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RMICRO > Virology > Flashcards

Virology Flashcards

1
Q

infectious progeny particles, formed by de novo self- assembly, vehicle for transmission of the viral genome

A

virion

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2
Q

obtained crystals of TMV in 1935

A

Wendell Stanley

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3
Q

direct visualization of virus particles for the first time in 1930a was done using the

A

electron microscope

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4
Q

giant viruses infecting amoeba

A

mimivirus

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5
Q

like other organisms virsuses;

A

possess genes
evolve by natural selection
reproduce by creating multiple copies

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6
Q

unlike any other life forms viruses;

A

do not have cellular structure
do not have their own metabolism
cannot naturally reproduce outside a host cell

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7
Q

observed that the causative agent of tobacco mosaic disease was not retained by filters 1892

A

Dmitri Ivanovsky

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8
Q

discovered that TMD is caused by a distinctive agent which is a infectious liquid; contagium vivum fluidum= soluble living germ; confirmed and extended Ivanovsky’s results 1898

A

Martinus Beijerinck

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9
Q

discovered that the causative agent of foot and mouth disease can pass through filters; infectious filterable agents- small particles (could be retained by a finer filter); virus as a particulate matter

A

Friedrich Loeffler
Paul Frosch

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10
Q

origin of viruses; genetic elements that gained the ability to move between cells

A

progressive/ escape hypothesis

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11
Q

origin of viruses; previously free-living organisms that became parasites

A

regressive/reduction hypothesis

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12
Q

origin of viruses; precursors of life

A

virus first hypothesis

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13
Q

cell components that are potential candidates as precursors of viruses

A

eukaryotic mRNA
plasmid
transposon

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14
Q

contains relatively large repertoire of putative genes associated with translation which may be remnants of a previously complete translation system; depend less on their host cell for replication; does not differ significantly from parasitic bacteria (Rickettsia prowazekii)

A

Giant mimivirus (microbe-mimicking virus)

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15
Q

an isolate whose genome sequence differs from that of a reference virus (may contain on or more mutations)

A

virus variants

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16
Q

variant that possesses a unique and stable phenotypic characteristics

A

virus strain

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17
Q

a group of closely related viruses with a common ancestor

A

lineage

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18
Q

hypermutable viruses; there is no fixed sequence of basis for their genome; genome exist as a large # of variants “quasispecies”

A

RNA viruses

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19
Q

a population structure of viruses with a large number of variant genomes

A

viral quasispecies

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20
Q

results from high mutation rates as mutants arise continually and change in relative frequency as viral replication and selection proceeds

A

quasispecies

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21
Q

process that results in the production of new genome derived from 2 parental genomes

A

recombination

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22
Q

a category of recombination that may occur with segmented genome viruses having all the segments packaged in one virion (reovirus, bunyavirus, influenza viruses)

A

reassortment

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23
Q

progeny virions containing mixtures of genome segments from two parental strains

A

reassortants

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24
Q

a change in the phenotype because of the accumulation of point mutations over time

A

antigenic drift

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25
Q

change in the surface glycoproteins (ie influenza) because of genetic reassortment

A

antigenic shift

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26
Q

ultimate species jumper

A

influenza virus

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27
Q

evolutionary relationships between viruses are determined through

A

sequence comparisons

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28
Q

to determine/identify evolutionary relationships between closely related viruses you try to identify the

A

virus hallmark (vh) genes

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29
Q

functions of the virion:

A

protects the genome
delivers the genome
delivers protein contained in the virion
interactions with the host

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30
Q

functions of capsid:

A

protects the viral genome
recognition & interaction with hose cell
facilitate transfer of the viral NA
determines the antigenic characteristic of the virus

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31
Q

basic protein building block of the capsid

A

protomer

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32
Q

morphological unit on the surface of the virus, mau have pentamer or hexamer protomers

A

capsomere

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33
Q

virion symmetry; 20 faces each an equilateral triangle, 12 vertices each formed where the vertices of the five triangles meet, 30 edges at each of which sides of the two triangles meet

A

icosahedral (cubic, icosahedron)

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34
Q

why icosahedral shape is very common in viruses

A

allows tight packing of subunits
size of subunits can be smaller (economizing on genetic info)
most efficient arrangement for subunits in a closed shell (uses the smallest # of units to build a shell)

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35
Q

virion symmetry; NA is coiled in the form of a helix, protein subunits arranged helically like hollow cylinders around the coil (may either be rigid (plant viruses), or long and flexible (animal viruses)).

