TRANSFER VEHICLE FOR PRODUCING PROTEINS IN TRANSGENIC ANIMALS

There is provided a gene transfer vehicle comprising first and second site specific recombinase sites and at least one gene of interest located therebetween. The first and second site specific recombinase sites cannot recombine together. Optionally the vehicle encodes a recombinase enzyme. The gene transfer vehicle can be a viral vector, for example based on an adenovirus or retrovirus.The vehicle allows highly targeted insertion of a transgene enabling efficient insertion and expression.