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002 - Virology > (03) Pathogenic Mechanisms of Viruses > Flashcards

(03) Pathogenic Mechanisms of Viruses Flashcards

1
Q

(Infection)

  1. For a virus to survive it must do what?
  2. Does infection always mean disease?
  3. Disease outcome = ?
  4. can same pathogen cause different disease outcomes?
  5. When we say a virus can cause disease, we mean it is a what virus? the degree to which it can cause disease is called what?
A
  1. infect the host cell
  2. no
  3. virulence X host susceptibility
  4. yes
  5. pathogenic; virulence
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2
Q

(Host Susceptibility)

(Why are some infected while others not?)

  1. genetic differences (MHC, natural/exotic)
  2. critical receptors on target cells
  3. age
  4. stage of cell differentation (Parvovirus - S-phase)
  5. body temp (fever, fish, resp tract)
  6. physiology (pregnant)
  7. immune status (treatment with cortisol - herpes)
A
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3
Q

Look at this

A
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4
Q

(entry via respiratory tract)

  1. Viruses that are what?
  2. What are seven viruses that are inhaled?
  3. The respiratory tract is lined by what?
  4. Has what that carries stuff out?
  5. Particles of what size are carried out?
  6. What happens to particles that are about 5 um large?
  7. What are NALT and BALT? do what?
A
  1. inhaled
  2. Influezna, Rhinovirus, Bovine RSV, Adenovirus, Canine Distemper, Feline Calicivirus, Parainfluenza virus
  3. epithelial cells
  4. mucocilliary escalator
  5. > 10um
  6. engulfed by alveolar macrophages
  7. nasal and bronchiole associated lymphoid tissue; provide protection to site of infection
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5
Q

(Entry through the gut)

  1. What are viruses we get by eating?
  2. Upper GI susceptible to infection?
  3. What are three things in GI that virus has to overcome to infect?
  4. What is GALT?
  5. Stable or non-stable viruses?
  6. Which virus enters via buffering of suckled milk?
  7. Which viruses infect the gut by systemic spread?
A
  1. rotavirus, coronavirus, astrovirus, parvovirus, feline panleukopenia virus, enterovirus, bovine virus diarrhea
  2. except tonsils
  3. acid, mucus, digestive enzymes (bile and pacreatic secretions)
  4. Gut associated lymphoid tissue
  5. very stable
  6. coronavirus
  7. morbillivirus and parvovirus
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6
Q
  1. What are three ways viruses can get in through skin?
  2. What are three protective features of skin?
A
  1. arthropods, bites, latrogenic (medical procedures)
  2. keratininzed, ph (low), fatty acids
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7
Q
  1. What are viruses that enter via skin?
  2. Are lesions always at the site of infection?
  3. Can systemic spread cause skin lesions?
  4. Can virus be introduced into blood supply?
A
  1. papilomavirus(es), Arboviruses, Rabies, Poxviruses, swine vesicular disease virus, FIV
  2. no
  3. yes (small pox, sheep pox, lumpy skin disease)
  4. yes
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8
Q
  1. ‘What are viruses that enter throughsexual contact?
A
  1. herpesvirus, bovine papillomavirus, equine arteritis virus, adenovirus
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9
Q
  1. What are some in utero infections?
A
  1. new castle disease virus, avial luekosis, IBR virus, blutongue virus, EHV
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10
Q

(Virus replication)

  1. What is the first hurdle for a virus to establish an infection?
  2. What dose is required to be considered and infectious dose?
  3. Does being able to infect the animal make a virus pathogenic?
  4. Viruses initially replicate where?
  5. Once established what may they do?
A
  1. replication
  2. the dose of virus needed to infect 50% of the population
  3. no
  4. entry site
  5. spread to distant organs or remain localized in tissue they entered
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11
Q

(Virus Infection: Attachment)

  1. What is the first step and most critical?
  2. Interaction that defines what?
  3. Attach via what?
  4. do some viruses have several receptors?
  5. Are they specific to host (the receptors)?
  6. What can neutralize viruses?
A
  1. attachment
  2. tropism (where the virus will replicate)
  3. receptors and surface molecules
  4. yes
  5. yes
  6. antibodies to surface antigens

(also - some examples)

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12
Q

(Virus Penetration)

  1. How does enveloped virus get into cell?
  2. non enveloped?
  3. Is injection an energy dependent process?
  4. What are some other things viruses sometimes require?
A
  1. fusion of envelope (endocytosis?)
  2. direct injection
  3. yes
  4. pH dependent (picorna), enzyme activity (rotavirus)
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13
Q

What is the eclipse period?

