53
RNA VIRUS REPLICATION/ TRNSLATION STRATEGIES Sadia Anjum Virology lecture 5 1

RNA VIRUS REPLICATION/ TRNSLATION STRATEGIES

  • Upload
    gilead

  • View
    56

  • Download
    5

Embed Size (px)

DESCRIPTION

RNA VIRUS REPLICATION/ TRNSLATION STRATEGIES. Sadia Anjum Virology lecture 5. RNA -> RNA. RNA-dependent RNA polymerase . RNA -> DNA. RNA-dependent DNA polymerase - reverse transcriptase . Host cell DNA -> RNA. DNA-dependent RNA polymerase . RNA VIRUS STRATEGIES. AAA. - PowerPoint PPT Presentation

Citation preview

Page 1: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

1

RNA VIRUS REPLICATION/ TRNSLATION STRATEGIES

Sadia Anjum

Virology lecture 5

Page 2: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

2

RNA VIRUS STRATEGIES

RNA -> RNARNA-dependent RNA polymerase

RNA -> DNARNA-dependent DNA polymerase- reverse transcriptase

Host cell DNA -> RNADNA-dependent RNA polymerase

Page 3: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

3

All animal RNA viruses code for a polymerase

Need to make mRNAPLUS (POSITIVE) SENSE RNA GENOMES

AAA

(+ve) sense mRNA

Page 4: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

4

NEED TO MAKE MRNA

MINUS (NEGATIVE) SENSE RNA GENOMES

AAA(+ve) sense mRNA

(-ve) sense genomic RNA

Page 5: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

5

NEED TO MAKE MRNAMINUS (NEGATIVE) SENSE RNA GENOMES

RNA polymerase must be packaged in virion.

AAA(+ve) sense mRNA

(-ve) sense genomic RNAIf used, RNA modifying enzymes arepackaged in virion.

Page 6: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

6

DOUBLE-STRANDED RNA GENOMES

AAA(+ve) sense mRNA

Double-stranded genomic RNAIf used, RNA modifying enzymes arepackaged in virion.

RNA polymerase must be packaged in virion.

Page 7: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

7

RETROVIRUSES

DSDNA

+VE RNA

DSDNA

Reverse transcriptase must be packaged in virion.

Page 8: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

8

RNA VIRUSES THAT DO NOT HAVE A DNA PHASE

TranscriptionNon-infectiousYesDouble-stranded RNA

TranscriptionNon-infectiousYesNegative-stranded RNA

TranslationInfectiousNoPlus-stranded RNA

Initial event in cell

Infectivity of RNA

RNA-dependent RNA polymerase (=transcriptase) IN VIRION

Genome

TranscriptionNon-infectiousYesDouble-stranded RNA

TranscriptionNon-infectiousYesNegative-stranded RNA

TranslationInfectiousNoPlus-stranded RNA

Initial event in cell

Infectivity of RNA

RNA-dependent RNA polymerase (=transcriptase) IN VIRION

Genome

Page 9: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

9

RETROVIRUSESGenome RNA-

dependent DNA polymerase (=reverse transcriptase) in virion

Infectivity of RNA

Initial event in cell

Plus-stranded RNA Yes Non-infectious Reverse

transcription

Page 10: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

10

THE MONOCISTRONIC MRNA PROBLEM

Make one monocistronic mRNA per protein Make a primary transcript and use alternative splicing Make a large protein and then cut it into smaller

proteins Include special features in the mRNA which enable

ribosomes to bind internally

AAAAAAAA

RIBOSOMES

mRNA

PROTEIN

AAAAAAAA

Eukaryotes

Prokaryotes/viruses

Page 11: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

11

Page 12: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

12

POLYCISTRONIC VS MONOCISTRONIC

Page 13: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

13

RNA GENOME SIZE TAUTOMERIZATION PROOF READING GENOME SIZE

RNA VIRUSES HAVE SMALL GENOMES~10,000 NUCLEOTIDES(herpesvirus DNA ~200,000)

Page 14: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

14

GENOME SIZE POLYMERASE ATTACHMENT PROTEIN CAPSID PROTEIN RELATIVELY FEW OTHER PROTEINS VIRION SIZE MAY BE QUITE LARGE BUT

LIMITED NUMBER OF PROTEINS

Page 15: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

15

POSITIVE-STRANDED RNA VIRUSES

EXAMPLES

PICORNAVIRUSES

TOGAVIRUSES

FLAVIVIRUSES

Page 16: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

16

PICORNAVIRUS FAMILY (PICORNAVIRIDAE)

SMALL ICOSAHEDRAL POSITIVE SENSE RNA NON-ENVELOPED

Page 17: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

17

INTERNAL RIBOSOME ENTRY SITE (IRES)

GENOMIC (+ SENSE) RNA AAAAAVPg

IRES

start codonfor translation

stop codonfor translation

POLYPROTEIN

.

