L81 Flashcards
What are the major viral causes of diarrhea?
- Rotavirus
- Caliciviruses
- Noro
- Sapo
Enteric adenovirus, astrovirus
Rotavirus genome
DOUBLE stranded RNA
Segmented
Naked
“Wheel with spokes”
What are VP4 & VP7? Similarities vs differences?
Rotovirus OUTER capsid antigens Both involved in neutralization VP7 : G protein vs VP4 : P protein G + P determine serotype
How do you diagnose rotavirus?
VP6 = inner capsid antigen
Stool sample –> immuno-assay for this
What is the most common rotavirus serotype?
G1P8
How and where is rotavirus activated?
@ gut
Proteases remove VP7
Which surface antigen mediates attachment for rotavirus?
VP4
Attachment to gut
How is rotavirus released from host cells?
Lysis - naked virus
What type of diarrhea does rotavirus cause? Name the 3 possible mechanisms.
Watery diarrhea
1. Cytolytic infection of intestine villi –> blunting of microvilli –> less water absorbed
Actin rearrangement
In response, secretory crypt cell migrate out to repair damage faster, but they are immature –> increased water secretion
2. Entertoxin mediated by NSP4 (non-structural) protein
3. ENS activated - increased secretions
Rotavirus transmission
Fecal-oral… makes sense
Is rotavirus more common in adults or kids?
Kids
Incubation and disease timelines for rotavirus
Incubate = 2 days Sick = 4-8 days
Rotavirus complications
- Dehydration
Electrolyte changes/malabsorption
Diarrhea
Acidosis
Where in the world is rotavirus common?
Bangladesh or West Africa
Describe current rotavirus vaccines
Live, oral, attenuated
Very effective - given example of herd immunity
Enteric adenovirus genetics - include relevant serotypes
dsDNA
Icosahedral capsid w/ penton fibre at each apex
2 serotypes - 40 & 41
If enteric adenovirus has the same symptoms as rotavirus, how do you tell them apart?
Enteric = longer timeframe
- 5-12 days sick
P2P transmission
Astrovirus genetics
+ssRNA
Naked
Astrovirus transmission and duration of illness
P2P transmission (or food/water) 3-7 days sick
Caliciviruses genetics
+ ssRNA
Naked
2 major caliciviruses
Noro
Sapo
Infection with these is SUPER common
What is the seasonality of calico viruses?
Noro peaks in winter
But environmentaly stable
Calici virus transmission
**LOW infectious dose
P2P
Fecal-oral
Air - kids daycare
Which blood type has increased risk for calico infection
Grp O
Describe how you would test the enteric viruses for infection
- Rota - immuneassay for grp A antigen
- Enteric - serotyping for 40/21
- Calici and astrocytes - nothing available
