HIV/AIDS

• HIV stands for human immunodeficiency virus.
• HIV is a retrovirus, meaning that its genetic material is RNA instead of DNA. It contains the enzyme reverse transcriptase, which is used to convert its RNA to DNA in order to take control of a cell's processes.
• The genetic material and enzymes within an HIV are surrounded by two layers of protein molecules (capsid).
• HIV also has a layer of phospholipid around itself, called the viral envelope, which is actually part of the host's cell-surface membrane that is picked up as the virus leaves the host cell in which it was produced.
• The phospholipid (viral) membrane contains two types of glycoproteins, called gp41 and gp120, which enable the virus particle to identify, bind to, and fuse with, potential host cells in order to infect them.
• 𝙃𝙄𝙑 𝙎𝙏𝙍𝙐𝘾𝙏𝙐𝙍𝙀:

  A) glycoproteins

  B) capsid

  C) reverse transcriptase

  D) genome

  E) lipid

  
• 𝙃𝙄𝙑 𝙍𝙀𝙋𝙇𝙄𝘾𝘼𝙏𝙄𝙊𝙉:

  HIV infects a particular type of helper T-cell. Once it has entered a cell, its RNA is converted to DNA via the enzyme reverse transcriptase. This DNA has base sequences that code for the production of new viruses and is incorporated into the chromosomes of the host cell so that it is replicated when the cell divides.
• The immune system produces antibodies against the virus which can be detected in the blood - however, these antibodies cannot enter the infected cells and therefore can only detect viral particles in the bloodstream.
• When the viral DNA is activated, it is transcribed and translated by the host cell's own enzymes and ribosomes. Large numbers of new viruses are formed and assembled, and burst out of the cell, ready to infect more helper T-cells.
• Gradually, the number of functioning helper T-cells in the body decreases. These cells are necessary to activate B-cells and cytotoxic T-cells, so the ability to produce antibodies decreases and the specific immune response becomes weaker.
• A person is said to have AIDS (Acquired Immunodeficiency Syndrome) when they have so few helper T-cells in their body that they are unable to fight off other infections or destroy cancer cells that have formed in their body.
• AIDS makes people much more susceptible to diseases such as tuberculosis and malaria, and many die from pneumonia and various gut infections.
• 𝙃𝙄𝙑 𝙏𝙍𝙀𝘼𝙏𝙈𝙀𝙉𝙏:

  Today, drug therapy is available that can greatly slow down the development of AIDS. Many HIV-positive people now have life expectancies almost as long as if they had never been infected.

  The drugs used are antiretrovirals, or ARVs. They work by binding to the viral reverse transcriptase and stopping it from copying the virus's RNA to make DNA.

  These drugs cannot cure AIDS but do keep the quantity of the virus in the body to a low level, ensuring the person retains a healthy amount of helper T-cells and a well-functioning immune system.
• HIV is a lentivirus (meaning 'slow virus', named because of the long time it takes to produce any effects on the body) that attacks the immune system.
• The closest related lentivirus to HIV is SIV (Simian Immunodeficiency Virus) which affects monkeys and has been around far longer. It is generally believed that SIV gave rise to HIV by a mutation that enabled the virus to transfer between species.
• The human immunodeficiency virus, HIV, is a retrovirus. It contains RNA and is surrounded by protein coats (capsid) and a phospholipid membrane derived from its host cell.
• Once in a host cell, the RNA of the virus is used to make a complementary DNA molecule, which inserts itself into one of the cell's own chromosomes. Eventually, the code on the DNA is used by the cell's enzymes and ribosomes to make new viruses.
• HIV infects a particular type of helper T-cell and destroys them. This weakens the immune response, so that a person is not able to defend themselves against pathogens. This causes the disease AIDS.
• AIDS cannot be cured, but the replication of HIV in T-cells can be greatly reduced by antiretroviral drugs (ARVs).