Copyright Pearson Prentice Hall I will understand that compromised immune systems may be unable to fight usually benign pathogens. MT: Immune System Photo Credit: © David Scharf/Peter Arnold, Inc. Human Immunodeficiency Virus Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Autoimmune Diseases What is an autoimmune disease? When the immune system attacks the body's own cells, it produces an autoimmune disease. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Autoimmune Diseases Some examples of autoimmune diseases include: Type I diabetes attacks insulin-producing cells. Rheumatoid arthritis attacks connective tissues around joints. Multiple sclerosis (MS) destroys functions of brain and spinal cord neurons. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall AIDS In 1983, researchers identified the cause of AIDS—a virus that is caused by the HIV for human immunodeficiency virus. HIV is a retrovirus—a virus that carries its genetic information in RNA, rather than DNA. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall AIDS HIV attacks and destroys helper T cells (good cells). As the number of helper T cells decreases, the body becomes more susceptible to other diseases. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall HIV Infection HIV travels through the bloodstream, where it binds to receptors on helper T cells. Once inside the cell, the virus directs the cell to produce many new viruses. These new viruses are quickly released back into the bloodstream, where they travel to new cells and destroy them. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall AIDS Envelope Viral RNA Reverse transcriptase enzyme Capsid Protein coat 1 Virus attaches to host cell membrane by recognizing specific molecules on the cell surface. 1 Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall AIDS Viral coat fuses with cell membrane and viral RNA enters the cell 2 2 Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall AIDS Viral RNA is used as a template to make viral DNA. 3 3 Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall AIDS Viral DNA enters nucleus and attaches to host chromosome. There it may remain dormant (lysogenic cycle) or begin directing the synthesis of viral mRNA (lytic cycle). 4 4 Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall AIDS 5 Viral mRNA directs the host cell to assemble viral proteins. 5 Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall AIDS Capsids are assembled around the viral proteins and RNA. The new viruses bud off from the host cell membrane ready to infect other T cells. 6 6 Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall AIDS Transmission of HIV HIV is not transmitted through casual contact. HIV can only be transmitted through the exchange of blood, semen, vaginal secretions, or breast milk. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall AIDS How can AIDS be prevented? Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall AIDS Preventing HIV Infection The only no-risk behavior with respect to HIV and AIDS is ABSTINENCE. Don’t do drugs (so you don’t share needles) Don’t have unprotected sex (so you don’t exchange semen, vaginal fluid, or blood) Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall AIDS Can AIDS Be Cured? At present, there is NO CURE for AIDS. The virus can be controlled by expensive multidrug and multivitamins that fight the virus. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall AIDS Does a person die from HIV or AIDS? Directly no. The virus attacks the immune system, so when a usually benign pathogen (common cold, pneumonia, bacteria) enters the body, the immune system cannot fight it off, and thus leads to death. Copyright Pearson Prentice Hall