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Unit 4 AOS1 How do organisms respond to pathogens? Chapter 7- Dealing with disease  physical, chemical and microbiota barriers Key knowledge as preventative mechanisms of pathogenic in...

Unit 4 AOS1 How do organisms respond to pathogens? Chapter 7- Dealing with disease  physical, chemical and microbiota barriers Key knowledge as preventative mechanisms of pathogenic infection in animals and plants the innate immune response including the steps in an inflammatory response and the characteristics and roles of macrophages, neutrophils, dendritic cells, eosinophils, natural killer cells, mast cells, complement proteins and interferons Responding to antigens initiation of an immune response, including antigen presentation, the distinction between self-antigens and non-self antigens, cellular and non-cellular pathogens and allergens  initiation of an immune response, including antigen presentation, the distinction between Detecting pathogens self- antigens and non-self antigens, cellular and non-cellular pathogens, and allergens Antigens are unique molecules, or parts of molecules, that initiate an immune response. Most are protein based. Antigens are expressed or presented on the surface of the plasma membrane of cells. However, some antigens, such as toxins released by bacteria, circulate freely in body fluids. Self antigens are produced within a person. Non-self antigens that are not produced within a person and initiate an immune response.  initiation of an immune response, including antigen presentation, the distinction between Major Histocompatibility Complex (MHC) self- antigens and non-self antigens, cellular and non-cellular pathogens, and allergens The MHC proteins are proteins on the surface of your body’s cells that present self or non-self antigens. Substances that could be identified as non-self include: a pathogen or a cell, such as a blood cell or cell in an organ transplant. MHC markers have a groove that is capable of holding a short peptide, which is the antigen. Immune cells such as specific B and T cells and Antigen Presenting Cells with a complementary receptor bind to the MHC/antigen complex, self or non-self.  initiation of an immune response, including antigen presentation, the distinction between MHC I and MHC II self- antigens and non-self antigens, cellular and non-cellular pathogens, and allergens Two classes of MHC proteins that are important in antigen presentation are MHC class I (MHC-I) and MHC class II (MHC-II). Class I MHC proteins: Are found on all healthy cells of the body that have a nucleus. MHC-I proteins allow the immune system to recognise these cells as ‘self’ so it does not attack the cells. Class II MHC proteins: MHC-II is usually only present on specialised antigen-presenting cells (such as dendritic cells, macrophages and B cells). MHC-II presents non-self antigens that that have been processed by phagocytosis.  initiation of an immune response, including antigen presentation, the distinction between Pathogens as a source of non-self antigens self- antigens and non-self antigens, cellular and non-cellular pathogens, and allergens A pathogen is an agent able to cause disease in a host. Most pathogens contain unique antigens that can be recognised by the immune system. Pathogens may be: Non-cellular agents do not have a cellular structure and are non-living. Examples include prions and viruses Cellular agents that have a cellular structure and are living organisms, including micro-organisms. Examples include bacteria, fungi, worms and protozoa.  initiation of an immune response, including antigen presentation, the distinction between Bacteria (cellular) self- antigens and non-self antigens, cellular and non-cellular pathogens, and allergens Bacteria are typically single-celled, prokaryote organisms that do not have a membrane-bound nucleus and other cell organelles. Bacteria have a cell wall and a single major chromosome- a circular thread of DNA double helix. They reproduce via binary fission. Some bacterial diseases that affect humans are diphtheria, food poisoning, wound infections, tetanus, pneumonia, tuberculosis, meningitis. Antibiotics are naturally occurring substances that inhibit the growth of, or destroy, bacteria.  initiation of an immune response, including antigen presentation, the distinction between Fungi (cellular) self- antigens and non-self antigens, cellular and non-cellular pathogens, and allergens Fungi are eukaryotic organisms that include yeasts and moulds that contain filaments known as hyphae. They obtain nutrients from decomposition of dead organic matter. Many fungi are ectoparasites (parasites that live on the surface of their host.) Most fungal infections are superficial because they effect the skin, nails and hair and rarely penetrate into living tissue. They reproduce via spore formation. Examples include ringworm, tinea, thrush. Treatment includes anti-fungal ointments and oral preparations. Most common infections in plants and treated by fungicides  initiation of an immune response, including antigen presentation, the distinction between Worms (cellular) self- antigens and non-self antigens, cellular and non-cellular pathogens, and allergens Parasitic worms are multicellular organisms that can infect plants and animals. They include flatworms such as tapeworms, and roundworms such as hookworms, pinworms and threadworms.  