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POD > 3.1, 3.2 Virology Basics > Flashcards

3.1, 3.2 Virology Basics Flashcards

1
Q

A virus is an infectious __________________ parasite comprising ___________ surrounded by a ___________ and/or an __________ derived from a host __________________.

A

obligate intracellular; genetic material (DNA or RNA); protein coat; envelope; cell membrane

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2
Q

what protects the viral nucleic acid genome

A

protein coat

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3
Q

How do viruses replicate

A

inside host cells

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4
Q

All viruses must make __________, to be translated by ____________

A

mRNA; host ribosomes

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5
Q

T/F viruses are dependent on the infected cell ribosomes to synthesize viral proteins

A

T; this is partly why they are obligate intracellular parasites

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6
Q

T/F viruses can use the host cell to provide energy for replication, or they can use their own energy sources

A

F; they are absolutely dependent on the host to provide energy

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7
Q

Viruses are ABSOLUTELY DEPENDENT on the host for what (2)

A

1) ribosomes to translate their viral mRNA into viral proteins
2) energy for viral replication

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8
Q

What is the difference between virus and virion

A

Virus is a broad term to describe the viral particles in any stages, as well as the nucleic acids and proteins; virion refers exclusively to the physical particle in its extra-cellular phase

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9
Q

what are 2 similarities between viruses and bacteria

A

1) both have either DNA or RNA (bacteria have both)
2) both CAN be obligate intracellular pathogens (all viruses and some bacteria)

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10
Q

T/F you can see viral particles with a light microscope

A

F; however, you can see cytoplasmic or nuclear aggregates of viral particles/nucleic acids on light microscopy

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11
Q

what are the 4 basic components of viruses

A

1) viral genome (DNA or RNA)
2) proteins (structural or non-structural)
3) lipids (form the envelope of some viruses)
4) carbohydrates (glycolipids or glycoproteins)

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12
Q

what are 4 ways to CLASSIFY viruses

A

1) nature and sequence of nucleic acid
2) diameter or shape
3) symmetry of protein shell
4) presence or absence of lipid envelope

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13
Q

what 3 terms can be used to describe the symmetry of a viral protein shell

A

icosahedral, helical, complex

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14
Q

what is the outermost surface of a non-enveloped virus

A

the capsid

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15
Q

what is the outermost surface of an enveloped virus? what does it contain?

A

lipid bilayer envelope; contains viral glycoproteins

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16
Q

are enveloped or non-enveloped viruses more stable outside the host

A

non-enveloped

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17
Q

T/F non-enveloped (naked) viruses are rapidly inactivated by solvents, detergents, and bile salts

A

F; enveloped viruses are

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18
Q

are most enteric animal viruses enveloped or non-enveloped

A

enveloped

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19
Q

what are the consequences of asymptomatic or subclinical viral infections

A

persistent infection, immunity or recovery

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20
Q

what are the consequences of acute viral infection/disease

A

death, recovery or persistent infection

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21
Q

what are the consequences of chronic viral infection/disease

A

recurrent clinical disease or persistent infection

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22
Q

what are the stages of viral replication

A

1) recognition
2) attachment
3) penetration
4) uncoating
5) mRNA synthesis
6) protein synthesis
7) genome replication
8) assembly
9) lysis and release (naked) OR budding and release (enveloped)

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23
Q

what influences tissue tropism for viral infection

A

presence of cellular receptors that permit entry of the virus

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24
Q

what explains species susceptibility to viruses

A

animal species express different cell surface receptors

25
Q

receptors can be (4)

A

proteins, glycoproteins, carbohydrates or lipids

26
Q

what often determines the mechanism of virus entry into the cell

A

the nature of the receptor

27
Q

describe the lock and key fashion of viral entry into host cells

A

viral proteins/glycoproteins interact with host receptors/co-receptors

28
Q

what are the 3 methods of viral entry into a cell

A

1) direct penetration
2) receptor-mediated endocytosis
3) fusion

29
Q

what virus types enter a cell by receptor-mediated endocytosis

A

all non-enveloped and some enveloped

30
Q

what virus types enter a cell by fusion

A

enveloped viruses

31
Q

what mediates fusion

A

1+ virion surface glycoproteins

32
Q

on what two membranes can fusion occur

A

PM or endosomal membrane

33
Q

T/F fusion proteins can be native fusion competent or require a conformational change

A

T

34
Q

what is the fusion peptide made of

A

hydrophobic amino acids

35
Q

fusion allows the creation of a ____________ that facilitates release of viral ____________ into the cytoplasm

A

fusion pore; nucleocapsids

36
Q

what is uncoating

A

when the virus genome separates from the capsid proteins

37
Q

with few exceptions, RNA viruses uncoat in the ____________ and DNA viruses uncoat in the ___________

A

cytoplasm; nucleus

38
Q

genome replication is needed to produce (2)

A

mRNA for translation of proteins and a genome copy for the progeny virus

39
Q

what is unique about - sense RNA virus polymerases

A

they encode RNA dependent RNA polymerase

40
Q

what type of viruses require RNA dependent RNA polymerase

A

negative sense RNA viruses

41
Q

T/F DNA viruses use cellular polymerases to replicate their genome

A

T

42
Q

assembly takes place through __________ and ___________ interactions

A

protein-protein; protein-genome

43
Q

T/F assembly can take place as a separate or concurrent step to release

A

T

44
Q

what are inclusion bodies

A

sites of viral multiplication in an infected cell; aggregates of replication intermediates

45
Q

T/F inclusion bodies can be in the cytoplasm or the nucleus

A

T

46
Q

do RNA or DNA viruses have higher mutation rates

A

RNA

47
Q

mutations are responsible for

A

antigenic drift

48
Q

reassortment of segmented genomes is responsible for

A

antigenic shift

49
Q

what types of viruses can undergo antigenic shift

A

segmented RNA viruses

50
Q

viral pathogenesis involves (4)

A

1) entry
2) replication
3) lesions in organs affected
4) dissemination to the next host

51
Q

what is the incubation period

A

part of infection where you are asymptomatic; before clinical disease

52
Q

transmission of a virus depends on the nature of (2)

A

1) virus
2) host

53
Q

what are the 5 ways that viruses result in disease

A

1) tissue/cell damage
2) inflammation
3) transformation
4) secondary bacterial infection
5) immunosuppression

54
Q

what are the best types of vaccines

A

RNA vaccines

55
Q

what are some potential targets of antivirals

A

virus-encoded enzymes; processes critical to viral replication

56
Q

T/F an antiviral is ok as long as it blocks replication slightly

A

F; must block completely or resistance

57
Q

when should you give an antiviral

A

immediately after infection or appearance of clinical signs

58
Q

T/F antivirals are uncommon in food animal medicine

A

T

59
Q

what is characteristic of cytopathic effect (4)

A

1) rounding/clumping of cells
2) fusion of cells
3) syncytia (giant cells)
4) vacuolation

POD (18 decks)

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