M2-C3-L62 --> Plus Stranded Rna

Front 1

List six plus stranded RNA virus families.

Back 1

Coronaviridae
Flaviviridae

Picornoviridae
Astroviridae
Togaviridae
Caliciviridae

(hepeviridae)

Front 2

Where do ALL PLUS stranded RNA viruses replicate?

Back 2

In the cytoplasm

Front 3

For plus-stranded RNA, the genomic RNA serves as a?

What process is first utilized by genomic PLUS RNA?
- what provides this?
- what is the product of this process
- what is that product subjected to?

Back 3

message

translation
- cellular translation factors
- Polyprotein
- Virally-encoded proteases cleave the polyprotein.

Front 4

T/F - For plus-stranded RNA, the genomic RNA is infectious.

Back 4

True

Front 5

T/F - For plus-stranded RNA, the virions contain enzymes.

Back 5

False.

Plus-stranded RNA do not contain enzymes

Front 6

Since PLUS RNA VIRUS has no enzymes associated, how does it get viral proteins?

Back 6

Genomic viral RNA translated into polyproteins by cellular factors.

Polyprotein is then cleaved by inherent virally-encoded proteases

Front 7

PLUS RNA VIRUS REPLICATION
GENERAL STEPS

- What first happens with the incoming virion?

Back 7

- Uncoated

then

-RNA genome released in to cytoplasm

Front 8

PLUS RNA VIRUS REPLICATION
GENERAL STEPS

- Once viral PLUS RNA is dumped into cytoplasm, what happens?

- what is produced as a result?
- what significant molecule is produced here also?

Back 8

- Translation

- Nonstructural viral proteins
(enzymatic)

- Viral RNA PY

Front 9

PLUS RNA VIRUS REPLICATION
GENERAL STEPS

- the RNA genome replicated by generating what?

Back 9

- a NEGATIVE-stranded INTERMEDIATE

Front 10

PLUS RNA VIRUS REPLICATION
GENERAL STEPS

T/F : Structural proteins are translated in all virus families.

Back 10

FALSE:

in SOME, but not all

Front 11

PLUS RNA VIRUS REPLICATION
GENERAL STEPS

Once the viral RNA PY makes the MINUS intermediate, what makes from it, additional copies of the PLUS Strands?

Back 11

- same ol' RNA PY

Front 12

PLUS RNA VIRUS REPLICATION
GENERAL STEPS

Once progeny is made, what happens to them?

Then what?

Back 12

They are packaged

Virions leave the cell
(thru various types of mechanisms)

Front 13

PLUS RNA VIRUS REPLICATION
GENERAL STEPS

Briefly go over all the 6 steps.

Back 13

1. Virions are UNcoated & Genome is released into cytoplasm

2. Translation to produce NON-structural (enzygmatic) viral proteins
(including RNA Pol Y

3. MINUS stranded INTERMEDIATE made to replicate genome

4. Structural proteins made in some families

5. Progeny virions are packaged

6. Virions exit the cell

Front 14

Which families of plus-stranded RNA viruses translate only one polypeptide?

Back 14

Picornoviridae

Flaviviridae

Front 15

Which families of plus-stranded RNA viruses translates one polypeptide early and one polypeptide late.

Back 15

Caliciviridae

Togaviridae

Front 16

Picornoviridae family:

- capsid
- diameter
- envelope?

- unique aspect?

Back 16

ICOSAHEDRAL

30nm

NOT enveloped

Shuts down cellular translation
(cleaves 4G & IRES recrutis)
(so no need 4E (CBP))

Front 17

List 6 members of Picornoviridae family affecting humans as natural hosts.

Back 17

PiCoRnA - HA
1. Poliovirus (Entero genus)
2. Coxsackievirus (ENTERO genus)
3. Rhinovirus (RHINIO genus)
4. Hepatitis A (HEPATO genus)

5. Human Parechovirus (PARECHO genus)
6. Aichi virus (KOBO genus)

Front 18

How many regional divisions does the picornovirus polyprotein have?

List them & their functions.

