Bovine Immune Response to Shiga-Toxigenic Escherichia coli O157:H7

• Published in: Clinical and Vaccine Immunology Vol. 13; no. 12; pp. 1322 - 1327
• Main Authors: Hoffman, M.A, Menge, C, Casey, T.A, Laegreid, W, Bosworth, B.T, Dean-Nystrom, E.A
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 01-12-2006
• Subjects: Animals; Antibodies, Bacterial - blood; antibody formation; Cattle; cattle diseases; Cattle Diseases - immunology; Cattle Diseases - microbiology; cell-mediated immunity; Escherichia coli; Escherichia coli Infections - immunology; Escherichia coli Infections - microbiology; Escherichia coli Infections - veterinary; Escherichia coli O157 - immunology; Escherichia coli O157 - metabolism; Escherichia coli O157 - pathogenicity; Escherichia coli O157:H7; Escherichia infections; excretion; fecal shedding; feces; Humans; humoral immunity; Leukocytes, Mononuclear - immunology; Lymphocyte Activation; lymphocyte proliferation; Shiga toxin; Shiga Toxin 2 - biosynthesis; toxigenic strains; Veterinary Immunology
• ISSN: 1556-679X; 1556-6811; 1556-679X
• DOI: 10.1128/CVI.00205-06

Although cattle develop humoral immune responses to Shiga-toxigenic (Stx+) Escherichia coli O157:H7, infections often result in long-term shedding of these human pathogenic bacteria. The objective of this study was to compare humoral and cellular immune responses to Stx+ and Stx- E. coli O157:H7. Three groups of calves were inoculated intrarumenally, twice in a 3-week interval, with different strains of E. coli: a Stx2-producing E. coli O157:H7 strain (Stx2+O157), a Shiga toxin-negative E. coli O157:H7 strain (Stx-O157), or a nonpathogenic E. coli strain (control). Fecal shedding of Stx2+O157 was significantly higher than that of Stx-O157 or the control. Three weeks after the second inoculation, all calves were challenged with Stx2+O157. Following the challenge, levels of fecal shedding of Stx2+O157 were similar in all three groups. Both groups inoculated with an O157 strain developed antibodies to O157 LPS. Calves initially inoculated with Stx-O157, but not those inoculated with Stx2+O157, developed statistically significant lymphoproliferative responses to heat-killed Stx2+O157. These results provide evidence that infections with STEC can suppress the development of specific cellular immune responses in cattle, a finding that will need to be addressed in designing vaccines against E. coli O157:H7 infections in cattle.