initiation of an immune response, including antigen presentation, the distinction between Protozoa (cellular) self- antigens and non-self antigens, cellular and non-cellular pathogens, and allergens Protozoa are single celled eukaryotes. Examples of diseases caused by protozoans include dysentery and malaria  initiation of an immune response, including antigen presentation, the distinction between Prions (non-cellular) self- antigens and non-self antigens, cellular and non-cellular pathogens, and allergens Prions are an infectious agent consisting of only protein, and without any genetic material that causes some forms of degenerative neurological diseases (transmissible spongiform encephalopathy, e.g. mad cow disease and scrapie.) It appears that we all contain the genetic instructions to make prion protein. The protein occurs mainly in nerve cells and its function is unknown. If we become infected with a defective prion it converts normal protein into prion protein by inducing misfolding Cells cannot not “kill” prions. Prions eventually cause a cell to burst and are free to infect other cells. The bursting of nerve cells results in the holes seen in an infected brain. No treatment is available for individuals infected with abnormal prions.  initiation of an immune response, including antigen presentation, the distinction between Viruses (non-cellular) self- antigens and non-self antigens, cellular and non-cellular pathogens, and allergens Viruses are particles consisting of genetic material surrounded by a protein coat that reproduces only in a host cell. Viruses contain either DNA or RNA enclosed by one or more protein coats, however, they lack the protein-making machinery of cells, hence the need to enter a host cell to reproduce. When a virus reproduces inside a host cell, the cell will die. In most cases viruses are host specific that is a particular virus causes disease in only one kind of organism. Some diseases that affect humans are the common cold, influenza, polio, measles, chickenpox, SARS-CoV-2 causing COVID 19.  initiation of an immune response, including antigen presentation, the distinction between Allergens (Allergies) self- antigens and non-self antigens, cellular and non-cellular pathogens, and allergens An allergen is a substance that initiates an allergic response by binding to antibodies that are already bound to receptors on mast cells. They initiate an immune response that is hypersensitive to a molecule that doesn’t normally cause harm (allergic reactions). Steps of an allergic response On first exposure B cells produce IgE antibodies specific to allergen IgE Antibodies attach to mast cells On second exposure the allergen creates a crosslink with the antibodies on mast cells. This causes the mast cell to release histamine. Histamine causes symptoms ie. watery eyes, runny nose, swelling, itching, excessive mucus production and constriction of airways.  physical, chemical and microbiota barriers Innate and adaptive immunity as preventative mechanisms of pathogenic infection in animals and plants There are several mechanisms by which the immune systems of organisms respond to non-self antigens and defend against pathogens. In vertebrates, immune responses are divided into innate (or non-specific) and adaptive (or specific) immune responses.  physical, chemical and microbiota barriers First line of defence as preventative mechanisms of pathogenic infection in animals and plants Organisms have a number of first-line defences (or barriers) that provide innate resistance against pathogens. These are divided into Physical Chemical Microbiological  physical, chemical and microbiota barriers First line of defence as preventative mechanisms of pathogenic infection in animals and plants Description Plant examples Animal examples Physical Barriers that prevent entry of - Thick bark - Intact skin pathogens - Waxy cuticle - Mucous secretions - Formation of galls - Cilia (fine hairs) trap - Presence of thorns pathogens. - Closing of stomata - producing ‘gum’ to seal off the wounded area Chemical Barriers that inhibit growth or - release of toxins such as - Lysozymes in tears and saliva development of pathogens defensins and tannins - stomach acid (includes chemicals and - production of enzymes such - earwax enzymes). as chitinases - acidic sweat Microbiota Non-pathogenic bacteria - presence of bacteria on the (normal “flora”) that prevent the skin, in the lower growth or colonisation of gastrointestinal tract and the microorganisms vagina.  the innate immune response including the steps in an inflammatory response and the Second line of defence characteristics and roles of macrophages, neutrophils, dendritic cells, eosinophils, natural killer cells, mast cells, complement proteins and interferons Pathogens are sometimes able to slip past or breach the first line of defence. The second line of defence is another component of the innate immune response, another form of non-specific and immediate protections against pathogens. There are two components of the second line of defence- cellular and non-cellular. All cells involved are called leukocytes, or white blood cells.  the innate immune response including the steps in an inflammatory response and the Cellular components characteristics and roles of macrophages, neutrophils, dendritic cells, eosinophils, natural killer cells, mast cells, complement proteins and interferons All cells involved in the second line of defence are called leukocytes, or white blood cells. The following *cytokines are signaling Neutrophils - phagocytosis of pathogens following migration to the molecules of the site of infection; release cytokines that attract other immune immune system cells and cause inflammation. allows cell to communicate with each other Macrophages -phagocytosis of pathogens; release cytokines (interferon) that attract other immune cells and cause inflammation; also play a role as antigen-presenting cells. Dendritic cells - phagocytosis of pathogens; migrate via lymphatic vessels to lymph glands where they act as antigen-presenting cell; characteristic star-shaped cell  the innate immune response including the steps in an inflammatory response and the Phagocytes characteristics and roles of macrophages, neutrophils, dendritic cells, eosinophils, natural killer cells, mast cells, complement proteins and interferons Phagocytes are cells that engage in phagocytosis- a process in which they consume and destroy foreign material such as pathogens present in the body by engulfing it through the process of endocytosis. Once engulfed, enzymes called lysozymes (contained in lysosomes) present in the cell destroy the foreign material by fusing with the vesicles containing the engulfed material.  