HIV and AIDS

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AIDS is constellation disorder from HIV (human immunodeficiency virus) infection. The HIV virus cripples human immune system and cause body more susceptible to various rare infectious disease. This is so called opportunistic infection. More than 95% of all cases and all death occur in developing countries. Over 33.6 million are infected worldwide. HIV infection is transmitted through unprotected sexual intercourse, oral sex, multiple sexual partners, needle injection sharing and mother to baby.

 

HIV virus is Retrovirus, which has an lipid envelope studded with glycoproteins. The envelope surrounds a protein coat. Single strand RNA and an enzyme called reverse transcriptase are covered inside.

 

HIV, RNA, Reverse transcriptase

HIV
Image credit: Wikimedia Commons

HIV Infection

  • HIV virus enter human body and infects antigen presenting cell such as macrophage and T helper cells.
  • HIV virus attaches to membrane of T helper cell and fuse into membrane.
  • RNA enters host cell.
  • Viral enzyme  reverse transcriptase uses the RNA as template and make DNA.
  • DNA is incorporated into host’s chromosomal DNA. It may dormant insides for many years.
  • DNA is sometimes transcribed into RNA and forms viral protein. Protein coat form the RNA and for new viruses.
  • Viruses bud from host cell. The plasma membrane form the lipid envelope for the new viruses and then they are released.
  • New generations of viruses infect other normal T helper cells.
  • estimated 2 billion T helper cells and 100 million to 1 billion virus particles are produced per day.
  • About half virus particles and replaces half lost T helper cells every two days.
  • More and more T helper cells are infected. Immune system are destroyed and the person becomes susceptible to infection.
  • Autoantibodies are produced and cause rare diseases such as rhemtoid arthritis, multiple sclerosis etc.


Video: HIV Life Cyle

File:HIV-budding-Color.jpg

HIV Budding
Image credit: Wikimedia Commons

Fig. 1.2 HIV Budding