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Microbiology > 4.37 > Flashcards

4.37 Flashcards

1
Q

Viral Gastroenteritis (3)

A

– Inflammation of stomach or intestines
– important disease of infants and children
– leading cause of childhood death in developing
countries

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2
Q

etiologic agent: Rotavirus, Group A
genome:
medical significance:

A

segmented dsRNA

major cause of diarrhea in children 6-24 months

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3
Q

etiologic agent: rotavirus, Groups B & C

genome:

A

segmented dsRNA

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4
Q

etiologic agent: norovirus
genome:
medical significance:

A

(+) ssRNA

major cause of diarrhea outbreaks in children and adults

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5
Q

etiologic agent: sapovirus

genome:

A

(+) ssRNA

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6
Q

etiologic agent: enteric adenovirus

genome:

A

linear dsDNA

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7
Q

etiologic agent: astrovirus

genome:

A

(+) ssRNA

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8
Q

etiologic agent: aichi virus

genome:

A

(+) ssRNA

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9
Q

~–% of diarrhea cases still have unknown etiology

A

50

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10
Q

1st virus identified from stool samples by electron microscopic examination (1972)

A

Norwalk

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11
Q

Rotaviruses are members of the — family

A

Reovirus

Respiratory Enteric Orphan viruses

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12
Q

Rotaviruses (4)

A

Nonenveloped
Inner and outer capsids
RNA-dependent RNA polymerase
Genome = 11 segments of double-stranded RNA (dsRNA)

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13
Q

— of infected cells

A

Lysis

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14
Q 
Rotaviruses
characteristics (3)
A

potentially fatal dehydration
fecal-oral transmission
watery-diarrhea

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15
Q

Rotaviruses

fecal-oral transmission

A

acid stability conferred by double capsid structure
up to 1012 virus particles per ml stool
as few as 10 virus particles can cause infection

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16
Q

Rotaviruses

watery-diarrhea

A

virus produces an enterotoxin
binds integrins; signaling results secretion of chloride and water
infected gut epithelial cells destroyed & replaced by immature epithelial
cells (reduced uptake of ions, water; less absorption of foods molecules
(carbs))

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17
Q

Rotaviruses

detection

A

Group A most common type in United States

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18
Q

Rotaviruses

tx

A

Rotavirus vaccine for infants (>75% effective)

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19
Q 
Noroviruses
characteristics (3)
A

positive strand RNA genome
~7,500 bases in length
Naked capsid virions

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20
Q

Noroviruses

replication

A 
Replication similar to
picornaviruses (poliovirus)
except 2nd phase of
translation involves
subgenomic RNAs (like
coronaviruses).
- Has a 5VPg protein on RNA
(like picornaviruses)
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21
Q 
Adenovirus 
characteristics (3)
A

linear double-stranded DNA genome
nonenveloped
icosahedral capsid

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22
Q

adenovirus
•viral nucleoprotein complex
enter

A

cell nucleus

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23
Q

Adenovirus gene expression
— regulation
pre-early, early, late genes

A

temporal

24
Q

—- regulators
produced during one phase
act to promote transcription
of genes of subsequent phase

A

transcriptional

25
Q

Adenovirus DNA replication

A

only one of the 2 DNA strands is copied at each replication fork
no discontinuous replication (lagging strand replication)
priming is by a viral protein, pTP (preterminal protein)

26
Q

Adenovirus infections

widespread: —% of all viral infections

A

5-10

27
Q

Adenovirus infections

symptoms

A

usual symptoms resemble common cold

28
Q

Adenovirus infections

vaccine

A

Vaccine (live virus) given to new military recruits

targets serotypes 4 and 7

29
Q

disease: acute respiratory disease (ARD)

adenovirus serotypes: (2)

A

4, 7

30
Q

adenovirus

Mechanisms for evasion of host defense

A 
block MHC class I mRNA production
block transport of MHC class I proteins to the cell surface
viral E3gp19K protein does this (see next slide)
results in block of killing by cytotoxic T cells
31
Q

Adenovirus drives the host cell into cell division (3)

A

necessary for adenovirus to replicate (needs cellular S phase factors)
Adenovirus E1a and E1b proteins interfere with cell division controllers
Viral infection can potentially drive a cell toward a cancerous state

32
Q

Adenovirus E1a and E1b proteins interfere with cell division controllers
E1b sequesters —
E1a sequesters —

A

p53

Rb (retinoblastoma protein)

33
Q

Example: DNA damage during G1

A

P53 recognizes DNA damage and activates P21 (p53 recognizes certain types of DNA mismatches)
P21 binds and inactivates the cyclin-CDK complex which has already begun to be produced in
response to different signals
DNA repaired, p53 decreases, P21 no longer blocks cyclin-CDK, cell cycle progression

34
Q

P53 act as a checkpoint controller to stop

A

cell-cycle progression

35
Q

Inactivation of p53 by adenovirus E1b protein

prevents

A

activation of p21 (and Bax)

36
Q

Adenovirus E1a protein binding to Rb complex

prevents

A

Rb from negatively regulating E2f

37
Q 
Human papillomaviruses (HPVs) 
characteristics (2)
A

nonenveloped viral particles

genome is a ds circular molecule

38
Q

Human papilloma viruses (HPV)

At least — different HPV types

A

100

39
Q

Human papilloma viruses (HPV)

— HPV or — HPV

A

cutaneous

mucosal

40
Q

Infection process

— month process (usually)

A

3-4

41
Q

Infection process

3-4 month process (usually)

A

HPV accesses basal layer through breaks in skin
Viral early genes stimulate cell growth (which facilitates
viral replication)
HPV reproduction coordinated with development of
keratinocytes (Keratinocytes = nondividing, physical
barrier; anuclear)
As cells move through skin layers HPV gene expression
and DNA replication begins (uses cellular DNA
polymerase)
Late proteins (capsid proteins) only made in
differentiated layers
Assembly occurs in nucleus during keratinocyte
development
Nuclear remnant with viral particles shed at skin
surface. HPVs are not lytic.

42
Q

Koilocytes -

A

enlarged keratinocytes with clear halos

around enlarged nuclei - characteristic of HPV infection

43
Q

HPV spread by skin-to-skin contact:

3

A 
breaks in skin
-for example, scratching
mucous membranes
- more susceptible, sexual contact
During birth
44
Q

HPV symtoms (3)

A

Warts of oropharynx
laryngeal papillomas (HPV-6 and -11)
respiratory papillomatosis

45
Q

respiratory papillomatosis (2)

A

hoarseness is usual symptom (signify obstructing HPV lesions)
respiratory distress and secondary bacterial pneumonia in

46
Q

Single oral papillomas are the most

A

benign epithelial tumors of the oral cavity

47
Q

Anogenital warts

A

condylomata acuminata (90% caused by HPV-6 and -11)

48
Q

Cervical papillomas

HPV is present in —% of a cervical cancers

A

99.7

49
Q

> —% of cervical carcinomas contain integrated HPV DNA

A

85

50
Q

HPV (2) (and 31& 45) are high-risk types

A

16 and 18

51
Q

pap smear

A

cells are scraped from the cervix and examined under a microscope to check for disease or other problems

52
Q

HPV

vaccines (2)

A

Gardasil: HPV 16&18 (cervical cancer)
Cervarix: HPV 16&18

53
Q 
The HPV (2) proteins are important for cancer development. They are
the only 2 HPV proteins always expressed in
A

E6 and E7

cervical cancer cells.

54
Q

E7 protein of HPV prevents — from controlling cell division

A

Rb

55
Q

E7 protein of HPV prevents Rb from controlling cell division

4

A

Similar to proteins of other viruses
these proteins bind Rb complex and prevent Rb from
negatively regulating E2f
HPV E7 protein acts like the SV40 virus LT protein
SV40 LT promotes disassembly of Rb-E2f
complex. E2f is now free to activate
transcription of cellular DNA synthesis genes

Microbiology (42 decks)

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