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Corona-picorna-arbo viruses Flashcards

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1
Q 
corona
RNA/DNA?
strand?
envelope? 
agent of
A

+ strand RNA viruses
enveloped
SARS-CoV-2 is agent of COVID-19

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2
Q

what causes up to 30% common colds

A

corona virus

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3
Q

• SARS-CoV is agent of:

A

severe acute respiratory syndrome (SARS)= atypical pneumonia

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4
Q

middle east respiratory syndrome (MERS)
caued by?
mortality?
from?

A

caused by corona too
30-40 mortality
zoonoitc

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5
Q

corona virus life cyle

A
  1. adsorbed- spike pro bind receptor
  2. virus uncoated/ + RNA undergoes 1st translation= polyproteins formed and proteolysis occurs to form non-structural proteins and an RNA dependent RNA polymerase
  3. replicate transcriptase complex forms
  4. transcription and RNA replication occur
  5. products assemble to form nucleocapsid
  6. acquire membrane from budding at ER
  7. follow exocytosis path
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6
Q

clincal presentation of SARS Cov-2 infection

different severity?

A

asymptomatic

mild: sore throat, cough
moderate: some lower respiratory disease, lower O2
severe: SpO2 under 94%, PaO2/FiO2 under 300mmHg, respiratory freq under 30 breaths a minute/ lung infiltrates over 50%
critical: respiratory failure, spetic shock, organ dysfunction

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7
Q

entry of SARS-Cov 2 into cell

A

Spike protein will bind ACE2

spike then cleaved by TMPRSS2

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8
Q

effects of SARS CoV 2 entry

A

direct cytotoxic effect

dysregulation of RAAS due to downregulated ACE2: decreased cleavage of angiotensin I

endothelial cell damage and thromboinflammation

dysregulated immune response: virus can inhibit interferon signaling, t cell lyphodepletion, and production of inflammatory cytokines

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9
Q

COVID only effect pulmonary?

A

no, multiple systemic effects

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10
Q

Picornaviruses
DNA/RNA
envelope?

A

+ stranded RNA

no envelope

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11
Q

Picornaviruses classes

A
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12
Q

enteroviruses
habitat
includes what viruses?

A

habitat = gastrointestinal tract
include: poliovirus and coxsackievirus
also echoviruses - enteric cytopathic human orphan viruses

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13
Q

rhinoviruses habitat

A

respiratory epithelium

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14
Q

why would enteroviruses be in GI tract?

A

very stable in food and water

also stable at pH 3 (stomach)

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15
Q

why are rhinoviruses confined to the respiratory tract?

A

Sensitive to acidic pH

Replicate poorly above 33 C

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16
Q

enterovirus replication occurs where?

organ involvement

A

in oropharynx/intestines then to lymphoid tissues, can progress to viremia
organ involvement only occurs if viremia persists

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17
Q

where do rhino viruses replicate

A

upper respiratory tract

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18
Q

poliovirus, types?
genome
symmetry

A

3 antigenic types: PV1, PV2, PV3= Capsid differences between types
plus strand RNA genome 7500 nt in length
Icosahedral capsid

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19
Q

Poliovirus replication/life cyclce

A
  1. adherence via virus binds CD155 receptor, penetrance
  2. +RNA in the cell
  3. translation occurs= viral proteins made, includes a RNA dependent RNA poly
  4. replication of RNA occurs, + and - strands made (- used to make more positive strands)
  5. proteins and RNA packaged into nucleocapsid and released, cell destroyed via lysis NO ENVELOPE FORMED
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20
Q

danger of polivirus RNA alone

A

alone even this can cause infection

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21
Q

polio as a lytic virus

A

lytic virus - destruction of host cells virus is shed into stool
(up to 10,000 virus per infected cell) even weeks to months after symptoms gone

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22
Q

transmission polio virus

A

fecal oral

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23
Q

Poliovirus IRES

difference in start site due to this?

Study These Flashcards
A

Internal Ribosome Entry Site
IRES serves as the “cap” of the viral RNA, promoting translation of viral RNA into viral proteins

Because of IRES, translation starts far from the 5’ end of
poliovirus RNA (normal mRNA translation starts near 5’ end)
24
Q

