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BacT, Virology, Parasit > Virology Exam 1 > Flashcards

Virology Exam 1 Flashcards

1
Q

List the characteristics used to describe viruses

A

small, 20-300 nm, filterable
simple
obligate intracellular parasites
infectious
include important pathogens

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2
Q

what are some important milestones in veterinary virology

A

smallpox vx
transmission & vx rabies
filterability of foot/mouth dx
isolated swine flu influenza virus
electron microscopy of virus/TMV
cell culture system & poliovirus
ectromelia pathogenesis
rinderpest vx & eradication
co-evolution of virus & host
first recombinant DNA virus
identification of avian bornavirus by gene microarray method
identification of Theiler’s dx associated virus by mass sequencing method

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3
Q

3 types of virsuses

A

iscosahedral
helical
complex structure

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4
Q

enveloped viruses

A

lipoprotein outercoving of virions of some viruses, derived from cell membranes

easier to eliminate

DNA and RNA genomes

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5
Q

non-enveloped viruses

A

no lipoprotein outer covering

harder to eliminate/resistant

DNA and RNA genomes

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6
Q

helical viruses

A

enveloped RNA genome (e.g. Rhabdoviridae aka rabies)

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7
Q

define virion

A

complete virus particle

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8
Q

define capsid

A

protein shell that surrounds viral nucleic acid, protects viral genome from destructive agents, introduction of viral genome into host cells

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9
Q

define nucleocapsid

A

capsid + nucleic acid

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10
Q

define capsomers

A

cluster of proteins on capsid that make up one morphologic unit seen by e- microscopy

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11
Q

list the steps of viral replication

A
  1. attachment
  2. penetration & uncoating
  3. transcription
  4. translation
  5. replication
  6. assembly of virions & release
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12
Q

what protein is important for the attachment step of a virus to cell receptor

A

viral attachment protein (VAP)

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13
Q

describe DNA viruses

A

dsDNA or ssDNA with linear or circular DNA
low mutation rates
DNA polymerase
more durable
degraded by DNAases & heat
DNA viral inclusions are present in nucleus

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14
Q

describe RNA viruses

A

dsRNA or +, -, or ambisense (both +,-) ssRNA
higher mutation rates
degraded by RNAases, heat, formaldehyde, UV light
RNA viral inclusions present in cytoplasm

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15
Q

virus’s routes of transmission

A

skin, conjunctiva, oral cavity, respiratory tract, GI tract, urogenital tract

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16
Q

virus’s mechanisms of spread

A

viruses restricted to epithelia
subepithelial invasion, lymphatic spread
viremia
infection of other organs

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17
Q

virus’s mechanisms of spread

A

viruses restricted to epithelia
subepithelial invasion, lymphatic spread
viremia
infection of other organs

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18
Q

what factors restrict viruses to epithelia

A

specific cell receptors
temperature aspects of replications
topography of viral budding
polarization of epithelial cells
virus dependence on host cell machinery
topography of virus maturation
protected from specific host defenses

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19
Q

what organs are more commonly affected by secondary viremia

A

nasal/oral mucous membranes
brain
skin
lungs
kidney

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20
Q

what organs are more commonly affected by primary viremia

A

liver and spleen

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21
Q

define a cell-free virus

A

virus doesn’t utilize immune cells

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22
Q

define a cell-associated virus

A

virus utilizes macrophages, lymphocytes, platelets, RBC to evade immune response and infect host

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23
Q

innate immunity for viruses
-anatomic
-physiologic
-cells
-mechanisms

A

anatomic: skin, mucosa, ciliary apparatus
physiologic: lysozymes, gastric acid, bile, digestive enzymes
cells: dendritic cells, macrophages, NK cells
mechansims: interferons, cytokines, complement

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24
Q

type I IFN-alpha

A

leukocytes
antiviral

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25
Q

type I IFN-beta

A

fibroblasts epithelium
antiviral

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26
Q

type II IFN - gamma

A

T cells, NK cells
immunoregulatory

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27
Q

what do IFN cause

A

flu-like symptoms - fever, chills, nausea, malaise

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28
Q

four classic signs of inflammation

A

redness, pain, heat, swelling

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29
Q

acquired immunity

A

neutrophils, eosinophils, macrophages, lymphocytes
T cells, B cells, NK cells
Antibodies (IgG, M, A)
passive transfer

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30
Q

antibody functions

A

neutralization
opsonization
antibody-dependent cell-mediated cytotoxicity
complement activation

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31
Q

MHC I

A

CD8+ (CTL)
endogenous

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32
Q

MHC II

A

CD4+ (T helper and suppressor/reg)
exogenous

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33
Q

what do viral infections and modified live vaccines stimulate?

A

B cells (antibodies)
CTL’s

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34
Q

what do inactivated/killed viral vaccines and subunit vx stimulate?

A

B cell & T helper cell activity (cytokines)

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35
Q

what can be measured by serological testing?

A

parenteral inoculation (IV,IM,SQ) with viral vaccines due to systemic immunity

e.g. parvovirus

36
Q

how are viruses shed

A

respiratory and oropharyngeal secretions
feces
urine
skin
milk
blood
genital secretions

37
Q

type I hypersensitivity

A

anaphylaxis
IgE

38
Q

type II hypersensitivity

A

cytotoxic
IgM/IgG

39
Q

type III hypersensitivity

A

immune complex
IgG

40
Q

type IV hypersensitivity

A

cell-mediated, delayed hypersensitivity
CTLs

41
Q

autoimmunity

A

immune response directed against normal host components
primarily cell-mediated or humoral
vx-induced suspected cases
broad & directed against many organs or can be organ/antigen specific

42
Q

how do viruses induce autoimmune dx

A

exposure of hidden antigens
molecular mimicry
failure of regulatory control of immune response