A
  • the period in which the virus is in the cell getting ready to replicate - but is still no ready to infect another cell
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14
Q

(Incubation vs. Infectious Period)

  1. What is the time from when the virus enters the body to the first clinical signs?
  2. Duration?
  3. Is the infectious period the same as the incubation period?
A
  1. Incubation Period
  2. Short to long (hrs to yeras)
  3. not necessarily (with some infections the animal may be infectious before symptoms start to show)
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15
Q

(Spread within the host)

1-5. What are the five ways that viruses spread within the host?

A
  1. on epithelial surfaces
  2. sub-epithelial invasion and lymphati spread
  3. blood (viremia)
  4. through cells (Macrophages, RBC, etc)
  5. through nerves
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16
Q

(Epithelial surfaces)

  1. Replicates where?
  2. What happens?
  3. Is the restriction of epithelium due to lack of virulence?
  4. Name 6 viruses that use this route
A
  1. at site of infection
  2. sequential infection of neighboring cells
  3. no
  4. orf virus, papiloavirus, infuenza, parainfluenza, most rotaviruses, coronavirus
17
Q

(Sub-epithelial invasion and lymphatic spread)

  1. Goes from subdermal region into where?
  2. Is this free virus or is it associated with cells?
  3. Is Equine Herpes Virus an example of this? Influenza?
  4. Also a couple of points he didn’t touch on

bidirectional release of virus (apical surface, basolateral membrane)

+ local inflammatory response

A
  1. bloodstream or the lymphatics
  2. can be either
  3. yes, it spreads; no it stays localized in respiratory tract
18
Q

(Viremia (virus in the blood))

  1. Is it the most effective for spread?
  2. Is it free or cell associated?
  3. what is primary viremia?
  4. What is secondary viremia?
  5. What can free virus encounter?
A
  1. yes
  2. can be either
  3. when virus travels from site of infection to organs
  4. When virus travels from organs back to site of infection to be shed
  5. vascular endothelium and macrophages
19
Q

(Viruses that travel through nerves)

  • Can travel through cranialnerves and get into brain
    1. Give me three examples
A
  1. rabies virus, bornavirus, and herpes
20
Q

(How Do Viruses Cause Disease?)

1-2 Name two ways viruses can cause disease (one with two subpoints)

3-4. Two ways the immune system is involved

A
  1. destruction of infected cells and tissue (acute or chronic - persistent infections)
  2. Cause tumors
  3. Damage to the immune system
  4. induce immune system to cause disease
21
Q
  1. What are cytocidal effects (vs. non-cytocidal)?
  2. What is a permissive cell?
  3. What is a productive infection?
A
  1. morphologic changes in cells
  2. a cell that allows viral replication
  3. When a virus is able to replicate and produce new virus
22
Q

look at this slide - he barely talked about it - but it was because he was running out of time

23
Q

(Cell destruction in acute Infection)

24
Q
  1. Does cytopathic virus = Disease?
  2. Does severity of disease always correlate with cytopathology?
  3. Do viruses cytopathic in cultured cells alwys produce signs in vivo (enterovirus)
  4. Can non-cytopathic viruses cause lethal disease?

* Rift valley fever virus may dstroy a large number of liver cells in sheep without causing clinical damage

* minor consequence in some tissues (muslces, s/c tissue) and of great importance in other tissues (brain)

A
  1. no
  2. no
  3. not always
  4. yes (rabies)
25
Q

Give me the term

  1. Virus is demonstrable continuously, whether or not there is an ongoing disease (Si Nombre Virus in Deer Mice)
  2. Virus is not demonstrable except when reactiviated (herpes)
  3. Infectious virus gradually increases during a very long preclinical phase, lead to a slow, progressive lethal disease (scrapie, HIV)
  4. Continuing replication of the virus in not involved in progression of disease (eg fetal infection with feline panleukopenia virus causes cerebellar syndrome in young cats)
A
  1. Persistent infection
  2. latent infections
  3. slow infections

4. Acute infections with late clinical manifestations

002 - Virology (14 decks)

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