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- Qadri, Firdausi, et al.
(författare)
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Reduction in capsular content and enhanced bacterial susceptibility to serum killing of Vibrio cholerae O139 associated with the 2002 cholera epidemic in Bangladesh
- 2005
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Ingår i: Infect Immun. ; 73:10, s. 6577-6583
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Tidskriftsartikel (refereegranskat)abstract
- Vibrio cholerae O139 emerged in 1992 as a major cause of epidemic cholera. However, the incidence of disease due to this new serogroup subsequently decreased for almost a decade. In April 2002, there was a dramatic resurgence of V. cholerae O139 in Bangladesh. We compared the phenotypic properties of the bacterial isolates and the immunological responses in patients with disease due to V. cholerae O139 during the 2002 epidemic with those dating to the emergence of this disease in 1993 to 1995. Strains isolated from patients in the two time periods were compared with respect to capsular polysaccharide, their resistance to the bactericidal effect of serum, and their capacity to be used as target strains in complement-mediated vibriocidal assays. Phase-contrast microscopy showed that strains isolated in 2002 had less capsular material than those isolated from 1993 to 1995 (P = <0.001), a finding confirmed by electron microscopic studies. Strains isolated in 2002 were more susceptible to the bactericidal activity of serum compared to strains from 1993 to 1995 (P = 0.013). Compared to results using a standard O139 strain, a modified vibriocidal assay utilizing a 2002 strain, CIRS 134, as the target organism detected higher vibriocidal responses in both O139-infected cholera patients as well as O139 vaccine recipients. The vibriocidal assay utilizing the less encapsulated 2002 strain, CIRS 134, is a more sensitive indicator of adaptive immune responses to recent infection with V. cholerae O139. Consequently, this assay may be useful in studies of both O139-infected patients and recipients of O139 vaccines.
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- Bhuiyan, T. R., et al.
(författare)
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Assessing antigen specific HLA-DR plus antibody secreting cell (DR plus ASC) responses in whole blood in enteric infections using an ELISPOT technique
- 2018
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Ingår i: Microbes and Infection. - : Elsevier BV. - 1286-4579. ; 20:2, s. 122-129
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Tidskriftsartikel (refereegranskat)abstract
- Antibody secreting cells (ASCs) generate antibodies in an antigen-specific manner as part of the adaptive immune response to infections, and these cells increase their surface expression of HLA-DR. We have studied this parameter (HLA-DR+ASC) in patients with recent diarrheal infection using immuno-magnetic cell sorting and an enzyme linked immunospot (ELISPOT) technique that requires only one milliliter of blood. We validated this approach in adult patients with cholera (n = 15) or ETEC diarrhea (n = 30) on days 2, 7 and 30 after showing clinical symptom at the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr, b) hospital in Dhaka, and we compared responses to age-matched healthy controls (n = 7). We found that HLA-DRthorn ASC (DR+ASC) responses specific both for T cell-dependent (cholera toxin B subunit), and T cell-independent (lipopolysaccharide) antigens were elevated at day 7 after showing clinical cholera symptom. Similarly, DR+ASCs were elevated against both heat-labile toxin and colonization factors following ETEC infection. We observed significant correlations between antigen-specific DR+ASC responses and antigen-specific, gut homing ASC and plasma antibody responses. This study demonstrates that a simple ELISPOT procedure allows determination of antigen-specific ASC responses using a small volume of whole blood following diarrhea. This technique may be particularly useful in studying DR+ASC responses in young children and infants, either following infection or vaccination. (c) 2017 The Authors. Published by Elsevier Masson SAS on behalf of Institut Pasteur.
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- Bhuiyan, T. R., et al.
