1
Q
Is Mers a covid virus?
A
yes
2
Q
what are viruses?
A
molecular parasites
3
Q
what do viruses do?
A
infect all biota of the planet
4
Q
T/F: viruses do not have a metabolism of their own.
A
true
5
Q
How much smaller are viruses to gram positive bacteria?
A
2X - 60X smaller
6
Q
what are the components of a virus?
A
nucleic acid genome, capsid, and envelopes
7
Q
T/F: a viruses genome is always single stranded DNA.
A
false it can be either RNA, or DNA and can be single or double stranded
8
Q
what is a capsid?
A
protein shell
9
Q
T/F: all viruses are enveloped.
A
false
10
Q
what is an envelope
A
a lipid envelope derived from the host cell
11
Q
what does the membrane contain?
A
virus derived glycoproteins
12
Q
what are the glycoproteins for?
A
viral tropism
13
Q
what are the three main shapes of viruses?
A
helical, polyhedral, and complex
14
Q
what do the spikes do?
A
these give it specificity for an organism and virality
15
Q
what is virion adsorption?
A
when cell receptors or co-receptor proteins neutralize antibodies produced by the immune system which determines tropism
16
Q
what is the viral penetration of the cell surface?
A
membrane fusion or endocytosis
17
Q
what happens when the viral genome is uncoated?
A
pH changes in endocytotic vesicle and the capsid is degraded.
18
Q
explain the process of primary transcription in a viral infection.
A
this will begin right after entry using viral poluymerases or strong transcription activators carried with them
19
Q
what is the fifth step of a viral infection?
A
viral proteins will replicate the genome
20
Q
what is the sixth step of a viral infection?
A
secondary transcription and the expression of progeny genomes, early and late proteins
21
Q
what is step seven of a viral infection?
A
capsid proteins self assemble and the nucleic acid in inserted thus packaging progeny genomes
22
Q
what is the final step of a viral infection?
A
the release of the progeny virions and enveloped viruses will aquire a lipid bilayer
23
Q
what is a field or street isolate?
A
isolate obtained directly from the natural host not cycled in a cell culture
24
Q
what is a co-infection of viruses?
A
infection by two or more viruses and could lead to re-assortment and new biologic/antigenic properties
25
what is phenotypic mixing or pseudotype formation?
viruses switching coats
26
T/F: RNA lacks proof reading abilities.
true
27
when might phenotypic mixing happen?
during co-infection
28
How might doctors control viral infections?
1. vaccination
2. antiviral drugs
3. vaccine types
29
what are the types of vaccines?
killed, live-attenuated, subunit
30
what are newly developed vaccine types?
RNA-based, DNA-based, multiple vaccine vectors
31
how is transcription in the nucleus done in DNA viruses?
completed by the host RNA polymerase
32
how is transcription in the cytoplasm done in DNA viruses?
viral RNA polymerases
33
T/F: Human DNA viruses are always double-stranded.
false, they are usually ds but some are ss
34
what are the 5 types of dsDNA virus families?
1. papovaviridae
2. poxviridae
3. adenoviridae
4. herpesviridae
5. hepadnaviridae
35
What does papovaviridae look like?
circular genome with an icosahedral symmetry
36
what does poxviridae look like?
exceptionally large enveloped viruses, linear genomes, complex viral capsid symmetry
37
what does adenoviridae look like?
linear genome with icosahedral symmetry
38
what is the difference between papovaviridae and adenoviridae?
papo has a circular genome whereas adeno is linear
39
which type of virus is generally used for biowarfare? and how?
adenoviridae which is gutted and can be reused as something harmful or gene therapy in some cases
40
what do herpesviridae look like?
linear genome, icosahedral symmetry
41
what does hepadnaviridae look like?
very small, circular genome, partially double-stranded, icosohedral symmetry,
42
how does hepadnaviridae replicate?
using viral encoded reverse transcriptase
43
what are the two ssDNA virus families?
1. parvoviridae
2. anelloviridae
44
what does parvoviridae look like?
small linear genome that is non-segmented with icosahedral symmetry
45
What does anelloviridae look like?
circular genome that is non-segmented and has icosahedral symmetry
46
what must happen with ssDNA virus families?
must be converted to dsDNA before transcription and translation
47
T/F: annelloviruses are in all of us.
true they are commensal
48
What does the genome of RNA viruses look like?
double stranded RNA, or single stranded (+ or -), ambisense (both + and -), and either segmented or non-segmented
49
What does ambisense mean?
there are both positive and negative sections in the genome
50
What does a segmented genome imply?
rapid evolution and change due to re-assortment of genomic segments
51
how are the three sub-groups based on gene expression?
1. single large polyprotein that is proteolytically cleaved
2. two or more poly proteins encoded in genome and subgenomic RNAs produced during infection
3. production of numerous protein-coding subgenomic RNAs from large genomes
52
What are the SS + RNA virus families?
