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.


CONCLUSIONS
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.
Rao
Malla R
MR
Division of Epidemiology, Statistics, and Prevention Research, National Institute of Child Health and Human Development, Bethesda, Maryland 20910-7500, USA.
Wierzba
Thomas F
TF
Savarino
Stephen J
SJ
Abu-Elyazeed
Remon
R
El-Ghoreb
Nemat
N
Hall
Eric R
ER
Naficy
Abdollah
A
Abdel-Messih
Ibrahim
I
Frenck
Robert W
RW
Svennerholm
Ann-Mari
AM
Clemens
John D
JD
D000907:Antibodies, Bacterial / Q000097:blood*; D001426:Bacterial Proteins / Q000032:analysis / Q000276:immunology; D001427:Bacterial Toxins / Q000032:analysis / Q000276:immunology*; D016022:Case-Control Studies; D002675:Child, Preschool; D003967:Diarrhea / Q000382:microbiology* / Q000517:prevention & control*; D004534:Egypt; D004768:Enterotoxins / Q000032:analysis / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000276:immunology* / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000276:immunology* / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000032:analysis / Q000276:immunology*; D005260:Female; D036781:Fimbriae Proteins / Q000032:analysis / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007223:Infant; D008297:Male; D037521:Virulence Factors / Q000032:analysis / Q000276:immunology
D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D007074:Immunoglobulin G; D037521:Virulence Factors; C022924:colonization factor antigens; D036781:Fimbriae Proteins; C027538:heat-labile enterotoxin, E coli