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microbiology > Gastro-Adeno-Papilloma > Flashcards

Gastro-Adeno-Papilloma Flashcards

1
Q

Viral Gastroenteritis
inflamm of?
important diseased of?
leading cause of?

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

viral cause of gastroeneritis

A
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3
Q

rotavirus and group A, b and c genomes

A

segemented dsRNA

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4
Q

medical significance of group A reovirdiae

A

major cause of diarrhea in infants

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5
Q

norovirus significance

A

major cause of diarrhea outbreaks in adults/children

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6
Q

~____% of diarrhea cases still have unknown etiology

A

50

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7
Q

Norwalk identification

A

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

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8
Q

Rotaviruses are members of the_________family

A

Reovirus= Respiratory Enteric Orphan viruses

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9
Q

Reovirus family envelope/caspids

A

nonenveloped with inner/outer capsids

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10
Q

rotavirus/reovirus replication

A

enters via endocytosis
full genome replication
uses own RNA poly
buds from ER

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11
Q

genome of rotaviruses

A

11 segments of double-stranded RNA (dsRNA)

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12
Q

end result rotavirus infection on cell

A

Lysis of infected cells

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13
Q

Rotaviruses may cause?

A
  • potentially fatal dehydration
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14
Q

transmission of rotaviruses
what allows them to be transmitted this way?
how infectious?

A

fecal-oral transmission
acid stability conferred by double capsid structure
up to 10^12 virus particles per ml stool and as few as 10 virus particles can cause infection

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15
Q

how do rotaviruses cause potentially fatal 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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16
Q

most common group of rotaviruses in US

A

group A

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17
Q

rotavirus vax?

A

Rotavirus vaccine for infants (>75% effective)

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18
Q

norovirus genome/ strucutre

A

+ RNA

naked capsid virions

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19
Q

norovirus replication, similar to what other virus?

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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20
Q

Adenovirus
genome
structure/ geometry

A

linear dsDNA
non enveloped
iscohedral

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21
Q

adenovirus cell entry

A

•Adenovirus attaches to receptors on surface of host cells (CAR = coxsackievirus
adenovirus receptor)
•most cells express CAR
•receptor-mediated endocytosis
•pH drop in endosome induces viral uncoating
•endosome ruptures, releasing contents into cytoplasm
•viral nucleoprotein complex enter cell nucleus

22
Q

adenovirus gene expression and transcription regulators

where does viral DNA go?

A

Adenovirus gene expression temporal regulation: pre-early, early, late genes
RNAs are spliced

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

VIRAL DNA ENTERS NUCLEUS

23
Q

adenovirus DNA replication, priming?

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)
strand not copied can self bind and be primed for replication

24
Q

what primes adenovirus DNA syn

A

Priming of DNA synthesis by pTP serine residue

25
Q

adenovirus infections commonality?

symptoms?

A

widespread: 5-10% of all viral infections

similar to common cold

26
Q

adenovirus vax type

targets which serotypes?

A

Vaccine (live virus) given to new military recruits

targets serotypes 4 and 7

27
Q

acute respiratory disease (ARD) caused by what virus/serotypes

A

adenovirus serotypes 4, 7, and 21

28
Q

adenovirus interference with host cell function

A

interefers with gene expression to reduce mRNA transport/ translation= stops host cell pro synthesis

29
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= results in block of killing by cytotoxic T cells

30
Q

Adenovirus

E3 region

A

cluster of genes mediating evasion of host defense

31
Q

adenovirus will drive the host cell into?
why?
proteins used? actions?
can potentially lead to what state?

A

Adenovirus drives the host cell into cell division
necessary for adenovirus to replicate (needs cellular S phase factors)

Adenovirus E1a and E1b proteins interfere with cell division controllers
E1b sequesters p53 and E1a sequesters Rb (retinoblastoma protein)

Viral infection can potentially drive a cell toward a cancerous state

32
Q

Brief background on cell cycle factors: Rb and E2F example

A

Example: DNA damage during G1
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

P53 act as a checkpoint controller to stop cell-cycle progression

33
Q

Inactivation of p53 by adenovirus

A

done by E1b protein- prevents activation of p21 (and Bax)

34
Q

Adenovirus E1a protein

A

binding to Rb complex prevents Rb from negatively regulating E2f

35
Q

Human papillomaviruses

genomes and strucutres

A

circular dsDNA

non enveloped

36
Q

Human papilloma viruses (HPV) serotypes

A

100s

37
Q

types of HPV

A

mucosal or cutaneous

38
Q

HPV infection process timeframe

A

3-4 month process (usually)

39
Q

HPV access into body

what stimulates early growth?

A

HPV accesses basal layer through breaks in skin

Viral early genes stimulate cell growth (which facilitates viral replication)

40
Q 
HPV reproduction coordinated with?
HPV gene expression? 
late proteins made when? 
Assembly?
nuclear remnants shed?
A

HPV reproduction coordinated with development of keratinocytes (Keratinocytes = nondividing, physical barrier; nuclear)

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.

41
Q

Koilocytes

A

enlarged keratinocytes with clear halos around enlarged nuclei - characteristic of HPV infection

42
Q

HPV spread by?

A

skin-to-skin contact: breaks in skin or example, scratching mucous membranes more susceptible
sexual contact
During birth

43
Q

HPV oral/ airway symptoms

A

Warts of oropharynx

laryngeal papillomas (HPV-6 and -11)

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

44
Q

most benign tumors of oral cavities

A

HPV Single oral papillomas are the most benign epithelial tumors of the oral cavity

45
Q

Anogenital warts, main strains?

A

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

46
Q

Cervical papillomas
%?
strains?

A

HPV is present in 99.7% of a cervical cancers
>85% of cervical carcinomas contain integrated HPV DNA
HPV 16 and 18 (and 31& 45) are high-risk types

47
Q

detection of cervical cancer

A

Koilocytic cells in Pap smears indicate HPV

48
Q

HPV infection often visable?

A

Often infections are not recognizable (asymptomatic)
up to 50% of a population positive for HPV DNA but majority
have no visible evidence of infection

49
Q

HPV prevention

A

vax available for strains 16 and 18, prevention of cervical cancer

50
Q

HPV proteins important in cancer

A

The HPV E6 and E7 proteins are important for cancer development.
They are the only 2 HPV proteins always expressed in cervical cancer cells.

51
Q

HPV E6 protein action

A

Inactivation of p53: leads to ubiquitination of p53 and degradation

52
Q

E7 protein action

A

prevents Rb from controlling cell division

these proteins bind Rb complex and prevent Rb from negatively regulating E2f
E2f is now free to activate transcription of cellular DNA synthesis genes.

microbiology (42 decks)

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