MICROBIO320 EXAM 2-Fall 2009 Name _____________________________ True/False (1 point each) __T__ 1. All active VSG expression site are located near telomeres. __T__ 2. Giardia species use a specialized structure called the adhesive disk to colonize the host __F__ 3. Nuclear run on assays are used to determine steady state levels of mRNAs. __T__ 4. Neisseria gonorhoeae is a bacterium that undergoes antigenic variation. __F__ 5. Giardia Dicer protein is localized to the nucleus. __T__ 6. Some organisms evade the harsh environment of the phagolysosome by escaping to the cytoplasm. __T__ 7. Injection of a specific antigen or peptide is a method to desensitize an individual with allergies. __T__ 8. RNA interference is mediated by dsDNA molecules. __T__ 9. When RNA interference is inhibited in Giardia it results in the accumulation of multiple antigenic variants on the cell surface. __T__10. Although only a single VSP protein is expressed at a time, Giardia transcribes most all of the variant surface antigen genes. __T__11. The host site of a late stage infection with Trypanosoma brucei rhodesiense is the central nervous system. __F__12. Cysts are semi-protective stages that are susceptible to common reagents such as chlorine. __T__14. Giardia lack classic eukaryotic features such as mitochondria and peroxisomes. __F__15. Trypanosoma brucei is transmitted to the human host through a protective cyst stage. __F__16. Trypanosomes contain only a few VSG genes that all undergo recombination to mosaic molecules. __T__17. Th1 cells promote destruction of intracellular pathogens while Th2 cells promote neutralizing antibodies. __T__18. Antigenic variation in trypanosomes is mediated by recombination mechanisms. __T__19. Excystation in Giardia is triggered by acidic (low pH) environments. /19 1 MICROBIO320 EXAM 2-Fall 2009 Name _____________________________ Fill-in For each of the parasites listed, fill in the name (ie. Morphological form) of the replicating stage in the Host and the infective stage. (4 pts) Replicating stage in host Infective stage 21. Bloodstream form or 22. Metacyclic Trypanosoma brucei rhodesiense trypomastigote trypomastigote Giardia lamblia 23. Trophozoite 24. Cyst stage List the three (3) biological (physiological) effect resulting from Mast cell activation. For each, also fill in what the complement components are recognizing. (6 pts) Specific factor mediating effect Biological Effect 25. Vascular leak OR 24. Biogenic amines OR histamine Bronchoconstriction OR Instestinal hypermotility 26. Cytokines 27. Inflammation 28. Enzymes 29. Tissue damage Vascular leak OR Bronchoconstriction OR Lipid mediators Instestinal hypermotility OR Inflammation Properties Trypanosoma brucei gambiense Trypanosoma brucei rhodesiense Parasitemia 30. LOW 31. HIGH (high or low?) Disease progression 32. SLOWER/ CHRONIC INFECTION 33. FAST/ ACUTE INFECTION Please fill in the following table related to Giardia antigenic variation: Properties Answer YES or NO VSP is the variant-specific surface protein involved 34. YES Antigenic variation is observed only in the host 35. NO Antigenic variants differ in size 36. YES The surface antigen is a glycoprotein 37. NO /18 2 MICROBIO320 EXAM 2-Fall 2009 Name _____________________________ Define the following terms: Please keep to one or two sentences (each 1 pt) 38. Molecular Mimicry - A mechanism that may explain some forms of autoimmune disease, where the immune system attacks self-antigens that are structurally similar to pathogen antigens. Some pathogen use molecular mimicry to avoid immune attack. 39. siRNA - Short double-stranded fragments of 20–25 base pairs generated by Dicer or introduced directly into experimental system. 40. Dicer - Multidomain enzyme that initiates RNA interference by cleaving dsRNA into smaller dsRNA molecules through the RNAse domains. 41. Type IV hypersensitivity – also known as delayed type hypersensitivity takes days to develop and IS NOT antibody mediated but is a cell-medaited immune response. Briefly describe two reasons why an infection with Trypanosoma brucei is so devastating. 42. A. Deadly disease if untreated; B. No vaccine available; C. few drugs available for treatment; D. Toxic drugs still in use; E. developing drug resistance in parasite population; F. Parasite has ability to continuously evade the immune system through 43. antigenic variation with a huge repertoire of available antigens; G. considered one of the great neglected parasitic diseases; H. is a re-emerging uncontrolled disease 44-45. Briefly describe why phosphoinositides are important for phagolysosome maturation. (2 pt) Name two proteins that are required for the RNA interference mechanism and briefly indicate their respective roles in this process. (4 pts) 46-47. Dicer – cleavage of dsRNA molecules into siRNAs RdRP – RNA dependent RNA polymerase – catalyzes the duplication of RNA from an RNA template – for RNA interference, this protein participates in an amplification step to generate more dsRNA. 