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Microbiology > Exam2Lec6IntrotoVirology > Flashcards

Exam2Lec6IntrotoVirology Flashcards

1
Q

What are viruses?

A

A collection of genetic info (RNA or DNA) inside a protective protein coat

OBLIGATE INTRACELLULAR PATOGEN

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2
Q

Viruses cannot do what?

A

DO NOT encode ribosome

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3
Q

Since Viruses cannot encode ribosomes thus:

A

cannot divide and replicate on their own

needs host cell machinery to replicate

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4
Q

What are the 6 virus classifications

A

genetic content

structure

host range

replication strategy

Disease

Containment level

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5
Q

What is genetic content in classification?

A

DNA vs RNA

Signal stranded (ss) vs Double stranded (ds)

Segmented and non-segmented

Positive sense and negative sense

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6
Q

What is structure in classification

A

Icosahedral vs helical

Enveloped vs. non enveloped

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7
Q

What is host range in classification

A

Which species can be infected by the virus

Tropism: which cells or cell type are infected by the virus

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8
Q

What is tropism

A

which cells or cell type are infected by the virus

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9
Q

List out the ICTV classification

A

order: general genome organization

Family subfamily: genome organization/gene arrangement

genus subspecies:genome organization/size and sequence homologies

Species subspecies : ecological niche

Serotype: antigens

Strain : geography

Isolate

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10
Q

What is the typical case of RNA viruses

A

Usually single stranded genomes

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11
Q

what are the two genomes in RNA viruses, explain them

A

Plus stranded genome
-mRNA sense=translated
***directly translated to make proteins
-mostly isosahedral

Minus stranded genome
- genomic RNA : transcribed to make mRNA
*** templates of RNA so they need to be transcribed first then translated
-ALL helical capsizes

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12
Q

Explain + stranded

A

-mRNA sense=translated
***directly translated to make proteins
-mostly isosahedral

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13
Q

Explain - stranded

A
  • genomic RNA : transcribed to make mRNA
    *** templates/compliments of RNA so they need to be transcribed first then translated
    -ALL helical capsizes
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14
Q

what is the typical case of DNA viruses genome?

A

Usually double stranded genomes

DNA virus genomes are linear or circular

Most have icosahedral capsid symmetry

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15
Q

Explain non enveloped

A

Consist of a genome (n.a) surrounded by protein shell (capsids)

VERY STABLE to environment (days to weeks)

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16
Q

What are examples of non-enveloped viruses

A

poliovirus

adenovirus

foot and mouth disease virus

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17
Q

Explain enveloped viruses

A

consist of capsid (nucleocapsid ) surrounded by a lipid bilayer that has viral proteins protruding from it

SENSITIVE to environment (hours to days)

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18
Q

example of enveloped virus

A

Influenza virus

19
Q

Explain icosahedral capsids

A

Remember usually + stranded

  • CLOSED structure with FIXED volume

Subunits self assemble and form stable interacting within clusters

Larger viruses have scaffolding proteins
**keep genome stable as they build

20
Q

Isosahedral capsid a closed or open structure and fixed or variable volume?

A

Closed and fixed

21
Q

Explain helical capsids

A

Remember: (-) stranded

Open conformation ie. variable volume

Rodlike or filamentous structures

Generally ENVELOPED VIRUSES (use budding to acquire envelope)

22
Q

Helical capsid a closed or open structure and fixed or variable volume?

A

open and variable volume

23
Q

Explain helical capsid assembly and budding

A
  1. individual capsomers associate to form disc
  2. disc translates to form a LOCKWASHER structure, by stacking on each other forming beginning of helix
  3. Viron RNA loop feeds through central hole to continue helix elongation
  4. Buds into lipid bilayer of cell
24
Q

Explain stages of replication

A

Initial infection: virus low but then builds

Local immunity (IFN) are kicked in to kill virus

Then we get symptoms from our reaction to virus

25
Q

Why do we get symptoms from a virus

A

It is our own immune reaction to the virus causes the symptoms

26
Q

What is an incubation period

A

time between initial infection and symptoms

27
Q

Acute infection is followed by viral clearance

explain this

A

either localized or disseminated
ultimately eradicated
** no more virus left in body

28
Q

What are examples of acute infection flood by viral clearance

A

colds, rest intections
***rhinoviruses, coronaviruses

Variola (smallpox)

Influenza

29
Q

Acute infection followed by latent infection

A

initial infection and apparent clearances

viral genomes maintained in specific tissues, cell types

Reactivation by physiological response to external stimuli

30
Q

what are virus examples of Acute infection followed by latent infection

A

HERPES SIMPLEX VIRUS (HVS-1)

31
Q

Explain the acute infection followed by latent infection in HVS-1

A

initial infection in epithelium (oral tissues)

Spread to neurons and maintenance of genomes in cell bodies

Reactivation by responses to stress

32
Q

Explain acute infection followed by chronic infection

A

initial infection and partial clearance

persistent infection and production of virus

33
Q

What are example viruses of acute infection followed by chronic infection

A

HIV and Tumors (cancer)

34
Q

What are the 3 containment levels

A

Category A, B, C

35
Q

Explain Cat A

A

Early disseminated or transmitted person to person

cause high mortality with the potential for major public health impact

might cause public panic and social disruption

require special action for public health preparedness

36
Q

What is examples of cat A

A

smallpox and viral hemorrhagic fevers

37
Q

Explain cat B

A

moderately easily to disseminate
cause moderate morbidity and low mortality

rewrite specific enhancements of CDC’s diagnostic capacity and enhanced disease surveillance

38
Q

What an example of cat B

A

encephalitis viruses

39
Q

Explain cat C

A

readily available

easy to produce and disseminate

potential for high morbidity and mortality and major health impact

40
Q

what is an example of cat C

A

emerging viruses

41
Q

What are the containment levels

A

endemic

epidemic

pandemic

42
Q

Endemic

A

continuous transmission within a population
ex: flu

43
Q

epidemic

A

peaks of disease above baseline or expected rate

44
Q

pandemic

A

worldwide epidemic

Microbiology (18 decks)

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