Gastro-Adeno-Papilloma

Question 1

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

Answer 1

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

Question 2

viral cause of gastroeneritis

Answer 2

Question 3

rotavirus and group A, b and c genomes

Answer 3

segemented dsRNA

Question 4

medical significance of group A reovirdiae

Answer 4

major cause of diarrhea in infants

Question 5

norovirus significance

Answer 5

major cause of diarrhea outbreaks in adults/children

Question 6

~____% of diarrhea cases still have unknown etiology

Answer 6

50

Question 7

Norwalk identification

Answer 7

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

Question 8

Rotaviruses are members of the_________family

Answer 8

Reovirus= Respiratory Enteric Orphan viruses

Question 9

Reovirus family envelope/caspids

Answer 9

nonenveloped with inner/outer capsids

Question 10

rotavirus/reovirus replication

Answer 10

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

Question 11

genome of rotaviruses

Answer 11

11 segments of double-stranded RNA (dsRNA)

Question 12

end result rotavirus infection on cell

Answer 12

Lysis of infected cells

Question 13

Rotaviruses may cause?

Answer 13

• potentially fatal dehydration

Question 14

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

Answer 14

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

Question 15

how do rotaviruses cause potentially fatal diarrhea

Answer 15

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))

Question 16

most common group of rotaviruses in US

Answer 16

group A

Question 17

rotavirus vax?

Answer 17

Rotavirus vaccine for infants (>75% effective)

Question 18

norovirus genome/ strucutre

Answer 18

+ RNA

naked capsid virions

Question 19

norovirus replication, similar to what other virus?

Answer 19

Replication similar to picornaviruses (poliovirus) except 2nd phase of translation involves subgenomic RNAs (like coronaviruses).

Has a 5VPg protein on RNA (like picornaviruses)

Question 20

Adenovirus
genome
structure/ geometry

Answer 20

linear dsDNA
non enveloped
iscohedral

Question 21

adenovirus cell entry

Answer 21

•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

Question 22

adenovirus gene expression and transcription regulators

where does viral DNA go?

Answer 22

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

Question 23

adenovirus DNA replication, priming?

Answer 23

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

Question 24

what primes adenovirus DNA syn

Answer 24

Priming of DNA synthesis by pTP serine residue

Question 25

adenovirus infections commonality? | symptoms?

Answer 25

widespread: 5-10% of all viral infections | similar to common cold

Question 26

adenovirus vax type | targets which serotypes?

Answer 26

Vaccine (live virus) given to new military recruits | targets serotypes 4 and 7

Question 27

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

Answer 27

adenovirus serotypes 4, 7, and 21

Question 28

adenovirus interference with host cell function

Answer 28

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

Question 29

adenovirus Mechanisms for evasion of host defense

Answer 29

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

Question 30

Adenovirus | E3 region

Answer 30

cluster of genes mediating evasion of host defense

Question 31

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

Answer 31

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

Question 32

Brief background on cell cycle factors: Rb and E2F example

Answer 32

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

Question 33

Inactivation of p53 by adenovirus

Answer 33

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

Question 34

Adenovirus E1a protein

Answer 34

binding to Rb complex prevents Rb from negatively regulating E2f

Question 35

Human papillomaviruses | genomes and strucutres

Answer 35

circular dsDNA | non enveloped

Question 36

Human papilloma viruses (HPV) serotypes

Answer 36

100s

Question 37

types of HPV

Answer 37

mucosal or cutaneous

Question 38

HPV infection process timeframe

Answer 38

3-4 month process (usually)

Question 39

HPV access into body | what stimulates early growth?

Answer 39

HPV accesses basal layer through breaks in skin | Viral early genes stimulate cell growth (which facilitates viral replication)

Question 40

``` HPV reproduction coordinated with? HPV gene expression? late proteins made when? Assembly? nuclear remnants shed? ```

Answer 40

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.

Question 41

Koilocytes

Answer 41

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

Question 42

HPV spread by?

Answer 42

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

Question 43

HPV oral/ airway symptoms

Answer 43

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

Question 44

most benign tumors of oral cavities

Answer 44

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

Question 45

Anogenital warts, main strains?

Answer 45

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

Question 46

Cervical papillomas %? strains?

Answer 46

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

Question 47

detection of cervical cancer

Answer 47

Koilocytic cells in Pap smears indicate HPV

Question 48

HPV infection often visable?

Answer 48

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

Question 49

HPV prevention

Answer 49

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

Question 50

HPV proteins important in cancer

Answer 50

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

Question 51

HPV E6 protein action

Answer 51

Inactivation of p53: leads to ubiquitination of p53 and degradation

Question 52

E7 protein action

Answer 52

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.