Research Article

Serum Antibodies Protect against Intraperitoneal Challenge with Enterotoxigenic Escherichia coli

Figure 1

Salmonella vaccine H683-pC1 stimulates elevated anti-CFA/I fimbriae Ab titers and protects against i.p. ETEC challenge. (a) BALB/c mice (5/group) were orally immunized twice on days 0 and 28 with CFUs of S. Typhimurium H683-pC1 and H647, respectively. Elevated serum IgG and mucosal IgA anti-CFA/I fimbriae Ab responses were induced. Depicted are the mean ± SEM from two independent experiments. (b) At wk 6, serum IgG subclass analysis was performed, and statistical differences in the endpoint Ab titers were determined. * , ** , *** versus IgG1; ¶¶ versus IgG2a. (c)–(e) Comparison of different routes of challenges with wt ETEC H10407 among CFA/I fimbriae-immunized BALB/c mice. At 6-wk postprimary immunization, mice were challenged with wt ETEC H10407 (c) orally with or CFUs, (d) i.n. with or CFUs, or (e) i.p. with CFUs. Mice survival was monitored for two wks. Results are from two independent experiments; survival fractions obtained from vaccinated mice were compared to H647-immunized mice, and significance was determined; * .
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