Module 5 : GENE TRANSFER TECHNIQUES

Lecture 1 : Gene Transfer Techniques : Biological Methods

5-1.4. Viral vectors

Various kinds of viruses can be used as viral vectors, but five classes of viral vector are used in human gene therapy-

  1. Adenovirus
  2. Adeno- associated virus (AAV)
  3. Herpes virus
  4. Retrovirus
  5. Lentivirus

Vector

Host cells

Entry pathway

Vector genome
forms

Transgene expression

Uses

Retrovirus

Actively dividing cells

Receptor-binding,
membrane fusion

Integrated

Long term (years)

SCID, Hyperlipedemia, solid tumors

Lentivirus

Dividing and non-dividing cells

Receptor-binding,
membrane fusion

Episomal

Stable

Hematopoetic cells, muscles,
neuron,
hepatocytes

Adeno virus

Most cells

CAR (Coxsackie and Adenovirus Receptor)-mediated
endocytosis
endosomal escape

Episomal

Transient (short term for weeks)

CNS, hepatocytes,
pancreas

Adeno- associated virus

Most cells

Receptor-mediated
endocytosis
endosomal escape

Episomal (90%)
Integrated
(10%)

Medium to long term (year)

lung , muscle, heart, CNS

Herpes virus

Most cells

Endocytotic or membrane fusion

Episomal

Transient

Suitable particularly for nervous system

Table 5-1.4: Viral vectors and their properties.