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A virus is made up of nucleic acids. They infect ALL groups of living cells. They do not exhibit the characteristics of a living organism, but they can regulate life functions of their host cells.
Viruses are filterable agents
v Viruses are obligate intracellular “nucleic acid parasites”
v Viruses can’t make energy or proteins without the host cell
v Virus genomes can be DNA or RNA but NOT both
v Viruses can have a capsid or capsid + envelope
v Viral components are assembled and don’t replicate by division
Respiratory-Respiratory or salivary route
Zoonotic-vector (arthropod); animal to human
Sexually transmitted-sexual contact
Enteric- Enteroviruses (polio, coxsackie B); rotaviruses (diarrhea)
Respiratory- influenza, measles, rhinovirus (colds)
Zoonotic- rabies, cowpox, dengue
Sexually transmitted-herpes simplex virus-2, HIV
Capsid (protein coat)
Capsomers (make up capsid)
Naked virus + Envelope (lipid bilayer)
Naked Virus are
Environmentally stable to… (5)
Enveloped Virus are
Environmentally stable to…(4)
Influenza virus types A,B, and C;
sandfly fever virus,
Rhinoviruses, Rubella virus
Mode of infection of viruses from the moment they attach to host cell until they emerge after reassembly (4)
§ Endocytosis (enter by receptor-mediated endocytosis)
§ Viropexis (slip through; direct penetration; picornavirus & papovavirus). Hydrophobic structures of capsid proteins are exposed after virus binds to cells. This allows the virus and its genome to slip through the membrane.
§ Fuse their membrane with cellular membrane
§ Initiated by attachment to receptor or by acidic environment or proteases in an endosome or lysosome
§ DNA genome taken to nucleus while RNA genome stays in cytoplasm
§ Nucleocapsid delivered to the site of replication & the capsid is removed
§ Uncoating occurs during fusion.
§ Early mRNA & nonstructural protein synthesis (genes 4 enzymes & nucleic acid-binding proteins)
§ Genome Replication
§ Late mRNA & structural protein synthesis
§ Post-translational modification of protein
v Assembly of Virus
v Budding (ENVELOPED VIRUS)v Release of Virus
rapid onset of disease, brief period of symptoms, & resolution within days (influenza & rhinovirus)
a type of persistent infection, last through the life of the host, acute infection followed by period of no/little virus production, it is usually re-activated (Varicella-zoster & HSV-1 & 2)
§ Fast but non-specific; fast way to suppress infections & prevent disease
§ Non-specific no memory
§ Resistance not improved by repeated contact
§ Phagocytes & NK cells§ Soluble factors = lysozyme, complement, & acute phase proteins
Antigen-specific immune response
§ Produces recovery & a specific immunological memory
§ Specific memory
§ Resistance improved by repeated contact
§ B& T lymphocytes§ Soluble factors = antibodies
§ Antibody- Mediated Response
§ Involved B cells that recognize pathogens (antigens) in the lymph
§ Antigen binds to B cell
§ Helper T cell co stimulates B cell
§ B cells proliferate & make plasma cells. Plasma cells release antibodies specific to the antigen
§ B cells produce memory cells
§ Involves T cells
§ This response occurs when cells display MHC markers
§ APC displaying foreign antigens bind to T cells
§ Interleukins costimulates T cell activation
§ If MHC-I & endogenous antigens are displayed, T cells proliferate producing cytotoxic T cells. CYT T cells destroy cells that present antigens
§ If MHC-II & exogenous antigens are displayed, T cells proliferate producing helper T cells. HTC release interleukins that stimulate B cells to make antibodies that bind to antigens & stimulate NK and macrophages to destroy the antigen.
Physical Barriers – skin, sweat
Antimicrobial substances – lysozymes (tears, saliva),
lactoferrin (saliva), mucus (respiratory and geneital tract)
Normal Flora – normal flora crowds the intestines making it harder for pathogens to attach, if the pathogen cannot attach, it cannot infect the cell.
Mechanical – peeing, bowel movement, skin, removal of inhaled particles, cilia, mucus, fatty acid, sweat
Neutrophils – anaerobic manner of killing, phagocytize (2 rxns)
Basophils – mast cells found in cells of the tissue, inflammatory reactions use histamine to stimulate blood flow
Eosinophils – WBCs that are all over tissue, work with mast cells to control asthma and allergies, release chemicals and engulf and kill invader
very specific (adaptive immune response), identify and destroys pathogen
• phagocytic cells (neutrophils, monocytes, and macrophages);
• cells that release inflammatory mediators (basophils, mast cells, and eosinophils);
• natural killer cells (NK cells); and
• molecules such as complement proteins, acute phase proteins, and cytokines.
Which cells are involved in the innate immune response
• Humoral immunity – involves the production of antibody molecules in response to an antigen and is mediated by B-lymphocytes
• Cell-mediated immunity – involves the prodcution of cytotoxic T-lymphocytes, activated macrophages, activated NK cells, and cytokines in response to an antigen and is mediated by T-lymphocytes
OpsonizationLysis of foreign cells
Chemoattractants, such as C5a, attract phagocyte to organisms to be ingested.
C3b coats organisms and attaches to C3b receptors on phagocyte.
Organism is engulfed into a phagosome.
