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Study Shows Differences in Natural Immunity in Cloned Pigs

WASHINGTON, Oct. 26--Studies by scientists with the U.S. Department of Agriculture and the University of Missouri indicate that the natural immune system of young cloned pigs does not appear to fight diseases as effectively as the immune system of non-cloned pigs.

Animal physiologist Jeff Carroll of USDA's Agricultural Research Service collaborated with University of Missouri-Columbia scientists Bart Carter, Randall Prather and Scott Korte on the study. The pigs were cloned at the University of Missouri by Prather and his colleagues. ARS is USDA's chief scientific research agency. At the time of the study, Carroll worked at ARS' Animal Physiology Research Unit in Columbia, but he is now based at the agency's Livestock Issues Research Unit in Lubbock, Texas.

In their experiments, the scientists gave a naturally occurring toxin called lipopolysaccharide to seven young, cloned pigs and 11 genetically similar, non-cloned pigs. Although the non-cloned pigs' immune response was adequate, the cloned pigs' immune system did not produce sufficient quantities of natural proteins called cytokines, which fight infections. Animals must have an adequate cytokine response to survive infections.

Cloned pigs, as well as cloned cows, have been known to have a higher-than-normal number of deaths around the time of birth. Many die from bacterial infections.

As newborns, both the cloned and non-cloned pigs received some disease protection through their consumption of colostrum, a natural substance passed to a newborn pig via its mother's milk. The colostrum helps protect the young animal until its own immune system begins to function.

The cloned pigs are being used only for research purposes, and are not part of the food supply.