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CMBM exam 3 > Viral Structure, Replication and Pathogensis > Flashcards

Viral Structure, Replication and Pathogensis Flashcards

1
Q

What are the classifications of viruses?

A 
Polio
Rota
Human papillo
Adeno
Semliki
Influenza
Paramyxo
Smallpox
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2
Q

What is virology?

A

Scientific study of viruses and disease they cause

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3
Q

What is a virus?

A

Infective agent typically consisting of a of a nucleic acid in a a protein coat
Obligate intracellular parasite that depends on the host for reproduction

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4
Q

How are viruses similar to living organisms?

A

Proteins and glycoproteins

Nucleic acid

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5
Q

How are viruses different from living organism?

A

No polysaccharides, small molecules or ions
If they are lipid they are only enveloped
No ribosomes

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6
Q

Do antibiotics work against viruses?

A

No

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7
Q

Does a virus contain DNA and RNA?

A

No they can only have DNA or RNA, never both

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8
Q

What are possible structures for DNA viruses?

A

Single or double strand
Linear or circular
Open or closed
Continuous or nicked

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9
Q

What are some possible structure for RNA viruses?

A

Single or double strand
Linear
Possible segmentation
Single strand may be plus or minus sense

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10
Q

What are the steps to name a virus?

A
  1. Structure: size morphology and nucleic acid
  2. Biochemical characteristics: structure and mode of replication
  3. Disease
  4. Means of transmission:
  5. Cell, tissue or organ
  6. Host cell range
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11
Q

What a virion?

A

Structurally complete infective virus particle

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12
Q

What is a capsid and what are capsomeres?

A

A protein shell that encloses the nucleic acid

Capsomeres are units on the surface in clusters

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13
Q

What is a nucleocapsid?

A

Capsid along with the inside nucleic acid

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14
Q

What is the tegument of a virus?

A

Proteinaceous material between envelope and capsid

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15
Q

If a virus is said to have an icosahedral shape, what does it look like?

A

Rigid and uniform structure

ex. Multiside hexagon

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16
Q

If a virus is said to have a helical shape, what does it look like?

A

Swirly squiggly

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17
Q

A naked virus…

A

Protects viral genes from inactivation by adverse environments
Packaged, protect and deliver genome
Mediate attachment (VAP)
Release by cell lysis

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18
Q

An enveloped virus…

A 
Has a lipid bilayer with embed proteins
More susceptible to chemical agents
Determines host cell specificity and penetration 
Facilitates attachment 
Released by budding
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19
Q

A virus is icosahedral naked. What types of genome does it have?

A

dsDNA, ssDNA, dsRNA, ssRNA

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20
Q

A virus with an icosahedral shape and is enveloped has what types of genome?

A

dsDNA, dsRNA, ssRNA

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21
Q

A virus has a helical shape and is naked. What are its genomes?

A

dsDNA, ssDNA, ssRNA

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22
Q

An enveloped helical virus is found. What genome will it have?

A

ssRNA

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23
Q

What are the 2 types of exceptions to viral symmetry?

A

Complex viruses: poxvirus and bacteriophages

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24
Q

What is tropism?

