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Virology > Replication-Pathogenesis (Ex1) > Flashcards

Replication-Pathogenesis (Ex1) Flashcards

1
Q

What is a permissive cell?

A

a cell in which a virus is able to replicate, the cell machinery supports replication of the virus

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2
Q

What is a non-permissive cell?

A
  • cells in which a factor or factors necessary for viral reproduction are not present
  • or one detrimental to reproduction is present
  • absence of appropriate receptors
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3
Q

What is MOI?

A
  • multiplicity of infection

- refers to the number of virions that are added per cell during infection

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4
Q

What is burst size?

A

number of infectious virions released per average cell

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5
Q

What is the eclipse period of the virus growth curve?

A
  • time interval between uncoating and appearance of virus intracellularly
  • not infectious virus can be detected during this period
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6
Q

What is the latent period of the virus growth curve?

A
  • the time before new infectious virus appears in the medium

- from uncoating to just before the release of the first extracellular virions

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7
Q

What are the steps of virus replication?

A
  • attachment
  • penetration
  • uncoating
  • synthesis of viral components
  • assembly and maturation
  • release in large numbers
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8
Q

Clathrin-Mediated Endocytosis

A
  • virion attaches to host receptor which induces binding of adaptor protein
  • adaptor proteins bind to clathrin
  • clathrin multimerizes to form a pit
  • Dynamin pinches off pit to form vesicle
  • clathrin detached from vesicle
  • viral contents delivered to endosomes
  • pH changes to acidic in endosome, viral genome released into cell
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9
Q

What two functions must the parent virus do once it enters the cell?

A
  • generate multiple copies of DNA/RNA to create progeny

- synthesize viral proteins for capsid and successful replication

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10
Q

Replication of double-stranded DNA

A
  • using DNA-dependent RNA polymerase, the negative strand is copied to create a positive strand of RNA (mRNA), which makes the viral proteins
  • The positive strand makes a negative strand and vice versa
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11
Q

What is capping?

What is its function?

A
  • addition of 7-methylguanosine to the 5’ end
  • stability of mRNA
  • binding of mRNA to ribosomes
  • mark mRNA as “self”
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12
Q

What are exons?

What are introns?

A
  • exons code for amino acids
  • exons joined together during splicing
  • introns do not code for amino acids
  • introns are removed during splicing
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13
Q

What is Constitutive Splicing?

A

every intron is spliced out

every exon is spliced in

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14
Q

What is Alternative Splicing?

A

all introns sliced out

only selected exons spliced in

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15
Q

What is Monocistronic mRNA?

A
  • encodes one polypeptide

- will translate into a single protein

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16
Q

What is Polycistronic mRNA?
Endonuclease?
Translation?

A
  • encodes several polypeptides
  • endonuclease chops it into monocistronic mRNAs, which undergo translation to form functional proteins
  • translation forms a polyprotein, which is chopped into individual proteins by protease
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17
Q

What is a Disseminated Infection?

A

when the infection spreads beyond the primary site of infection

18
Q

What is Viremia?

A

the presence of virus in the blood

19
Q

What is Passive Viremia?

A
  • direct inoculation or virus in blood

- bug bite or contaminated syringe

20
Q

What is Primary Viremia?

A

initial entry of virus into the blood after infection

21
Q

What is Secondary Viremia?

A

virus has replicated in major organs and once more entered the circulation

22
Q

What is Active Viremia?

A
  • viremia following initial virus replication in host

- release or virions from initial site of replication into the blood

23
Q

What happens to viruses that are free in plasma?

Cell-associated in the blood?

A
  • free in plasma: short duration

- cell-associated: prolonged viremia, multiple in macrophages or lymphocytes

24
Q

Virus Interactions with Macrophages (5)

A
  • failure to phagocytose infected cells
  • virions transferred to adjacent cells
  • virus enters monocyte, carried across blood vessels
  • virions phagoctyosed and destroyed
  • virions phagocytosed and replicated inside macrophages
25
Q

What is a Neurotropic Virus?

A

virus that can infect neural cells

26
Q

What is a Neuroinvasive virus?

A

virus that enters the CNS after infection of a peripheral site

27
Q

What is a Neurovirulent virus?

A

virus that causes disease of nervous tissue

- neurological symptoms and often death

28
Q

What is Retrograde spread of virus?

A
  • travels opposite direction of nerve impulse

- invades axon terminals, then spreads to dendrite or cell body, and then to another axon terminal

29
Q

What is Anterograde spread of virus?

A
  • travels in the direction of nerve impulse

- invades dendrites or cell bodies, then spreads to axon terminals

30
Q

Features of Localized Acute Infections

site, incubation, viremia, duration, IgA

A 
site: portal of entry
incubation period: short
viremia: no
duration of immunity: variable, may be short
secretory IgA: very important
31
Q

Features of Systemic Acute Infections

site, incubation, viremia, duration, IgA

A 
site: distant sites
incubation period: long
viremia: yes
duration of immunity: mostly life long
secretory IgA: not important
32
Q

What is Tropism?

What are Pantropic Viruses?

A

the specificity/affinity of a virus for a particular host tissue
- Pantropic: can replicate in more than on host organ/tissue

33
Q

What is Disseminated Intravascular Coagulation?

A
  • widespread activation of the clotting cascade resulting in formation of blood clots in small blood vessels
34
Q

What is Teratogenesis?

A

the abnormal development of the embryo or fetus

35
Q

What is Immunopathology?

A
  • tissue injury mediated by host immune reponse
36
Q

Describe an Inapparent Infection

A
  • clinical signs not evident
  • few cells infected
  • stimulate host immune response
  • possible source of virus spread
37
Q

Describe an Acute Infection

A
  • short-term
  • very severe clinical signs
  • rapid clearance from immune response
38
Q

Describe a Persistent Infection

A
  • virus remains in the body, may not have clinical signs or disease
  • may develop late, or may not develop
  • cells can turn cancerous
  • not cleared by adaptive immune response
39
Q

Describe a Latent Infection

A
  • virus not demonstrable until reactivation occurs
  • reactivation stimulated by immunosuppression or cytokine/hormone, or stress
  • Virus goes dormant
40
Q

Describe a Chronic Infection

A
  • virus continuously shed or present in infected tissue

- host immunity unable to clear virus from acute infection

41
Q

Describe a Slow Infection

A
  • prolonged incubation period
  • quantities of virus gradually increase during preclinical phase
  • slow progressive lethal disease

Virology (15 decks)

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