the innate immune response including the steps in an inflammatory response and the Antigen presenting cells characteristics and roles of macrophages, neutrophils, dendritic cells, eosinophils, natural killer cells, mast cells, complement proteins and interferons Antigen-presenting cells (APC) are specialised for presenting antigens. When an APC engulfs a pathogen, the antigens of the pathogen are broken into small peptides in the cell. These antigen fragments bind to MHC-II molecules inside the cell. The antigen–MHC-II complexes then move to the cell surface to present the antigens to helper T lymphocytes (third line of defence).  More cellular components Natural killer cells- kill virus infected cells, or abnormal cells caused by cancer, by releasing cytotoxic granules. Natural killer cells examine the cells MHC class I molecules which have been destroyed or suppressed due to disease processes. They also have receptors for stress molecules. Cell death is only initiated in infected or abnormal cells with missing MHC I markers – that is, when the killer activation receptor is activated and the killer inhibitory receptor is unable to bind to a sufficient number of MHC I markers.  the innate immune response including the steps in an inflammatory response and the characteristics and roles More cellular components of macrophages, neutrophils, dendritic cells, eosinophils, natural killer cells, mast cells, complement proteins and interferons Mast cells - when they detect injury, they release of histamine (via exocytosis) to assist in the inflammatory response. They release histamine in response to allergens causing the symptoms of allergies. Regions of the body histamine can act on include: Skin or nose tissue muscles in blood vessels.  the innate immune response including the steps in an inflammatory response and the More cellular components characteristics and roles of macrophages, neutrophils, dendritic cells, eosinophils, natural killer cells, mast cells, complement proteins and interferons Eosinophils- large granulated cells containing various chemical mediators such as DNases, RNases and proteases which help destroy pathogens. They target pathogens too large for phagocytosis (ie. parasites).  the innate immune response including the steps in an inflammatory response and the Non-cellular components characteristics and roles of macrophages, neutrophils, dendritic cells, eosinophils, natural killer cells, mast cells, complement proteins and interferons Include complement proteins, and interferons (a type of cytokine). Interferons - a cytokine released by virally infected cells that increases the viral resistance of neighbouring uninfected cells. This prevents the virus spreading between cells. Complement proteins - Destroy bacteria by punching holes in the plasma membrane, causing them to lyse/burst. They also stick to the outside of the surface of pathogens, attracting phagocytes Processes of the innate response - the innate immune response including the steps in an inflammatory response and the inflammation characteristics and roles of macrophages, neutrophils, dendritic cells, eosinophils, natural killer cells, mast cells, complement proteins and interferons Inflammation increases blood flow to an injured area, bringing a greater number of immune cells and non-cellular components to fight pathogens and help clear debris. It results in heat, pain, swelling and redness. Bacteria or other pathogens breach the barriers that provide a first line of defence, such as through an open cut or wound in the skin. Injured cells release cytokines that attract neutrophils and macrophages to the area. Mast cells release histamine → histamine increases permeability of the blood vessels (allows neutrophils to move through to tissue) and causes vasodilation (more blood and therefore white blood cells to area). Processes of the innate response - inflammation Complement proteins stick to the outside of of the surface of pathogens, attracting phagocytes to destroy the pathogen. Neutrophils and macrophages activated by cytokines, do phagocytosis of pathogens at the site of infection. They digest the pathogen using enzymes such as lysozymes. The inflammatory response continues until the pathogen is eliminated and the wound has healed  the innate immune response including the steps in an inflammatory response and the Summary characteristics and roles of macrophages, neutrophils, dendritic cells, eosinophils, natural killer cells, mast cells, complement proteins and interferons *fever is not examinable Key knowledge the role of the lymphatic system in the immune response as a transport network and the role of lymph nodes as sites for antigen recognition by T and B lymphocytes the characteristics and roles of the components of the adaptive immune response against both extracellular and intracellular threats, including the Acquiring immunity actions of B lymphocytes and their antibodies, helper T and cytotoxic T cells.  