What is a retrovirus and why is it so important in gene therapy?
Most viruses and all cellular organisms carry their genetic material as DNA – deoxyribonucleic acid. Retroviruses do not. They carry their genetic blueprint in the form of ribonucleic acid (RNA). Retroviruses are responsible for certain cancers and slow virus infections of animals and cause at least one type of human cancer. A type of retrovirus called a Moloney murine leukaemia virus was the first virus used in human gene therapy. Retroviruses are useful for gene therapy as they are very good at getting into host cells, and because they combine their genetic material with that of the host permanently, any therapeutic DNA they are carrying can have long term expression – they can offer a permanent cure. There are some problems with the use of retroviruses. There is no way to have control over exactly where on the cells strand of DNA the therapeutic gene inserts itself. This means there is risk of mutation, or even triggering cancer, because insertion may disrupt the host genes. In addi