A

Helical

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36
Q

virion symmetry; influenced by both NA and capsomeres

A

size of helical capsid

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37
Q

virion symmetry; determined by size, shape, and protein interaction

A

diameter/width

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38
Q

virion symmetry; determined by the length of NA

A

length

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39
Q

virion symmetry; atypical viruses; ie poxvirus, bacteriophage T4

A

complex

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40
Q

genomes of most plant viruses

A

ssRNA

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41
Q

genomes of most fungal viruses

A

dsRNA

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42
Q

genomes of most prokaryotic viruses

A

dsDNA genomes

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43
Q

genomes of large viruses

A

dsDNA

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44
Q

example of viruses with the largest RNA genomes

A

some coronaviruses (33kb)

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45
Q

largest virus genome

A

pandoravirus 2.8mb larger than the smallest genomes of cellular organisms

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46
Q

segmented genomes with segments that are in the same capsid not contained; each genome segment is packaged into a separate virus particle; occurs in both DNA and RNA plant viruses; solves the problem of breakages but all virus particles must be taken up by a single host cell to establish productive infection

A

multipartite genomes

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47
Q

much more common amongst RNA viruses than DNA viruses

A

segmented genomes

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48
Q

genome type common among plant viruses

A

multipartite genomes

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49
Q

predilection of viruses to infect particular cell types

A

tropism

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50
Q

acquired by ingestion (fecal-oral transmission) and replicate primarily in the intestinal tract

A

enteric viruses

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51
Q

acquired by inhalation or by fomites and replicate primarily in the respiratory tract

A

respiratory viruses

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52
Q

replicate in their hematophagous arthropod vectors, transmitted to bite to vertebrate hosts (virus replication via viremia

A

arboviruses

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53
Q

acquired by close contact, injection, fomites and by unknown means ( infects only specific cells in particular target organs, become persistent and may evoke transformation of the host cells (malignancy))

A

oncogenic viruses

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54
Q

method to determine the number of virus particles

A

titration

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55
Q

period between apparent disappearance of the infecting virus and the release of newly synthesized progeny; extracellular virus cannot be detected

A

latent period: eclipse and maturation phase

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56
Q

event during eclipse phase

A

early viral genes are transcribed into RNA
translation of early gene products

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57
Q

three main types of early gene products

A

proteins that shut down cellular NA and protein synthesis
proteins that regulate the expression of the viral genome
enzymes required for the replication of the viral NA

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58
Q

nucleus as the site of transcription and DNA replication
utilize cellular RNAP II and other cellular enzymes

A

most DNA viruses

59
Q

replicate in the cytoplasm
lack enzymes to copy RNA from an RNA template
viral genome itself must function as an mRNA or the virus must encode and carry its own RNA polymerase to transcribe RNA from the RNA genome

A

most RNA viruses

60
Q

interval in which progeny virions accumulate in the cell or in the surrounding medium at exponential rates

lytic viruses; infected cells cease metabolic activity and lose structural integrity (viral production ceases, titers slowly drop)

non-lytic viruses: cells may continue to synthesize virions indefinetely

A

maturation phase

61
Q

virus replication cycle; initiation phase

A
  1. attachment
  2. penetration
  3. uncoating
62
Q

virus replication cycle; replication phase

A
  1. transcription of early mRNA
  2. translation of early proteins
  3. replication of viral NA
  4. transcription of late mRNA
  5. translation of late proteins
63
Q

virus replication cycle; release phase

A
  1. assembly of virions
  2. release
64
Q

HIV gp120 receptor

A

CD4

65
Q

HIV gp41 receptor; coreceptor of CD4

A

CCR5, CXCR4

66
Q

two main mechanisms virions can enter cells during penetration/ uptake

A

receptor-mediated endocytosis (viropexis)
membrane fusion

67
Q

viropexis vesicles is coated with

A

clathrin

68
Q

viropexis; after clathrin coat is removed, it is followed by

A

endosome fusion then release of the viral nucleocapsid into the cytoplasm

69
Q

entry by direct fusion of envelope and plasma membrane
merging of two different membranes occur as a result of the activity of specific viral fusion proteins that mediate the process
herpesviruses, paramyxoviruses, HIV