the characteristics and roles of the components of the adaptive immune response against both Third line of defence extracellular and intracellular threats, including the actions of B lymphocytes and their antibodies, helper T, and cytotoxic T cells The innate immune response may or may not be successful in eliminating the invader. Vertebrates also have adaptive / specific immunity. There are two distinguishing features of the adaptive immune response: Specificity—the ability to recognise and respond exclusively to specific antigens. Immunological memory—the ability of cells of the adaptive immune system to ‘remember’ antigens after primary exposure, and to mount a larger and more rapid response when exposed to the same antigen.  the characteristics and roles of the components of the adaptive immune response against both Lymphocytes extracellular and intracellular threats, including the actions of B lymphocytes and their antibodies, helper T, and cytotoxic T cells The cells that are crucial to the adaptive immune response are lymphocytes (white blood cells). Each lymphocyte has a different and specific receptor for a particular antigen, and is able to proliferate, creating clones of the initial lymphocyte with the specific receptor for the antigen - clonal selection. Lymphocytes are classified as either B lymphocytes or T lymphocytes according to their interaction with the antigen and their response to it. Lymphocytes travel through the lymphatic system and become activated when they encounter antigens specific to their receptors.  the characteristics and roles of the components of the adaptive immune response against both Types of adaptive immunity extracellular and intracellular threats, including the actions of B lymphocytes and their antibodies, helper T, and cytotoxic T cells There are two mechanisms of adaptive immunity: humoral immunity: which involves B cells and their antibodies secreted into the extracellular fluid. B cells mature in the bone marrow. cell-mediated immunity: which involves the action of T cells. T cells mature in the thymus.  initiation of an immune response, including Antigen presentation antigen presentation, the distinction between self-antigens and non-self antigens, cellular and non-cellular pathogens and allergens Antigen presentation selects a type of T lymphocyte called a T helper cell. Antigen-presenting cells (APCs) (Dendritic Cells, Macrophages and B cells) phagocytose pathogens and present the foreign antigen on their MHC II protein, then travel via the lymphatic system to lymph nodes to present foreign antigens to T helper cells which have specific, complementary receptors for a single antigen.  the characteristics and roles of the components of the adaptive immune response against both Humoral Immunity extracellular and intracellular threats, including the actions of B lymphocytes and their antibodies, helper T, and cytotoxic T cells Humoral immunity involves the selection and proliferation of B lymphocytes. B cells are covered in receptors, also known as antibodies. They travel around the body in the bloodstream and reside in high numbers within lymph nodes. The activation of these B lymphocytes occurs through their interaction with pathogenic antigens and T helper cells. Humoral immune response (B cells) When a naïve B cell comes in contact with an antigen it divides via clonal selection into: Plasma cells: produces and secretes free antibodies B Memory cells: Has an antibody receptor specific to antigen so as the ability to recognise it again.  the characteristics and roles of the components of the adaptive immune response against both Humoral Immunity extracellular and intracellular threats, including the actions of B lymphocytes and their antibodies, helper T, and cytotoxic T cells  the characteristics and roles of the components of the adaptive immune response against both Humoral Immunity extracellular and intracellular threats, including the actions of B lymphocytes and their antibodies, helper T, and cytotoxic T cells  the characteristics and roles of the components of the adaptive immune response against both Antibodies extracellular and intracellular threats, including the actions of B lymphocytes and their antibodies, helper T, and cytotoxic T cells Antibodies bind to specific antigens by having a complementary antigen binding site. Antibodies are proteins that have 2 heavy chains (blue) and 2 light chains (yellow). The antigen binding sites (also known as the variable region) is what is different from each specific antibody. Free antibodies secreted by plasma cells enable Agglutination – creates a complex of pathogens and antibodies allowing for phagocytosis Neutralisation – stops pathogens from entering cells (bacteria) or attaching to cells (viruses). Opsonisation- tag pathogen/toxin for phagocytes Antibodies leads to recovery by increasing the rate of phagocytosis and limiting the severity and duration of the infection  the characteristics and roles of the components of the adaptive immune response against both Cell mediated immunity extracellular and intracellular threats, including the actions of B lymphocytes and their antibodies, helper T, and cytotoxic T cells Cell-mediated immunity is regulated by T lymphocytes. When a naive T cell with a T cell receptor that matches the antigen being presented the cell mediated immune response will be initiated and clonal selection will occur. T helper cells: secretes cytokines which tell other immune cells to divide (clonal expansion/selection). They recognize antigens on MHCII markers. Cytotoxic T cells: recognise and kill foreign, infected or abnormal host cells by releasing toxic compounds. This includes virus-infected host cells, cancer cells and foreign cells such as those in transplanted tissue. They recognize antigens on MHCI markers. T memory cells: have receptors to recognise same antigen on subsequent exposures.  