Back 18

Three


P1 - Viral capsid proteins

NON-STRUCTURAL:
P2 - Protein processing & Genome replication
P3 - Protein processing & Genome replication

Front 19

In plus stranded RNA viruses, why must translation occur first? x2

Back 19

1. No cellular RNA PY can copy viral genome.

2. No viral enzymes are packaged in particle

Front 20

VIRAL TRANSLATION

Picornoviridae lacks a 5' cap. What occurs as a result?

Back 20

VPg exists,
AND
it is cleaved as soon as the as the viral RNA enters cytosol.

Front 21

VIRAL TRANSLATION

During picornoviridae translation, ribosomes will bind to what?

Back 21

IRES
(extensive regions of secondary structure)

Front 22

VIRAL TRANSLATION

Host translational factors can be recruited and associate with what 2 things.

Back 22

5' caps (cellular)

&

IRES elements (picornovirus)

Front 23

VIRAL TRANSLATION

T/F - Viral mRNA can NOT be translated when cellular translation is inhibited.

Back 23

False.

Viral mRNA is still translated even though cellular translation is inhibited.

Front 24

How do you expand the number of functions encoded by limited sequence information?

Back 24

Multiple processing events.

Front 25

T/F - Picornovirus RNA replication is symmetric.

Back 25

False

It is Asymmetric
(25 to 65x more +sense than -sense)

Front 26

How conservative is picornovirus RNA replication?

Back 26

Error-prone

misincorporating 1-2 nucleotides per replication event.

Front 27

Picornovirus capsid:

- composition
- Shel formed how?

Back 27

VP1, VP2, VP3, VP4

with
VP1, VP2, VP3 interaction,
with VP4 internal

Front 28

Discuss the rate of replication for a picornovirus.

Back 28

Very rapid (5-10 hrs)

Front 29

PICORNAVIRIDAE
PARTICLES ASSEMBLY

- Describe the steps

Back 29

1.) P1 encodes (V0, V1, & V3) a PROTOMER (5S)

2.) Five protomers combine to make a PENTAMER (14S)

TWO PATH OPTIONS

3a.) Pentamers can merge to form a EMPTY CAPSID, later addition makes iit a provirion

3b.) pentamers merge to form a PROVIRUS

4.) VO is cleaved to V2 & V4

5.) After cleavage we get a VIRION (160S)

Front 30

Flaviviridae family:

- capsid
- size
- envelope

- 3 important genera

Back 30

- ICOSAHEDRAL
- 40-60 nm in diameter
- Enveloped

- Flavivirus
- Hepacivirus (hep C)
- Pestivirus (animal dz)

Front 31

Flavivirus:

- vectors x2
- thus what kind of virus?
- diseases x3

Back 31

Mosquitoes & ticks

- Arbovirus

Denque
Yellow Fever
West Nile encephalitis

Front 32

Flaviviridae Family

- similarities with Picronoviridae?

- differences with Picornoviridae? x2

Back 32

- only ONE Polyprotein translated

- bigger
- ENVELOPE

Front 33

Calicivirus family:

- capsid
- size
- envelope?
- 5' cap?
- 3' Poly A?

Back 33

Icosahedral

35-39 nm in diameter

NOT enveloped

No
(but has VPg covalently)

Yes

Front 34

List four pathogenic viruses belonging to the Calciviridae genera.

(include associated pathology)

Back 34

1. Sapovirus
(PEDS gastroenteritis)

2. Norovirus
(NON-bacterial gastroenteritis worldwide)

3. Lagovirus
(Rabbit Hemorrhagic Dz)
(highly contagious & fatal hemorrhagic)

4. Vesivirus
(common cause of resp. dz in cats)

Front 35

The 5' end of the Calicivirus is uncapped. What is in place to compensate for this?

Back 35

VPg
(genome-linked protein)

Front 36

With caliciviruses, production of late polyprotein involves synthesis of what?

- this is found where?

Back 36

A subgenomic mRNA encoding structural protein.

