Geneticists conducting gene therapy

Geneticists conducting gene therapy have several viruses to choose from as
possible delivery vehicles (vectors). These viruses fall into one of two classes:
 Those that integrate their DNA directly into the host’s genome
 Those that climb into the cell nucleus to become permanent but separate
residents (called episomes)
Within these two categories, three types of viruses — oncoretroviruses,
lentiviruses, and adenoviruses — are popular choices for gene therapy.