Download Picornavirus Structure, Classification, and Infection: A Comprehensive Guide and more Quizzes Virology in PDF only on Docsity!
GMS 6121 EXAM 1 MODULE 1.1 &
MODULE 6.1 TO 6.4 (EU) QUESTIONS
AND CORRECT ANSWERS 100%
VERIFIED
"Capsids are usually: - CORRECT ANSWER=> simple = 1-3 proteins symmetrical" "What are the two configurations of capsids? - CORRECT ANSWER=> icosahedral helical for both enveloped and naked" "What is the configuration of a helical naked capsid virus? - CORRECT ANSWER=> nucleic acid spiraled in the center proteins wrap around outside ex. tobacco mosaic virus" "What are two helical enveloped viruses? - CORRECT ANSWER=> Influenza A = orthomyxovirus Measles virus = paramyxovirus" "What are icosahedrons? - CORRECT ANSWER=> regular polygons with 20 triangular faces regular = each face is identical icosahedral capsids exhibit the same SHAPE but are not "regular" polygons" "What symmetry do icosahedral shapes exhibit and what does it mean? - CORRECT ANSWER=> 5:3: symmetry 6 5-fold axes = point of the star 10 3-fold axes = middle of each triangular face 15 2-fold axes = side that joins each face together no matter how you rotate each axis = identical" "How many proteins form the simplest icosahedral capsids? - CORRECT ANSWER=> 60 identical proteins 3 proteins = 1 complex
1 complex self-assembles with other complexes to form 20 faces of icosahedral shape 3x20 = 60" "What is the size range for icosahedral capsids? - CORRECT ANSWER=> 20nm - 500nm parvovirus = 20nm" "What does the use of multiple proteins in a capsid structure allow for? - CORRECT ANSWER=> Larger capsids poliovirus = 60 faces, 3 DIFFERENT proteins per face" "what are two examples of icosahedral naked viruses? - CORRECT ANSWER=> Adenovirus Foot and mouth disease virus" "what is an example of icosahedral enveloped virus? - CORRECT ANSWER=> Herpes simplex virus nucleocapsid cryoEM model = yellow mac n cheese ball" "What is unique about bacteriophage capsids? - CORRECT ANSWER=> Exhibit both icosahedral and helical the head of the bacteriophage is icosahedral base = helical" "What is the most widely used classification system for viruses? - CORRECT ANSWER=> Baltimore classification system takes into account: virus genome structure use of reverse transcriptase" "How many groups are in the Baltimore classification system and what are their differences? - CORRECT ANSWER=> Group I = dsDNA Group II = ssDNA Group III = dsDNA Group IV = + strand RNA Group V = - strand RNA Group VI = retroviruses w/ RT Group VII = ss/dsDNA w/ RT" "At a more detailed level, what do virus classification schemes take into account? - CORRECT ANSWER=> Basic molecular architecture of various groups a. type of nucleic acid genome (DNA/RNA) b. Strandedness of nucleic acid (single or double, plus or minus)
nonenveloped positive sense RNA 7.2-8.5kb Lacks 5' cap - translated from internal ribosome entry site (IRES) family includes: poliovirus Hep A virus Foot-and-mouth disease virus (FMDV) Rhinoviruses" "Which of the following is incorrect regarding picornavirus? A)Small B)Enveloped C)Positive sense D)Lacks 5' cap structure - CORRECT ANSWER=> B)Enveloped It is nonenveloped" "T/F: Because the picornavirus lacks a 5' cap structure, it has to be translated from internal ribosome entry site (IRES) - CORRECT ANSWER=> True" "What does IRES stand for? - CORRECT ANSWER=> Internal ribosome entry site" "Name four different types of picornavirus - CORRECT ANSWER=> Poliovirus Hepatitis A Foot and mouth disease Rhinoviruses" "Describe diversity, genera, pathological spectrum of picornaviruses - CORRECT ANSWER=> Extremely diverse All genera contain viruses that infect vertebrates Wide pathological spectrum" "What new families does the picornaviruses infect? - CORRECT ANSWER=> 1. Plants (Secoviridae)
- Insects (Dicistroviridae, Iflaviridae)
- Algae (Marnaviridae)" "How is the picornavirus's genome organized(memorize)? P1 = _____
P2 & P3 = _____
