The research will evaluate oral administration of avian anti=0157:H7 immunoglobulin to cattle in order to clear E. coli 0157:H7 from the intestinal tract. Similar to the principals involved in passive immunity, the hypothesis that the binding of immunoglobulin to E. coli 0157: H7 will inhibit motility, attachment, and/or efficient uptake of nutrients and decrease the ability of this bacterium to effectively compete with native microbial flora. The most probable point of application of these antibodies is immediately pre-harvest and attempts will be made to optimize clearance in a reasonable timeframe. Antibodies to E. coli 0157:H7 are commercially available, but at a $150 per mg, it would cost approximately $7500->$10,000 per dose to achieve the target level of 50-100 pg per ml of rumen fluid in an adult cow. The levels needed for feed and water based administration may be even higher. The production and cost of egg yolk antibody will be much less expensive and will comprise a small portion of the time and budget of this project. The influence of egg yolk anti-0157:H7 antibodies on shedding of E. coli 0157:H7 in cattle will be evaluated by the following specific objectives:<ol>
<li> Immunize chickens with formalin-fixed E. coli 015TH7
<li> Harvest and titer anti-0157:H7 immunoglobulin G from eggs
<li> Evaluate immunoglobulin stability in different vehicles (i.e., water, feed, phosphate buffer, egg) and forms (i.e., dry or liquid).
<li> Inoculate steers with E. coli 0157:H7 and monitor shedding after oral administration of the anti-0157:H7 immunoglobulin. Compare the duration of shedding in untreated (control) steers with those administered immunoglobulin.
<li> Extend application of passive immunity to the clearance of other Shiga-toxin producing E. coli (i.e., serotype 026:Hl 1) once successfully demonstrated with serotype 0157:H7 </ol>
Status:<BR> Laying hens were obtained and immunized intramuscularly with formalin- fixed E. coli 0157:H7 (strain 86-24). The formalin-fixed cells were administered first in Freund's complete and two weeks later in Freund's incomplete adjuvant. Eggs have been harvested from six immunized hens for the past 6 weeks and freeze dried in batches. The anti-0157:H7 antibody in each of these batches will be titered. If titers are satisfactory, inoculation studies will begin.