Retroviral Vectors

By:Maryam shakeel

Retrovirus Class of enveloped virusesSingle stranded RNA Retroviruses are one of the mainstays of

current gene therapy approaches. The recombinant retroviruses such as the

Moloney murine leukemia virus have the ability to integrate into the host genome in a stable fashion

Genome of Retrovirus• LTR (long terminal repeat)

U5 envpolgag5’ 3’

• PBS (primer binding site)

• “Pol” gene• “gag” gene• “env” gene• “Ѱ” packaging signal site• 5’ss & 3’ss site

Ѱ

5’ss 3’ss

U3 R U5U3 R

LTR LTR

• PPT (polypurine Test)

Construction of Replication defective Retroviral Vector:

• Retroviral vectors are derived from wild type retroviruses (Moloney murine leukaemia provirus) and are engineered to carry a foreign gene of interest into a target cell.

• Retroviral vectors are composed of the gene of interest and the cis-acting elements of the viral genome , with the removal of the trans-acting viral genes (gag, pol, and env)

LTR LTRenvpolgag5’ 3’

Ѱ

5’ss 3’ss

LTR LTR5’ 3’

Ѱ

5’ss

Gene of Interest

Applications in Gene therapy:

Limitations:

• Moloney retrovirus involves the requirement for cells to be actively dividing for transduction.

• insertional mutagenesis due to integration into the host genome might lead to cancer or leukemia.

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