Midterm review Flashcards
(144 cards)
1
Q
Define quasi-Equivalence
A
The relationships between capsid proteins structures are similar but not identical
2
Q
Prions
A
Organisms that do not contain nucleic acids
3
Q
Nucleocapsid
A
The discrete substructure within the virion of an enveloped virus
4
Q
Subunit
A
Single folded polypeptide
5
Q
Structural Subunit
A
Basic unit that builds capsid/nucleocapsids and can be comprised of one or more subunits
6
Q
Equivalent Relationships
A
All subunits have the same packaging environment
7
Q
Order
A
always ends in -virales
8
Q
Invertebrate Viruses
A
Viruses based on the Latin name of the insect host and an indication of the effects of infection
9
Q
Primary Cell Cultures
A
Culture that is derived from live tissue, composed of multiple cell types
10
Q
Diploid Cell Strains
A
Culture that is of a single cell type = mainly epithelial, fibroblast
11
Q
Continuous (Immortal) Cell Lines
A
Culture that is homogenous in cell type and is often cancerous
12
Q
Latent Period
A
The time between adsorption and first extra-cellular virion
13
Q
Burst Size
A
The sum of virions produced in a single cell
14
Q
Biosynthesis
A
The synthesis of viral components required for building the next generation of viruses
15
Q
Transcription
A
The production of mRNAs from genome (DNA –> RNA)
16
Q
Reverse Transcription
A
Production of DNA using RNA as a template
17
Q
Translation
A
Production of proteins using cell machinery
18
Q
Genome Replication
A
The production of nascent viral genomes
19
Q
Immediately Early Genes
A
Encode regulatory proteins rendering cells enter S phase, induce expression of other viral genes, inhibit host biosynthesis
20
Q
Early Genes
A
Enzymes and factors required for genome replication
21
Q
Potato virus X
A
A virus that associates with the endoplasmic reticulum as its intra-cellular membrane
22
Q
Grapevine fleck virus
A
A virus that associates with the mitochondria as its intra-cellular membrane
23
Q
Tomato buch stunt virus
A
A virus that associates with the peroxisome membrane as its intra-cellular membrane
24
Q
Poliovirus
A
A virus that associates with the vesicular membrane as its intra-cellular membrane
25
Sindbis virus
A virus that associates with the endosomal membrane as its intra-cellular membrane
26
Turnip Yellow Mosaic virus
A virus that associates with the chloroplast as its intra-cellular membrane
27
Retroviruses
A type of virus that contains 2 (+)RNA strands, reverse transcriptase, and integrase
28
Host Range
the range of hosts that can be infected by a given virus
29
Tissue Tropism
the preference of a given virus for certain types of cell and tissue in its hosts
30
Susceptible Cells
cells that allow attachment and entry of a given virus
31
Permissive Cells
cells that permit the replication of a given virus
32
Tobamovirus
The genus of the Tobacco Mosaic Virus
33
Virgaviridae
The family of the Tobacco Mosaic Virus
34
Cap Protein Mediated Resistance
Excess CP from the transgene blocks virus disassemble, thus leading to resistance against the virus
35
Poliovirus and Picornaviridae
A family of viruses that are icosahedral, (+)ssRNA, and are naked
36
VPg (Viral Protein Genome-linked)
a protein that is covalently attached to the 5′ end of positive strand viral RNA and acts as a primer during RNA synthesis
37
IRES (Internal Ribosome Entrance Structure)
Contains extensive secondary and tertiary structures in 5' UTR that allows for translation complex binding
38
Jeffery Amherst
-Suggested using germ warfare
-Spread smallpox through contaminated blankets
-Infect Indian allies of the French
39
Captain Simeon Ecuyer
-Distributed infected blankets and handkerchiefs to Indians at peace talks
40
Ivanovsky
"-Created a porcaline filter that will retain bacteria. Anything that flows through will not contain bacteria, rather the viruses. Filters based on size:
1. Filtrate the abstracts
2. Use filtrate to inoculate healthy plant
41
Beijerinck
1. Passed abstract through filter
2. Diluted the filtrate
3. Inoculated healthy plants
4. Showed similar disease all around
5. Concluded that it was not bacteria
-Abstract included bacteria producing toxins. Dilution killed the toxins. When plants became infected they therefore concluded that it could not have been the bacteria, rather something else
