HIV: The "AIDS Virus"

The Players The Virus. The human immunodeficiency virus (HIV) causes a weakness of the immune system. When it infects the body, it prefers to attack certain cells of our defense system. These cells are called helper T cells which are a fundamental part of our immune system. HIV almost fully specializes on these white blood cells since these helper T cells have CD4 molecules on the surface to which HIV binds.
Host Cell HIV, to put it simply, consists of genetic information on the inside and a protective outer shell of proteins and glycoproteins. Since viruses use the host cell's resources for reproduction, they don't need to contribute much themselves. That's why they are much smaller than the host cells, e.g. helper T cells. In the host cell's nucleus, displayed in blue here, there are more than 100,000 times as much genetic information stored than under the protein shell of HIV. However, there is no way for the host cell to stop the virus once the cell has been infected.
What Happens T-cell Infection The infection proceeds in this manner: The virus anchors itself to a special protein (CD4) on the surface of the helper T cell. This causes the viral membrane to fuse with the host cell's membrane. This way the genetic information gets inside the cell.
Retroviruses HIV belongs to a special group of viruses, called "retroviruses." Its genetic information is not encoded as DNA, but instead as RNA (ribonucleic acid) and therefore has to be reverse transcripted into DNA. The tools for this are delivered by the host cell itself, except for a little helper protein (reverse transcriptase) which the virus has brought with itself. The DNA is now legible for the cell and is transferred to the nucleus. This process is already finished by a half of a day after infection. The foreign piece of DNA is then inserted randomly into the host DNA and it is now ready to be transcribed.
Break-apart At the beginning of AIDS, the viral DNA is being transcribed to form many RNA molecules--the signal which causes this is yet unknown. The accruing RNA is carried to the cytoplasm of the cell, where it can start making proteins.
Replication The RNA, with the help of the host's resources, begins to make many copies of the different parts of HIV (the protective shell and the helper and anchor proteins).
After everything has been copied, thousands of bubbles like these are produced and migrate to the cell membrane surface and fuse with it.
Release Finally, a copy of the RNA genetic information is added to the bubble. Then this section of the cell membrane turns inside out and new viruses leave the cell.
The Result Cell Death Naturally, the release of the new virus particles significantly weakens the host cell which soon dies. Thats how the immune system weakens.