Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Virology > Complex +ssRNA viruses > Flashcards

Complex +ssRNA viruses Flashcards

(52 cards)

Start Studying
1
Q

What are the different families of complex + strand RNA viruses

A

Caliciviridae
Togaviridae
Astroviridae
Coronaviridae

Make more than 1 mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are common viruses within the family Togaviridae

A

Alphaviruses and Rubiviruses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What virus family do Alphaviruses and Rubiviruses belong to

A

Togaviridae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are morphological features of Togaviridae

A

complex +RNA
enveloped viruses
genome is about 10-13kb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What disease does the rubella virus cause and is there a vaccine

A

rubella virus use to be the major cause of birth defects before there was a vaccine

yes there is a vaccine

belong to togaviridae family, enveloped and complex positive RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What diseases do alphaviruses cause

A

are arthropod-bourse viruses

generally cause severe encephalitis or severe arthritis

belong to togaviridae family, enveloped and complex positive RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are common alphaviruses

A

Chicken gunya virus

Equine Encephalitis virus: Eastern, Western, Venezuelan

Ross River virus

Semliki Forest virus

named by location and they all cause a similar disease such as encephalitis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How many positive sense RNA molecules are produced during infection by alphaviruses

A

two positive sense RNA molecules are produced during infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Do alphaviruses have a poly A tail at the 3’ end and a 5’ cap

A

yes, alphaviruses have both a poly A tail and a 5’ cap

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the 2 types of positive sense RNA molecules produced by alphavirus gene expression

A

full length genome mRNA and

shorter subgenomic mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where and how is the full length genome, mRNA produced in alphavirus

A

produced by polymerase that starts at the 3’ terminus of the - sense RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where and how is the sub-genomic RNA produced in alphavirus

A

produced when the polymerase starts at the internal initiation site

this is a cis acting RNA structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what type of sense (+ or -) is the sub genomic RNA created as in alphavirus

A

only as + sense RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Is the genome RNA or sub genomic RNA used as the template for translation of non-structural proteins in alphavirus

A

genome RNA is used as the template for translation of non-structural proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does the 5’ end of the genome RNA of the alphavirus encode for

A

5’ end of the genome encodes a polyprotein which then cleaves into nsPs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does the 3’ end of the alphavirus encode for

A

3’ end of the genome encodes for a polyprotein which is then cleaved into structural proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What cleaves the polyprotein

A

protease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the non-structural proteins in alphavirus

A

nsP1-4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the main role of nsP1 in alphavirus

A

capping enzymes

methyl and guanylyl transferase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the main role of nsP2 in alphavirus

A

protease

helicase: unwinds RNA
triphosphatase: prepares RNA for capping

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the main role of nsP3 in alphavirus

Study These Flashcards
A

macrodomain: binds to an hydrolyzes ADP-ribose

alphavirus unique domain
hypervariable domain

22
Q

What is the main role of nsP4 in alphavirus

23
Q

Do nsP1-4 work together or independently of one another and what is their role

Study These Flashcards
A

work in concert to replicate RNA

  1. nsP2 cleaves P1234 into P123 and nsP4: this directs negative strand RNA synthesis
  2. nsP2 cleaves P123 into P23 and nsP1: these make + genomic RNA
  3. nsP2 cleaves P23 into nsP2 and nsP3
  4. final complex makes both + RNA strands: the genomic and sub-genomic

makes more subgenomic RNA than genomic RNA this allows more structural proteins to be made than non structural proteins

24
Q

Is more genomic or subgenomic RNA made in alphavirus

Study These Flashcards
A

subgenomic, because these code for structural proteins allowing more structural proteins to be made than non-structural proteins