A

membrane fusion

70
Q

intracellular transport ( transport from the cytoplasm to a location close to the nucleus ) is via

A

microtubules with motor proteins

71
Q

necessary for the viral genes to become available for transcription
removal of capsid, freeing the nucleic acid, exposing the viral genome to the host cell machinery
genetic material of the virus is introduced into the cell, often accompanied by essential viral protein cofactors

A

uncoating

72
Q

production of virion components including the genomic NA
sometimes, cellular enzymes replicate the viral genome, assisted by viral proteins
in most cases, viral proteins are responsible for genome replication although they utilize cellular proteins to aid this

A

replication phaseq

73
Q

viruses arranged based on the different form of NA that is incorporated into virions; widely differ in their abundance, diversity of the constituent viruses and other MGE, and spread among the cellular life forms

A

Baltimore classes of viruses

74
Q

two most abundant and diverse classes of viruses

A

dsDNA which dominates the prokaryotic virome
(+) RNA viruses which is most common in eukaryotes

75
Q

mimic the replication expression strategy of cellular life forms

A

class I

76
Q

typically replicate via RCM

A

Class II

77
Q

genome same polarity as the mRNAs for virus proteins

A

class IV

78
Q

genome is an ssRNA complementart to the mRNa (or in some groups of viruses, an ambisense RNA)

A

class V

79
Q

+RNA genome replicated via a DNA intermediate, produced by reverse transcriptase of the genome

A

class VI

80
Q

replicate via reverse transcription, package dsDNA form or an RNA-DNA hybrid into virions

A

class VII

81
Q

viral DNA genomes

A

host genetic system is based on DNA
many DNA viruses emulate the host
almost all viral DNA genomes are not like cell chromosomes

82
Q

viral RNA genomes

A

cells have no RdRp
encode RdRp
RdRp produce RNA genomes and mRNA from RNA templates

83
Q

retrovirus; virus integrated into the host chromosome; can remain latent; target T cells (HIV)

A

provirus

84
Q

release phase; assembly

A

packaging of the genome into the capsid to from the nucleocapsid
many viruses are assembled all at the same time

85
Q

release phase; assembly; can condense in the absence of NA

A

icosahedral capsid

86
Q

release phase; assembly; cannot form without the viral NA

A

nucleocapsid of viruses with helical symmetry

87
Q

release phase; maturation

A

further modification which happens after assembly such as addition of the envelope
happens at membrane sites with added viral proteins

88
Q

release phase; exit from the cell

A

final step of the rep cycle
rise period; rapid rise in the extracellular virus titer until a constant titer is reached at the end of the replication cycle

89
Q

unique occurrence during the final stage of maturation of viruses like HIV and paramyxoviruses

A

does not occur until virus particle is released from the host cell
HIV; viral glycoprotein has to be cleaved by a virus-coded protease after virus release
Paramyxoviruses; cleavage of surface glycoprotein spikes to become infectious upon virus release

90
Q

outcomes of virus infection; results to production of progeny virion; often lysis

A

productive infection

91
Q

outcomes of virus infection; persistence of viral genomes but not infectious viral particles in transiently permissive cells without the destruction of the infected cell; sequence integrated into cell genome or as multiple copies of cccDNA; may be activated to become productive; can be episomal

A

latent infection

92
Q

outcomes of virus infection; infection of a susceptible cell, which may be non-permissive, allowing only a few viral genes to be expressed
infection of either permissive or non-permissive cells with defective viruses, which lack a full complement of viral genes

A

abortive infection

93
Q

outcomes of virus infection; infected cells may be only transiently permissive. and that the virus persists in the cell until the cell becomes permissive; only a few of the cells in a population produce viral progeny at any time; may have serious consequences- cell transformation and cancer

A

restrictive/ restringent infection

94
Q

outcomes of virus infection; death of cell prior to the production of progeny virions; apoptosis- suicide mechanisms among cells

A

PCD

95
Q

cell culture; prepared form animal tissues, limited life span (5-20 cell div); derived from monkey, kidney, human foreskin

A

primary cell culture

96
Q

cell culture; homogenous population of a single type, can divide up to 100 times, can retain diploid number (human embryonic lung WI-38 strain)

