Week 12 Flashcards
1
Q
Rotavirus
A
- Cause more severe diarrhoea and dehydration than other agents
- Vaccination since 2006 –> reduced hospitalization by 45%
2
Q
Other disease manifestations of rotavirus
A
- Low-level viraemia
- CNS disease
- Liver involvement
- Autoimmunity modulation -T1 diabetes, celiac
3
Q
Rotavirus belongs to which family?
A
- Reovirus - dsRNA genome, multi-layered capsid, icosahedral symmetry
- Rotavirus - new genus, differences in viral proteins
4
Q
Viral proteins
A
- VP7 and VP4 = outer capsid, VP7: serotype determinants
- VP4 - major receptor interaction, cleaved by trypsin into VP5 and VP8 for full infectivity
- Core: 11 segments of ds RNA + VP2 (binds RNA genome) + VP1 (RNAP)
- Inner capsid: VP6 - used to identify rotavirus species
5
Q
Rotavirus fingerprints
A
Each gene segment encodes a structural or nonstructural protein
6
Q
Lab diagnosis
A
- Stool virus detection using ELISA (VP6), RT-PCR, electron microscopy
- Seroconversion - IgG, IgM, IgA
- IgA conversion in stools
7
Q
Efects of rotavirus infection on intestinal villi
A
- Villi are blunted –> diarrhoea
- NSP4 = enterotoxin and contributes to severity of dehydration and diarrhoea
- Cells migrate from crypt to villus = new set of susceptible cells every 3 days
8
Q
Rotavirus-neutralizing antibodies
A
- Directed to outer capsid proteins - VP7 and VP4
- Serotypes - VP7 and 4 ELISA
- Genotypes: RT-PCR
- 5 VP7 (G) serotypes most common in humans
- 3 VP4 (P)
- Serotype diversity generated by virus gene segment reassortment
9
Q
Rotavirus reassortment
A
- Coninfect same cell with 2 rotavirus strains
- Different combination of virus particles
- Select for combinations using monoclonal antibodies to VP4 and VP7
10
Q
Rotavirus entry
A
- Initial attachment of VP8 to glycans
- e.g. terminal (sialidase sensitive) or branched sialic acid (sialidase resistant)
- Sialidase removes sialic acid at ends of chain
- e.g. Histo-blood group antigens - Type A is implicated
- Binding/entry occurs via endocytosis using VP5 and VP7 recognition of integrins
11
Q
Rotaviruses and sialic acid
A
- Human rotavirus Wa and RV-3: sialidase resistant - use branched sialic acid
- RV3 also uses HBGA A type
- Monkey strain: sialidase sensitive - uses terminal sialic acid (acetyl)
- Pig rotavirus: sialidase sensitive - uses terminal and subterminal sialic acid, glycolyl
12
Q
How to study receptor interactions?
A
- Blocking interaction of virus and receptor
- Structural studies of receptor-ligand complex
- Expressing the receptor on cells that don’t normally express it –> increase infection?
- Glycan arrays
- Bioinformatics - look for presence of motifs in proteins
13
Q
Rotavirus using integrins
A
- a2B1:
- bound to VP4
- rotavirus cellular receptor
- VP5 competes with virus for binding
- axB2, avB3:
- recognised by VP7
- cofactor
14
Q
Type 1 diabetes + rotavirus
A
- Rotavirus may accelerate progression to diabetes 1 (already have genetic predisposition)
- NOD mice used:
- 5 days - diarrhoea and extraintestinal spread
- 12 weeks - no diarrhoea, virus found in mesenteric and pancreatic lymph nodes, advanced insulitis
15
Q
Development of diabetes
A
- Plasmacytoid DCs take up virus, activated by TLR 7 –> Type 1 interferon –>
- Activated lymphocytes –> pancreatic lymph nodes
- Activated CD8+ T cell
- B cell death –> diabetes
16
Q
Rotavirus epidemiology
A
