Technical Information
Life Cycle of HIV
HIV is a virus. Virus survive by invading living cells and then changing the genetic material in that cell.
The HIV virus mainly attaches itself to a cell called a T lymphocyte cell (sometimes referred to as a CD4 cell or T cell). Once it recognises those cells it locks onto the outer cell wall a bit like a key into a lock and then puts its viral genetic material into the T cell. The virus is now safely within the human T cell but it is hidden. Our immune systems natural responses to having a virus in the body is not triggered off because the cell infected with the virus is hidden and therefore the virus cannot be attacked.
The virus continues to reproduce and makes billions of copies of infected cells. It is suggested that this cycle of finding one T cell, infecting it and reproducing millions of copies of infected cells, takes only one and a half days.
HIV Anatomy
HIV has a diameter of 1/10,000 of a millimetre and has an outer shell known as the viral envelope. Embedded in the viral envelope is a protein 'key' which helps it 'lock' on to surface receptors of other cells. This outer protuding 'key' is called glycoprotein 120 or gp120 and the stem part of the key is called gp 41. Inside the envelope is an HIV protein called matrix or p17 and then within that is the viral core or capsid. The capsid make up consists of two single strands of HIV RNA, p7 protein and enzyme proteins which converts the HIV RNA into HIV DNA. These enzymes are called reverse transcriptase and protease. The importance of these two enzymes is that new drug combinations work on preventing these enzymes from their work in the replication process.
HIV is in a class of viruses called retroviruses. Retroviruses are composed of RNA molecules but do not have any DNA, remember RNA and DNA are the building blocks or genetic instruction codes that govern the reproduction of living things. HIV, like all retroviruses have the ability to copy its RNA genetic material as DNA and so integrate itself with its host, so what starts as a CD4 cell ends in being an HIV cell.
There are activities which increase your risk of becoming HIV positive and some groups of people may put themselves more at risk than others. World wide 5 million people became infected with HIV in 2002 (source: Avert.org.uk). This brings the total number of people in the world living with HIV to 42 million. In the UK, there were a total of nearly 55,000 people who had been diagnosed HIV positive by the end of 2002, over half of whom had become infected through male homosexual intercourse. Over 15,000 HIV positive people have died in the UK.