the characteristics and roles of the components of the adaptive immune response against both Cell mediated immunity extracellular and intracellular threats, including the actions of B lymphocytes and their antibodies, helper T, and cytotoxic T cells  the characteristics and roles of the components of the adaptive immune response against both Cell mediated immunity extracellular and intracellular threats, including the actions of B lymphocytes and their antibodies, helper T, and cytotoxic T cells Steps of the immune response when an antigen is recognised 1.Antigen presenting cell recognises non-self antigen and engulfs pathogen. Pathogen is destroyed and antigen is presented on APC cell surface (MHC2 marker). 2. APC migrates to lymph node. 3.T-helper cells, detect non-self antigen and produce cytokines to stimulate proliferation of naive B cells. 4.B cells differentiate to produce plasma cells, which produce specific antibodies which neutralizes and agglutinates pathogen. 5.B cells also differentiate into memory cells. Bring about a larger and quicker response to subsequent exposures. *T memory cells also formed.  the characteristics and roles of the components of the adaptive immune response against both The third line of defence extracellular and intracellular threats, including the actions of B lymphocytes and their antibodies, helper T, and cytotoxic T cells  the characteristics and roles of the components of the adaptive immune response against both Summary of the third line of defence extracellular and intracellular threats, including the actions of B lymphocytes and their antibodies, helper T, and cytotoxic T cells  the characteristics and roles of the components of the adaptive immune response against both Immunological memory extracellular and intracellular threats, including the actions of B lymphocytes and their antibodies, helper T, and cytotoxic T cells The response arising from the first encounter of a T or B lymphocyte with a specific antigen is known as the primary immune response. After the initial exposure, B and T lymphocytes form B and T memory lymphocytes. B memory cells contribute to immunological memory by rapidly dividing and forming new antibody-producing plasma cells when they encounter an antigen that matches their receptor. They also constantly secrete low amounts of their antibody. In this way, a person who is immune to a pathogen will always have trace amounts of the antibody against that pathogen in their blood. T memory cells proliferate rapidly into T helper cells and cytotoxic T cells upon stimulation by an antigen-presenting cell that is presenting a previously encountered antigen. Immunological memory advantages: More rapid and larger antibody production on subsequent exposures to the specific antigen, this helps prevent formation of the disease/symptoms. Innate and adaptive immune responses summary Innate (non-specific) 1st and 2nd line of defences i.e. barriers, phagocytosis, inflammation. Not specific to antigen. No memory formed. Adaptive (specific) 3rd line of defence Specific to antigen- antigen is detected and causes clonal selection/expansion of specific B and T cells with receptors for antigen. Memory B and T cells formed with receptors for antigen. Upon subsequent exposures, a faster and larger immune response (antibody production) occurs.  the role of the lymphatic system in the immune The lymphatic system response as a transport network and the role of lymph nodes as sites for antigen recognition by T and B lymphocytes Lymphatic system is the transport system for antigen presenting cells including dendritic cells. Antigen presenting cells engulf and destroy pathogen and present antigen on MHCII marker. They travel to the lymph nodes to present the antigen to T helper cells.  the role of the lymphatic system in the immune Primary lymphoid organs response as a transport network and the role of lymph nodes as sites for antigen recognition by T and B lymphocytes The primary lymphoid organs are bone marrow and the thymus. Bone marrow contains stem cells from which B and T lymphocytes originate. B lymphocytes undergo several stages of development in the bone marrow then enter the bloodstream and travel to the spleen and other secondary lymphoid tissues, where they complete their maturation. Immature T lymphocytes travel from the bone marrow to the thymus, where they mature. The thymus is considered a primary lymphoid organ because of its role in the maturation of T lymphocytes.  the role of the lymphatic system in the immune Secondary lymphoid organs and tissues response as a transport network and the role of lymph nodes as sites for antigen recognition by T and B lymphocytes Lymph nodes are composed of lymphoid tissue, and are located at regular intervals along the lymphatic system. Lymph passes through lymph nodes on its way back to the bloodstream. Lymph nodes are the site of antigen recognition by B and T cells. Clonal selection/expansion of B and T cells specific to an antigen occurs here. Lymph is similar to blood plasma — it is the fluid from the circulatory system that flows into the spaces surrounding tissues. Lymph contains immune cells such as lymphocytes and phagocytes. The lymph flows in one direction.  