Transgenic expression of a mouse milk protein impaired mammary
development and function in pigs.
Pig (Sus domesticus).
Mouse genomic DNA containing the gene for whey acidic protein (WAP).
Goal of These Studies:
Investigate the feasibility of using mouse WAP regulatory sequences
to produce transgenic proteins in the milk of pigs.
Results of This Study:
In 3 of the 5 lines of transgenic pigs, lactation was impaired in some
animals. The problems were discovered when, after 10 days of nursing,
piglets started to lose weight.
Pigs from the other 2 transgenic lines appeared to lactate normally,
and the transgenic WAP protein was discovered in their milk. However,
one of these animals produced an unknown form of the WAP protein, which
the authors speculated could be "the result of some rearrangement within
the transgene locus" (p. 4558). The amount of this unexpected protein
decreased over time, while the amount of normal WAP protein increased
over the course of the lactation.
Mammary tissue from the transgenic pigs, even those with apparently
normal lactations, had abnormal morphology, indicative of immature
Precocious WAP gene expression was detected in five-month-old juvenile
pigs from the lactation-impaired lines, but not in pigs from the
lactation-competent and non-GM lines.
Shamay, A., V. G. Pursel, E. Wilkinson, R. J. Wall et al. (1992).
"Expression of the Whey Acidic Protein in Transgenic Pigs Impairs Mammary
Development," Transgenic Research vol. 1, pp. 124-32.
Shamay, A., S. Solinas, V. G. Pursel, R. A. McKnight et al. (1991).
"Production of the Mouse Whey Acidic Protein in Transgenic Pigs During
Lactation," Journal of Animal Science vol. 69, pp. 4552-62.
National Institutes of Health; ETH-Zentrum, Switzerland; USDA Agricultural
Research Service, Maryland; University of Illinois, Chicago;
University of Tennessee College of Veterinary Medicine.
Not on the market as of 2009.
Copyright 2009 The Nature