(författare)
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Enumeration of Gut-Homing beta 7-Positive, Pathogen-Specific Antibody-Secreting Cells in Whole Blood from Enterotoxigenic Escherichia coli- and Vibrio cholerae-Infected Patients, Determined Using an Enzyme-Linked Immunosorbent Spot Assay Technique
- 2016
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Ingår i: Clinical and Vaccine Immunology. - : American Society for Microbiology. - 1556-6811 .- 1556-679X. ; 23:1, s. 27-36
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Tidskriftsartikel (refereegranskat)abstract
- Vibrio cholerae and enterotoxigenic Escherichia coli (ETEC) are noninvasive mucosal pathogens that cause acute watery diarrhea in people in developing countries. Direct assessment of the mucosal immune responses to these pathogens is problematic. Surrogate markers of local mucosal responses in blood are increasingly being studied to determine the mucosal immune responses after infection. However, the volume of blood available in children and infants has limited this approach. We assessed whether an approach that first isolates beta 7-positive cells from a small volume of blood would allow measurement of the antigen-specific immune responses in patients with cholera and ETEC infection. beta 7 is a cell surface marker associated with mucosal homing. We isolated beta 7-expressing cells from blood on days 2, 7, and 30 and used an enzyme-linked immunosorbent spot (ELISPOT) assay to assess the gut-homing antibody-secreting cells (ASCs) specific to pathogen antigens. Patients with ETEC diarrhea showed a significant increase in toxin-specific gut-homing ASCs at day 7 compared to the levels at days 2 and 30 after onset of illness and to the levels in healthy controls. Similar elevations of responses to the ETEC colonization factors (CFs) CS6 and CFA/I were observed in patients infected with CS6- and CFA/I-positive ETEC strains. Antigen-specific gut-homing ASCs to the B subunit of cholera toxin and cholera-specific lipopolysaccharides (LPS) were also observed on day 7 after the onset of cholera using this approach. This study demonstrates that a simple ELISPOT assay can be used to study the mucosal immunity to specific antigens using a cell-sorting protocol to isolate mucosal homing cells, facilitating measurement of mucosal responses in children following infection or vaccination.
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- Chowdhury, Fahima, et al.
(författare)
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Concomitant enterotoxigenic Escherichia coli infection induces increased immune responses to Vibrio cholerae O1 antigens in patients with cholera in Bangladesh.
- 2010
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Ingår i: Infection and immunity. - 1098-5522. ; 78:5, s. 2117-24
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Tidskriftsartikel (refereegranskat)abstract
- Vibrio cholerae O1 and enterotoxigenic Escherichia coli (ETEC) are major bacterial pathogens that cause dehydrating disease requiring hospitalization of children and adults. The cholera toxin (CT) produced by V. cholerae O1 and the heat-labile toxin (LT) and/or heat-stable toxin (ST) of ETEC are responsible for secretory diarrhea. We have observed that about 13% of hospitalized diarrheal patients are concomitantly infected with V. cholerae O1 and ETEC. In order to understand the outcome of such dual infections on the clinical and immunological responses in cholera patients, we studied patients infected with V. cholerae O1 (group VC; n = 25), those infected with both V. cholerae O1 and ETEC (group VCET; n = 25), and those infected with ETEC only (group ET; n = 25). The VCET group showed more severe dehydration and had a higher intake of intravenous fluid and more vomiting than the ETEC group (P = 0.01 to 0.003). The VCET patients showed higher vibriocidal responses and increased antibody titers to cholera toxin and lipopolysaccharide (LPS) in plasma than did the V. cholerae O1 patients (P = 0.02 to <0.001). All responses in the V. cholerae O1 and in the VCET groups were more robust than those seen in the group infected with ETEC only (P = 0.01 to <0.001). We thus show that concomitant colonization with ETEC induces immune responses to V. cholerae antigens that are more robust than those seen with V. cholerae O1 infection alone. It is possible that LT or other factors expressed by ETEC may play a role as a mucosal adjuvant in enhancing the immune responses to V. cholerae O1.
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- Harris, Aaron M, et al.
(författare)
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Shifting prevalence of major diarrheal pathogens in patients seeking hospital care during floods in 1998, 2004, and 2007 in Dhaka, Bangladesh.
- 2008
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Ingår i: The American journal of tropical medicine and hygiene. - 1476-1645. ; 79:5, s. 708-14
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Tidskriftsartikel (refereegranskat)abstract
- Bangladesh experienced severe flooding and diarrheal epidemics in 2007. We compared flood data from 2007 with 2004 and 1998 for diarrheal patients attending the ICDDR,B hospital in Dhaka. In 2007, Vibrio cholerae O1 (33%), rotavirus (12%), and enterotoxigenic Escherichia coli (ETEC) (12%) were most prevalent. More severe dehydration was seen in 2007 compared with 2004 and 1998 (P < 0.001). In 2007, V. cholerae O1 Inaba (52%) and Ogawa (48%) were seen, whereas in 2004 and 1998 it was primarily Inaba and the Ogawa types, respectively (P < 0.001). In 2007, 51% of ETEC produced the heat labile toxin (LT) (P < 0.001 compared with 2004), 22% expressed the heat stable (ST) (P < 0.001), and 27% were ST/LT positive (P = 0.231). The CS7 colonization factor (CF) was the most prevalent in 2007 (20% compared with 6% in 2004; P = 0.05). Our findings demonstrate alterations in clinical features and phenotypic changes of major bacterial pathogens in the recent Bangladesh flood.
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