- in infected cells

Front 37

List the steps in the Calicivirus replication scheme. x6

Back 37

1. Virus entry & uncoating

2. Nonstructural protein synthesis

3. Genomic Replication of PLUS sense and MINUS sense

4. Subgenomic RNA replication

5. Structural protein synthesis

6. Particle assembly

7. Particles egress and release from cell

Front 38

For caliciviruses, what MUST be produced in order for progeny genome production.

Back 38

Full-length minus strands

Front 39

What are the two models for production of subgenomic mRNA?

Back 39

1. Internal initiation

2. Premature termination

Front 40

For caliciviruses RNA replication, internal initiation must be done on which molecule?

Back 40

longer-than-subgenomic length minus strands.

Front 41

For caliciviruses RNA replication, premature termination occurs when?

What occurs?

Back 41

Minus strand synthesis

Subgenomic sized minus strand serves as template for sgmRNA

Front 42

Calicivirus uniqueness:

- stability
- capsid x2
- structure

Large hollows at what axes? x2

Back 42

Extremely stable
(pH 2.7, low [cl-], freezing 60C)

- Single capsid unique to animal viruses.

Contains 90 dimers of capsid protein;
forming shell with
90 archlike
capsomere protrusions

Large hollows at 5- and 3- axes

Front 43

Togavirus:

- capsid
- size
- envelope

Back 43

ICOSAHEDRAL

60-80 nm in diamter

Enveloped

Front 44

List two members of the Togavirus genera.

Back 44

Alphavirus (arbovirus - mosq. & ticks)

Rubivirus (rubella virus)

Front 45

List two members that are +stranded RNA that have a 5'cap and a polyA tail.

Back 45

Coronaviridae

Togaviridae

Front 46

Coronaviruses:

- capsid
- size
- envelope

Back 46

Spherical

120 nm

Enveloped

Front 47

PICORNAVIRIDAE

- List the genera associated with human pathogens. x5

- Which genera has a LEADER protein?

Back 47

ERK PH

- Enterovirus
- Rhinovirus

- Kobuvirus
- Parechovirus
- Hepatovirus

ONLY Kobuvirus has Leader protein.

Front 48

PICORNAVIRIDAE

- List the diseases associated with human pathogens (and include their genera)

Back 48

ENTEROVIRUS
- Polio virus
- Coxsackie

RHINOVIRUS
- Rhino virus

KOBUVIRUS
- Aichi virus

PARECHOVIRUS
- Human Parechovirus

HEPATOVIRUS
- Hepatitis A virus

Front 49

PICORNAVIRIDAE GENOME @ 5' END

- is there a cap?
- what protein is there?
- fate of this protein?

Back 49

- NO cap

- VPg

- cleaved upon entering cells cytoplasm

Front 50

PICORNAVIRIDAE GENOME @ 5' END

- what stretch of genomic region is at the 5' end?

- what does this encode?

- what is its fate?

Back 50

- UTR (UnTranslated Region)

- encodes NOTHING

- Folds into secondary structure known as IRES

Front 51

PICORNAVIRIDAE GENOME @ 5' END

- IRES F(x)?

- how can it do so without CBP?

- resultant effect?

Back 51

- recruits host translation factors

- eIF4G is cleaved, thus eIF4E (CBP) is no longer needed.

- Translation proceeds UNIMPEDED without CBP

Front 52

PICORNAVIRIDAE GENOME @ 5' END

- what type of proteins are translated from the 5' translation region?

- what about the 3' end?

Back 52

- Structural proteins
(capsid)

- NON-structural proteins
(enzymatic)

Front 53

PICORNAVIRIDAE GENOME

Translation for:
- P3B
- P3CD
- P3C
- P3D

Above is an example of?

Back 53

-VPg

- Protease inhibiting host Transcription
(goes to nucleus)

- Protease

- RNA Polymerase

Multiple processing events expanding the number of Functions encoded by a limited sequence

Front 54

PICORNAVIRIDAE GENOME

- once a polyprotein is processed, what are the 5 types of resulting proteins?

Back 54

- Pro-apoptotic
- Anti-apoptotic

- Shuts down host Transcription
(nucleus)
- Shuts down host Translation

- Viral replication complex