗。结果电泳均存在相对分子质量为２０ ．５ ×１０３ 的条带;ＤＢＩ结果为阳性。小鼠血清ＩｇＧ 以皮下ＭＳＴＣＰ 组最高（１∶７ ６８０） ,唾液中的ｓＩｇＡ 以口服ＭＳＴＣＰ 组最高（１∶６０） 。保护力试验中口服组的保护力约为３０ ％ ～４０ ％ ,而皮下组为７０ ％ ～９０ ％ 。结论　 口服组主要诱导粘膜免疫,皮下组主要诱导全身性免疫。ＴＣＰ 是霍乱弧菌的共同抗原之一,可作为霍乱疫苗的候选抗原。     

Acute Cholecystitis Caused by Nontoxigenic Vibrio cholerae O1 Inaba

A rare case of acute cholecystitis caused by serogroup O1 Vibrio cholerae in an 83-year-old man is presented. His risk factors for cholecystitis included advanced age and previous abdominal surgeries. The patient had consumed raw oysters several days before presentation. The patient had a poor outcome after admission for this infection, likely due to his underlying illnesses that complicated his hospital course.     

One-Step Immunochromatographic Dipstick Tests for Rapid Detection of Vibrio cholerae O1 and O139 in Stool Samples

We describe the development and evaluation of a rapid diagnostic test for Vibrio cholerae O1 and O139 based on lipopolysaccharide detection using gold particles. The specificity ranged between 84 and 100%. The sensitivity of the dipsticks ranged from 94.2 to 100% when evaluated with stool samples obtained in Madagascar and Bangladesh. The dipstick can provide a simple tool for epidemiological surveys.     

Induction of the Lysogenic Phage Encoding Cholera Toxin in Naturally Occurring Strains of Toxigenic Vibrio cholerae O1 and O139

In toxigenic Vibrio cholerae, the CTX genetic element which carries the genes for cholera toxin (CT) is the genome of a lysogenic bacteriophage (CTXΦ). Clinical and environmental strains of V. cholerae O1 or O139 and stools that were culture positive for cholera were analyzed to study the induction and transmission of CTXΦ. To our knowledge, this is the first report of the examination of CTXΦ in clinical materials and in naturally occurring strains. DNA probe analysis revealed that 4.25% (6 of 141) of the isolated V. cholerae strains spontaneously produced a detectable level of extracellular CTXΦ particles in the culture supernatants whereas another 34.04% (48 of 141) produced CTXΦ particles when induced with mitomycin C. CTXΦ isolated from 10 clinical or environmental strains infected a CT-negative recipient strain, CVD103, both inside the intestines of infant mice and under laboratory conditions. All culture-positive stools analyzed were negative for the presence of CTXΦ both in the DNA probe assay and by in vivo assay for the infection of the recipient strain in infant mice. These results suggested that naturally occurring strains of toxigenic V. cholerae are inducible lysogens of CTXΦ but that cholera pathogenesis in humans is not associated with the excretion of CTXΦ particles in stools, indicating that induction of the phage may not occur efficiently inside the human intestine. However, in view of the efficient transmission of the phage under conditions conducive to the expression of toxin-coregulated pili, it appears that propagation of CTXΦ in the natural habitat may involve both environmental and host factors.     

应用环介导等温扩增法快速检测O139群霍乱弧菌

目的 建立一种适合基层检验部门及小型实验室使用的快速检测O139群霍乱弧菌的方法.方法 应用环介导等温扩增技术(loop-mediated isothermal amplification,LAMP),针对O139霍乱弧菌wbfR基因设计4条引物(2条内引物、2条外引物);优化LAMP反应条件和反应体系,对反应体系中的引物、dNTP、Mg2+/Mn2+离子及Calcium等浓度进行优化;并对13株种系背景明确的霍乱弧菌不同实验对照株、30株O139群霍乱弧菌地方分离株、10株O1群霍乱弧菌地方分离株、32株其他肠道菌进行检测,验证该方法的特异性;通过肉眼目测或电泳检测比较结果.结果 所有O139群霍乱弧菌经LAMP榆测均呈绿色并电泳有阶梯状条带为阳性,O1群霍乱弧菌及其他肠道菌均检测呈橙色并电泳无相应条带为阴性;该体系最低检测限为63 CFU/反应;检测结果在白光下通过肉眼即可判断;从菌株核酸的提取至检测完成仅需1.5 h左右.结论 本研究建立的LAMP方法能够快速、灵敏、特异地检测O139群霍乱弧菌,无需昂贵的仪器,简单方便,非常适合基层检验部门或小型实验室以及流行病学人员于应急车上或现场监测等使用,值得推广.     

