MODEL RELEASED. Drug bioengineering. Masked pharmaceutical technicians examine one of several genetically engineered cell cultures through a microscope. The cultures, fed by a growth medium, are producing drug preparations. The cells have had small sections of DNA (deoxyribonucleic acid) that code for a desired protein inserted into them. As they reproduce the inserted DNA is also copied, so the cells produce this protein, which can then be harvested". One example of this process is the production of interferon. Interferons, produced by T-lymphocyte white blood cells, inhibit intracellular viral replication and so help to fight infection."