Serologic correlates of protection against enterotoxigenic Escherichia coli diarrhea

• 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.

Nyckelord

Antibodies

Bacterial/*blood

Bacterial Proteins/analysis/immunology

Bacterial Toxins/analysis/*immunology

Case-Control Studies

Child

Preschool

Diarrhea/*microbiology/*prevention & control

Egypt

Enterotoxins/analysis/*immunology

Enzyme-Linked Immunosorbent Assay

Escherichia coli/*immunology/pathogenicity

Escherichia coli Infections/*immunology/microbiology

Escherichia coli Proteins/analysis/*immunology

Female

Fimbriae Proteins/analysis/immunology

Humans

Immunoglobulin G/blood

Infant

Male

Virulence Factors/analysis/immunology

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