Plasmids are an indispensable tool that are used to clone, transfer, and manipulate genes. These small, circular fragments of DNA are typically found in bacteria but are also present in some archaea and eukaryotes. They carry only a few genes which makes them easy to genetically modify.

Gene therapy has had its share of setbacks, but finally gene therapies are proving successful at treating diseases like neuromuscular disorders, cancer and blindness. Adeno-associated virus (AAV) has emerged as a leading gene delivery vehicle because it is efficient and has demonstrated safety in humans.