Orally administered anti-Escherichia coli O157:H7 chicken egg yolk antibodies reduce fecal shedding of the pathogen by ruminants

Spray-dried whole egg prepared from eggs laid by non-immunized hens (EG) or hens immunized with the C-terminal domain of Escherichia coli O157:H7 intimin (EG-IgY) was fed to experimentally inoculated sheep, to investigate the efficacy of orally administered polyclonal anti-E. coli O157:H7 antibodies (IgY) for reducing the duration and level of fecal shedding of E. coli O157:H7 by ruminants. Thirty Canadian Arcott ram lambs were orally inoculated on day 0 with 10 10 colony-forming units (CFU) of a three-strain mixture of nalidixic acid-resistant E. coli O157:H7. On each of days 2, 3 and 4, the rams (n = 6) were fed 100 g of EG and/or EG-IgY in proportions of 100:0 (CON), 0:100 (HIGH), 50:50 (MED), or 75:25 (LOW). A fifth treatment (denoted variable, VAR) comprised feeding HIGH, MED and LOW on days 2, 3, and 4, respectively. Fecal samples collected on 19 occasions over 85 d (4 × in the first wk; 2×/wk for 3 wk; and 1×/wk for 9 wk) were assessed for E. coli O157:H7 by direct plating or enrichment and immunomagnetic separation. Throughout the 85 d, numbers of E. coli O157:H7 shed by the rams were lower (P < 0.001) in HIGH and MED than in CON, and the duration of shedding was shorter (P < 0.005) in HIGH than in CON. Fewer (P < 0.005) samples were culture-positive in HIGH than in CON. Oral dosing of specific IgY has potential to decrease the duration and level of fecal shedding of E. coli O157:H7 by ruminants. Key words: E. coli O157:H7, egg-yolk IgY, fecal shedding, immunotherapy, ruminants, sheep