42
Wendell Stanley
"-Crystallised TMV
-Determined it was protein in nature "
43
Bawden and Pirie
"-Discovered that protein made up ~95% of TMV
-~5% is nucleic acid. Perhaps the genetic material? (RNA)""-Discovered that protein made up ~95% of TMV
-~5% is nucleic acid. Perhaps the genetic material? (RNA)"
44
Enst Ruska
"-First observed the TMV using an EM
-RNA molecule is enclosed within the protein shell
-TMV is indeed a physical entity that has a specific structure with protein, RNA"
45
Fraenkel-Conrat
"-Determined that RNA and not the protein, was the genetic material
-Capsular Protein alone on the plant is not infectious
-Capsular Protein and RNA is infections
-RNA alone is infectious
-Therefore determined that RNA was in fact responsible for the propagation and infect-ability of viruses"
46
Loeffler and Frosch
"-Discovered the first animal virus "the foot"
-Was a filterable, and therefore easily transmissible virus. "
47
Carlos Finlay
"-First individual to propose the yellow fever was transmitted through mosquitos
-Recruited medical doctors, soldiers,"
48
Walter Reed
-Effectively identified the first human virus = Yellow Fever
49
Frederick Twort
"Understood the vaccination concept, but actually wanted to bring this concept to life
-Tried to grow vaccine on agar plate
-When he colonised bacteria, he recognised different morphologies of the cells
-Some were glassy. He thought something may be eating the bacteria?
50
Felix d'Herelle
"Cultured and plated shigella bacteria and recognised similar glossy morphology of cells
-Realises a virus is causing glossy appearance because of cell lysis
-Termed bacteriophage (eater of bacteria) therefore a virus
-Saw great potential for using bacteriophages for therapy for disease
-Dream was to use bacteriophages to cure all bacterial infections in humans"
51
Ruska
-Obtaines the first EM graphs of TMV particles
52
Delbruck and Ellis
"-Created the One Step Growth Curve which was the synchronisation of bacteriophages to start replication at the same time point
-Were then able to study specific steps of viral replication and infection "
53
Luria, Delbruck, Ellis (Phage Group)
-Group made impactful discoveries
54
Martha Chase and Alfred Hershey
"-Discovered DNA as the genetic material
-Used 2 different radioisotopes (35S and 32P)
-35 will mostly label proteins (amino acids)
-32 will label mostly DNA nucleic acids (phosphate groups)
-After incubation, they blended the mix aggresively to break off bacteriophage cell so it gets released into the solution
-Then centrifuged
-35: Majority was found in supernatant
-32: Majority of radioactivity was found in pellet (radioactive cells)
-Was able to determine that DNA was responsible for genetic information"
55
Watson
-Determined that the structure of TMV particle is helical
56
Watson and Crick
-Proposed that spherical viruses are built as cubic structures
57
Baltimore
"-Created the Baltimore classification for viruses
-Isolated the first RNA-Dependant RNA Polymerase from a Polio infected cell"
58
Enders, Weller, Robbins
-Produced animal cel cultures that would be used to study viruses
59
Henrietta Lacks
-Her cancer cells were the source of the HeLa cell line (cervical cancer)
60
Rosalind Franklin
-Described RNA in TMV particle
61
Francis Holmes
"-Created the Necrotic Local Lesion Assay
-Abraded surface of leaves, rubbed diluted virus stalk, watched for infection"
62
Nishiguchi
"-Discovered the temperature sensitive TMV mutant, Ls1
-Aided in the discovery of movement proteins"
63
Deom et. al
"-Discovered complementation by transgenic MP
-Aided in the discovery of movement proteins "
64
Dulbecco
"1. Purified different viruses into individual plaques
2. Can study the different characteristics of each virus and can titrate them
65
Salk
-Created the first inactive polio virus vaccine
66
Sabin
-Created the first live attenuated polio vaccine
67
Max Theiler
-Created the live attenuated vaccine strain 17-D used for Yellow Fever
68
Viroid
Smallest known infectious pathogens that are solely composed of a short strand of circular, single-stranded RNA without protein coat.
