2.  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. 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?

27. 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

32. The immune system protects the body from potentially harmful substances. The inflammatory response (inflammation) is part of innate immunity. It occurs when tissues are injured by bacteria, trauma, toxins,

34. 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

38. 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 b one marrow and mature there  T cells – also produced in bone marrow, but go to t hymus to mature

39. 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.specificantigen The specificity of binding resides in a receptor for antigen: the B cell receptor (BCR) for antigen and the T cell receptor (TCR) respectively.

48. The lymphoid stem cell provides specific defenses

49. 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 – the immune 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.

50. A two-pronged attack  Cell-mediated immune response – involves T cells  Humoral immune response – involves mainly B cells  Both controlled by helper T cells

51. First step …. macrophage contacts virus in lymphoid tissue and engulfs it… this is a non-specific response  Macrophage displays viral fragments on own surface …  Helper T cell with receptors matching the presented antigen encounters macrophage … here it is a specific response  Macrophage releases cytokine Interleukin-1 …  Helper T cell releases Interleukin-2 …

55.  Interleukin-2 stimulates helper T cells, cytotoxic T cells and suppressor T cells to divide rapidly  Cytotoxic T cells attach to viral antigens displayed on surface of infected cells  These killer T cells (CTLs) destroy infected cells by puncturing cell membrane  Suppressor T cells help to shut down immune response when viruses are cleared out  Memory T cells stay for future infections

58.  IL-2 and virus antigen presentation by a macrophage or helper T cell stimulate B cells to divide and become plasma cells and memory cells  Plasma cells secrete defensive proteins called antibodies  Antibodies are Y shaped, and are identical to the plasma cell’s antigen receptors (BCRs)  A plasma cell can make 30,000 antibodies/sec  Antibodies bind to specific viruses but do not destroy them directly

67.  Helper T cells ….. Secrete signal proteins (cytokines) that stimulate B cells and CTLs  Phagocytes (macrophages) and infected cells ….. Display viral protein fragments in surface protein complex (MHC) T cells ….. Recognize the antigen protein displayed by surface protein complex, but not either alone From the millions of different lymphocyte receptor shapes, an antigen will “select” a good fit, stimulating massive cloning

68.  Antibodies can … coat (neutralize) small antigens; coat larger antigens that may be engulfed by macrophages; build bridges between antigens (two binding sites per antibody) for macrophage engulfment; activate a protein complement system of destruction

69.  http://www.youtube.com/watch_popup?v=hQm aPwP0KRI Antibody mediated immune response http://www.youtube.com/watch_popup?v=hQm aPwP0KRI  http://www.youtube.com/watch?v=1tBOmG0Q MbA Cell Mediated Immune Response http://www.youtube.com/watch?v=1tBOmG0Q MbA  http://www.youtube.com/watch?v=Ys_V6FcYD5 I Specific immunity – antibodies http://www.youtube.com/watch?v=Ys_V6FcYD5 I  http://www.youtube.com/watch?v=KiLJl3Nwmp U Macrophage Cytokine Release http://www.youtube.com/watch?v=KiLJl3Nwmp U  http://www.youtube.com/watch?v=cL9KY_ECzf o Pathogen Recognition in a macrophage http://www.youtube.com/watch?v=cL9KY_ECzf o  http://www.youtube.com/watch?v=kskFjm1pKE s The Immune System: An Explanation http://www.youtube.com/watch?v=kskFjm1pKE s  http://www.youtube.com/watch?v=iDYL4x1Q6u U Macrophages, b-cells, pathogens, Antibody Immune Response http://www.youtube.com/watch?v=iDYL4x1Q6u U

70.  http://www.youtube.com/watch?v=E2e5J1dfi E0 T cell lymphocyte http://www.youtube.com/watch?v=E2e5J1dfi E0  http://www.youtube.com/watch?v=25fvwEJ DOKA TCellEd.mov http://www.youtube.com/watch?v=25fvwEJ DOKA  http://www.youtube.com/watch?v=r29CcpZ YFJY ANTIVIR.mov http://www.youtube.com/watch?v=r29CcpZ YFJY  http://www.youtube.com/watch?v=h9lxx6x3 HAM Immune response - viral infections http://www.youtube.com/watch?v=h9lxx6x3 HAM

71.  http://www.youtube.com/watch?v=v5LGqi- 8eZg HIV film http://www.youtube.com/watch?v=v5LGqi- 8eZg  www.mcat45.com/node/68 viral structure www.mcat45.com/node/68  http://www.youtube.com/watch?v=RJf2lolx7 P8 Gardasil, HPV http://www.youtube.com/watch?v=RJf2lolx7 P8  http://www.youtube.com/watch?v=v5LGqi- 8eZg HIV http://www.youtube.com/watch?v=v5LGqi- 8eZg  http://www.youtube.com/watch?v=3ykHoIK AtQI vaccination http://www.youtube.com/watch?v=3ykHoIK AtQI  www.coryvannote.com/folio/more/bio_virus. html virus cycles www.coryvannote.com/folio/more/bio_virus. html

80. Vaccines  Sanofi Pasteur (see Vaccine Essentials)  Glaxo Smith-Kline  Novartis  Novavax  Merck  MedImmune (Astra Zeneca) Monoclonal Antibodies  Genentech  Biogen Idec  Amgen  Centocor  Imclone (Eli Lilly)  Merck  MedImmune (Astra Zeneca)  Genzyme