Page 18: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

18

VPG VPg (viral protein genome-linked) is a protein that is

covalently attached to the 5′ end of positive strand viral RNA and acts as a primer during RNA synthesis in a variety of virus families including Picornaviridae and Caliciviridae.

The primer activity of VPg occurs when the protein becomes uridylylated, providing a free hydroxyl that can be extended by the virally encoded RNA-dependent RNA polymerase.

Aside from functioning as a primer, VPg also has a role in translation initiation by acting like a 5' mRNA cap

Page 19: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

19

INHIBITION OF HOST CELL TRANSLATION

HOST mRNA AAAAACAPUninfected cell

Factors+40S ribosomal subunit

HOST mRNA AAAAACAPAltered factors+40S ribosomal subunit

Infected cell

Page 20: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

20

VIRAL TRANSLATION

GENOMIC (+ SENSE) RNA AAAAA

IRES

VPgFactors+40S ribosomal subunit

Altered factors+40S ribosomal subunit

GENOMIC (+ SENSE) RNA AAAAA

IRES

VPg

Uninfected cell

Infected cell

Page 21: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

21

GENOMIC (+ SENSE) RNA AAAAAtranslation

Page 22: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

22

Page 23: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

23

RNA REPLICATION

GENOMIC (+ SENSE) RNA 3’VPg

(- SENSE) RNA 3’ VPg

GENOMIC (+ SENSE) RNA 3’VPg

Page 24: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

24

RNA REPLICATION viral RNA polymerase (replicase) host factors also involved as accessory

proteins new plus strands

packaged templates for more replication templates for more translation

Page 25: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

25

ASSEMBLYVP0, VP1, VP3

VP2, VP4, VP1, VP3VPg

VPg-RNA enters, VP0 is cleaved

Page 26: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

26

NON-SEGMENTED NEGATIVE STRAND VIRUSES

Examples:

Rhabdovirus family (Rhabdoviridae)

Paramyxovirus family (Paramyxoviridae)

Filovirus family (Filoviridae)

Page 27: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

27

RHABDOVIRUSES

helical nucleocapsid (RNA plus N protein)

G glycoprotein SPIKES

lipid bilayer membrane

polymerase complex

M protein

Page 28: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

28

MINUS (NEGATIVE) SENSE RNA GENOME

RNA polymerase must be packaged in virion.

AAA(+ve) sense mRNA

(-ve) sense genomic RNA

RNA modifying enzymes are packaged in virion.

Page 29: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

29

RHABDOVIRUSES

EXAMPLESvesicular stomatitis

virus (VSV)

rabies virus

Dr FS Murphyhttp://www.vetnet.ucdavis.edu/fam_graphics/download.html

Page 30: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

30

ADSORPTION AND PENETRATION

Page 31: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

31

CYTOPLASMIC REPLICATION

GENOMIC RNA REMAINS IN NUCLEOCAPSID FORM

Page 32: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

32

RNA SYNTHESIS3’ 5’

genome (-ve)

3’ 5’ (-ve)

full-length copy

5’ 3’ (+ve)

replication (protein synthesis is a pre-requisite)transcription

mRNAs (+ve sense)

AAA

AAA

AAA

AAA

AAA

= cap

Page 33: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

33

NEW MINUS STRAND

PACKAGED TEMPLATE FOR

MORE REPLICATION TEMPLATE FOR

MORE TRANSCRIPTION

3’ 5’genome (-ve)

3’ 5’ (-ve)

5’ 3’ (+ve)AA

AA

AA

AA

AA

Page 34: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

34

SOME POINTS TO NOTE ABOUT RHABDOVIRUSES ENTIRE CYCLE OCCURS IN CYTOPLASM RNA POLYMERASE AND RNA MODIFICATION

ENZYMES ARE: VIRALLY CODEDPRESENT IN THE VIRION

THERE IS NO EARLY/LATE DIVISION

Page 35: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

35

MEMBERS INCLUDEPARAINFLUENZA VIRUSMUMPS VIRUSMEASLES VIRUSRESPIRATORY SYNCYTIAL VIRUS

PARAMYXOVIRUSES

Page 36: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

36

PARAMYXOVIRUSES

M protein

helical nucleocapsid (RNA plusNP protein)

