| 1. |
- Adamsson, Jenni, 1977, et al.
(författare)
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Immune Responses Against Helicobacter pylori in Gastric Cancer Patients and in Risk Groups for Gastric Cancer.
- 2013
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Ingår i: Helicobacter. - : Wiley. - 1523-5378 .- 1083-4389. ; 18:1, s. 73-82
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: It has previously been reported that weak serum IgG but elevated IgA antibody responses against H.pylori may be associated with risk of gastric cancer (GC) development. To search for potential immunologic markers for GC, we analyzed antibody responses against H.pylori in risk groups of cancer development. MATERIAL AND METHODS: Sera and stomach biopsies collected from H.pylori-infected GC patients as well as from patients with gastric ulcer (GU), atrophic gastritis, intestinal metaplasia (IM) and duodenal ulcer and from H.pylori-infected control subjects without atrophy or IM, and in addition from H.pylori-negative subjects were analyzed for IgG and IgA antibodies against three different H.pylori antigen preparations, that is, membrane protein (MP), urease, and CagA. RESULTS: We observed an increased serum IgA/IgG titer ratio against H.pylori anti-MP in GC and GU patients, and against CagA in Hp-infected GC patients and risk groups. Female patients with GC had a higher serum anti-MP IgA/IgG titer ratio and a higher proportion of poorly differentiated cancer compared with male patients. As earlier observed, the non-tumorous mucosa of H.pylori-infected GC patients contained considerably lower levels of total IgA and H.pylori-specific IgA compared with H.pylori-infected controls. Similarly, we observed decreased specific mucosal anti-MP IgA response in patients with IM. CONCLUSION: We observed several differences in local and systemic immunologic responses against H.pylori in H.pylori-infected GC patients and putative GC risk group patients compared with H.pylori-infected controls. These findings may be of importance in efforts to identify risk groups of GC or early stages of GC.
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| 2. |
- Alam, M., et al.
(författare)
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Antigen-Specific Memory B-cell Responses to Enterotoxigenic Escherichia coli Infection in Bangladeshi Adults
- 2014
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Ingår i: PLoS Neglected Tropical Diseases. - : Public Library of Science (PLoS). - 1935-2727 .- 1935-2735. ; 8:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Multiple infections with diverse enterotoxigenic E. coli (ETEC) strains lead to broad spectrum protection against ETEC diarrhea. However, the precise mechanism of protection against ETEC infection is still unknown. Therefore, memory B cell responses and affinity maturation of antibodies to the specific ETEC antigens might be important to understand the mechanism of protection. Methodology: In this study, we investigated the heat labile toxin B subunit (LTB) and colonization factor antigens (CFA/I and CS6) specific IgA and IgG memory B cell responses in Bangladeshi adults (n = 52) who were infected with ETEC. We also investigated the avidity of IgA and IgG antibodies that developed after infection to these antigens. Principal Findings: Patients infected with ETEC expressing LT or LT+heat stable toxin (ST) and CFA/I group or CS6 colonization factors developed LTB, CFA/I or CS6 specific memory B cell responses at day 30 after infection. Similarly, these patients developed high avidity IgA and IgG antibodies to LTB, CFA/I or CS6 at day 7 that remained significantly elevated at day 30 when compared to the avidity of these specific antibodies at the acute stage of infection (day 2). The memory B cell responses, antibody avidity and other immune responses to CFA/I not only developed in patients infected with ETEC expressing CFA/I but also in those infected with ETEC expressing CFA/I cross-reacting epitopes. We also detected a significant positive correlation of LTB, CFA/I and CS6 specific memory B cell responses with the corresponding increase in antibody avidity. Conclusion: This study demonstrates that natural infection with ETEC induces memory B cells and high avidity antibodies to LTB and colonization factor CFA/I and CS6 antigens that could mediate anamnestic responses on re-exposure to ETEC and may help in understanding the requirements to design an effective vaccination strategies.
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| 3. |
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| 4. |
- Begum, Y. A., et al.
