Production of recombinant human protein C in the milk of transgenic rabbits from the F3 generation.

The stability of transgene transmission, milk production and milk content of recombinant human protein C (rhPC) in transgenic rabbits of the F3 generation was determined. Transgenic rabbits carrying the 4.2kb mouse whey acid protein promoter and 9.4kb genomic human protein C were produced after mating transgenic (F2 generation) and non-transgenic rabbits. PCR analysis of F3 samples showed that the transgene was transmitted. Milk production, obtained at the 10th, 15th, 20th and 30th day of the first lactation by the weight-suckle-weight method showed no significant difference between transgenic and non-transgenic does. Concerning rhPC secretion, Western blotting detected a light chain (21 kDa) of rhPC in the milk and an ELISA test confirmed rhPC at the level of 0.109-0.301 microg/ml. A milk sample from a non-transgenic rabbit was hPC negative. In conclusion, the stability of hPC transgene transmission and production of rhPC protein C was confirmed in generation F3 of transgenic rabbits, with similar efficiency as in F1 and F2 generations, without reduction of milk production.