A

diploid cell strains

97
Q

cell culture; single cell type, can be propagated indefinitely, aneuploid (HeLa cells)

A

continuous cell line

98
Q

characteristic morphologic changes in the host cells or tissue;
necrosis - poliovirus
syncytia- measles, hsv
inclusion bodies- rabies
transformation
lysis

A

cytopathic effects

99
Q

assays of infectivity, infectious unit count
ie plaque, end-point titration method

A

biological assays

100
Q

assays to measure non-infectious virus; ie electron microscopy, immunological methods

A

physical assays

101
Q

conc of a virus in a sample

A

virus titer

102
Q

useful for determining the tires of retroviruses that do not form plaques

A

transformation assay

103
Q

most common indirect method of measuring number of virus particles; gives relative estimates of titers

A

hemagglutination assay

104
Q

uses antibody to detect viral proteins; use viral proteins to detect immune response

A

serological assays

105
Q

dsDNA; largest genome; complex

A

poxvirus

106
Q

dsDNA; associated with latent infections; some oncogenic

A

herpesvirus

107
Q

dsDNA; respiratory, enteric infections; “gland”, excellent models for molecular studies of eukaryotic cell processes; conjunctivitis, gastroenteritis

A

adenovirus

108
Q

dsDNA; restricted host range; epitheliotrophic

A

papillomavirodae

109
Q

dsDNA; poxvirus; orthopoxvirus; extensive fatalities; eradicated

A

variola virus- smallpox

110
Q

dsDNA; poxvirus; cause milker’s nodes (pseudocowpox) and orf (sore mouth or contagious ecthyma, scabby mouth of sheep and goats, papulovesicular eruption in the lips, in humans lesion on the hand or forearm); occupational viral disease

A

parapoxvirus

111
Q

dsDNA; poxvirus; multiple discrete nodules 2-5mm in diameter; limited to the epidermis except on soles and palms; pink/white wart-like tumors having a central dimple

A

molluscipoxvirus infection; Molluscum contagiosum

112
Q

dsDNA; herpesvirus; realm

A

duplodnavaria

113
Q

dsDNA; herpesvirus; subfamily; short GC and cytolytic; genus simplex (HHSV 1,2), varicella (VZV), latent in neurons

A

alphaherpesvirus

114
Q

dsDNA; herpesvirus; subfamily; long GC, cytomegalic (genus cytomegalo) latent in gland, kidneys; CMV / long GV lymphoproliferative (genus roseola), HHSV6,7 latent in lymphoid tissue

A

betaherpesvirus

115
Q

dsDNA; herpesvirus; subfamily; variable GC, lymphoproliferative; lymphoid (genus lymphocrypto), Epstein-Barr virus, (genus Rhadino), Kaposi sarcoma-associated herpesvirus, latent in lymphoid tissue

A

gammaherpesvirus

116
Q

dsDNA; herpesvirus; alphaHV; oral-facial lesions; transmitted through DC with virus containing secretions (saliva), or with lesions on mucosal surface, herpetic whitlow

A

HSV 1

117
Q

dsDNA; herpesvirus; alphaHV; genital lesions; sexual contact, infection of a newborn during birth ; primary infection via mucoepithelia (genital herpes); latency in sacral or lumbar ganglia causing recurrent genital herpes

A

HSV 2

118
Q

dsDNA; herpesvirus; alphaHV; highly contagious; transmission via contact or respiratory route; febrile infection; primary and secondary infections (latency after PI in neuron); acyclovir can shorten duration and severity

A

VZV
PI-varicella or chicken pox
SI- zoster or shingles

119
Q

dsDNA; herpesvirus; betaHV; target T lymphocyte; transmission via direct contract/ respiratory; latency in T lymphocyte; cause roseola/exanthem subitum, febrile convulsions, encephalitis

A

HHV-6

120
Q

dsDNA; herpesvirus; gammaHV; KSHV; target endothelial cells; latency in leukocytes; transmission via exchange of body fluids

A

HHV-8

121
Q

dsDNA; herpesvirus; gammaHV; targets B lympho and epithelial cells; latency in B lympho; transmission via saliva known as kissing disease; cause infectious mononucleosis

