Chapter 37-39-40 Gastro Adeno Papilloma Flashcards
what is viral gastroenteritis
- inflammation of stomach or intestines
- important disease of infants and children
- leading cause of childhood death in developing countries
what is the genome and medical significance of group A rotavirus
-segmented dsRNA
- major cause of diarrhea in children 6-24 months
what is the genome of group B and C rotavirus
-segmented dsRNA
what is the genome and medical significane of norovirus
- positive ssRNA
- major cause of diarrhea outbreaks in children and adults
what is the genome of sapovirus
positive ssRNA
what is the genome of enteric adenovirus
linear dsDNA
what is the genome of astrovirus
positive ssRNA
what is genome of aichi virus
positive ssRNA
what percentage of diarrhea cases have unknown etiology
50%
rotaviruses are members of the _____ family
reovirus
what are reoviruses and what do they stand for
- respiratory enteric orphan viruses
-nonenveloped - inner and outer capsids
what do rotaviruses do
lysis of infected cells
what can rotaviruses cause
potentially fatal dehydration
how are rotaviruses transmitted
- fecal-oral
- acid stability conferred by double capsid structure
- as few as 10 virus particles can cause infection
how do rotaviruses cause watery diarrhea
- virus produces enterotoxin: binds integrins; signaling results secretion of chloride and water
- infected gut epithelial cells destroyed and replaced by immature epithelial cells
what is the most common type of rotavirus in the US
group A
what are the treatments for rotavirus
vaccine for infants is more than 75% effective
describe noroviruses
- positive strand RNA
- naked capsid virions
- replication similar to picornaviruses
- has a 5’ VPg protein on RNA
describe norovirus infections
- sympomatic/supportive therapy
- no vaccine yet
describe adenovirus
- linear double stranded DNA genome
- noneveloped
- isocahedral capsid
whats the mechanism of action for adenovirus
- viral nucleoprotein complex enter cell nucleus
what is the gene expression of adenovirus
- temporal: pre-early, early and late genes
when are transcriptional regulators produced and what do they do
during one phase
- act to promotoe transcription of genes of subsequent phase
describe adenovirus replication
only one of the 2 DNA strands is copied at each replication fork
- no discontinuous replication
- priming is by a viral protein
what accounts for 5-10% of all viral infections
adenovirus
what are the normal symptoms of adenovirus infection
common cold symptoms
what is the adenovirus vaccine and who is it given to
given to new military recruits
- targets serotypes 4 and 7
what serotypes is ARDs
4 and 7
what are adenovirus’ mechanisms for evasion of host defense
- block MHC class I mRNA production
- block transport of MHC class I proteins to the cell surface: results in blocking of killing by CTLs
how does adenovirus drive the host cell into cell division
- adenovirus E1a and E1b proteins interfere with cell division controllers
- E1b sequesters p53
- E1a sequesters Rb
viral infection can potentially drive a cell towards a ______
cancerous state
what is the associated cancer with adenoviridae
various solid tumors
how does the cell repair DNA during G1
- p53 recognizes DNA damage and activates P21
- P21 binds and inactivates the cyclin CDK complex which has already begun to be produced in response to different signals
- DNA is repaired, p53 decreases and p21 no longer blocks cyclin CDK
what does inactivation of p53 by adenovirus E1b protein prevent
activation of p21
what does adenovirus E1a protein binding to Rb complex prevent
Rb from negatively regulating E2f
what is the genome for HPV
double stranded ciruclar
- nonenveloped
what are the different types of HPV
cutaneous or mucosal
how long is the HPV infection process
3-4 months
what is the mechanism of action of HPV
- HPV accesses basal layer through breaks in skin, viral early genes stimulate cell growth
- HPV reproduction coordinated with development of keratinocytes
- as cells move through skin layers HPV gene expression and DNA replication begins
- late proteins only made in differentiated layers
- assembly occurs in nucleus during keratinocytes development
- nuclear remnant with viral particles shed at skin surface
- HPVs are not lytic
what are koilocytes
enlarged keratinocytes with clear halos around enlarged nuclei - characterisitic of HPV infection
how is HPV spread
skin to skin by:
- breaks in skin
- mucous membranes
- during birth
what are warts of oropharynx in HPC called and what do they lead to
- laryngeal papillomas
- respiratory papillomatosis: hoarseess is usualy symptom, respiratory distress and secondary bacterial pneumonia in children
what are the most benign epithelial tumors in the oral cavity
single oral papillomas
what are anogenital warts and what are they caused by
condylomata acuminata
-90% caused by HPV-6 and -11
HPV is present in ____% of cervical cancers
99.7%
_____% of cervical carcinomas contain integrated HPV DNA
greater than 85%
what are the high risk types of HPV
16 and 18
what is a pap smear
cells are scraped from the cervix and examined under a microscope to check for disease or other problems
how is cancer related HPV diagnosed
- wart confirmed microscopically
- hyperpalsia of prickle cells
- excess keratin production
what is the treatment for HPV
- gardasil for 16 and 18 (cervical cancer)
- cervarix for 16 and 18
what are the only 2 HPV proteins always expressed in cervical cancer cells
E6 and E7
what cancers do papillomaviruses cause
papillomas and carcinomas
what is the mechanism of action of papillomaviruses
- inactivation of p53 by HPV E6 protein
what does SV40 LT do
promotes disassembly of Rb-E2f complex
- E2f then is free to activate transcription of cellular DNA synthesis genes thereby preventing Rb from controlling cell division
