Caption

Viral gene therapy. Diagram of an adenovirus (upper left) being used to administer genetic material into a cell (bottom right). Adenoviruses are DNA (deoxyribonucleic acid) viruses that infect human cells by injecting DNA into the nucleus. Usually this results in a disease, but the virus can be genetically engineered so that it transplants human DNA into the cell nucleus without causing disease. DNA contains sections, called genes, which encode for each cell's structure, function and behaviour. Transplanting DNA is ideal for individuals whose cells have a gene that is faulty, as a normal version of the gene can be inserted to counteract the fault.