Lentiviral vector in gene therapy

Lentiviral vectors in gene therapy is a method by which genes can be inserted, modified, or deleted in organisms using lentivirus.

Lentivirus are a family of viruses that are responsible for notable diseases like HIV. The Lentivirus is unique in that it has been the basis of research using viruses in gene therapy. To be effective in gene therapy, there must be insertion, alteration and/or removal of host cell genes. To do this scientists use the Lentivirus' mechanisms of infection to achieve a desired outcome to gene therapy.

To understand the capabilities of the Lentivirus as a vector, the biology of the infectious process must be understood. The Lentivirus is a retrovirus, meaning it has a single stranded RNA genome with a reverse transcriptase enzyme. Lentiviruses also have a viral envelope with protruding glycoproteins that aid in attachment to the host cell's outer membrane. The virus contains a reverse transcriptase molecule found to perform transcription of the viral genetic material upon entering the cell. Within the viral genome are DNA sequences that code for specific enzymes effecting the incorporation of the viral DNA into the host cell genome. The "gag" domain codes for the structural components of the virus like the capsid, the matrix, nucleoproteins. The "pol" domain codes for the reverse transcriptase and integrase enzymes. Lastly, the "env" domain of the viral genome encodes for the glycoproteins and envelope on the surface of the virus.

There are multiple steps involved in the infection and replication of a Lentivirus in a host cell. In the first step the virus uses its surface glycoproteins for attachment to the outer surface of a cell. More specifically, Lentiviruses attach to the CD40 ligand glycoproteins on the surface of T-lymphocyte cells. The viral material is then injected into the host cell's cytoplasm. Within the cytoplasm the viral reverse transcriptase enzyme performs reverse transcription of the viral RNA genome to create a viral DNA genome. The viral DNA is then sent into the nucleus of the host cell where it is then incorporated into the host cell's genome with the help of the viral enzyme integrase. From there the host cell performs transcription and translation to create viral particles and assemble virions which then burst from the host cell when enough are made.

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