5' UTR includes _____ 3' UTR is binding site for _____complex Does or does not (circle one) have a PolyA tail - CORRECT ANSWER=> P1 = Capsid P2 & P3 = Non-structural proteins 5' UTR includes IRES 3' UTR is binding site for replicase complex Does have a PolyA tail" "T/F: Structural proteins are first and then non-structural proteins in picornavirus's - CORRECT ANSWER=> True" "T/F: picornavirus's has one large polyprotein - CORRECT ANSWER=> True" "T/F: Picornavirus has a helical capsid comprised of 60 protein subunits - CORRECT ANSWER=> False Picornavirus has a icosahedral capsid comprised of 60 protein subunits" "T/F: Picornavirus have stable pH. - CORRECT ANSWER=> True pH stability profiles reflect site of replication in host ex. Cardioviruses, enteroviruses, hepatoviruses, parechoviruses = enteric = resistant to low pH Rhinoviruses & aphthoviruses = intestinal tract = acid-labile" "While looking at a high-resolution structure of the Picornavirus, we an see that the basic building block of the capsid is _____. - CORRECT ANSWER=> Protomer" "How many protomers does a Picornavirus have? Name them? Where are they located - CORRECT ANSWER=> VP1 (Outside) VP2 (Outside) VP3(Outside) VP4 (Inside) 1-3 form shell, 4 is internal" "What is the Picornavirus symmetry? - CORRECT ANSWER=> 5:3:2" "What is a protomer? - CORRECT ANSWER=> Smallest subset of different subunits that form the oligomer. In structural biology, a protomer is the structural unit of an oligomeric protein. It is the smallest unit composed of at least two different protein chains that form a larger hetero-oligomer by association of two or more copies of this unit" "In a Picornavirus, VP1, VP2, and VP3 have no sequence ______, but the same ______ - CORRECT ANSWER=> In a Picornavirus, VP1, VP2, and VP3 have no sequence homology, but the same topology"
"What does topography mean? - CORRECT ANSWER=> The arrangement of the natural and artificial physical features of an area. In terms of a picornavirus it has a corrugated topography" "Picornavirus has a _____ (star shape) and a _____(deep depression) corrugated topography. - CORRECT ANSWER=> Picornavirus has a 5 fold axis (star shape) and a canyon(deep depression) corrugated topography." "T/F: For poliovirus and rhinovirus, the receptor binding site is in the 5 fold axis - CORRECT ANSWER=> False For poliovirus and rhinovirus, the receptor binding site is in the canyon" "T/F: All picornaviruses have canyons - CORRECT ANSWER=> False Not all have canyons - aphthoviruses & cardioviruses are smoother so receptor sites are thought to reside on surface loops" "What are the two general mechanisms for genome release from capsids? - CORRECT ANSWER=> 1. pH- dependent dissociation: FMDV, rhinovirus = receptor-mediated endocytosis followed by uncoating triggered by acidification in endosomes
- receptor-induced conformational changes in the virus result in formation of pore in cell membrane = poliovirus" "Fill in the blank (General mechanisms for genome release from capsids):
- pH-dependent dissociation: FMDV, rhinovirus = receptor-mediated endocytosis followed by uncoating triggered by ______in endosomes a)infection can be blocked by drugs that block acidification of endosomes b)Ab-coated virus particles ____ bind to Fc receptors and infect cells - CORRECT ANSWER=> 1. pH- dependent dissociation: FMDV, rhinovirus = receptor-mediated endocytosis followed by uncoating triggered by acidification in endosomes a)infection can be blocked by drugs that block acidification of endosomes b)Ab-coated virus particles can bind to Fc receptors and infect cells" "Fill in the blank (General mechanisms for genome release from capsids):
- receptor-induced conformational changes in the virus result in _______of pore in cell membrane = poliovirus a)capsids extremely _____ at even pH of 2, so acidification blocking drugs do not inhibit
b)Ab-coated virus particles ______ infect cells expressing Fc receptors - CORRECT ANSWER=> Fill in the blank (General mechanisms for genome release from capsids):
