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Human Immunodeficiency Virus

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Human Immunodeficiency Virus

  1. 1. Human immunodeficiency virus <ul><li>HIV </li></ul>
  2. 2. Human immunodeficiency virus <ul><li>HIV is the cause of acquired immune deficiency syndrome (AIDS) </li></ul><ul><li>It is a single stranded RNA virus </li></ul>
  3. 3. Human immunodeficiency virus <ul><li>It has a spherical shape with a diameter of about 0.1  m </li></ul><ul><li>It is outer lipid membrane is taken from material surrounding the host cell </li></ul>
  4. 4. Human immunodeficiency virus <ul><li>The genetic material is enclosed in a protein caspid </li></ul><ul><li>Within the caspid is also some molecules of reverse transcriptase </li></ul>
  5. 5. Human immunodeficiency virus <ul><li>It is a member of a group of viruses called retroviruses. </li></ul><ul><li>These viruses reverse the normal flow of genetic information </li></ul>
  6. 6. Human immunodeficiency virus <ul><li>The reverse transcriptase makes copies of DNA from the viral RNA. </li></ul><ul><li>The viral DNA made is known as a provirus </li></ul>
  7. 7. Human immunodeficiency virus <ul><li>The provirus is then spliced into the host cell’s own DNA in an act of piracy. </li></ul><ul><li>The host cell is now ready to make copies of the virus </li></ul>
  8. 8. Human immunodeficiency virus <ul><li>Visit </li></ul><ul><li>http://www.cellsalive.com/hiv1.htm </li></ul><ul><li>http://www.hopkins-aids.edu/hiv_lifecycle/hivcycle_txt.html </li></ul><ul><li>For a good overview of the “life-cycle “ of HIV </li></ul>
  9. 10. HIV and AIDS <ul><li>HIV is passed from human to human by: </li></ul><ul><li>Sexual contact with an infected person </li></ul><ul><li>Shared use of a hypodermic needle with an infected person </li></ul><ul><li>Injection of contaminated blood or blood products </li></ul><ul><li>From an infected mother to her fetus or suckling baby </li></ul>
  10. 11. HIV and AIDS <ul><li>HIV attacks the body helper T cells </li></ul><ul><li>These are WBC – lymphocytes </li></ul><ul><li>The T cells have proteins on their surface which bind to the HIV </li></ul>
  11. 12. HIV and AIDS <ul><li>The virus latches onto the T cells and uses them like ‘door handles’ to gain entry to the cell </li></ul><ul><li>Once inside the virus RNA is released into the cytoplasm </li></ul>
  12. 13. HIV and AIDS <ul><li>The reverse transcriptase transcribes the viral RNA into DNA </li></ul>
  13. 14. HIV and AIDS <ul><li>The enzyme integrase splices the viral DNA into the host cell DNA </li></ul>
  14. 15. HIV and AIDS <ul><li>The infective virus now exists as a segment of DNA in the host cell. </li></ul><ul><li>The cell may pass through a period of latency as the viral DNA awaits a chemical signal to prompt the host cell to start to produce new virus </li></ul>
  15. 16. HIV and AIDS <ul><li>The host cell then transcribes the viral DNA and starts to make many copies of the viral RNA and viral protein </li></ul>
  16. 17. HIV and AIDS <ul><li>These molecules spontaneously assemble into new viral particles </li></ul>
  17. 18. HIV and AIDS <ul><li>The virus escapes the T cell to infect other T cells </li></ul><ul><li>The infected T cell eventually is destroyed by the virus. </li></ul>
  18. 19. Treatment of AIDS <ul><li>There is no cure or vaccine for AIDS or HIV infection </li></ul><ul><li>A number of anti-HIV drugs are available </li></ul><ul><li>The most well known of these zidovudine (AZT) works by blocking the viral reverse transcriptase. </li></ul>

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