25
What are morphological features of Coronaviridae
``` complex +RNA virus enveloped helical nucleocapsid about 30kb genome largest known RNA virus ```
26
What illnesses/disease do coronaviruses cause
in humans generally cause mild respiratory illness, cause about 30% of common colds each year, 4 viruses are responsible for the common cold NL63, HKU1, 229-E, OC-43 are responsible for 3 major viral epidemics in the past two decades SARS-CoV, MERS-CoV, SARS-CoV-2 also cause of severe diseases in veterinary animals, PEDV/SADS-CoV
27
Do coronaviruses have a 5' cap and 3' poly A tail
coronaviruses have both a 5' cap and a 3' poly A tail
28
Where are non-structural encoded for in coronaviruses
non-structural proteins are encoded at the 5' end of the genome 2/3 of the way down the RNA
29
Where are structural encoded for in coronaviruses
structural proteins are encoded a the 3' end of the genome 1/3 of the way down the RNA
30
What are the other proteins dispersed in the 3' end of the coronaviruses genome
accessory proteins
31
Each CoV species/group has different
accessory proteins
32
What are the functions of accessory proteins in coronaviruses
immune evasion/ suppression transmission other unknown functions several RNA structural elements throughout the genome
33
How are nonstructural proteins specifically replicase proteins translated in coronaviruses
- ORF 1A/1AB are translated into 2 long polyproteins: pp1a and pp1ab - translation of pp1a1A vs pp1AB depends on a slippery sequence 25% of the time the ribosome slips back 1 nucleotide causing a frameshift nsp 12-16 are generally produced at lower levels than nsp1-10
34
What is the translation of two polyproteins pp1A and pp1AB dependent on in coronaviruses
depends on a slippery sequence 25% of the time the ribosome slips back 1 nucleotide causing a frameshift
35
How are the two polyproteins in coronaviruses cleaved
polyprotein is cleaved into individual proteins by 2 viral proteases nsp3: PLpro 1-2, 2-3, 3-4 nsp5: 3CLpro and all the other cleaveages
36
What are replication transcription complexes RTCs in coronaviruses and what is their role
membranous structures that require nsp3, 4, and 6 membranes are derived from the ER concentrate and localize required components for replication provide a scaffold to anchor the replication complex/confine the process to a specific location in the cytoplasm help prevent activation of innate immune system sensing of dsRNA
37
How many nsp does the coronavirus encode for
16 non-structural proteins encode for lots of enzymes
38
What is typically encoded for by nsps in coronaviruses
typical enzymes polymerase/helicase (nsp12/13) proteases (nsp3/5) capping enzymes (nsp 14,16,13,12)
39
What are unique/uncommon enzymes encoded for by nsps in coronaviruses
macrodomain-de-ADP-ribosylhydrolase (nsp3): block IFN production, counter antiviral response endoribonuclease (15): prevents dsRNA formation exoribonuclease (14): proofreading capability, only RNA viruses with proofreading, lower mutation rate than other RNA viruses
40
What is the role of macrodomain de-ADP-ribosylhydrolase in coronaviruses
blocks IFN production and counter antiviral response part of nsps3
41
What is the role of endoribonuclease in coronaviruses
prevents dsRNA formation nsp15
42
What is the role of exoribonuclease in coronaviruses
proofreading capability only RNA viruses with proofreading lower mutation rate than any other RNA viruses nsp14
43
What RNA viruses have the lowest mutation rate and why
coronaviruses they have a unique non-structural protein, exoribonuclease that is a proofreading capability this is the only RNA virus with a proofreading capability
44
How many RNAs are formed during coronavirus RNA synthesis (transcription and replication)
RNA synthesis involves the replication of genomic RNA and the transcription of MULTIPLE subgenomic RNAs
45
Genomic and sub-genomic RNAs are both copied from what in coronaviruses
both types of RNAs are copied through negative strand intermediates both - strand genome and + subgenomic genomes are made
46
subgenomic RNAs are mRNAS for what in coronaviruses
subgenomic RNAs are mRNAs for all the structural and accessory proteins
47
do subgenomic RNAs make polyproteins in coronaviruses
no, they generally encode for one protein, they do not make polyproteins all sgRNAs are co-terminal they have the same 3' end
48
what does co-terminal sgRNA mean in coronaviruses
they have the same 3' ends
49
What do each sgRNA contain in coronaviruses
a leader sequence TRS: transcription regulatory sequence body: encodes for a protein 3'UTR and a poly A tail leader and the TRS are needed for transcription
50
How are TRL and TRS (leader and regulatory sequence) sequences joined
occurs during negative strand synthesis when RdRP reaches a TRS-B it either - keeps moving and makes a negative genomic RNA - stall out at the TRS and recombine with TRSL at the 5' end of genome (preferred) - make more subgenomic RNA this makes sure there is more structural proteins than non-structural proteins
51
What serve as templates for + strand sub genomic RNAs
negative strand sgRNAs serve as templates for positive strand sgRNAs
52
What type of recombination are CoVs prone to
CoVs are prone to recombination between different but similar viruses infecting the same species

Virology (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions