Ch32-33 Corona- picorna- arbo Flashcards

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1
Q

describe coronaviruses

A
  • positive strand RNA viruses
  • enveloped
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2
Q

what is the agent of COVID 19

A

SARS-CoV-2

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3
Q

what is MERS and what is the mortality rate

A
  • middle east respiratory syndrome
  • viral respiratory illness
  • 30-40% mortality rate
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4
Q

what is the coronavirus life cycle

A
  • 1st phase of translation: includes an RNA dependent RNA polymerase
  • 2ns phase of translation
  • acquire viral envelope by budding of nucleocapsid into the ER
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5
Q

what are the clinical presentations of people with SARS CoV 2

A

-asymptomatic
- mild illness
- moderate illness
- severe illness: less than 94% O2, PaO2/FiO2 less than 300 mmHg, less than 30 breaths per minute
- critical illness: respiratory failure, septic shock, multiple organ dysfunction

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6
Q

explain the viral entry mechanism of SARS coV 2

A

RBD of spike protein binds to ACE2

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7
Q

what does ACE2 do

A

lowers BP

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8
Q

what does TMPRSS2 do

A

transmembrane protease, serine 2 cleaves spike protein

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9
Q

what are the proposed mechanisms of COVID 19 infection

A
  • direct cytotoxic effect
  • dysregulatino of RAAS
  • endothelial cell damage and thromboinflammation
  • dysregulated immune response
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10
Q

describe picornaviruses

A
  • positive stranded RNA viruses
  • do not have envelope
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11
Q

what is the habitat of enteroviruses and what are they types

A
  • GI tract
  • poliovirus and coxsackievirus
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12
Q

what are the types of picornaviridae

A
  • enterovirus
  • hepatovirus
  • parechovirus
  • rhinovirus
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13
Q

what are the types of enteroviruses

A
  • coxsackievirus A
  • cocksackievirus B
  • echovirus
  • enterovirus
  • poliovirus
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14
Q

what is the habitat for rhinoviruses

A

respiratory epithelium

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15
Q

describe enteroviruses

A
  • very stable in food and water
  • stable at pH3 (stomach)
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16
Q

describe rhinoviruses

A
  • sensitive to acidic pH
  • replicate poorly above 33 C
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17
Q

describe organ involvement for enteroviruses

A
  • only occurs if viremia persists
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18
Q

what are the 3 types of polioviruses and what are the differences between the types

A
  • PV1, PV2 and PV3
    capsid differences
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19
Q

what is the transmission of poilioviruses

A

fecal-oral

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20
Q

what is the poliovirus receptor

A

CD155

21
Q

what is the poliovirus IRES and what does it stand for

A
  • internal ribosome entry site
  • serves as the cap of the viral RNA, promoting translation of viral RNA into viral proteins
22
Q

because of IRES where does translation start

A

far from the 5’ end of poliovirus RNA

23
Q

how does poliovirus affect the CNS

A
  • flaccid paralysis: destruction of anterior horn cells in spinal cord
  • bulbar poliomyelitis: respiratory muscle paralysis
24
Q

what are the factors that increase the severity of poliovirus infections

A
  • physical exertion and trauma
  • tonsilectomy
25
Q

describe the poliovirus vaccine

A

live oral vaccine (Sabin) mimics the normal infection process of poliovirus

26
Q

what does group A coxsackieviruses cause

A

-aseptic meningitis
- herpangina: sudden fever, vesicles on tonsils and palate

27
Q

what does coxsackievirus type A16 cause

A

hand, foot and mouth disease

28
Q

what does group B coxsackievirus cause

A
  • heart (myocarditis)
  • respiratory tract (pleurodynia)
  • mucous membranes of eye ( hemorrhagic conjunctivitis)
29
Q

what accounts for 50% of the common cold cases

A

rhinoviruses

30
Q

what is the mechanism of action of rhinoviruses

A

binds to respiratory endothelial cells via ICAM-1 or VLDL receptor

31
Q

describe rhinoviruses

A

acid sensitive
33 C optimum for replication
- no tissue destruction

32
Q

what are the complications of infections of rhinoviruses

A

sinusitis, otis media
- worsening asthma

33
Q

why are vaccine prospects poor for rhinoviruses

A

too many variants

34
Q

what are arboviruses transmitted by and where do they multiply

A
  • arthropods
  • in tissues of vector, without producing disease
35
Q

describe arbovirus infections in humans

A
  • viremia of short duration
  • virus levels in blood are low
36
Q

what are the species that transmit arbovirus infection

A
  • togaviridae
  • flaviviridae
  • eastern equine ecephalitis
  • western equine encephalitis
  • St. louis encephalitis
  • west nile
  • zika
37
Q

descride togaviruses

A
  • plus stranded RNA
  • enveloped
38
Q

describe togavirus infection

A
  • 2 phases of translation
  • first produce early proteins and then late proteins
  • like coronavirus
39
Q

describe rubella virus

A
  • member of togavirus family but not arthropod borne
40
Q

what does rubella cause

A

german measles

41
Q

describe flaviviruses

A

-plus stranded RNA
- enveloped

42
Q

what does zika virus cause

A
  • mostly mild illness except congenital infection which leads to microcephaly
43
Q

how is zika virus transmitted

A

mosquitos and sexually

44
Q

what is dengue fever and what causes it

A
  • most prevalent disease caused by arboviruses
  • does not cause significant mortality
  • caused by a flavivirus
  • mosquitos
45
Q

what happens upon reinfection of dengue fever

A
  • dengue hemorrhagic shock
  • dengue shock syndrom e
46
Q

what is the first human disease found to be caused by a virus

A

yellow fever

47
Q

what causes yellow fever

A
  • a flavivirus
  • a mosquito
  • human to human
  • monkey to human
48
Q

what does yellow fever cause in severe cases

A
  • jaundice
  • lesions and hemorrhaging of infected organs
49
Q

what is the treatment for yellow fever

A

attenuated live vaccine and insect control measures