69
Satellite
a subviral agent composed of nucleic acid that depends on the co-infection of a host cell with a helper or master virus for its replication.
70
Agglutination
The process that occurs if an antigen is mixed with its corresponding antibody where the clumping of cells such as bacteria or red blood cells in the presence of an antibody or complement.
71
Icosahedral Symmetry
Is a limited (closed) structure and allows packaging of only limited genome sizes
72
Haemagglutination
Is a specific form of agglutination that involves red blood cells (RBCs).
73
Family
always ends in -viridae
74
MOI (Multiplicity of Infection)
The number of infectious viruses/ number of cells
75
Eclipse Period
The time between adsorption and first intra-cellular vision
76
Very Late Genes
Encode for polyhedrin of baculoviruses
77
The first plant virus discovered
Tobacco mosaic virus
78
The first animal virus discovered
Foot-and-mouth disease
79
The first human virus discovered
Yellow fever
80
Nucleic Acids
RNA or DNA as the genetic material
81
Proteins
Structural and non-structural
82
Lipids
For enveloped viruses only; derived from cellular lipid bilayer
83
Carbohydrate
In glycoproteins and glycolipids, involved in attachment to host cells
84
Components of a non-enveloped virus
Capsid
CPs
Nucleic acid
85
Components of an enveloped virus
Nucleocapsid
Glycoprotein spikes
Nucleic acid
86
Rigid rod
Non-flexible, can be broken, common in plant viruses
87
Filamentous
Flexible, common in plant viruses
88
Types of virus morphology
Rigid rod
Filamentous
Spherical
Irregular (brick shaped)
89
Virion
The complete virus particle
90
Capsid (coat)
The protein shell encasing the viral genome
91
Nucleocapsid
Nucleic acid + protein, the discrete substructure within the virion of enveloped viruses
92
Subunit
A single, folded polypeptide
93
Structural subunit
The basic unit for building capsid/nucleocapsid; may be a singular subunit of multiple
94
Envelope
Lipid membrane enclosing the nucleocapsid
95
Helical symmetry
Open structure, unlimited packing capacity for genome, rod-like and filamentous viruses
96
Helix pitch equation
P = μ x p
Pitch of helix = number of structural units per turn of helix x axial rise per subunit
97
Icosahedral symmetry
Closed structure, limited genome size, made up of 20 equilateral triangular faces, 12 pentagonal vertices, 2-, 3-, and 5-fold rotational symmetry
98
Triangulation number (T)
Number of small facets that exist within each of the 20 equilateral triangular faces of an icosahedral capsid
99
Quasi-equivalence
In icosahedrons with T>1, the relationships between capsid protein subunits are similar but not identical
99
Interactions between CP subunits
All non-covalent bonds (hydrophobic interactions, Van der Waals forces)
99
Beta-Barrel Jelly Roll
Conserved among viruses with icosahedral symmetry, allows for subunits to come together to form the virion structure
99
Transmission EM
Specimen fixed and stained, cut into small sections, image created using a beam of electrons captured by a magnetic lens
99
Atomic Force microscopy
Method designed specifically to reveal surface structure at high resolution
99
Scanning EM
Specimen is intact, scattering of electron beam is captured, topography of structure is revealed
99
Cryo EM
Method used to view native structure of a macromolecular complex, images gathered while tilting the specimen, images are combined and averaged to reconstruct the real image
99
X-ray crystallography and diffraction
Only for small viruses
100
Monothetic classification
Based on one characteristic of a virus at a time, problematic because it assumes all members of a group originated from the same ancestor
101
Polythetic classification
Based on the consideration of multiple properties at a time, does not assume common ancestry within a group, more similar to classification of living organisms
102
Quasi-species
