Acquisition of serum antibodies reactive with enterohemorrhagic Escherichia coli virulence-associated factors by healthy Brazilian children and adults.
BACKGROUND
Patients with hemorrhagic colitis or hemolytic uremic syndrome due to enterohemorrhagic Escherichia coli (EHEC) develop serum IgM and IgG response to lipopolysaccharide (LPS) and to virulence factors such as intimin. The small numbers of cases of diarrhea associated with EHEC strains in Brazil suggests a pre-existing immunity probably due to previous contact with diarrheagenic E. coli. Our aim was to evaluate the development of the serum antibody repertoire to EHEC virulence factors in Brazilian children and adults.


METHODS
Serum IgM and IgG antibodies were determined by enzyme-linked immunosorbent assay with LPS O111, LPS O26, and LPS O157 in 101 children between 2 months and 10 years of age and in 100 adult sera, by immunoblotting with protein membrane extracts and purified beta intimin; the ability of adult sera to neutralize Shiga toxin2 was also investigated.


RESULTS
Children older than 24 months had IgM concentrations reactive with the 3 LPS equivalent to those seen in the adult group, and significantly higher than the group of younger children (P < 0.05). Anti-O26 and anti-O157 LPS IgG concentrations were equivalent between the 2 groups of children and were significantly different from the adult group (P < 0.05). The anti-O111 LPS IgG levels in older children were intermediate between the younger group, and adults (P < 0.05). Immunoblotting revealed strong protein reactivity, including the conserved and variable regions of beta intimin and more than 50% of the adult samples neutralized Shiga toxin 2.


CONCLUSIONS
Our results demonstrate an increasing anti-LPS and antiprotein antibody response with age, which could provide protection against EHEC infections.
Palmeira
Patricia
P
Department of Pediatrics, Medical School, University of São Paulo, São Paulo, Brazil. patpalm@usp.br
Carbonare
Solange B
SB
Guth
Beatriz E C
BE
Carbonare
Cristiane B
CB
Pontes
Gerlândia N
GN
Tino-De-Franco
Milene
M
Zapata-Quintanilla
Lucy B
LB
Carneiro-Sampaio
Magda
M
D018829:Adhesins, Bacterial / Q000276:immunology; D000328:Adult; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood* / Q000276:immunology; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D001938:Brazil; D002648:Child; D002675:Child, Preschool; D002522:Chlorocebus aethiops; D003429:Cross Reactions / Q000276:immunology; D054324:Enterohemorrhagic Escherichia coli / Q000276:immunology* / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D007223:Infant; D008070:Lipopolysaccharides / Q000276:immunology*; D018709:Statistics, Nonparametric; D014709:Vero Cells
D018829:Adhesins, Bacterial; D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D008070:Lipopolysaccharides; C073819:eaeA protein, E coli