the role of the lymphatic system in the immune Summary of lymphoid tissues response as a transport network and the role of lymph nodes as sites for antigen recognition by T and B lymphocytes Chapter 8- Immunity  the difference between natural and artificial immunity and active and passive strategies for acquiring immunity Key knowledge the emergence of new pathogens and re-emergence of known pathogens in a globally connected world, including the impact of European arrival on Aboriginal and Torres Strait Islander peoples scientific and social strategies employed to identify and control the spread of pathogens, including identification of the pathogen and host, modes of transmission Disease challenges and and measures to control transmission vaccination programs and their role in strategies maintaining herd immunity for a specific disease in a human population the development of immunotherapy strategies, including the use of monoclonal antibodies for the treatment of autoimmune diseases and cancer.  the difference between natural and artificial Acquiring immunity immunity and active and passive strategies for acquiring immunity Types of immunity Active immunity is protection produced by an individual’s own adaptive immune response. This type of immunity takes time to develop, but the memory B and T cells that result can provide immunological memory that can last for many years, even a lifetime. Passive immunity is protection provided to an individual by the transfer of antibodies produced by another organism. This type of immunity is immediate, but will only protect the recipient for a few weeks or months because it does not result in immunological memory, and the transferred antibodies degrade over time and are removed from the body. Immunity can develop naturally through exposure to a pathogen, or be induced artificially through purposeful introduction of antigens or antibodies into the body. Both active and passive immunity can arise naturally or artificially.  the difference between natural and artificial Natural passive immunity immunity and active and passive strategies for acquiring immunity Passive transfer of antibodies from mother to foetus through the placenta prior to birth, and from mother to baby through breastfeeding. Lasts for weeks or months, while the baby’s own immune system is developing.  the difference between natural and artificial Artificial passive immunity immunity and active and passive strategies for acquiring immunity Individual receives antibodies produced by another organism, usually by injection of antibody—serum containing specific antibodies. Antibodies bind to the antigens on the pathogen or toxin, they form an antigen–antibody complex that inhibits the pathogen or toxin before it does much damage. For example, snake antivenom contains antibodies designed to neutralise the venom.  the difference between natural and artificial Natural active immunity immunity and active and passive strategies for acquiring immunity Natural active immunity develops from the adaptive immune response to a natural exposure to infection, the immune system makes antibodies in response to coming in contact with a pathogen and in the process creates memory cells. This means that if exposed to the same antigen again in the future, the immune system will recognise it immediately, and a secondary immune response will occur. Antibody production in secondary immune responses is much faster and larger than primary immune responses, and are therefore more likely to minimise disease. Eg. natural exposure and immunity to Varicella zoster virus, the virus that causes chickenpox.  the difference between natural and artificial Artificial active immunity immunity and active and passive strategies for acquiring immunity Artificial active immunity results from the administration of antigens to induce an adaptive immune response - vaccination (immunisation). Vaccines are made of attenuated (weakened) or inactivated pathogens that trigger an immune response. As they have specific antigen present, they initiate the immune response causing the production of B memory cells. On a subsequent exposure you have faster and greater antibody production Booster vaccines are often needed to stimulate the creation of more memory cells (B and T), thus a stronger secondary immune response providing longer-lasting immunity. Memory cells can also be short lived. Herd immunity Herd immunity is where most of the community is immune and this helps to protect, for example, babies or those few individuals who cannot be vaccinated. Due to the reduced number of infected individuals there are fewer hosts to pass the disease to others Therefore, less chance there is of an infectious agent spreading throughout a population.  the development of immunotherapy strategies, Immunotherapy including the use of monoclonal antibodies for the treatment of autoimmune diseases and cancer. Immunotherapy is a category of medical treatments that change the way the immune system functions. There are two broad categories of immunotherapy: activation immunotherapies, which aim stimulate or amplify an immune response used in cancer treatment. suppression immunotherapies, which aim to prevent or reduce an immune response, such as those in autoimmune diseases. Monoclonal antibodies are used to treat autoimmune diseases and cancer- they may stimulate, suppress or have no effect on the immune response.  the development of immunotherapy strategies, Monoclonal antibodies including the use of monoclonal antibodies for the treatment of autoimmune diseases and cancer. Immunotherapy is a category of medical treatments that change the way the immune system functions. Immunotherapy strategies such as monoclonal antibodies (mAbs) are antibodies produced by a single clone of a B cell that is grown in culture to produce a large volume of the same clone. The mAbs produced by the clones are all identical and specific to the same antigen. As they bind to specific antigens, they can be used to target specific types or parts of cells for a variety of outcomes. Monoclonal antibody production 1. Cancer cell antigens injected into mice. 2. B cells removed from mouse. 