43
Q

virus’s mechanisms of spread

A

viruses restricted to epithelia
subepithelial invasion, lymphatic spread
viremia
infection of other organs

44
Q

how does a virus spread from blood –> tissues

A

fenestrated/inflamed capillaries
transcytosis by endothelial cells
replication in endothelial cells
trafficking of infected lymphocytes & monocytes

45
Q

how do viruses invade the respiratory tract

A

aerosolized virus or self-inoculation of mucous membranes
replication in resp epithelium
level of tract dependent on size, temp, immunity

46
Q

how do viruses invade intestinal tract

A

ingestion or viremia
replicated in intestinal epithelium

47
Q

how do viruses invade the CNS

A

replication in blood vessels of meninges, choroid plexus, brain, spinal cord
transported across blood vessels via infected leukocytes
by CSF or neurons

48
Q

what happens if viruses invade the fetus

A

fetal death, abortion, stillbirth
congenital defects
immunotolerant carrier state
inapparent carrier state

49
Q

what other organs can viruses invade

A

liver, testis, pancreas, synovial cells

50
Q

what are dead-end organs
provide an example

A

organs that cannot shed a virus
e.g. brain

51
Q

what are the two components of viral dx

A
  1. effects of viral replication on host
  2. effects of host response on virus & host
52
Q

describe why vaccines are used

A
  1. stimulate a protective immune response (immunological memory)
  2. establish herd immunity
53
Q

Modified Live Vx
Pros

A

Pros
- best immune response, esp. cell-mediated
-few inoculations
-stimulates mucosal immunity IgA
-no adjuvants
-decreases change of hypersensitivity rxn
-induce IFN
-inexpensive

54
Q

Modified Live Vx
Cons

A

-risk of reversion to virulence
-cold storage
-inactivated by UV, heat, disinfectants
-contaminants
-cannot give to pregnant animals
-immune enhancement

55
Q

Inactivated Vx
Pros

A

stable in storage
unlikely to cause disease
unlikely to contain viable, contaminating organisms
cost effective

56
Q

Inactivated Vx
Cons

A

multiple doses
poor CMI response
large amounts of Ag
problems with disease if there is failure to completely inactivate virus
exacerbated diseases
adjuvants
vx induced tumors or grandulomas
immune disorders

57
Q

subunit vs
pros/cons

A

PROS
-specific & safe
CONS
-similar to inactivated vx

58
Q

mRNA vx
pros/cons

A

pros
-advanced technology
cons
-newer

59
Q

dna vx
pros/cons

A

PROS
-easy to administer
-expression of genes for 60 days
- pure, stable
-low cost
-no interference by maternal Ab
CONS
-insertional mutagenesis & oncogenesis

60
Q

synthetic peptide vx
pros/cons

A

pros
-safe, non-toxic, stable
cons
-expensive
-poorly immunogenic

61
Q

virus vector vx
pros/cons

A

pros
-safe
-easy to administer
-reduced replication due to gene introduction
cons
-possible disease due to vector itself
-reduced replication of the vector in unnatural host

62
Q

successful use of vaccines

A

lack of reservoir
long duration of immunity
lack of antigenic variation
safe efficacious vx
ease of administration
acceptability to client
cost-effective
appropriate storage and administer of vx

63
Q

vaccine failures

A

animal already infected
wrong virus used
non-protective antigens used
animal doesn’t respond to vx
incorrect administration
adverse rxns

64
Q

sensitivity equation

A

a/a+c = true +/total diseased
positive, possess disease

65
Q

specificity equation

A

d/b+d= total -/total non-diseased
negative, non-diseased

66
Q

inherent variability

A

variation can be caused by variation in animal subjects & reading of results by those reading them

67
Q

virus isolation (VI)

A

identification of unknown agents,
detects live virus (antigen)

68
Q

direct fluorescent antibody (FA)

A

fluorescent Ab detects antigen

69
Q

indirect FA

A

detects antigen using 2 Ab

70
Q

hemagglutination Inhibition (HI)

A

detects parvo & influenza - two important viruses that agglutinate RBC

Ab present “button” (HI)

Ab not present “lattice” (HA)

71
Q

polymerase chain reaction (PCR)

A

detects viral nucleic acids

72
Q

agar gel immunodiffusion (AGID)

A

detects antibody

73
Q

enzyme linked immunosorbent assay (ELISA) SEROLOGY

A

detects antibody

74
Q

titers

A

2-fold serial dilution of serum
detects antibody

75
Q

positive predictive value equation

A

a/a+b

76
Q

negative predictive vale equation

A

d/c+d

77
Q

prevalence _____ PPV and _____ NPV

A

increases PPV
decreases NPV

78
Q

components of validity

A

sensitivity
specificity
PPV
NPV

79
Q

screening test significance

A

sensitivity
fast, cheap

80
Q

diagnostic test significance

A

specificity
confirm clinically diseased animals

81
Q

qualities of a test
1.
2.

A
  1. precision
  2. validity
82
Q

best scenario test results

A

valid but not precise
valid and precise

83
Q

increasing sensitivity increases the likilhood of _________

A

false positives

84
Q

increasing specificity increases the likilhood of _________

A

false negatives

85
Q

components of virsuses

A

proteins & glycoproteins
nucleic acids (DNA/RNA)
lipids - envelope

86
Q

difference between structural proteins & non-structural proteins

A

structural: make up virion, protect genome, VAP for tropism, Ag that induce neutralizing Ab, CTL and Th cells, enzymes/regulatory proteins

non-structural: encoded by viral genome and expressed in infected cells, not part of virion, replication functions, host-interaction functions

87
Q

viral genome types

A

monopartite
multiparttite/segmented (can do reassortment)
diploid

BacT, Virology, Parasit (23 decks)

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