Two New Studies Confirm Effectiveness of E. Coli Vaccine
US - Two recently published studies conducted by the University of Nebraska-Lincoln have found that a vaccine product containing type III secreted proteins of Escherichia coli O157:H7 effectively reduces the probability for cattle to shed E.coli O157:H7 while also reducing E. Coli colonization of the terminal rectum under conditions of natural exposure, the first step in its evaluation as an effective intervention for food and environmental safety.
16 November 2007
2 minute read
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E.coli
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Said David R. Smith, DVM, PhD, one of the authors of the studies, "Together these studies provide important information about whether and how this vaccine works in field conditions. We gain confidence that the vaccine is effective by seeing that it reduces fecal shedding and colonization of cattle with E. coli O157:H7, observing the phenomena of herd immunity, and noticing that greater numbers of doses increases the effect."
In the first study, 608 same-source steers were utilized. Of these, 480 steers were assigned randomly to 60 pens (eight head per pen) and one of four vaccination treatments (120 cattle per treatment, two head per pen). The four treatments were: no vaccination; one dose, vaccinated on arrival day; two doses, vaccinated on arrival day and again on day 42; and three doses, on arrival day, day 21 and day 42. The remaining 128 steers were assigned randomly to 12 pens within the same feedlot to serve as unvaccinated external controls.
The study found that vaccine efficacy of receiving one, two and three doses of vaccine was 68, 66 and 73 percent respectively, compared with cattle in pens not receiving the vaccine. In addition, this study found that vaccinating a majority of cattle within a pen offered a significant protective effect (herd immunity) to unvaccinated cattle within the same pen.
In the second study, a blinded clinical trial was conducted on 288 steers that were assigned randomly to 36 pens (eight head per pen), and pens were randomized to vaccination treatment in a balanced fashion within six dietary treatments of an unrelated nutrition study. Treatments included vaccination or placebo. Fecal samples were collected and terminal rectum mucosal (TRM) cells were collected for culture. Researchers found vaccinated cattle were 98.3 percent less likely to be colonized by E. coli O157 in TRM cells.
Both of these studies can be found in the Journal of Food Protection, Volume, 70, No.11, pages 2561 and 2568.
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