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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
Q

What are some factors that allow viruses to enter cells?

A

Can use more than one receptor or many viruses use the same receptor

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26
Q

What are the most common routes of entry for a virus?

A 
Blood and bodily fluids
Insect bites 
Respiratory 
GI
Direct contact
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27
Q

What are some viruses that enter through blood or fluid?

A

CMV, EBV, HBV, HCV, HIV

28
Q

If an insect bites you, what viruses could it transmit?

A

Dengue, EEEV, WEEV, West Nile

29
Q

Oh no! You touched a surface covered in viruses! What could viruses could you get?

A

HSV, smallpox, VZV

30
Q

Viruses that can be inhaled are:

A

Small droplets: influenza, measles, smallpox, VZV
Large droplets: adenovirus, parainfluensa, parvovirus, smallpox
Direct to secretions: RSV, rhinovirus

31
Q

What viruses can be transmitted through the GI tract (facal-oral)?

A

Enteric adenovirus, HAV, norwalk virus, polio, rotavirus

32
Q

What the main routes for viral spread?

A

Hematogenous spread
Neural spread
Muliple pathways

33
Q

In hematogenous spread, what does it mean when primary replication proceeds initial viremia?

A

There are asymptomatic for prodromal symptoms (Enteric or respiratory viruses)
Dissemination to other tissues leads to amped up secondary viremia

34
Q

In hematogenous spread, what viruses travel freely or with other cells?

A

Enteroviruses, HBV, tagoviruses (free)
Rift valley fever, Colorado tick fever (RBCs)
CMV, EBV, HIV (lymph or monocytes)

35
Q

In the neural spread of viruses, where can entry happen?

A

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
Q

What are the basic steps of entry of an enveloped virus?

A

Attachment to cell receptors
Penetration of host cell by fusion protein
Merging of viral envelope and cell membrane

37
Q

What are the full steps to viral mutliplication?

A 
Attachment/ absorption
Penetration/ entry
Uncoating/ release of nucleic acid
Relication
Assembly
Release
38
Q

When is the viral titer stable?

A

During the period of attachment

39
Q

When is the viral titer unstable?

A

Eclipse phase: diassembly, transcription, translation, and genome replication

40
Q

When does the titer increase?

A

As the viral progeny are assembled and are infectious

41
Q

Which types of viruses make use of their own viral RNA polymerase for replication?

A

ssRNA+, ssRNA-, all dsRNA

42
Q

Which types of viruses use viral host RNA polymerase?

A

Hepadnavirus

Retrovirus (also needs viral reverse transcriptase)

43
Q

What viruses use viral RNA polymerase for protein synthesis?

A

ssRNA- and dsRNA

44
Q

What viruses use host RNA polymerase for protein synth?

A

Hepadnavirus, ssDNA, dsDNA

45
Q

Which viruses use host DNA polymerase for replication?

A

ssDNA

dsDNA (can also use viral DNA pol)

46
Q

During early transcription of DNA viruses what is necessary?

A

Regulatory proteins

47
Q

What is needed during late transcription of DNA viruses?

A

Structural proteins

48
Q

What type of cycle is an acute viral infection and how does it cause infection?

A

Lytic cycle
Multiple rounds of replication resulting in cell death
Many progency viruses produced and released
(ex. polio or influenza)

49
Q

What type of cycle is a chronic viral infection and how does it cause infection?

A

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
Q

What is a latent viral infection?

A

No replication until signaled
Limited to macromolecules
Genetic material: incorporates into cell or host genome
DNA virus or retrovirus

51
Q

How does a latent infection transform into an active one?

A

Malignancy of host cell
Invasive growth
Benign or cancerous growth

52
Q

In the prodrome phase of an actue viral infection what cytokine is active?

A

IFNgamma

53
Q

In the classical sign phase of an acute infection what immunoglobulin is active?

A

IgM (if primary infection)

54
Q

In the recovery phase of an acute infection what immune cells and immunoglobulin are active?

A

CD4+, CD8+, IgG

55
Q

What is a nonenveloped single stranded linear DNA virus?

A

Parvovirus

56
Q

What is a nonenveloped double strand linear DNA virus?

A

Adenovirus

57
Q

What are nonenveloped double strand circular DNA viruses?

A

Papillomavirus

Polymavirus

58
Q

What are enveloped double stranded linear DNA viruses?

A

Herpesviruses

Poxvirus

59
Q

What is an enveloped double stranded circular DNA virus?

A

Hepadnaviruses

60
Q

What are nonenveloped single stranded positive sense RNA viruses?

A

Astroviruses
Caliciviruses
Picornaviruses

61
Q

What are nonenveloped double strand RNA viruses?

A

Reoviruses

Rota viruses

62
Q

What are enveloped single strand positive sense RNA viruses?

A

Togavirus
Flavivirus
Coronavirus

63
Q

What are enveloped single strand negative sense linear RNA viruses?

A

Rhabdovirus

Paramyxovirus

64
Q

What are enveloped single strand negative sense segmented RNA viruses?

A

Arenavirus
Bunyavirus
Orthomyxovirus

65
Q

What are enveloped retroviruses (RNA)?

A

Lentivirus

Oncovirus

CMBM exam 3 (24 decks)

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