| 1. |
- Clemens, John, et al.
(författare)
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Development of pathogenicity-driven definitions of outcomes for a field trial of a killed oral vaccine against enterotoxigenic Escherichia coli in Egypt: application of an evidence-based method
- 2004
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Ingår i: J Infect Dis. ; 189:12, s. 2299-307
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: To design an efficacy trial of a killed oral vaccine against enterotoxigenic Escherichia coli (ETEC) diarrhea in Egyptian children, we derived for ETEC diarrhea an empirical definition that increased the probability that diarrhea associated with excretion of ETEC was caused by the detected ETEC. METHODS: We conducted a cohort study of 397 Egyptian children <24 months old and monitored them until they were 3 years old. Vaccine-preventable (VP) ETEC was defined as ETEC expressing >/=1 of the toxin- (heat-labile [LT] toxin) and colonization-factor antigens (CFA I, II, and IV) in the vaccine. RESULTS: Although fecal excretion of VP-ETEC was highly associated with diarrhea, excretion of LT-ETEC per se was not related to diarrhea (adjusted odds ratio [OR(A)], 1.16 [95% confidence interval [CI], 0.90-1.49]). The fecal excretion of antigenic types of VP-ETEC other than LT-ETEC (non-LT VP-ETEC) was highly associated with diarrheal symptoms (OR(A), 3.91 [95% CI, 2.78-5.49]; P<.001), and this association was greater for nonbloody than for bloody diarrhea. CONCLUSIONS: Because the vaccine had been anticipated to protect primarily against symptomatic ETEC diarrhea, these results indicate that the primary-outcome definition of ETEC diarrhea for the trial should be restricted to nonbloody diarrheal episodes associated with fecal excretion of non-LT VP-ETEC.
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| 2. |
- Hossain, M. Jahangir, et al.
(författare)
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A Perspective on the Strategy for Advancing ETVAX®, An Anti-ETEC Diarrheal Disease Vaccine, into a Field Efficacy Trial in Gambian Children: Rationale, Challenges, Lessons Learned, and Future Directions
- 2024
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Ingår i: MICROORGANISMS. - 2076-2607. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- For the first time in over 20 years, an Enterotoxigenic Escherichia coli (ETEC) vaccine candidate, ETVAX (R), has advanced into a phase 2b field efficacy trial for children 6-18 months of age in a low-income country. ETVAX (R) is an inactivated whole cell vaccine that has gone through a series of clinical trials to provide a rationale for the design elements of the Phase 2b trial. This trial is now underway in The Gambia and will be a precursor to an upcoming pivotal phase 3 trial. To reach this point, numerous findings were brought together to define factors such as safe and immunogenic doses for children, and the possible benefit of a mucosal adjuvant, double mutant labile toxin (dmLT). Considering the promising but still underexplored potential of inactivated whole cells in oral vaccination, we present a perspective compiling key observations from past ETVAX (R) trials that informed The Gambian trial design. This report will update the trial's status and explore future directions for ETEC vaccine trials. Our aim is to provide not only an update on the most advanced ETEC vaccine candidate but also to offer insights beneficial for the development of other much-needed oral whole-cell vaccines against enteric and other pathogens.
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| 3. |
- Khalil, Ibrahim, et al.
(författare)
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Enterotoxigenic Escherichia coli (ETEC) vaccines: Priority activities to enable product development, licensure, and global access
- 2021
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Ingår i: Vaccine. - : Elsevier BV. - 0264-410X .- 1873-2518. ; 39, s. 4266-4277
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Forskningsöversikt (refereegranskat)abstract
- Diarrhoeal disease attributable to enterotoxigenic Escherichia coli (ETEC) causes substantial morbidity and mortality predominantly in paediatric populations in low- and middle-income countries. In addition to acute illness, there is an increasing appreciation of the long-term consequences of enteric infections, including ETEC, on childhood growth and development. Provision of potable water and sanitation and appropriate clinical care for acute illness are critical to reduce the ETEC burden. However, these interventions are not always practical and may not achieve equitable and sustainable coverage. Vaccination may be the most cost-effective and equitable means of primary prevention; however, additional data are needed to accelerate the investment and guide the decision-making process for ETEC vaccines. First, to understand and quantify the ETEC disease burden, additional data are needed on the association between ETEC infection and physical and cognitive stunting as well as delayed educational attainment. Furthermore, the role of inappropriate or inadequate antibiotic treatment of ETEC-attributable diarrhoea may contribute to the development of antimicrobial resistance (AMR) and needs further elucidation. An ETEC vaccine that mitigates acute diarrhoeal illness and minimizes the longer-term disease manifestations could have significant public health impact and be a cost-effective countermeasure. Herein we review the ETEC vaccine pipeline, led by candidates compatible with the general parameters of the Preferred Product Characteristics (PPC) recently developed by the World Health Organization. Additionally, we have developed an ETEC Vaccine Development Strategy to provide a framework to underpin priority activities for researchers, funders and vaccine manufacturers, with the goal of addressing globally unmet data needs in the areas of research, product development, and policy, as well as commercialization and delivery. The strategy also aims to guide prioritization and co-ordination of the priority activities needed to minimize the timeline to licensure and use of ETEC vaccines, especially in in low- and middle-income countries, where they are most urgently needed.