3. Specific B cells are cloned into plasma cells that produce antibodies to the cancer antigen. 4. Plasma cells are fused with Myeloma to form Hybridomas. 5. Hybridomas are cloned and produce antibodies. 6. Antibodies are isolated and purified. 7. Antibodies are injected into patient to fight cancerous cells or autoimmune diseases.  the development of immunotherapy strategies, Monoclonal antibodies and cancer including the use of monoclonal antibodies for the treatment of autoimmune diseases and cancer. Cancer cells form due to the inability to regulate apoptosis- as a result these cells continue to replicate uncontrollably. Monoclonal antibodies are artificially made to bond/attach to the antigen of a cancer cell and they would then (one of): flag cancer cells to other immune system cells such as natural killer cells and Tc cells for destruction (stimulates immune response) deliver radiation or chemotherapy treatment (no effect on immune response). Their two variable regions have different-shaped variable regions. They are bispecific - meaning one variable region can attach to a cancer cell, the other to an immune cell or cancer drug. The advantage of using antibody-drug conjugate monoclonal antibodies is that, specifically cancer cells and not health cells, are targeted, resulting in fewer side effects. Monoclonal antibodies and autoimmune diseases Autoimmune diseases are where self cells are recognised as non-self and are attacked by the immune system causing symptoms of the disease. Autoantibodies produced by autoreactive B cells and attack self tissues. For example in MS it is the myelin sheath surrounding the axon of a neuron. Example of how monoclonal antibodies can be used in autoimmune diseases include. Monoclonal antibodies can bind to and neutralise inflammatory cytokines - the excessive inflammatory response in autoimmune diseases can be reduced, preventing tissue damage. Monoclonal antibodies that bind to autoreactive B and T cells can be used to either inhibit these cells or stimulate other immune cells to destroy them. Both suppress immune response the development of immunotherapy strategies, including the use of monoclonal antibodies for the treatment of autoimmune diseases and cancer.  the emergence of new pathogens and re-emergence of known pathogens in a globally Emergence of pathogens connected world, including the impact of European arrival on Aboriginal and Torres Strait Islander peoples Disease outbreaks can be classified into one of three categories based on the geographic spread of the disease: Epidemic - epidemic is the sudden increase in incidence in the number of cases of a disease above what is normally expected in that population in that area. Pandemic - A disease outbreak that spreads globally or a large geographic area Endemic- constant presence and/or usual prevalence of a disease or infectious agent within a in a specific geographic area at a particular time.  the emergence of new pathogens and re-emergence of known pathogens in a globally Emergence of pathogens connected world, including the impact of European arrival on Aboriginal and Torres Strait Islander peoples Diseases can also be considered emerging or reemerging. Emerging disease is an infectious disease that has appeared in a population for the first time or that may have existed previously but are rapidly increasing in incidence or geographic range. Zika virus emerged as a significant health threat in new regions in 2015 when it was linked to birth defects in infants. Re-emerging disease is an infectious disease that was previously under control but that is now increasing in incidence. Measles is considered a re-emerging disease in several regions around the world, primarily due to declining vaccination rates Pathogens introduced by European arrival to Australia The arrival of the first convicts and settlers from England to Australia in 1788 brought about the introduction of disease among the Indigenous population. When colonists arrived in Australia, they brought with them a number of diseases that quickly spread throughout the non-immune Aboriginal and Torres Strait Islander populations, infecting and killing thousands of Indigenous people. These included smallpox, syphilis, tuberculosis, influenza, and measles. Disease in the Indigenous population When colonists arrived in Australia, they brought these diseases with them, unleashing them on the local population and causing widespread disease and death (Figure 3). A number of factors contributed to Australia’s Indigenous population being particularly susceptible to these diseases at this time. Lack of immunity in the Indigenous population- unlike the Europeans who contracted such disease in childhood, for the Indigenous Australian population, no such immunity for these diseases existed, meaning they were more likely to contract and experience severe symptoms from them. Indigenous people had no knowledge about how to avoid or treat the foreign infections. Also, their ability to practice Indigenous medicine was often prevented, meaning Indigenous people were left without any form of medical treatment to help them when infected. Access to food and water was restricted forced into camps at the edges of towns, where the opportunities for infection was heightened due to increased population densities.  