应用环介导等温扩增法快速检测O139群霍乱弧菌

目的 建立一种适合基层检验部门及小型实验室使用的快速检测O139群霍乱弧菌的方法.方法 应用环介导等温扩增技术(loop-mediated isothermal amplification,LAMP),针对O139霍乱弧菌wbfR基因设计4条引物(2条内引物、2条外引物);优化LAMP反应条件和反应体系,对反应体系中的引物、dNTP、Mg2+/Mn2+离子及Calcium等浓度进行优化;并对13株种系背景明确的霍乱弧菌不同实验对照株、30株O139群霍乱弧菌地方分离株、10株O1群霍乱弧菌地方分离株、32株其他肠道菌进行检测,验证该方法的特异性;通过肉眼目测或电泳检测比较结果.结果 所有O139群霍乱弧菌经LAMP榆测均呈绿色并电泳有阶梯状条带为阳性,O1群霍乱弧菌及其他肠道菌均检测呈橙色并电泳无相应条带为阴性;该体系最低检测限为63 CFU/反应;检测结果在白光下通过肉眼即可判断;从菌株核酸的提取至检测完成仅需1.5 h左右.结论 本研究建立的LAMP方法能够快速、灵敏、特异地检测O139群霍乱弧菌,无需昂贵的仪器,简单方便,非常适合基层检验部门或小型实验室以及流行病学人员于应急车上或现场监测等使用,值得推广.     

应用环介导等温扩增法快速检测O139群霍乱弧菌

目的 建立一种适合基层检验部门及小型实验室使用的快速检测O139群霍乱弧菌的方法.方法 应用环介导等温扩增技术(loop-mediated isothermal amplification,LAMP),针对O139霍乱弧菌wbfR基因设计4条引物(2条内引物、2条外引物);优化LAMP反应条件和反应体系,对反应体系中的引物、dNTP、Mg2+/Mn2+离子及Calcium等浓度进行优化;并对13株种系背景明确的霍乱弧菌不同实验对照株、30株O139群霍乱弧菌地方分离株、10株O1群霍乱弧菌地方分离株、32株其他肠道菌进行检测,验证该方法的特异性;通过肉眼目测或电泳检测比较结果.结果 所有O139群霍乱弧菌经LAMP榆测均呈绿色并电泳有阶梯状条带为阳性,O1群霍乱弧菌及其他肠道菌均检测呈橙色并电泳无相应条带为阴性;该体系最低检测限为63 CFU/反应;检测结果在白光下通过肉眼即可判断;从菌株核酸的提取至检测完成仅需1.5 h左右.结论 本研究建立的LAMP方法能够快速、灵敏、特异地检测O139群霍乱弧菌,无需昂贵的仪器,简单方便,非常适合基层检验部门或小型实验室以及流行病学人员于应急车上或现场监测等使用,值得推广.     

应用环介导等温扩增法快速检测O139群霍乱弧菌

目的 建立一种适合基层检验部门及小型实验室使用的快速检测O139群霍乱弧菌的方法.方法 应用环介导等温扩增技术(loop-mediated isothermal amplification,LAMP),针对O139霍乱弧菌wbfR基因设计4条引物(2条内引物、2条外引物);优化LAMP反应条件和反应体系,对反应体系中的引物、dNTP、Mg2+/Mn2+离子及Calcium等浓度进行优化;并对13株种系背景明确的霍乱弧菌不同实验对照株、30株O139群霍乱弧菌地方分离株、10株O1群霍乱弧菌地方分离株、32株其他肠道菌进行检测,验证该方法的特异性;通过肉眼目测或电泳检测比较结果.结果 所有O139群霍乱弧菌经LAMP榆测均呈绿色并电泳有阶梯状条带为阳性,O1群霍乱弧菌及其他肠道菌均检测呈橙色并电泳无相应条带为阴性;该体系最低检测限为63 CFU/反应;检测结果在白光下通过肉眼即可判断;从菌株核酸的提取至检测完成仅需1.5 h左右.结论 本研究建立的LAMP方法能够快速、灵敏、特异地检测O139群霍乱弧菌,无需昂贵的仪器,简单方便,非常适合基层检验部门或小型实验室以及流行病学人员于应急车上或现场监测等使用,值得推广.     

应用环介导等温扩增法快速检测O139群霍乱弧菌

目的 建立一种适合基层检验部门及小型实验室使用的快速检测O139群霍乱弧菌的方法.方法 应用环介导等温扩增技术(loop-mediated isothermal amplification,LAMP),针对O139霍乱弧菌wbfR基因设计4条引物(2条内引物、2条外引物);优化LAMP反应条件和反应体系,对反应体系中的引物、dNTP、Mg2+/Mn2+离子及Calcium等浓度进行优化;并对13株种系背景明确的霍乱弧菌不同实验对照株、30株O139群霍乱弧菌地方分离株、10株O1群霍乱弧菌地方分离株、32株其他肠道菌进行检测,验证该方法的特异性;通过肉眼目测或电泳检测比较结果.结果 所有O139群霍乱弧菌经LAMP榆测均呈绿色并电泳有阶梯状条带为阳性,O1群霍乱弧菌及其他肠道菌均检测呈橙色并电泳无相应条带为阴性;该体系最低检测限为63 CFU/反应;检测结果在白光下通过肉眼即可判断;从菌株核酸的提取至检测完成仅需1.5 h左右.结论 本研究建立的LAMP方法能够快速、灵敏、特异地检测O139群霍乱弧菌,无需昂贵的仪器,简单方便,非常适合基层检验部门或小型实验室以及流行病学人员于应急车上或现场监测等使用,值得推广.