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MT1_practice - NAB/Em l w 2., 3 4. 5 6. mm . MIDTERMI April...

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Unformatted text preview: NAB/Em l w 2., 3 4. 5 6. mm . MIDTERMI April 25 7. W s m “ 9. ,,,, m rorAL DB134 General Animal Virology 1. (is pie) Discovery and classification of viruses. - r a. Virology as a scientific field started as a branch of pathology nearly one hundred years ago. What are the two important characteristics of viruses discovered by Ivanovsiry and Beijerinck? b. Suppose that you are a pathologist and that you isolated what you believe to be a new virus from a sample of human tissue obtained from a patient in the Infectious Diseases Unit of UC Med Center. What biochemical and biophysical properties would you attempt to determine in order to classify the mystery virus, culled 13450l. c. The schematic diagrams shown at the right, based on electron micrographs obtained with purified virus preparations, illustrate viruses from the two taxonomic families considered so far this quarter. What is the virus family to which each likely belongs? A. l B. g. (12 pts) Purification and assay of viruses, _ 3. Suppose you used equilibrium ultracentriiugation as a step in the purification of 134SOl virus, and that you obtained two bands of particles which appeared to have the same size and shape when viewed by negative staining with the electron rrticroscope, What is a likely explanation for the two bands? b. Suppose that the plaque assay was used to measure the infectivity of a sample of purified 1343M virus. Three monolayer dishes of lieLa cells were each infected with O.l ml of a 10‘3 dilution of virus stock. The number. of plaques observed on the three dishes were 75, 125 and 100. What is the infectious titer of the virus stock? (3. The preparation of 134Sill virus was treated with ether, and then the titer of infectious virus was determined and compared to the virus control that was not treated (2.!) above). The number of plaques observed on three dishes of Eels cells infected with 0.l ml of a ll)6 dilution of ether-treated virus were 90, 100, and 119. is the l34$0i virus likely a member of the virus family shown above by schematic A or B (see Le)? Why? ” I ' 3. (l8 pts, Zea.) Complete the following statements by placing a circle around the single most accurate answer from among the choices that follow. a. Quantitative assays for animal viruses that provide a measurement for infectious virions include i) the plaque assay; 2) hemagglutination essay; 3) immunofluorescence assay; 4) focus fonnation assay; 5) l and 2; 6) 3 anti 4; ’i) 2 and 3; 8) land 4; 9) l,2,3,and 4. 1). Transmission of poliovirns from an infected individual to another individual was commonly characterized by the following: 1) the involvement of an insect intermediate; 2) fecal—oral transmission via contaminated water supplies; 3) respiratory excretions in crowded buses; 4) all of the above. 1:. The genome nucleic acid of poliovirus is: 1) plus ssRNA; 2) minus ssRNA; 3) 3’mpolyadenylated; 4) S’covalently linked to protein; 5) S’wcapped; 6) l,3,4; 7) 2,3,5; 8) 1,4; .9) 2,5. d. The genome nucleic acid of vesicular stomatitus virus is: 1) plus ssRNA; ’2) minus ssRNA; 3) larger than poliovirus genome; 4) smaller than poliovirus genome; 5) 1,4; 6) 2,3; 7) 1,3. c. The following is no; part of the innate inunune response to viral infection: 1) natural killer cell activation; 2) secreted cytoitines interferon and 11:12; 3) cytotoxic T lymphocytes; 4) l, 2; 5) i, 3. f. Cytokines that elicit a Till antiviral inflannnatory response include i) IFNny; 2) ill-=4; 3) lL~12; 4) 1 and 2; 5) l and 3; o).none of the above g. Cells of the immune system that kill vitally infected cells by lysis include i) NK cells; 2) CTLs; 3) B cells; 4) land 2; 5) i and 3; and 6) 2 and 3. h. The following is (lg part of the adaptive immune response to viral infection: 1) C313; 2) iFcht/fl; 3) antibody production; d) activated macrophages. ' I i. Picomavimses include the folioWing animal viruses: 1) foot-and-mouth disease virus; 2) rabies virus; 3) hepatitis A virus; 4) vesicular stomatitis virus; 5) 2 and 3; 6) l and 3; 7) 2 and 4. g. (s poi) Virus attachment to host cells. Studies with poliovirus provided key evidence for the involvement of specific receptors in the initiation of virus infection. Briefly describe one line of experimental evidence in support of the conclusion that specific receptors are involved in the virus attachment to host cells. - ,5. (6 pts) Protein capsldsg The protein capsid cost of a virus fulfills several important functions, List three of the functions fulfilled by copsidsg NAME s. (6 pie, 1 es.) Provide the key word or phrase that most accurately completes the following statements“ a. The term refers to virus particle. 