(författare)
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Shift in Phenotypic Characteristics of Enterotoxigenic Escherichia coli (ETEC) Isolated from Diarrheal Patients in Bangladesh
- 2014
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Ingår i: Plos Neglected Tropical Diseases. - : Public Library of Science (PLoS). - 1935-2735. ; 8:7
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Tidskriftsartikel (refereegranskat)abstract
- Background: Enterotoxigenic Escherichia coli (ETEC) is one of the most common causes of bacterial diarrhea. Over the last decade, from 1996 to 2012, changes in the virulence antigen properties of ETEC such as heat labile (LT) and heat stable (ST) toxins, colonization factors (CFs), and 'O'-serogroups have been observed. The aim of this prospective study was to compare changes in antigenic profiles of ETEC strains isolated from a 2% surveillance system at the icddr,b hospital in Dhaka, Bangladesh between 2007-2012 and an earlier time period of 1996-1998 conducted at the same surveillance site. Methodology: In the surveillance system every 50th patient attending the hospital was screened for major enteric pathogens including ETEC, Vibrio cholerae, Shigella spp. and Salmonella spp. from January 2007 to December 2012. Principal Findings: Of the 15,152 diarrheal specimens tested between 2007-2012, the overall rate of ETEC isolation was 11%; of these, 43% were LT/ST, 27% LT and 30% ST positive. Isolation rate of ST-ETEC (p<0.009) and LT/ST ETEC (p<0.011) during 2007-2012 period differed significantly compared to those seen between 1996-1998. In comparison to the 19961998 period, difference in CF profile of ETEC isolates during 2007-2012 was observed particularly for strains expressing CS7 (12.4%), CS14 (9.5%) and CS17 (10.0%). The predominant CF types were CS5+CS6, CFA/I, CS7, CS17, CS1+CS3, CS6 and CS14. The most common serogroups among the CF positive ETEC isolates were O115, O114, O6, O25 and O8. A strong association was found between CFs and 'O' serogroups i.e. between CS5+CS6 and (O115 and O126); CS7 and (O114), CFA/I and (O78 and O126), CS17 and (O8 and O167) and CS1/CS2+CS3 and (O6). Conclusion: The analyses show a shift in prevalence of antigenic types of ETEC over the study period; the information is important in designing effective ETEC vaccines with broad protective coverage.
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| 5. |
- Bhuiyan, Taufiqur Rahman, 1974, et al.
(författare)
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Evaluation of immune responses to an oral typhoid vaccine, Ty21a, in children from 2 to 5 years of age in Bangladesh
- 2014
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Ingår i: Vaccine. - : Elsevier BV. - 0264-410X. ; 32:9, s. 1055-1060
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Tidskriftsartikel (refereegranskat)abstract
- Young children are very susceptible to typhoid fever, emphasizing the need for vaccination in under five age groups. The parenteral Vi polysaccharide vaccine is not immunogenic in children under 2 years and the oral Ty21a vaccine (Vivotif) available in capsular formulation is only recommended for those over 5 years. We studied immune responses to a liquid formulation of Ty21a in children 2-5 years of age. Since children in developing countries are in general hypo responsive to oral vaccines, the study was designed to determine if anti-helminthic treatment prior to vaccination, improves responses. In a pilot study in 20 children aged 4-5 years, the immune responses in plasma and in antibody in lymphocyte secretions (ALS) to the enteric coated capsule formulation of Ty21a was found to be comparable to a liquid formulation (P > 0.05). Based on this, children (n = 252) aged ≥2-<3 years and ≥3-<5 years were randomized to receive a liquid formulation of Ty21a with and without previous anti-helminthic treatment. The vaccine was well tolerated with only a few mild adverse events recorded in <1% of the children. De-worming did not improve immune responses and both age groups developed 32-71% IgA, IgG, and IgM responses in plasma and 63-86% IgA responses in ALS and stool specimens to a membrane preparation (MP) of Ty21a. An early MP specific proliferative T cell response was also seen. We recommend that safety and efficacy studies with a liquid formulation of the vaccine are carried out in children under five, including those less than two years of age to determine if Ty21a is protective in these age groups and applicable as a public health tool for controlling typhoid fever in high prevalence areas of typhoid fever including Bangladesh. © 2014 Elsevier Ltd. All rights reserved.