HN/H/G glycoprotein SPIKES

polymerase complex

lipid bilayer membrane

F glycoprotein SPIKES

pleomorphic

Page 37: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

37

PARAMYXOVIRIDAE PARAMYXOVIRUS SUBFAMILY

PARAMYXOVIRUS RUBULAVIRUS MORBILLIVIRUS

PNEUMOVIRUS SUBFAMILY PNEUMOVIRUS GENUS METAPNEUMOVIRUS GENUS

Page 38: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

38

GENUS GLYCOPROTEINS TYPICAL MEMBERS

Paramyxovirus HN, F HPIV1, HPIV3Rubulavirus HN, F HPIV2, HPIV4, mumps virusMorbillivirus H, F measles virus

Pneumovirus G, F respiratory syncytial virusMetapneumovirus G, F metapneumoviruses

PARAMYXOVIRUS FAMILY SURFACE GLYCOPROTEINS

PARAMYXOVIRUS SUBFAMILY

PNEUMOVIRUS SUBFAMILY

Page 39: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

39

TRANSCRIPTION, TRANSLATION, REPLICATION

3’ 5’genome (-ve)

full-length copy

5’ 3’ (+ve)

3’ 5’ (-ve)

replication (protein synthesis is a pre-requisite)transcription

mRNAs (+ve sense)

AAA

AAA

AAA

AAA

AAA

= cap

AAA

Page 40: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

40

SOME DIFFERENCES BETWEEN RHABDOVIRUSES AND PARAMYXOVIRUSES

two:one attachmentone fusion

one (has both attachment and fusion activities)

glycoproteins

neutralphysiological

acidicfusion pH

roundpleomorphic

bulletbacilliform

shape

PARAMYXOVIRUSESRHABDOVIRUSES

Page 41: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

41

ORTHOMYXOVIRUSES

M1 protein

helical nucleocapsid (RNA and NP protein)

HA - hemagglutinin

polymerasecomplex

lipid bilayer membrane

NA - neuraminidase

Page 42: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

42

ADSORPTION AND PENETRATION

NUCLEUS

Page 43: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

43

TRANSCRIPTION (MRNA SYNTHESIS)

AAAAviral endonuclease

A

host cell mRNA

influenza mRNA

=cap

influenza virus nucleocapsidAU

AU

viral polymerase

Page 44: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

44

RNA SYNTHESIS

Endonuclease is virally coded and packed in the virion

RNA polymerase is virally coded and packed in the virion

Poly(A) polymerase is virally coded and in the virion

Why doesn’t the virus use host cell enzymes?

Page 45: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

45

RNA SPLICING

Several segments give rise to transcripts which can have one of two fates

AAAAAA

AAAAAA

Page 46: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

46

RNA REPLICATION nuclear authentic copies replicase and

transcriptase probably same enzyme

coated with protein as made

no clear early/late

3’ 5’genomic (-ve)

3’ 5’ genomic (-ve)

5’ 3’ (+ve)

Page 47: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

47

NUCLEUS

acid pH inside endosome

- HA conformational change, now active in membrane fusion

Infection of next cell

HA cleavage by host cell enzymes

Flu Virus

Page 48: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

48

PARAMYXOVIRIDAE ORTHOMYXOVIRIDAE

genome nonsegmented segmented

RNA synthesis cytoplasmic nuclear

need for RNA primer

no yes

hemagglutinin, neuraminidase

if both, part of same protein (HN)

Influenza A and B viruses have both, but on different proteins (HA and NA)

syncytial formation

yes (F functions at physiol. pH)

no (HA functions at acid pH)

Page 49: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

49

REOVIRUS FAMILYdouble stranded RNA genome

outer capsid

inner capsid

Page 50: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

50

DOUBLE-STRANDED RNA GENOMES

AAA(+ve) sense mRNA

Double-stranded genomic RNARNA modifying enzymes arepackaged in virion.

RNA polymerase must bepackaged in virion.

Page 51: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

51

REOVIRUS FAMILYdouble stranded RNA genome

outer capsid

inner capsid

RNA polymerase plus 5’ endmodification enzymes

Page 52: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

52

REOVIRUS FAMILY INCLUDES

REOVIRUSES ROTAVIRUSES

IMPORTANT HUMAN PATHOGENS ORBIVIRUSES

INCLUDE COLORADO TICK FEVER VIRUS

Page 53: RNA VIRUS  REPLICATION/ TRNSLATION STRATEGIES

53

Annual Review of Microbiology 51:227 RF Ramig