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10. Characterize the mechanisms of action and the effect(s) on the host of the following general types of exotoxins: A-B toxins, membrane-disrupting toxins (leukocidins, hemolysins, and streptolysins), and superantigens.

1) A-B toxins: B attached to host cell, -> membrane of host invaginate and exotoxin enters by receptor enclosed by endocytosis-> A-B exotoxin receptor are enclosed by a pinched off portion of membrane-> B is released for reuse. 2) A-B toxins contain an enzyme component (A part) and a binding component (B part) (Ex: piptheria toxin) 3) Membrane-disruptign toxins: lyse lost cells by disrupting plasma membranes (from protein channels) -Leukocidins: kill phagocytic leukcytes -Hemolysins: kil erythrocytes by forming protein channels -streptolysins: hemolysis produced by streptococci 4) superantigens: cause an intense immune response due to release of cytokines from host (T cells) cells. -Cause symptoms of fever, nausea, vomiting, diarrhea, shock, and death.

16. Discuss the virulence factors associated with pathogenic fungi, protozoa, helminths, and algae.

1) Pathogen fungi -Toxic metabolic products. -provoke an allergic response. -trichnothecene toxins inhibit protein synthesis. -proteases modify host cell membranes -capsules prevent phagocytosis -Ergot: are alkaloid toxins that cause hallucinations. -Aflatoxin: carcinogenic toxin produced by aspergillum -Mycotoxins: are produced by mushrooms and are neurotoxic. 2) Protozoa -Presence of protozoa and their water products cause symptoms. -Avoid host defenses by: 1-digesting cells and tissue fluids. 2-growing in phagocytes. 3-antogenic variation. 3) Helminths -use host tissue for growth. -produce large masses; cause cellular damage. -produce waste products. -produce waste product that cause symptoms 4) Algae -some produce a neurotoxin called saxitioxin. -paralytic shellfish poisoning.

11. Describe the action and microbial source of the following examples of exotoxins: diphtheria toxin, erythrogenic toxins, botulin toxin, tetanus toxin, vibrio enterotoxin, and staphylococcal enterotoxin.

1-Diptheria toxin: Corynebacterium diptherial A-B -cytotoxin inhibits protein synthesis, especially in nerve, heart, and kidney cells. 2-Erythrogenic toxin: toxic shock syndrome superantigens 3-Bolulia toxin: clostridum botulinum/Botulism A-B -Neurotoxin prevents transmission of nerve impulses, flaccid paralysis results. 4-Tetanus toxin: Clostridium tetani/ Tetanus A-B -Neurotoxin blocks nerve impulses to muscle relaxation pathway; results in uncontrollable muscle contractions. 5-Vibrio enterotoxin: Vibrio cholerae/cholera A-B -Enterotoxin causes secretion of large amounts of fluids and electrolytes that result in diarrhea. 6-Staphylococcal enterotoxins: Staphylococcus aureus (food poisoning) Superantigen -Enterotoxin causes recreation of fluids and electrolytes that results in diarrhea.

8. Describe the manner in which microbial pathogens may induce direct damage in host cells, and contrast this effect with that of toxin production.

1-Direct damage: as pathogens metabolize and multiply in cells, the cells rupture (Ex: E. coli, shigella, salomonella, induce host epithelial cells to engulf them) 2-toxins: poisonous substances produced by certain microorganisms that produce fever, cardiovascular disturbances, diarrhea, shock, (also inhibit protein synthesis, destroy blood cells, vessels, and disrupt nervous system)

9. Distinguish between the nature and the effects of endotoxins and exotoxins.

1-Exotoxins: produced inside bacteria and are secreted in to surrounding medium; can act over and over again; easily diffuse into the blood; destroy particular parts of host cells cell by inhibiting function. 2-Endotoxin: part of the outer cell wall of gram-neg. bacteria; lipopolysaccharides; released when bacteria die; stimulate cytokine production.

13. Describe the roles of plasmids and prophage in specific examples of virulence factors associated with microbial pathogens.

1-Plasmids: resistance to antibiotics, carry info. that determines pathogenicity. -May carry genes for toxins, production of antibiotics and enzymes. 2-Prophage: lysogeny- bacteriophages incorporate their DNA into the bacterial chromosome; some bacterial pathogenesis caused by prophages. -lysogenic conversion: changes characteristics of a microbe due to incorporation of a prophage.