- receptor-induced conformational changes in the virus result in formation of pore in cell membrane = poliovirus a)capsids extremely stable at even pH of 2, so acidification blocking drugs do not inhibit b)Ab-coated virus particles CANNOT infect cells expressing Fc receptors" "What kind of changes does receptor-induced conformational changes make? Results in ____ N termini & ____ myristate group insertion into the membrane A trigger, possible Ca2+ flux, expands pore, removes ____ plug temporarily, releases viral RNA into the cell Different mechanisms - CORRECT ANSWER=> What kind of changes does receptor-induced conformational changes make? Results in VP1 N termini & VP4 myristate group insertion into the membrane A trigger, possible Ca2+ flux, expands pore, removes VP3 plug temporarily, releases viral RNA into the cell Different mechanisms" "In picornaviruses conformational change, describe the pocket created? - CORRECT ANSWER=> Hydrophobic pocket factor = fatty acid-like ligand" "What initiated picornavirus translation cycle? - CORRECT ANSWER=> translation initiated by IRES" "Describe the replication cycle of a picornavirus How long does it take to complete: What initiates translation: What does it require: Does it require cap to initiate translation: - CORRECT ANSWER=> How long does it take to complete: 5- 10hr to complete What initiates translation: translation initiated by IRES What does it require: requires a reduced set of initiation factors
3-4hpi: permeabilization of the plasma membrane 4-6hpi: virus assembly in the cytoplasm 6-10hpi: cell lysis; release of virus particles" "T/F: Picornavirus RdRp - 3D^pol is highly inefficent - CORRECT ANSWER=> False highly efficient = ~50,000 progeny genomes produced per infected cell" "T/F: Picornavirus RdRp - 3D^pol catalyzes the synthesis of both (-) & (+) strands - CORRECT ANSWER=> True Catalyzes the synthesis of both (-) & (+) strands Viral RNA synthesis is asymmetric 25 to 65-fold more (+) sense made than (-)" "T/F: Picornavirus RdRp RNA synthesis of the (-) and (+) is symmetric - CORRECT ANSWER=> False Viral RNA synthesis is asymmetric 25 to 65-fold more (+) sense made than (-)" "T/F: Picornavirus RdRp is template and primer-dependent - CORRECT ANSWER=> True" "T/F: Picornavirus RdRp is error-prone - CORRECT ANSWER=> True IS error-prone = 1-2nt per replication event, mutation rate is at threshold for genetic maintenance" "T/F: VPg is a primer for RNA replication in picornaviruses - CORRECT ANSWER=> True" "Fill in the blank (VPg is a primer for RNA replication in picornaviruses); VPg is _______ by 3D^pol and this is used to prime both positive and negative-strand synthesis - CORRECT ANSWER=> VPg is uridylylated by 3D^pol and this is used to prime both positive and negative- strand synthesis" "Fill in the blank (VPg is a primer for RNA replication in picornaviruses); Template for uridine addition is cos-replicating element (cre) ______ - CORRECT ANSWER=> Fill in the blank (VPg is a primer for RNA replication in picornaviruses); Template for uridine addition is cos-replicating element (cre) hairpin" "What do the different replication proteins do? (Word bank: 3CD, 2C, cellular factors, 3AB, 3D)
_____ interacts with RNA and membranes ____ inserts into membranes and interacts with ____ and ____ _______ needed for each step - CORRECT ANSWER=> What do the different replication proteins do? (Word bank: 3CD, 2C, cellular factors, 3AB, 3D) 2C interacts with RNA and membranes 3AB inserts into membranes and interacts with 3CD and 3D cellular factors needed for each step" "T/F: Picornavirus RNA is circular - CORRECT ANSWER=> True" "How are particles assembled? - CORRECT ANSWER=> P1 cleaved = VP0 (VP2+4), VP3, VP one copy of each VP 5 protomers assemble" "Fill in the blank: ____ = RNA threaded into 80S to form provirion; would require a pore that has not been seen in crystal structures _____ = 14S pentamers + RNA assemble to form provirion; empty capsids would be storage of 14S pentamers (but they are so stable that dissociation under physiological conditions unlikely) NOT understood how VP0 cleavage occurs since cleavage site is on interior of capsid and thus INACCESSIBLE to proteases = autocatalytic?? - CORRECT ANSWER=> Model 1 = RNA threaded into 80S to form provirion; would require a pore that has not been seen in crystal structures Model 2 = 14S pentamers + RNA assemble to form