Phagosome fuses with lysosome to produce phagolysosome
Digestion and breakdown of organism within phagolysosome.
phagocytosis to make pathogen more susceptible to phagocytes
Injury intoduces microbial products (flagella, DNA, LPS) à mast cells release cytokines à attract neutrophils and activate endothelial cells of blood vessels (vasodilation) (that display ICAM and P and E Selectin on their surface) Neutrophil form transient adhesion that slow their movement in blood Release of platelet activating factors from endothelial cells will activate integrin on neutophils that will increase binding to ICAM on endothelial cell
• Neutrophil stops and change shape and squeeze b/w adjacent endothelial blood vessel cells à reach infected area
• Macrophages help the healing process by enguling bacteria and dead cellsICAM – integrin cell adhesion molecule
Describe the process of initiation and development of inflammation. Include in your description the role of cytokines in dilations of blood vessels, chemotaxix, leakage of fluid into tissues ,cells involved …in the right chronological order.
Inflammation – Innate
Antibodies – Adaptive
• Antigens – Adaptive
• Memory Response – Adaptive
• Neutrophils – Both
• Basophils – Innate
• Mast cells – Innate
• Eosinophils – Innate
• Macrophages – Both
• B cells – Adaptive
• T cells – Adaptive Complement – Innate Interferon fever – Innate Natural killer (NK) cells – both
immunoglobulin will recognize an antigen in a specific manner and will bind + destroy it
foreign molecules that belongs to pathogen and is detected by immune cells
B and T cells have memory cells in case of reinfection for a faster and more efficient immune response
· Lead to production of antibodies (Ab) aka Ig (immunoglobulins)
· 1 antibody = 1 antigen
· B lymphocytes aka B cells produce antibodies
Cell Mediated Immunity
· Activate Tc Cells which destroy infected self cells
Fab region – antigen binding, variable region
Write the function of the following specific regions of an antibody
(dimer in secretions) – prevents attachment of pathogen on tissue or surface of cell, most predominant, found in mucus and breast milk
(pentamere) – has 10 variable regions that detects more than others and complement activation
(monomer) – surrounds pathogen, most numerous during infection, cross placenta and go to the fetus (ONLY one that can do this), does opsonization, ADCC (antibody dependent cellular cytotoxicity) and compliment activation
(monomer) – sits on basophils and mast cells (inflammation/allergic reactions), blood circulation
(monomer) – occurs on B cells, involved with development and maturation of antibody response
once stimulated, differentiate into (plasma cells) and secrete antibodies (found in bone marrow à spleen)
goes in blood and release antibody that will destroy pathogens in the tissue
remembers antigen and which antibody to use
helps B cells make antibodies
present antigen to Th cell. Th cell must have a receptor that will recognize MHC-II.
Plasma cell –
Memory B cell
T cytotoxic cell –
T helper cell –)
Memory T cell –Macrophage
cells involved in cell mediated immunity
helps macrophages to kill intracellular infection (found in bone marrow à thymus)
– recognizes antigen and releases chemicals
Initial defense as part of the innate immune system
Antigen presentation to Th cells
polymorphonuclear neutrophils a. phagocytosis
eosinophils b. inflammation and immunity against parasites
basophils c. release histamine
lymphocytes d. antibodiese. carry oxygen
White blood cells called leukocytes are important in immunity. T or F
Mast cells are only found in the blood.
Lymphocytes are the cells primarily responsible for the specific immune responses.
Lymphocytes that mature in the bone marrow are called T cells.
Gram-negative bacteria are less susceptible to complement lysis than Gram-positive
Interferon directly interacts with and destroys viruses.
Neutrophils are the second phagocytic cell to respond to an infection.
Fever often enhances bacterial survival during an infection.
Defensins are short antimicrobial peptides found within mucus membranes and
55. IgG a. found on the surface of B cells
56. IgM b. agglutinates antigens
57. IgA c. protects mucous membranes
58. IgE d. involved in hypersensitivity59. IgD e. first antibody produced during primary response
T cells are responsible for directly manufacturing antibodies. T or F
T cell receptors are identical to antibodies.
Antibody and antigen are held to one another by covalent bonds.
Immune complex, T cells, antibodies/complement, IgE
a. Type I
b. Type II
c. Type III
d. Type IVe. Type V
Natural active = get the disease
Natural passive = mother to baby (IgG/IgA)
Artificial active = get antigen à antibodies
Natural active =
Natural passive =
Artificial active =Artificial passive =
inactivated toxins which may produce better immunity than natural infection due to relative amts of antigen exposure
Alive but weakened pathogen (avirulent)
used against Cholera, Plague, Influenza, Rabies, Salk vaccine and IPV for polia
made of products of portions of an agent
genetically engineered used against Hep B
used against Pertussis
Active immunity develops only after a natural infection and not after vaccination. T or F
Attenuated agents often give rise to a long-lasting immunity.
Recombinant vaccines and inactivated vaccines typically require several shots to be effective. T or F
o To identify unknown antigens such as microorganisms.
o Uses a preparation of antibodies, called antiserum, to identify the antigen
o To detect antibodies being made against an antigen in a patient’s serumo Antibodies in a patient’s serum being made against an antigen associated w/ a disease using a known antigen
Antiglobulin – anti human gamma globulins which are produced against human IgG· By immunizing a mouse with IgG antibody → production of antiglobulin Anti IgG
Unknown antigen being identified is fixed to the slide. Antibodies of known specificity, to which a fluorescent dye has been attached, are added.
Know antigen is fixed to the slide. Patient’s serum (contains antibodies of unknown specificity) is added.
Fluorescence-labeled anti-human IgG antibodies are added.
•Looks for specific antigen
–Specimen placed in wells of microtiter plate
»Wells treated with antibody for antigen
•Looks for antibody in patient serum
–Wells of plate treated with known antigen
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