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| 6. |
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| 7. |
- 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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| 8. |
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| 9. |
- Gonzales, Lucia, et al.
(författare)
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Molecular Characterization of Enterotoxigenic Escherichia coli Isolates Recovered from Children with Diarrhea during a 4-Year Period (2007 to 2010) in Bolivia
- 2013
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Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 51:4, s. 1219-1225
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Tidskriftsartikel (refereegranskat)abstract
- Enterotoxigenic Escherichia coli (ETEC) is an important cause of childhood diarrhea. This study aimed to characterize ETEC strains isolated from Bolivian children aged <5 years according to enterotoxin profile, colonization factors (CFs), suggested virulence genes, and severity of disease. A total of 299 ETEC isolates recovered from children with diarrhea and 55 ETEC isolates from children without diarrhea (controls) were isolated over a period of 4 years. Strains expressing heat-labile toxin (LT) or heat-stable toxin (ST) alone were about equally common and twice as common as ETEC producing both toxins (20%). ETEC strains expressing human ST (STh) were more common in children aged <2 years, while ETEC strains expressing LT plus STh (LT/STh) were more frequent in 2- to 5-year-old children. Severity of disease was not related to the toxin profile of the strains. CF-positive isolates were more frequently identified in diarrheal samples than in control samples (P = 0.02). The most common CFs were CFA/I and CS14. CFA/I ETEC strains were more frequent in children aged <2 years than CS1+CS3 isolates and CS14 isolates, which were more prevalent in 2- to 5-year-old children. The presence of suggested ETEC virulence genes (clyA, eatA, tia, tibC, leoA, and east-1) was not associated with disease. However, east-1 was associated with LT/STh strains (P < 0.001), eatA with STh strains (P < 0.001), and tia with LT/STh strains (P < 0.001). A minor seasonal peak of ETEC infections was identified in May during the cold-dry season and coincided with the peak of rotavirus infections; this pattern is unusual for ETEC and may be important for vaccination strategies in Bolivia.
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| 10. |
- Gonzales, Lucia, et al.
(författare)
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Prevalence, seasonality and severity of disease of pathogenic Escherichia coli in children with diarrhea in Bolivia.
- 2013
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Ingår i: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 62:11, s. 1687-1695
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Tidskriftsartikel (refereegranskat)abstract
- The prevalence of infection caused by different categories of diarrhoeagenic E. coli (DEC) strains, including enteroaggregative (EAEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), enteroinvasive (EIEC) and enterohaemorrhagic (EHEC) E. coli, in children who suffered from diarrhoea (n=3943) or did not have diarrhoea (n=1026) were analysed in two areas in Bolivia over a period of 4 years. We also analysed the seasonality of DEC infections and severity of diarrhoea in children with DEC infection and compared antibiotic resistance in DEC strains isolated from children with and without diarrhoea. Stool samples were analysed for the presence of DEC by culturing followed by PCR. The most prevalent DEC categories in samples from the children were: EAEC (11.2%); ETEC (6.6%); EPEC (5.8%); and EIEC and EHEC (<1%). DEC strains were isolated significantly more often from diarrhoea cases (21.6%) than from controls (17.6%; P=0.002). The number of children with diarrhoea associated with EAEC, EPEC and ETEC infections peaked in the Bolivian winter (April–September), although the proportion of DEC-positive stool samples was higher during the warm rainy season (October–March). High levels of antibiotic resistance were detected among the DEC strains. In particular, resistance to tetracycline and sulfamethoxazole–trimethoprim was significantly higher in strains isolated from individuals with diarrhoea than in samples from controls. The severity of disease in children infected with EAEC, EPEC and ETEC varied from mild to severe diarrhoea, although disease severity did not differ significantly between the different DEC categories. ETEC, EPEC and EAEC are commonly found in Bolivia and may cause severe disease in children.
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