When HIV enters the body, it attaches itself to the wall of the white CD4 blood cell (also called the helper T-cell). This cell, or lymphocyte, belongs to a class of lymphocytes called T-cells. T-cells form a critical part of the body’s immune system as they organise the overall immune response to a variety of infectious diseases.
Like other viruses, HIV can only reproduce itself inside a living cell which it parasites for the purpose of reproduction. After attaching itself to the CD4 cell, the virus injects its RNA (as well as reverse transcriptase) into the cell (1). Viral RNA is changed to viral DNA through a process called reverse transcription (2). The viral DNA joins with the cell’s DNA in the core of the cell, causing it to produce more viral RNA (3). The viral RNA produces more HI-viruses (4). The new viruses break free from the cell, killing it and infecting more cells (5). This results in fewer CD4 cells to organise the immune response, resulting in increased vulnerability to infections.
As the immune system weakens, a critical point is reached where the condition is diagnosed as Aids. From that point forward, numerous opportunistic infections can invade the body with little resistance, ultimately resulting in death.
Why HIV is called a retrovirus?
HIV does the reverse of what other viruses do. The normal transcription from genetic information in cells is from DNA to RNA to proteins. The genetic information of HIV is contained in RNA. HIV uses an enzyme (reverse transcriptase) to transform its viral RNA into DNA in order to produce more viruses.
Does HIV infect only CD4 cells?
It is not only CD4 cells that are infected by HIV. The glycoproteins on the virus’s outer layer attach themselves to the CD4 receptors which are present on various types of cells such as monocytes, macrophages, tissue cells in mucous membranes (found in the genital tract and the anal-rectal area) and certain brain cells.