Antibody responses in humans against coli surface antigen 6 of enterotoxigenic Escherichia coli

Abstract

Enterotoxigenic Escherichia coli (ETEC) strains expressing only coli surface antigen 6 (CS6) have previously been isolated from patients with diarrhea, but the immunogenicity of CS6 has not been established in humans. We have detected CS6-specific immunoglobulin A responses in the feces and blood of patients convalescing from natural ETEC disease and of volunteers given an oral ETEC vaccine.

FIG. 1

Immunoblot showing CS6-reactive IgA antibodies in fecal extracts (A) and plasma (B) of Bangladeshi adults with natural CS5⁺ CS6⁺ ETEC infections. (A) Feces was obtained from patient ETP-009 on the day of admission to the hospital (day 0) (lane 1) and 9 days later (lane 2) and from patient ETP-010 on days 0 (lane 3) and 9 (lane 4). (B) Plasma samples were collected from patients ETP-009 and ETP-010 3 (lanes 1 and 3, respectively) and 9 (lanes 2 and 4, respectively) days after hospitalization. The arrow indicates the position of the CS6 band as determined by using a CS6-specific MAb (CS6-20:11:9) (lane 5). The symbols at the bottom of the figure correspond to the intensity grading of the CS6 band [−, no reactivity; (+), weak reactivity; and +, strong reactivity].

FIG. 2

Immunoblot showing CS6-reactive IgA antibodies in plasma or serum collected from a Bangladeshi adult with a natural CS5⁺ CS6⁺ ETEC infection 9 days after admission to the hospital (ETP-009) (A) and from a Swedish vaccinee postvaccination (Ec-215) (B). The specimens were diluted 1:60 (lane 1), 1:180 (lane 2), 1:540 (lane 3), 1:1,620 (lane 4), and 1:4,860 (lane 5).

FIG. 2

Immunoblot showing CS6-reactive IgA antibodies in plasma or serum collected from a Bangladeshi adult with a natural CS5⁺ CS6⁺ ETEC infection 9 days after admission to the hospital (ETP-009) (A) and from a Swedish vaccinee postvaccination (Ec-215) (B). The specimens were diluted 1:60 (lane 1), 1:180 (lane 2), 1:540 (lane 3), 1:1,620 (lane 4), and 1:4,860 (lane 5).