A

Factors that affect host range

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25
What are some factors that allow viruses to enter cells?
Can use more than one receptor or many viruses use the same receptor
26
What are the most common routes of entry for a virus?
``` Blood and bodily fluids Insect bites Respiratory GI Direct contact ```
27
What are some viruses that enter through blood or fluid?
CMV, EBV, HBV, HCV, HIV
28
If an insect bites you, what viruses could it transmit?
Dengue, EEEV, WEEV, West Nile
29
Oh no! You touched a surface covered in viruses! What could viruses could you get?
HSV, smallpox, VZV
30
Viruses that can be inhaled are:
Small droplets: influenza, measles, smallpox, VZV Large droplets: adenovirus, parainfluensa, parvovirus, smallpox Direct to secretions: RSV, rhinovirus
31
What viruses can be transmitted through the GI tract (facal-oral)?
Enteric adenovirus, HAV, norwalk virus, polio, rotavirus
32
What the main routes for viral spread?
Hematogenous spread Neural spread Muliple pathways
33
In hematogenous spread, what does it mean when primary replication proceeds initial viremia?
There are asymptomatic for prodromal symptoms (Enteric or respiratory viruses) Dissemination to other tissues leads to amped up secondary viremia
34
In hematogenous spread, what viruses travel freely or with other cells?
Enteroviruses, HBV, tagoviruses (free) Rift valley fever, Colorado tick fever (RBCs) CMV, EBV, HIV (lymph or monocytes)
35
In the neural spread of viruses, where can entry happen?
Near the CNS and then spreads It can be near synaptic endings, motor neurons, sensory neuronsm infection of schwann cells and olfactory rods (HSV, rabies, VZV)
36
What are the basic steps of entry of an enveloped virus?
Attachment to cell receptors Penetration of host cell by fusion protein Merging of viral envelope and cell membrane
37
What are the full steps to viral mutliplication?
``` Attachment/ absorption Penetration/ entry Uncoating/ release of nucleic acid Relication Assembly Release ```
38
When is the viral titer stable?
During the period of attachment
39
When is the viral titer unstable?
Eclipse phase: diassembly, transcription, translation, and genome replication
40
When does the titer increase?
As the viral progeny are assembled and are infectious
41
Which types of viruses make use of their own viral RNA polymerase for replication?
ssRNA+, ssRNA-, all dsRNA
42
Which types of viruses use viral host RNA polymerase?
Hepadnavirus | Retrovirus (also needs viral reverse transcriptase)
43
What viruses use viral RNA polymerase for protein synthesis?
ssRNA- and dsRNA
44
What viruses use host RNA polymerase for protein synth?
Hepadnavirus, ssDNA, dsDNA
45
Which viruses use host DNA polymerase for replication?
ssDNA | dsDNA (can also use viral DNA pol)
46
During early transcription of DNA viruses what is necessary?
Regulatory proteins
47
What is needed during late transcription of DNA viruses?
Structural proteins
48
What type of cycle is an acute viral infection and how does it cause infection?
Lytic cycle Multiple rounds of replication resulting in cell death Many progency viruses produced and released (ex. polio or influenza)
49
What type of cycle is a chronic viral infection and how does it cause infection?
Non-lytic, productive Undergoes replication and shedding that continues even after acute illness ends +/- symptoms and cell injury Continue infecting Can be localized (warts) or systemic (HIV)
50
What is a latent viral infection?
No replication until signaled Limited to macromolecules Genetic material: incorporates into cell or host genome DNA virus or retrovirus
51
How does a latent infection transform into an active one?
Malignancy of host cell Invasive growth Benign or cancerous growth
52
In the prodrome phase of an actue viral infection what cytokine is active?
IFNgamma
53
In the classical sign phase of an acute infection what immunoglobulin is active?
IgM (if primary infection)
54
In the recovery phase of an acute infection what immune cells and immunoglobulin are active?
CD4+, CD8+, IgG
55
What is a nonenveloped single stranded linear DNA virus?
Parvovirus
56
What is a nonenveloped double strand linear DNA virus?
Adenovirus
57
What are nonenveloped double strand circular DNA viruses?
Papillomavirus | Polymavirus
58
What are enveloped double stranded linear DNA viruses?
Herpesviruses | Poxvirus
59
What is an enveloped double stranded circular DNA virus?
Hepadnaviruses
60
What are nonenveloped single stranded positive sense RNA viruses?
Astroviruses Caliciviruses Picornaviruses
61
What are nonenveloped double strand RNA viruses?
Reoviruses | Rota viruses
62
What are enveloped single strand positive sense RNA viruses?
Togavirus Flavivirus Coronavirus
63
What are enveloped single strand negative sense linear RNA viruses?
Rhabdovirus | Paramyxovirus
64
What are enveloped single strand negative sense segmented RNA viruses?
Arenavirus Bunyavirus Orthomyxovirus
65
What are enveloped retroviruses (RNA)?
Lentivirus | Oncovirus

CMBM exam 3 (24 decks)

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