RNA viruses and retroviruses
103
Bacterial phage nomenclature
Based on specific coding
104
Plant virus nomenclature
Based on host where the virus was first identified followed by a descriptor of the symptoms
105
Invertebrate virus nomenclatre
Based on latin name of insect host and/or effects of infection
106
Vertebrate virus nomenclature
Based on disease and symptoms
107
Characters for genus/family in viruses (5)
1. Nature and organization of viral genome
2. Morphology of virion and architecture of capsid
3. Strategies for replication and expression of viral genome
4. Number and size of structural and non-structural proteins
5. Enzymes needed from host cell and enzymes encoded for by viral genome
108
Characteristics to define viral species (7)
1. Natural host cell range
2. Cell and tissue tropism
3. Pathology and cytopathology
4. Mode of transmission
5. Physico-chemical properties of virions
6. Antigenic properties of viral proteins
7. Sequence relatedness in genes and genomes
109
Categories in the Baltimore classification system (6)
1. dsDNA
2. + ssDNA
3. dsRNA
4. + ssRNA
5. - ssRNA
6. + ssRNA with RTase
110
Types of cell cultures (3)
1. Primary cell culture
2. Diploid cell culture
3. Continuous cell lines
111
MOI
Multiplicity of infection; number of infectious viruses/number of cells
112
Phases of the viral replication cycle
1. Attachment
2. Entry and uncoating
3. Biosynthesis
4. Assembly
5. Egress
113
Specific attachment occurs between:
The attachment protein of the virus and the receptor on the surface of the host cell
114
Attachment strategy of naked viruses
Attachment via surface features of the virus; canyons or depressions on the virus surface attaching to cell receptors
115
Attachment strategies for enveloped viruses
Glycoproteins and surface proteins
116
Receptor-mediated endocytosis
Selective import of extracellular molecules into a cell through receptor and membrane interaction
117
Biosynthesis
The synthesis of all viral components required for building the next generation of viruses
118
Immediate early genes
Genes encoded right after viral infections; encode regulatory proteins to make cells enter S phase, induce expression of viral genes
119
Early genes
Enzymes and factors required for genome replication
120
Late genes
Structural proteins required for virus assembly
121
Assembly of Adenovirus
Formation of pentons requires fiber and penton base
122
Assembly of polio virus
A single polyprotein and proteolytic cleavage
123
Structural unit of capsid
Double-discs
124
Host range
The range of hosts that can be infected by a given virus
125
Tissue tropism
The preference of a given virus for certain types of cell and tissue in its hosts
126
Susceptible cells
Cells that allow attachment and entry of a given virus
126
Permissive cells
Cells that permit the replication of a given virus
127
What supergroup of viruses does TMV belong to?
Alphavirus-like supergroup
128
Necrotic local lesion assay
Experimental process to determine the effect of dilution of TMV solution
129
TMV: structure of capsids and genome packaging
Double-disc structural unit; genome segment is threaded though the growing helix of double-discs
130
Coat protein-mediated resistance
Plants expressing the TMV CP have delayed onset of the disease; transgenic resistance
131
Movement of TMV between plant cells
- after viral replication, VRC dock at the plasmadesmata
- cross into new cell with the help from MPs
132
Plasmadesmata
Allow for passive diffusion between plant cells; channel is too small for TMV to pass through so it acts through MPs to increase the size
133
TMV and actin filaments
Actin filaments allow movement of VRC around the cell
134
TMV and microtubules
Microtubules are involved in the degradation of the VRC of TMV
135
What family is Poliovirus a part of?
Picornaviridae
136
Features of poliovirus
Naked, icosahedral, +ssRNA
