4.2. Retroviral vector

A replication-defective recombinant retrovirus LXSN provided kindly by Dr. Miller, Fred Hutchinson Cancer Research Center, Seattle, USA, (Miller & Rosman 1989) was used as a vector for gene transfer into the mammary gland in goats. For packaging, cell line amphotropic retrovirus helper cells PA 317 (American Type Culture Collection #CRL 9078, USA) were used. The vector carried the human growth hormone gene (hGH cDNA), whose expression as a human growth hormone in the goat’s milk served as an indicator of successful gene transfer.