Life cycle of HIV.

HIV Life Cycle:

T HIV is Human immunodeficiency virus.

Virus doesn’t have nucleus and cannot replicate on its own. For replication viruses need living cells. (Replication is the process by which a cell divides and produces indentical cells)

Before knowing the life cycle of HIV , knowing its structure would be useful.

HIV is a retro virus which belongs to genus lentivirus . Lenti means slow growing.

HIV  life cycle can  be divided into following stages:

1.       Attachment of virus to Host cells.

2.       Fusion of Virus with Host(CD4) cells

3.       Conversion of virus RNA into DNA

4.       Integration of HIV RNA into host DNA

5.       Production of viral proteins and enzymes

6.       Assembling of virus .

7.       Budding of virus from CD4 cells

Attachment of virus to Host cells:

This is the process by which HIV binds to a specific type of CD4 receptor and a co-receptor on the surface of the CD4 cell. This is similar to a key entering a lock. Once unlocked, HIV can fuse with the host cell (CD4 cell) and release its genetic material into the cell.

Fusion of Virus with Host(CD4) cells:

 HIV can fuse with the host cell (CD4 cell) and release its genetic material into the cell

Conversion of virus RNA into DNA:

A special enzyme called Reverse transcriptase changes the genetic material of the virus, so it can be integrated into the host DNA.

Integration of HIV RNA into host DNA:

The virus’ new genetic material enters the nucleus of the CD4 cell and uses an enzyme called integrase to integrate itself into your own genetic material, where it may “hide” and stay inactive for several years.

Production of viral proteins and enzymes:

When the host cell becomes activated, and the virus uses your own enzymes to create more of its genetic material along with a more specialized genetic material which allows it make longer proteins.

Assembling of virus:

A special enzyme called protease cuts the longer HIV proteins into individual proteins. When these come together with the virus’ genetic material, a new virus has been assembled.

Budding of virus from CD4 cells:

This is the final stage of the virus’ life cycle. In this stage, the virus pushes itself out of the host cell, taking with it part of the membrane of the cell. This outer part covers the virus and contains all of the structures necessary to bind to a new CD4 cell and receptors and begin the process again.