replication of ds RNA virus

Question 1

what does the genome structure look like of dsRNA virus?

Answer 1

genome is segmented

Question 2

what does the virion structure of dsRNA look like?

Answer 2

complex, 3-layered protein shell
insensitive to detergents (non-enveloped) but glycoproteins

3 layers: virion
2 layers: subviral particle
1 layer: core

Question 3

explain the replication cycle of reoviridae

Answer 3

1.receptor binding via hemagluttin and endocytosis
2.acid induced proteolysis within the endosome: conversion of the virion into infectious subviral particle –> this can also already happen in intestine
3.penetration through endosomal membrane into cytoplasm
4.cytoplasm: conversion from ISVP to core particle
5.synthesis of capped viral mRNA takes place into core particle
6.association of mRNAs with newly translated proteins to RNase sensitive subviral particles SVP
7.transcription of mRNA into - strand and formation of RNA resistant SVP with 10 dsRNA segments
8.formation of virions by assembly of preformed outer capsid proteins

Question 4

how does the structural organisation of the RNA in the rotavirus core particle look like?

Answer 4

25 % of dsRNA in ordered structure

Question 5

where does the RNA transcription of rotaviruses take place?

Answer 5

in double layered core particle

mRNA leaves core particles via channels

each channel has polymerase and capping enzyme

–> dsRNA formation in virion –> dsRNA is never exposed to cytoplasm

Question 6

how can reoviruses and retroviruses enter the cytoplasm?

Answer 6

use of hydrophobic parts to cross the membrane

reovirus; cathepsin B/L cleaves molecules off which locally dissolve membrane

rotavirus: Trypsin cleaves to expose hydrophobic parts

Question 7

what are the characteristics of blue tongue disease?

Answer 7

animals: sheep, cattle, goat
transmission: gnats
variability: high –> 24 serotypes
virus family: reoviridae
diagnosis: Pathogen detection via RT-PCR or Ab detection via ELISA

Question 8

why can real time RT-PCR only be used at the very beginning of infection? What can be detected in later stages and how?

Answer 8

viral RNA eventually eradicated by immune system –> no detection

later: serology test for antibodies –> detect antibodies via ELISA, NT

Question 9

how was blue tongue disease countered and controlled?

Answer 9

duty of disclosure
prohibition of transfer
zones
export szop
monitoring
quarantine
immunisation