MICROBIOLOGY: Vaccinating Cattle

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Science  16 Jan 2004:
Vol. 303, Issue 5656, pp. 287c
DOI: 10.1126/science.303.5656.287c

Contaminated food—hamburgers are a notorious example—is the primary source of dangerous enteric infections by Escherichia coli O157:H7 (EHEC), which in humans can cause bloody diarrhea and, in some cases, hemolytic uremic syndrome. Because EHEC has been found in almost 50% of beef carcasses in North America, an important commercial aim is to reduce exposure to the bacteria by reducing the extent to which EHEC colonizes the cattle intestine.

EHEC virulence is attributed to the ability to secrete determinants, via a type III secretion system, that include the adhesins Tir and EspA and the pore-forming protein EspB, which together promote bacterial attachment to host cells. Potter et al. have chosen these molecules as constituents of a trial vaccine for calves. The trial was carried out under commercial livestock-rearing conditions, and the trial animals were then exposed to the O157:H7 strain. Vaccination increased specific antibody titer 45-fold after a single booster and reduced the duration and quantity of EHEC shedding. As well as being economical to prepare, a livestock vaccine must be effective enough to minimize the number of times an animal has to be handled, which would add to rearing cost. Plus, developing a livestock vaccine might be a useful route to a human vaccine against EHEC. — CA

Vaccine 22, 362 (2004).

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