scientific and social strategies employed to identify and control the spread of pathogens, Identifying pathogens including identification of the pathogen and host, modes of transmission, and measures to control transmission In order to control transmission of PCR: Detects and disease it is important to identify the amplifies specific DNA pathogen. or RNA sequences from the pathogen. It is a molecular technique that Specific pathogens have specific methods provides information of transmission. They may require specific about the presence of the pathogen's genetic methods of control such as a particular material in a sample. antiviral drug/antibiotic/antifungal. ELISA: Detects proteins, Incorrect identification can lead to typically antigens continued infections and spread. associated with the pathogen or antibodies produced by the host in Identifying the pathogen also allows for response to the isolation of antigens. This would enable pathogen. It is an immunological assay that the production of a vaccine or produce a measures these proteins drug with a complementary shape. If the through a color change majority of the population was vaccinated caused by enzyme reactions. or treated with this drug, this would greatly reduce the transmission of the disease.  scientific and social strategies employed to identify and control the spread of pathogens, Identifying pathogens including identification of the pathogen and host, modes of transmission, and measures to control transmission  scientific and social strategies employed to identify and control the spread of pathogens, Controlling transmission including identification of the pathogen and host, modes of transmission, and measures to control transmission Scientific strategies to control Airborne Transmission transmission Wearing face masks Pathogens spread through Isolating infected individuals tiny particles that remain Handwashing airborne for extended Wearing PPE Medications (antivirals, periods after being antibiotics expelled by an infected person. These particles Social strategies to control can be inhaled by others, transmission causing illness even after Physical distancing education Promoting vaccination the original host has Promoting good ventilation left. Education of cough etiquette/hand washing Examples- Tuberculosis Community education of recognising (TB), COVID-19, Measles symptoms  scientific and social strategies employed to identify and control the spread of pathogens, including identification of the pathogen and host, modes of transmission, and measures to control transmission Scientific strategies to control Droplet Transmission transmission Wearing face masks Pathogen-laden droplets Isolating infected individuals can stay airborne briefly Handwashing before landing on Disinfecting surfaces Wearing PPE surfaces. If a person Medications (antivirals, touches these surfaces and antibiotics then their eyes, mouth, or nose, they can become Social strategies to control infected transmission Physical distancing education Examples- Influenza, Promoting vaccination Promoting good ventilation Common Cold, Pertussis Education of cough etiquette/handwashing Community education of recognising symptoms  scientific and social strategies employed to identify and control the spread of pathogens, including identification of the pathogen and host, modes of transmission, and measures to control transmission Scientific strategies to control Direct physical contact transmission Pathogens spread through physical contact, Isolation of infected including skin-to-skin, individuals (example dependent) bodily fluids, sexual or PPE use oral contact, vertical Topical antimicrobial treatments transmission (mother to baby), or contaminated Social strategies to control materials in medical transmission procedures Education on hand hygiene Examples- Ebola, Scabies, Education of safe sexual Leprosy practices Education of PPE use  scientific and social strategies employed to identify and control the spread of pathogens, including identification of the pathogen and host, modes of transmission, and measures to control transmission Scientific strategies to control Indirect physical transmission contact Disinfecting Indirect sterilisation techniques isolation of infected transmission individuals occurs via fomites (e.g., food, Social strategies to control water, tissues, transmission needles) Hand hygiene education Avoid sharing personal items Examples- MRSA, Regular cleaning awareness Norovirus  scientific and social strategies employed to identify and control the spread of pathogens, including identification of the pathogen and host, modes of transmission, and measures to control transmission Scientific strategies to control Faecal-oral transmission transmission Safe water sanitation Pathogens in Isolation of infected faeces can individuals Detecting contaminated water contaminate food or water and be Social strategies to control ingested. transmission Examples- Proper handwashing Safe food handling (including Hepatitis A, proper cooking and storage Cholera, Rotavirus  scientific and social strategies employed to identify and control the spread of pathogens, including identification of the pathogen and host, modes of transmission, and measures to control transmission Vector borne Scientific strategies to control transmission (type transmission of indirect) Vector control (bed nets, spraying insecticides) Pathogens are spread Medications (antivirals, via vectors such as antibiotics) mosquitoes, ticks, Vaccine development or other insects. Social strategies to control transmission Examples- Malaria, Yellow fever, Dengue Education on mosquito bite Fever, Zika Virus prevention ie. Bed nets, insect repellents. Eliminate breeding sites (water sources) Community education on vaccines where appropriate.