13. The presence of virus in the bloodsn‘eam is known as am . c. A regular polyhedron composed of 20 equilateral triangular faces that is a commonly observed shape of naked virus particles is called clan “m 77777777777777777777777 N 777777 r ________ .7 . d. PFU is an acronym that stands for m e. CPE is an acronym that stands for N m . f, The n as s sy for physical virions that could be used for the assay of influenza vims A Virions with rbc’s. Z, (20 pm Protein synthesis. Poliovirus and vesicular stomatitis virus utilize different processes to produce their respective mature viruseoded protein products found in infected cells, a. ‘mmm is the process by which protein is synthesized from genetic information encoded indie ssRNA loiown as mRNA, The direction of protein synthesis is ’ to ’ With respect to the mRNA template? and mm—terminal to wtemiinal with respect to the protein product! i). Virusnspecific proteins include both structural and non—structural proteins encoded by the virus genome. Briefly describe the difference between a virus smctural protein and a virus nonstructural protein, and. give ‘ a specific example (either PV or VSV protein) of each, c. Briefly describe the mechanism used by poliovirus to produce the mature virusnspecific Proteins found in infected cells. ' ‘ d. Briefly describe what effect poliovirus infection has on the synthesis of cellular proteins, What is the mechanism by which policvii'us mediates the change in cellular protein synthesis? §. (13 yrs) RNA synthesis, Vesicular stomatitis virus (VSV) and poliovinis (PV) both encode a polymerase enzyme that catalyzes the synthesis of viral RNA. 3- __ is the process by which complementary ssRNA of the polarity of inan is synthesized from a template gene. The direction of RNA synthesis is mm,“ to ’ with respect to the template, and m’ to ’ with respect to the product. is. Which virus, PV or VSV or both, possesses a virion~associated polymerase? Provide one line of experimental evidence in support of the conclusion that a virus possesses a virion~assocrated polymerase. c. Examination of the mechanism of RNA synthesis in poliovirus infected cells led to the identification of a major intermediate structure known as the Replicativc Intermediate. Briefly describe the composition of the replicative intermediate. include in your answer the strand polarity distribution expected for nucleic acid molecules gresent in the structures isolated at 4 hours after infection. » (1. List tines functions fulfilled by viral plus polarity single-stranded RNA in polio virus-infected cells. 2, (4 pct) Important contributors. Eagle, Endors, Dulbecco, and Salk all made fundamental contributions to our understanding of animal viruses and cells that ultimately contributed to development of effective vaccines against poliovirus, Circle the number that corresponds to the description on the right that best describes their scientific connioution. (a) Eagle ll Discovery of the ability to grow poliovirus in cell culture. (l, 2, 3, 4) Nobel Prize, 1954 (h) Butlers 2. Discovery of the metabolic requirements (media) for growth of animal (l, 2, 3, 4) cells in culture. . (c) Dulbecco 3, Discovery of first vaccine against poliovirus, which was a chemically (l, 2, 3, 4) inactivated Grilled) virus preparation. (d) Sell; 4. Discovery of quantitative assay of infectious virus in cell culture, anti {1, 2, 3, 4) interactions between viruses and their host cell. Nobel Prize, l9‘75. 4 ...
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This note was uploaded on 06/08/2010 for the course MCDB 134 taught by Professor Samuels during the Spring '10 term at UCSB.

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MT1_practice - NAB/Em l w 2., 3 4. 5 6. mm . MIDTERMI April...

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