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 10^th, 15^th, 20^th and 30^th 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 μg/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.