3. Describe mechanisms by which pathogens adhere to host tissues, including citing examples.

1-adherence: means of attaching themselves to host tissue at their portal of entry. 2-adhesins/ligands: bind specifically to complementary surface receptors on the cells of certain host tissues. -glycocalyx: strepococcus mutans these are all M proteins: streptococcus pyogenes -pili -fimbriae: Escherichia coli -flagella

1. Identify the principal portals of entry of pathogens, and distinguish between those, with examples of pathogens utilizing each.

1-mucous membrane 2-respiratory tract (flu, measles, small pox) 3-gastrointestinal tract(contaminated water, Hep A, typhoid fever) 4-genitourinary tract (STD, herpes, syphilis) 5-conjuntiva (pink eye) 6-skin (broken skin, hair follicles) 7-parental route-direct deposition beneath the skin or membrane (needles, bites, yellow fever, malaria, HIV, Hep B)

15. Characterize the types of cytopathic effects (CPEs) produced by animal viruses.

1-stopping cell synthesis. 2-causing cell lysosomes to release enzymes. 3-creating inclusion bodies in the cell cytoplasm. 4-fusing cells to create a syncytium. 5-chaning host all function or inducing chromosomal changes. 6-Inducing antigenic changes in the cell surface. 7-loss of contract inhibition in the cell, leading to cancer. 8-producing infections to protect uninfected cells.

14. Characterize the general mechanisms utilized by viruses in evading host defenses.

1-viruses can penetrate and grow inside host cells where components of the immune system can't reach them. 2-viruses gain access to cells because they have attachment sites for receptors on their target cells. When an attachment site is brought together w/an appropriate receptor the virus can bind to and penetrate the cell. 3-Some viruses gain access to host cells because their attachment site mimic substances useful to those cells. 4-AIDS viruse hides its attachment sites from the immune response and by attaching components of the immune system directly.

6. Define antigenic variation in the context of its contribution to microbial pathogenicity.

Antigenic variation: pathogens alter their surface antigens -antibodies are rendered ineffective

4. Describe the relationships between capsules and cell walls and microbial pathogenicity.

Capsules : prevent phagocytosis -streptococcus pneumoniae (pneumonia) -haemophilus influenzae (pneumonia and meningitis) -bacillus anthracis (anthrax) Cell wall components -M protein: resist phagocytosis (streptococcus pyogenes) -Opa protein: inhibits T helper cells (Neisseria gonrrhoeae) -mycolic acid: waxy lipid, resists digestion (myobacterium tuberculosis)

12. Characterize the general biochemical characteristics, sources, and effects of endotoxins.

Endotoxins 1-bacterial source: Gram-neg. bacteria 2-Relation to microorganisms: present in LPS of after membrane of cell wall and released w/destruction of cell or during cell division. 3-Chemistry: lipid portion (lipid A) of LPS of outer membrane (lipopysaccharide) 4-Pharmacology (body effect): general, such as fever, weakness, aches, and shock, all produce same effects. 5-Heat stability: stable can withstand autoclaving 121C for 1 hour. 6-Toxicity (ability to cause disease): low. 7-Fever producing: yes. 8-Immunology (relation to antibodies): not easily neutralized by antitoxin, therefore effective toxoids can't be made to immunize against toxin. 9-Lethal dose: considerably large 10-Rep. diseases: Typhoid fever, urinary, tract infec. and meningococcal meningitis.

5. Describe the biochemical action of the exoenzymes coagulase, kinase, hyaluronidase, collagenase, and IgA protease, and the relationship between these enzymes and microbial pathogenicity.

Enzymes 1-capsules: coagulates fibrinogen 2-kinases: digest fibrin clots 3-hyaluronidase: hydrolyzes hyaluronic acid (digests polysaccharides that hold cells together) 4-collagenase: hydrolyzes collagen (breaks down) 5-IgA protease: destroy IgA antibodies Direct Damage -disrupt host cell function -produce waste products -toxins

2. Differentiate between ID50 and LD50.

ID50: infectious dose for 50% of sample population measures virulence of a microbe. LD50: lethal dose for 50% of sample population measures potency of a toxin.

7. Describe the function of siderophores in microbial pathogenicity.

Siderophores: when a pathogen needs iron, they are released into the medium, where they take the iron away from iron transport proteins. -iron is required for most pathogenic bacteria -siderophores are proteins secreted by pathogens that bind iron more tightly than host cells. Direct Damage: -disrupts host cells function -uses host cell nutrients -produces waste products -multiplies in host cells and cause ruptures