- picornaviridae
- flaviviridae
- togaviridae
- astroviridae
- coronaviridae
- arteriviridae
- hepeviridae
53
what is rhinovirus? and what are its traits?
common cold, unstable at low pH, low temperature preference, and upper-respiratory infections only
54
what is poliovirus?
central nervous system infection (poliomyelitis), virtually eradicated due to highly effective vaccine
55
Flaviviridae is primarily spread by what?
insect vectors
56
which virus is a athropod borne encephalitis?
togaviridae
57
T/F: negative ss RNAs all contain a nucleocapsid.
true
58
what are the - ssRNA virus families?
- paramyxoviridae
- rhabdoviridae
- filoviridae
- bornaviridae
- orthomyxoviridae
- bunyaviridae
59
What is different about rhabdoviridae vaccines and why is it like that?
they can be applied post-exposure, because there is protracted time to cross the neuromuscular junction
60
what is the one dsRNA virus?
reoviridae
61
how are retro viruses classified?
on their own as they have both positive RNA and Negative RNA
62
during infection of retro viruses what happens?
the RNA converted to DNA by reverse transcriptase which integrates into the cellular genome
63
what do infectious disese outbreaks require?
rapid methods to identify the source of infection, diagnose patients, and explain routes of transmission
64
what must viral isolation do?
avoid extreme pH, direct sunlight and freezing temperatures to preserve material as isolated, generally on ice and analyzed asap
65
how might viruses be isolated in animals?
embryonic chicken eggs, primary cell lines from animal tissues, continuously replicating human cell lines
66
if the viruses cannot be grown in cell lines what might happen?
injection into suckling mice or in chimpanzees
67
what is the cytopathic effect?
round and enlarged cells growing in grape-like clusters, cell fusion and subsequent detachment from the substrate, formation of large multinucleated cells or cells with reduced nuclei and proliferation of membranes
68
how does an electron microscope work?
uses beam of electrons rather than light
69
what are the virus particle morphology?
ribbon-like, rod-shaped, spherical, filamentous, spheres with spikes
70
how is electron microscopy enhanced?
negative staining or ultrathin sectioning
71
what are the four types of serological assays?
1. neutralization assay
2. hemagglutination assay
3. immunostaining
4. enzyme-linked immunosorbent assay (ELISA)
72
what is a neutralization assay?
antibodies are mixed with the virus and assayed for infectivity
antibodies that recognize the virus bind and prevent infection within this assay viruses can be placed in serogroups depending on which antibodies are effective in neutralizing infection
73
explain a hemagglutination assay.
erythrocyte suspensions are mixed with viruses and added to a V-bottom microtitre plate, single erythrocytes sink to bottom forming red dot and aggregated red blod cells uniformly coat the well
74
what is immunostaining?
polyclonal antisera and monoclonal antisera linked to a fluorescent dye or enzyme enables detection of interacting molecules by microscopy
75
explain the ELISA test
most common serological assay, captures virus antigens or antibodies on solid surface then exposes these to a substrate allowing detection
76
what are the advantages of nucleic acid-based methods?
can identify viruses that cannot be cultured and does not need quality antibodies, allows the inactivation of the virus- reducing transportation concerns
77
T/F: PCR will not detect viruses
false they can be directly detected by PCR
78
what do RNA viruses require in PCR based detection?
initial reverse transcripase before pcr amp.
79
how are the pcr products detected?
may be sequenced directly or cloned into vectors before sequencing
80
How does molecular epidemiology determine the path of virus transmission?
using phylogenetic methods to reconstruct path of virus transmission based on heredity
81
what do phylogenetic trees indicate?
specific modes of transmission
82
Explain the details of the Schmidt case
a guy gave his mistress a "vitamin B" shot and she was then diagnosed as being HIV+ but all her previous sexual partners were HIV- but he also does not have HIV
83
what is homoplasy?
similarity by change
84
what is homology?
similiarity by common ancestor
85
what two genes were analyzed for the HIV case?
gp120 (envelope protein), and RT (reverse transcriptase)
86
how did phylogeny help solve the case?
revealed that the victim HIV arose from within the clad of viruses and indicates a potential source
87
what are the types of engineered viruses?
1. recombinant DNA
2. Synthetic poliovirus
88
what issues were brough forward because of synthetic poliovirus?
can a virus ever really be eradicated?
should there be restrictions on access to genome sequences of viruses?
should this type of work be banned, classified, or regulated?
89
why might phylogeny analyses be difficult?
possibility of shuffling sequences during the creation of synthetic viruses, one can envision making viruses look like they came from a specific place
90
what precident was created by the schmidt case?
admissibility of phylogenetic trees in a court
91
what is antigenic drift?
mutations occuring gradually over time - some mutations resulting in amino acid changes allowing viruses to escape antibodies previously generated
92
what is an outcome of antigenic drift?
seasonal influenza vaccines
93
microbial
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