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| 4. |
- Rao, Malla, et al.
(författare)
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Serologic correlates of protection against enterotoxigenic Escherichia coli diarrhea
- 2005
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Ingår i: J Infect Dis. ; 191:4, s. 562-70
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: We conducted a nested case-control study in 397 rural Egyptian children <36 months of age to assess the correlation between serum levels of antibodies against toxin and colonization factors (CFs) and the risk of homologous enterotoxigenic Escherichia coli (ETEC) diarrhea. METHODS: Active case detection was performed via semiweekly home visits, and blood was obtained at 3-month intervals. After each serosurvey, case subjects were selected from children experiencing a CF antigen (CFA)/I-, CFA/II-, CFA/IV-, or heat-labile enterotoxin (LT)-ETEC diarrheal episode during the subsequent 3 months. Up to 5 control subjects per case subject were selected from children who did not experience an ETEC diarrheal episode during the corresponding interval. Serum titers of immunoglobulin G antibodies against CFA/I, coli surface antigen (CS) 3, CS6, and LT were measured by enzyme-linked immunosorbant assay. RESULTS: The distribution of serum titers of LT, CS3, and CS6 antibodies did not differ between the case and control subjects. For children <18 months of age, serum titers of CFA/I antibody were inversely related to the risk of CFA/I-ETEC diarrhea; reciprocal serum titers of CFA/I antibody > or =76 were associated with a 77% reduction in the odds of CFA/I-ETEC diarrhea. CONCLUSION: Induction of reciprocal serum titers of antibodies against CFA/I within or above the 76-186 range should be further evaluated as a predictor for assessment of the ability of candidate vaccines to protect against CFA/I-ETEC diarrhea.
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| 5. |
- Shaheen, H. I., et al.
(författare)
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Phenotypic profiles of enterotoxigenic Escherichia coli associated with early childhood diarrhea in rural Egypt
- 2004
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Ingår i: J Clin Microbiol. ; 42:12, s. 5588-95
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Tidskriftsartikel (refereegranskat)abstract
- Enterotoxigenic Escherichia coli (ETEC) causes substantial diarrheal morbidity and mortality in young children in countries with limited resources. We determined the phenotypic profiles of 915 ETEC diarrheal isolates derived from Egyptian children under 3 years of age who participated in a 3-year population-based study. For each strain, we ascertained enterotoxin and colonization factor (CF) expression, the O:H serotype, and antimicrobial susceptibility. Sixty-one percent of the strains expressed heat-stable enterotoxin (ST) only, 26% expressed heat-labile enterotoxin (LT) alone, and 12% expressed both toxins. The most common CF phenotypes were colonization factor antigen I (CFA/I) (10%), coli surface antigen 6 (CS6) (9%), CS14 (6%), and CS1 plus CS3 (4%). Fifty-nine percent of the strains did not express any of the 12 CFs included in our test panel. Resistance of ETEC strains to ampicillin (63%), trimethoprim-sulfamethoxazole (52%), and tetracycline (43%) was common, while resistance to quinolone antibiotics was rarely detected. As for the distribution of observed serotypes, there was an unusually wide diversity of O antigens and H types represented among the 915 ETEC strains. The most commonly recognized composite ETEC phenotypes were ST CS14 O78:H18 (4%), ST (or LTST) CFA/I O128:H12 (3%), ST CS1+CS3 O6:H16 (2%), and ST CFA/I O153:H45 (1.5%). Temporal plots of diarrheal episodes associated with ETEC strains bearing common composite phenotypes were consistent with discrete community outbreaks either within a single or over successive warm seasons. These data suggest that a proportion of the disease that is endemic to young children in rural Egypt represents the confluence of small epidemics by clonally related ETEC strains that are transiently introduced or that persist in a community reservoir.
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