Figure 5-1.4.1(b):. Adenovirus vectors in gene transfer.

Role in gene therapy

• Mainly used for cancer treatment. Gendicine, a recombinant adenovirus, is the first gene therapy product to be licensed for cancer treatment.

Advantages of Adenoviral vectors

•  High transduction efficiency

•  Insert size up to 8 kilobases

•  Generation of high virus titres

•  High level of expression in a wide variety of cell types

•  No mutagenic effects due to lack of random integration into the host genome.

Disadvantagesof Adenoviral vectors

•  Transient expression due to lack of integration into the host.

•  Pathogenic to humans.

5-1.4.2. Adeno-associated virus

•  It was first discovered as a contaminant in an adenoviral isolate in 1965.

•  It is a small, non-enveloped virus packaging a linear single stranded DNA belonging to Parvovirus family.

•  It is naturally replication defective thus requiring a helper virus (usually adenovirus or herpes virus) for productive infection.

•  In human cells, the provirus integrates predominantly into a 4-kb region (AAVS1) on chromosome 19. Subsequent infection by adenovirus or herpes virus can ‘rescue' the provirus and induce lytic infection.