provirion; empty capsids would be storage of 14S pentamers (but they are so stable that dissociation under physiological conditions unlikely) NOT understood how VP0 cleavage occurs since cleavage site is on interior of capsid and thus INACCESSIBLE to proteases = autocatalytic??" "Where does viral replication primary occur at for an enterovirus? - CORRECT ANSWER=> Oropharynx and intestine"
"Which disease caused the iron lung to be invented? Why? - CORRECT ANSWER=> Poliomyelitis Vasomotor and respiratory centers (muscles) didn't work well anymore [respiratory muscles went into paralysis]" "What is the name of the vaccine that we use now for Poliovirus? - CORRECT ANSWER=> IPV" "What is the name of the vaccine for poliovirus that we no longer use? - CORRECT ANSWER=> OPV" "How do you administer IVP? OPV? - CORRECT ANSWER=> IVP:inject OPV: take orally" "Why did we stop using OPV even though it provided community protection (can be transmitted to unvaccinated children) - CORRECT ANSWER=> Caused infection when it mutated since it was a live virus" "What was launched in 1988 for polio? - CORRECT ANSWER=> World Health Assembly launched Global Polio Eradication Initiative (GPEI) goal = eradicate by 2000 26 years, $9 billion later, close but not complete" "How many countries still polio-endemic - CORRECT ANSWER=> 2 Afghanistan Pakistan India achieved eradication in 2014 = HUGE success" "which of the following is NOT a picornavirus - CORRECT ANSWER=> influenza virus" "the receptor binding domain of all picornaviruses resides in the protruding domains of the virion surface, also referred to as the plateaus - CORRECT ANSWER=> false" "which of the following is a mechanism by which picornaviruses can release their genomes into the cytoplasm of target cells - CORRECT ANSWER=> formation of pores in the plasma membrane (poliovirus) and pH dependent dissociation in endosomes (rhinovirus)" "What factor recruits host translation initiation factors to the 5' end of picornavirus genomes to initiate protein production? - CORRECT ANSWER=> an internal ribosome entry site (IRES)" "Which poliovirus vaccine is in common use in the United States today? - CORRECT ANSWER=> IPV (inactivated Polio vaccine)"
"Which virus was first isolated in CA in 1962 and causes rare infections until recently (smaller outbreaks in 2016 and 2018). This virus primarily causes respiratory disease in children, those with asthma most at risk. Rarely causes polio-like symptoms-acute flaccid myelitis(FAM) - CORRECT ANSWER=> Enterovirus D68" "This disease is part of the picornavirus family but rarely causes polio-like symptoms-acute flaccid myelitis(FAM) - CORRECT ANSWER=> Enterovirus D68" “How many cell types and organ systems do viruses target? - CORRECT ANSWER=> All of them" "Do individual viruses exhibit tropism? - CORRECT ANSWER=> Yes, they favor particular cell types and organs" "What type of parasites are viruses? - CORRECT ANSWER=> Obligate intracellular" "What do viruses lack that they must gain from their host? - CORRECT ANSWER=> 1. enzymes that produce basic chemical building blocks
- enzymes that generate usable energy
- enzymes, tRNAs, and/or ribosomes that direct protein synthesis
- membranes that concentrate and localize key molecules" "What do ALL viruses have? - CORRECT ANSWER=> nucleic acid capsid - protein coat encoded by the virus" "What do SOME viruses have? - CORRECT ANSWER=> envelope - lipid membrane provided by the host" "What is a virion? - CORRECT ANSWER=> a complete, infectious virus particle" "How do viruses compare to bacteria? - CORRECT ANSWER=> MUCH smaller first discovered because of their size, used a filter to screen out bacteria and found pathogenic particles still present = virus" "What is the basic virus structure? - CORRECT ANSWER=> DNA or RNA + Capsid protein = nucleocapsid Nucleocapsid = naked capsid virus Nucleocapsid + lipid membrane, glycoproteins = enveloped virus" "What are the differences between naked capsid and enveloped viruses? - CORRECT ANSWER=> Naked Capsid = resistant to drying, heat, detergents, acid Enveloped virus = sensitive to drying, heat, detergents, acid"
