Their task now is to deliver copies of these 'dystrophin' genes efficiently into muscle and to make sure that they stay put, get to work and stay working.
Viruses come in many forms and cause many different symptoms.
They are responsible for colds and flus, warts, polio, herpes, rabies and smallpox to name but a few. They are designed to trick cells into accepting them. In their unaltered state, viruses are infectious and can be harmful. This means removing those bits of coding that cause symptoms, e.g. cold symptoms, and also the coding that would allow the virus to multiply inside the cell. A virus can multiply itself millions of times and the new viruses can go on to infect other cells within the body in an uncontrolled way.