48-49. Argonaute - proteins that bind siRNA fragments and have endonuclease activity directed against complimentary mRNA strands Other answers were also accepted. /12 3 MICROBIO320 EXAM 2-Fall 2009 Name _____________________________ Matching: Match the statement to the best word. Use the master list below. (1 point each) Please note that there may be more than one correct answer that matches to the definition. __I__ 50. This disease has a characteristic cyclical repeating pattern of fever. __H__ 51. An autoimmune disease characterized by inflammation of the joints. S,X, Y 52. Marker found on a mature phagolysosome. __T__ 53. Molecule that generates pores in the phagosome membrane. __E__ 54. This inflammatory disease effects roughly 90% women with the production of IgGs that recognize a wide range of self antigens. R,U,W,Y 55. Marker found on early phagosomes. _ V__ 56. Molecule that hydrolyzes PI(3)P to prevent phagosomal maturation. __G__ 57. An autoimmune disease resulting from autoantibodies that bind to the acetylcholine receptor. __Q__ 58. Recruits Rab1 to promote fusion with endoplasmic reticulum vesicles. __F__ 59. An inflammatory disease of the central nervous system. Master List A. AIDS Q. DrrA B. DiGeorge Syndrome R. EEA1 C. Giardiasis S. LAMP2 D. Insulin Dependent Diabetes Mellitus T. LLO E. Lupus Erythematosus U. PI(3)P F. Multiple Sclerosis V. PIM G. Myasthenia gravis W. Rab5 H. Rheumatoid Arthritis X Rab7 I. Trypanosomaisis Y. V-ATPase Please list the four (4) stages of phagolysosome maturation. (1 pt each) Phagolysosome Maturation Stages 60. Early events OR Early endosome fusion 61. Intermediate events OR Multivesicular body fusion 62. Late events OR Late endosome fusion 63. Mature phagolysome OR Lysosome fusion /14 4 MICROBIO320 EXAM 2-Fall 2009 Name _____________________________ Multiple choice – Please circle the correct answer. (1 point each) 64. The usual sequence of events in an allergic reaction is as follows: A. The allergen combines with circulating IgE, and then the IgE:allergen complex binds to mast cells. B. The allergen binds to IgE fixed to mast cells. C. The allergen is processed by antigen-presenting cells and then binds to histamine receptors. D. The allergen is processed by antigen-presenting cells and then binds to mast cells. E. The allergen combines with IgG. 65. RNA interference is: A. a post-translational gene silencing mechanism B. results in a gene deletion on the chromsome C. mediated by a protein complex called RISC D. All of the above E. None of the above 66. A highly toxic drug used to treat African Sleeping sickness: A. Pentamidine B. Penicillin C. Tetracycline D. Melarsoprol E. All of the above 67. Most autoimmune diseases are caused by a: A. single genetic defect. B. known infectious organism. C. constellation of genetic and environmental events. D. hormonal dysregulation. E. B-cell defect. 68. An expression site body is: A. characterized by the complete complement of DNA replication components B. exactly colocalized with the nucleolus C. associated with RNA polymerase III activity D. the transcriptional site for an active VSG gene E. All of the above 69. Positive skin tests for delayed-type hypersensitivity to intradermally injected antigens indicate that: A. a humoral immune response has occurred. B. a cell-mediated immune response has occurred. C. both T cell and B cell systems are functional. D. the individual has previously made IgE responses to the antigen. E. immune complexes have been formed at the injection site. 70. Members of the Order Diplomonadida are characterized by the following: A. the presence of flagella B. bilateral symmetry C. they contain 2 identical nuclei D. All of the above E. None of the above 5 MICROBIO320 EXAM 2-Fall 2009 Name _____________________________ 71. The following structure in Giardia is rich in microtubules: A. Flagella B. Ventral disk (Adhesive disk) C. Basal bodies D. All of the above E. None of the above 72. Which statement about Trypanosomatid characteristics is FALSE? A. Cause diseases with high mortality B. Vector transmitted pathogens C. Disease caused by these organisms are easily treated with antibiotics. D. Early diverging eukaryote E. All of the above 73. The following is/are possible mechanism(s) for the recognition of self-components by the immune system in autoimmune diseases: A. alteration of a self-antigen so it is recognized as foreign B. leakage of sequestered self-antigen C. loss of suppressor cells D. infection with a microorganism that carries a cross-reactive antigen E. Any of the above. 74.