A

EBV

122
Q

dsDNA; closely related to papilloma, smaller

A

polyomaviridae

123
Q

dsDNA; polyomaviruses; cause a fatal illness known as progressive multifocal leukoencephalopathy (PML)

A

JC virus

124
Q

dsDNA; polyomaviruses; affects kidneys of immunosurpressed transplant patients and produces a mild respiratory infection

A

Polyomavirus hominis 1 or BK virus

125
Q

dsDNA; polyomaviruses; respiratory infections

A

KI and WU viruses

126
Q

dsDNA; polyomaviruses; form of skin cancer

A

Merkell cell polyomavirus

127
Q

ssDNA; small; one human pathogen, B19; has tropism for red blood cell progenitors, one genus contains replication-defective viruses

A

parvovirus

128
Q

dsDNA; parvovirus; erythema infectiosum/ fifth disease/ slapped cheek rash; transmission via direct contact, droplet infection; cause aplastic anemia with chronic hemolytic anemia, hydrops fetalis, acute arthritis

A

HPV-B19

129
Q

dsRNA; respiratory enteric orphans; double capsid shell allows them to resist vey low pH in gut thus assoc with enteric infections; linear, segmented 10-12; genetic reassortment (rotavirus- major cause of infantile diarrhea); realm riboviria

A

reoviridae

130
Q

dsDNA; reovirus; transmitted by wood ticks (Dermocentor andersoni); dengue like disease with frequent rash, headache, chills, muscle pain, occasional encephalitis, hemorrhagic symptoms esp in children; deaths are rare

A

colorado tick fever

131
Q

+ssRNA; large genome; S proteins; HFr

A

coronaviridae

132
Q

+ssRNA; small RNA virus; among the oldest and most diverse virus; host range at least 5 of the 7 vertebrae classes; cytoplasmic rep; realm ribovaria

A

picornaviridae

133
Q

+ssRNA; picornaviridae; major global animal health problem (infectious); genus Aphthovirus; 7 serotypes O,A,C SAT 1, SAT 2 SAT 3 , ASIA 1; vaccination via blocking symptoms not virus transmission

A

foot and mouth disease by FMDV

134
Q

+ssRNA; picornaviridae; one of the 1st disease ever recorded; genus Enterovirus - inflammation of grey matter, spinal cord; transmission fecal-oral, respiratory; vaccine available

A

poliomyelitis

135
Q

+ssRNA; picornaviridae; inflammation of the liver; infectious/ epidemic; transmitted via fecal-roal,sexual anal-oral, and blood transfusion; symptoms include yellow eyes (jaundice), loss of apetite, nause, diarrhea, fatigue, abdominal pain

A

Hepatitis A

136
Q

+ssRNA; picornaviridae; common colds; replication restricted in URT; ~10 serotypes hence repeated infections; spread via aerosol/ hand contact 2-3 days IP; no vaccine due to antigenic diversity

A

Rhinoviruses

137
Q

+ssRNA; yellow; 13/70 cause disease in humans; prev classified under group B arboviruses and togaviruses; spread through arthropod vectors mainly ticks and mosquitoes; host range mammals of all genera

A

flavivirus

138
Q

+ssRNA;flavivirus; most important human -arthropod borne viral disease in the world; break-bone fever/ bonecrusher disease; 1-4 viruses; A. aegypti,albopticus, scutellaris; high fever, frontal headace, retro-orbital pain, myaligias, arthralgias, nausea, vomiting, and often maculopapular rash

A

Dengue fever

139
Q

+ssRNA;flavivirus; vector Aedes; sexual transmission; cause of microcephaly; symptoms include mild fever, skin rash, conjunctivitis, muscle and joint pain, malaise or headache

A

zika virus

140
Q

+ssRNA;flavivirus; blood-borne, sexual (low risk); major target cells is hepatocytes; no vaccine; cirrhosis, hepatocarcinoma

A

Hepatitis C virus

141
Q

+ssRNA; non segmented; enveloped alphaviruses; replication in cytoplasm; mosquito/arthropod borne; realm ribovaria;

A

togaviruses

142
Q

+ssRNA; new family of rubella; not arthropod borne; only one recognized species (Rubivirus- Rubella virus)

A

matonaviridae

143
Q

rubella (german measles) is caused by; measles (tigdas) is caused by

A

rubella virus ( matonaviridae); paramyxovirus

RMICRO (3 decks)

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