1 / 88

The Immune System, Viruses, and Disease

The Immune System, Viruses, and Disease. Virus essentials. Viruses are not cells Replicate by invading host cell Use host organelles and enzymes to make more viruses Called obligate intracellular parasites

nerita
Download Presentation

The Immune System, Viruses, and Disease

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. The Immune System, Viruses, and Disease

  2. Virus essentials • Viruses are not cells • Replicate by invading host cell • Use host organelles and enzymes to make more viruses • Called obligate intracellular parasites • Outside cell, virus is lifeless – spread by wind, in water, in food, or via blood or other body fluids

  3. Viral structure Essential features: • nucleic acid – RNA or DNA • capsid – protein coat • surface protein receptors • some have an envelope made of lipids taken from a host cell – influenza, chickenpox, herpes simplex, HIV • Are viruses alive?

  4. Flu invades lung cilia

  5. Obamaflu

  6. Swine flu

  7. H1N1 cells (recently budded)

  8. Flu virus

  9. H1N1

  10. Hemagglutinin

  11. HIV virus

  12. HIV

  13. Cold virus

  14. The HPV virus

  15. Herpes virus

  16. Herpes simplex virus emerges from host nucleus into cytoplasm

  17. RSV --Respiratory syncytial virus

  18. RSV

  19. There are many different species of mosquito, which can carry some of the world's most common and significant infectious diseases, including West Nile, Malaria, yellow fever, viral encephalitis, and dengue fever. (Image courtesy of the Centers for Disease Control and Prevention.)

  20. The meninges

  21. Defenses Against Viruses Non-specific defenses •skin – with its tough keratin shield •mucous membranes – line respiratory and digestive systems, urethra, vagina; secrete mucus that traps pathogens • cilia – in respiratory tract; sweep mucus and pathogens to pharynx for swallowing •inflammatory response -- includes phagocytes like macrophages; natural killer cells (NK’s) •Interferon -- protein that inhibits virus production; signals healthy neighbor cells to defend themselves •Fever -- when moderate, stimulates bodies defenses; goes beyond best temp for virus reproduction

  22. Cilia

  23. Macrophage

  24. Interferon

  25. Inflamatory response

  26. Defenses cont’d. Specific defenses – Adaptive immunity • Organs -- bone marrow, thymus, lymph nodes, tonsils, adenoids, spleen • Bone marrow – soft, inside long bones; makes billions of new wbc’s every day • Lymph nodes – along lymph vessels; filter viruses and expose them to lymphocytes • Spleen – just behind stomach; filters viruses; stocked with wbc’s

  27. Lymphatic system

  28. Specific defenses (cont’d.) • Lymphocytes – leukocytes (white blood cells) found in these organs and in blood and lymph; accumulate in lymph and lymph nodes, but are also in spleen and blood • B cells – one of two main types of lymphocytes; produced in bone marrow and mature there • T cells – also produced in bone marrow, but go to thymus to mature

  29. B Cells and T Cells Lymphocytes are one of the five kinds of white blood cells or leukocytes, circulating in the blood. Although mature lymphocytes all look pretty much alike, they are extraordinarily diverse in their functions. The most abundant lymphocytes are: • B lymphocytes (often simply called B cells) and • T lymphocytes (likewise called T cells). B cells are not only produced in the bone marrow but also mature there. However, the precursors of T cells leave the bone marrow and mature in the thymus (which accounts for their designation). Each B cell and T cell is specific for a particular antigen. What this means is that each is able to bind to a particular molecular structure. The specificity of binding resides in a receptor for antigen: • the B cell receptor (BCR) for antigen and • the T cell receptor (TCR) respectively.

  30. Lymphocyte development

  31. Macrophages, T-cells, RBCs

  32. B cell

  33. Macrophage and lymphocytes

  34. Dendritic cells and macrophages

  35. The lymphoid stem cell provides specific defenses

  36. How do lymphocytes recognize viruses as foreign invaders? Antigen – any substance that the immune system recognizes as a foreign invader and provokes an immune response Receptor proteins – on surface of every lymphocyte; recognize and bind to antigens that match their their 3-D shape It’s all in the fit! Variety – theimmune system makes millions of different kinds of lymphocytes with different shaped receptors Specificity – due to specificity of antigen receptors on lymphocytes ; some have receptors for a cold virus (more than 100 viruses can cause a cold), some have receptors for a flu virus, etc.

  37. Immune Response A two-pronged attack • Cell-mediated immune response – involves T cells • Humoral immune response – involves mainly B cells • Both controlled by helper T cells

More Related