Lec 29 Viral GI Illnesses Flashcards
What is leading cause of childhood death?
diarrhea
What is most common viral cause of severe diarrhea in young children?
rotaviruses
Who gets rotaviruses?
children age 6 - 24 mos
What are signs of rotavirus infection?
- can be asymptomatic or severe dehydrating gastroenteritis
- fever
- vomiting
- watery diarrhea
- dehydration [more common in rotavirus than with other causes of infectious diarrhea]
Does rotavirus infect immuodeficient? HIV+?
- longer lasting more severe syndrome in immunodeficient
- not a common cause of diarrhea in HIV+ adults
Can reinfections of rotavirus occur?
- can occur but tend to be less severe
Whos gets rotavirus? when?
- almost all children infected before age 3
- adults infected when caring for infected infants
- seasonal infection –> peak in colder months, lower humidity
How is rotavirus transmitted?
- fecal oral route
- resistant to desiccation –> can survive 7 months in feces]
- shedding of large numbers of rotaviurs prior to, during and after infection
- short < 48 hr incubation time
- some evidence of maybe respiratory spread too
How is rotavirus diagnosed?
- ELISA or latex agglutination to detect viral antigen in stool
- RT-PCR of viral RNA
- electron micro of stool
- isolation in cell culture is possible
What are the 7 serogroups of rotavirus? where are they found?
groups A, B, C in animals and humans
groups D-G in animals
How are rotavirus serogroups determined?
reactivity of antibodies with VP6 [by ELISA]
How are the rotavirus serotypes determined?
- within each group based on reactivity of antibodies with VP7 [G antigen]
- also type based on reactivity of antibodies wtih VP4 [P antigen]
What are the common serotypes most important for human disease?
Group A serotypes G1, G2, G3
What is function of VP4 gene in rotavirus?
takes part in cell attachment
contains: hemagglutinin, neutralizing epitopes, P antigen
What is function of VP6 gene in rotavirus?
contains major group [A-G] antigen
What is function of VP7 gene in rotavirus?
contains neutralizing epitopes, G antigen
What is function of NSP4 gene in rotavirus?
codes for enterotoxin that aids in ER protein/assembly
What is structure of rotavirus?
- rota = wheel appearance by EM
- non-enveloped with 3 layer protein struct [double capsid + core]
- segmented [11 segments]
- double strand RNA
Where in cell does rotavirus replicated?
in cytoplasm
What proteins are in outer capsid? inner capid? core?
outer capsid = VP4 [P] + VP7 [G]
inner = VP6
core = VP2
What are important points of rotavirus replication cycle?
- replicated in cyto
- only uses viral enzymes
- dsRNA always associated with subviral particles
- subviral particles form and mature by budding through ER where they acquire outer capsid proteins
How do you replicate dsRNA?
- copied into mRNA by RNA dependent RNA pol
What is pathogenesis of rotavirus?
- diarrhea begins before signficiant damage to intestinal mucosa
- get viremia
- NSP4 enterotoxin plays important part in diarrhea
- replicated in small intestinal epithelial cells
- net secretion water and loss of ions
What distinguishes bacterial from rotavirus diarrhea?
rotavirus diarrhea has minimal intestinal inflammation in comparison