pathogenesis of polio diagram

25
clinical manifestations of polio at CNS? most severe from? factors increasing severity?
central nervous system disease flaccid paralysis results from destruction of anterior horn cells in spinal cord bulbar poliomyelitis most severe form: respiratory muscle paralysis (medulla oblongata) ~25% mortality factors increasing severity of poliovirus infections: physical exertion and trauma tonsillectomy
26
Poliovirus vaccines:
Live oral vaccine (Sabin) mimics the normal infection process of poliovirus Killed parenteral vaccine (Salk) only generates serum antibodies
27
immune result of the live oral vax
elevated serum IgG increased nasal IgA increased duodenal IgA inital increased IgM
28
immune result to the killed parenteral vax
elevated serum IgG | initial increased IgM
29
nonpolio enteroviruses (EVD-68) are associated with what new disease?
acute flaccid myelitis
30
Coxsackieviruses groups
a and B
31
group A coxsackieviruses cause what? | type A16?
aseptic meningitis herpangina: sudden onset of fever vesicles/ulcers on tonsils and palate coxsackievirus type A16: hand, foot, and mouth disease blisters on hand, feet, and palate
32
group B coxsackieviruses targets/diseases?
heart (myocarditis) respiratory tract (pleurodynia) mucous membranes of eye (hemorrhagic conjunctivitis)
33
Rhinoviruses # serotypes responsible for how much of the common cold bind to what cells/how replication similar to what other virus? sensitive to? optimal temp? tissue destruction?
~100 serotypes account for ~1/2 the cases of the common cold bind to respiratory epithelial cells via ICAM-1 (most) or VLDL receptor (some) replication details very similar to poliovirus Acid sensitive and 33oC optimum for replication no tissue destruction
34
complications with rhinovirus infections
sometimes infection has complications: secondary infections with bacteria sinusitis, otitis media worsening of asthma (assoc. with 50% of attacks)
35
vax prospects of rhinovirus
poor, too many serotypes
36
Arboviruses transmitted by? multiply where? humans are what kind of host?
viruses transmitted by arthropods multiply in tissues of vector, often without producing disease For many arboviruses humans are “dead-end” hosts: viremia of short duration and virus levels in blood are low
37
togavirus disease caused vector geogrpahic distribution
encephalitis mosquito eastern and western US
38
flavivirus disease caused vector geogrpahic distribution
encephalitis mosquito North america
39
dengue disease caused vector geogrpahic distribution
fevers/hemmorhages mosquitos tropics
40
yellow fever disease caused vector geogrpahic distribution
hemorrhagic fever mosquito africa, central and south America
41
west nile disease caused vector geogrpahic distribution
encephalitis mosquito worldwide
42
zika disease caused vector geogrpahic distribution
encephalitis, birth defects mosquito africa; recently to americas
43
Togaviruses genome envelope?
plus stranded RNA (single linear molecule) | enveloped
44
Togavirus replication
2 phases of translation -first produce early proteins and then late proteins - like coronavirus 1. bind receptors/ internalized 2. nucleocapsid released into cyto 3. ribo bind + RNA 4. translate poly proteins, cleaved 5. cleavage includes a polymerase to transcribe the genome into a negative-sense RNA template. 6. The template is used to produce a full-length 42S positive-sense mRNA genome and a late 26S mRNA for the structural proteins. 7. viral assembly 8. budding from membrane to acquire capsule
45
Rubella virus member of what family? arthopod borne?
Member of Togavirus family Rubivirus genus but not arthropod-borne
46
rubella causes?
Rubella = German measles one of the 5 childhood exanthems (along with measles, roseola, chickenpox, and fifth disease)
47
``` rubella entry and spread where it enters? spreads to? what can block viral transfer/ viremia? immunologically def pregnancies? ```
Rubella enters and infects the nasopharynx and lung and then spreads to the lymph nodes and monocytemacrophage system. The resulting viremia spreads the virus to other tissues and the skin. Circulating antibody can block the transfer of virus and prevent primary and secondary viremia (prevent involvement of skin/placenta) In an immunologically deficient pregnant woman, the virus can infect the placenta and spread to the fetus.
48
Flaviviruses genome? envelope?
plus stranded RNA (single linear molecule) | enveloped
49
flavivirus life cycle/replication
1. virus adherence/ penetrance 2. disassembly in endosome- RNA released 3. polyproteins translated> RNA dependent RNA poly 4. RNA replicated 5. viral assembly and budding into ER- ACQUIRES MEM HERE 6. exocytosis cycle and release of virus
50
Disease syndromes of togaviruses and flaviviruses | immune protection?
Primary viremia may be associated with mild systemic disease, Most infections are limited to this. If sufficient virus is produced during the secondary viremia to escape immune protection and to reach critical target tissues, severe systemic disease or encephalitis may result. For dengue virus, rechallenge with another strain can result in severe dengue hemorrhagic fever (DHF), which can cause dengue shock syndrome (DSS) because of the loss of fluids from the vasculature.
51
zika virus is what kind of virus
flavivirus
52
Zika virus causes? | transmitted by?
(a Flavivirus) mostly mild illness (Zika fever) except for congenital infection of fetus, which leads to microcephaly and other birth defects transmitted by mosquitos from person to person (most common), possibly sexual Aedes aegypti mosquito
53
``` Dengue fever caused by? prevalence? mortality? transmission? ```
caused by a Flavivirus most prevalent disease caused by arboviruses, does not cause significant mortality generally not a zoonosis: transmitted by mosquitos from person to person
54
dengue fever when partial immunity exists due to prior infection virus will form? effect of this? memory t cells role? result?
dengue hemorrhagic shock (DHS)/ dengue shock syndrome (DSS) due to immune enhancement virus forms immune complex/readily enter macrophages= increases viral load Activates memory T cells, which release cytokines and initiate hypersensitivity reactions. These reactions cause weakening and rupture of vasculature, internal bleeding, loss of plasma
55
Yellow Fever caused by? historical? spread routes?
``` caused by a Flavivirus • historical importance – first human disease found to be caused by a virus – first viral disease confirmed to be spread by insect vector – Mosquito: Aedes aegypti • spread by two methods (via mosquito) – human to human – monkey to human ```
56
clinical manifestations of yellow fever (severe cases)
* jaundice | * lesions and hemorrhaging of infected organs
57
yellow fever vax
attenuated live vaccine and insect control measures

microbiology (42 decks)

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