single strand, negative sense RNA Viruses Elliot J.
Lefkowitz
Slide 2
Email [email protected] Web Site http://www.genome.uab.edu Office
BBRB 277A Phone 934-1946 Email [email protected] Web Site
http://www.genome.uab.edu Office BBRB 277A Phone 934-1946 Contact
Information: Elliot Lefkowitz, Ph.D. Associate Professor,
Microbiology
Slide 3
Objectives To understand the fundamental common and
distinguishing properties of (-) ssRNA viruses To understand the
basic replication strategies of (-) ssRNA viruses To be able to
identify human pathogens that belong to (-) ssRNA virus families,
and some of their biological and pathogenic properties To
understand the fundamental common and distinguishing properties of
(-) ssRNA viruses To understand the basic replication strategies of
(-) ssRNA viruses To be able to identify human pathogens that
belong to (-) ssRNA virus families, and some of their biological
and pathogenic properties
Slide 4
Reading Medical Microbiology, Murray et al. 6th Edition General
classification Chapter 4 RNA virus properties and replication
Chapters 58, 59, 60, 63 Pathogenesis Chapters 48, 67 Medical
Microbiology, Murray et al. 6th Edition General classification
Chapter 4 RNA virus properties and replication Chapters 58, 59, 60,
63 Pathogenesis Chapters 48, 67
Slide 5
Slide References Fields Virology, 5th Edition Viruses and Human
Disease Strauss and Strauss University of Leicester - Virology
Online http://www- micro.msb.le.ac.uk/3035/index.html International
Committee on Taxonomy of Viruses The 9th ICTV Report Primary
literature Fields Virology, 5th Edition Viruses and Human Disease
Strauss and Strauss University of Leicester - Virology Online
http://www- micro.msb.le.ac.uk/3035/index.html International
Committee on Taxonomy of Viruses The 9th ICTV Report Primary
literature
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Virus classification
Slide 7
The Virus World
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The (-) RNA Virus World
Slide 9
RNA Virus Genome Structure Number of strands Single or double
stranded Strand polarity Positive, negative, or ambisense (both +
and -) Positive (Plus) sense denotes the coding (mRNA) strand
Number of segments Single or multi-segmented Number of strands
Single or double stranded Strand polarity Positive, negative, or
ambisense (both + and -) Positive (Plus) sense denotes the coding
(mRNA) strand Number of segments Single or multi-segmented
Slide 10
single strand RNA virus genome polarity virion RNA (+) sense
virus mRNA (+) sense translation 3355 transcription virion RNA (-)
sense virus mRNA (+) sense 3355 5533 (+) sense RNA virus (-) sense
RNA virus
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Negative/Ambisense ssRNA Viruses
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Properties of (-) sense ssRNA Viruses Enveloped virion Helical
nucleocapsid Negative-sense, linear, single segment RNA genome
Bornaviruses, Filoviruses, Rhabdoviruses, Paramyxoviruses Negative
and Ambisense, linear, multi segment RNA genomes Arenaviruses,
Bunyaviruses, Orthomyxoviruses Cytoplasmic replication Exception:
Bornaviruses, Orthomyxoviruses Genomes are non-infectious An
initial round of transcription is required for genome replication
Virion must contain proteins required for transcription Enveloped
virion Helical nucleocapsid Negative-sense, linear, single segment
RNA genome Bornaviruses, Filoviruses, Rhabdoviruses,
Paramyxoviruses Negative and Ambisense, linear, multi segment RNA
genomes Arenaviruses, Bunyaviruses, Orthomyxoviruses Cytoplasmic
replication Exception: Bornaviruses, Orthomyxoviruses Genomes are
non-infectious An initial round of transcription is required for
genome replication Virion must contain proteins required for
transcription
Multi-Segment, (-) sense ssRNA viruses Orthomyxoviridae
Influenzavirus A 8 genome segments Influenzavirus B 8 genome
segments Influenzavirus C 7 genome segments Isavirus 8 genome
segments Thogotavirus 6 genome segments Orthomyxoviridae
Influenzavirus A 8 genome segments Influenzavirus B 8 genome
segments Influenzavirus C 7 genome segments Isavirus 8 genome
segments Thogotavirus 6 genome segments
Slide 15
Multi-Segment, Negative and Ambisense ssRNA viruses
Arenaviridae Two ambisense RNA segments Bunyaviridae Three RNA
segments Both negative-sense and ambisense segments Depends on
genus Arenaviridae Two ambisense RNA segments Bunyaviridae Three
RNA segments Both negative-sense and ambisense segments Depends on
genus
Slide 16
The Virus Virion, Genome, Proteins
Slide 17
Viral Proteins Attachment/entry G Membrane glycoprotein F
Fusion protein H Hemagglutinin N Neuraminidase Structural/Assembly
M Matrix Underlies lipid bylayer Replication N nucleocapsid protein
P Phosphoprotein L RNA dependent RNA polymerase Attachment/entry G
Membrane glycoprotein F Fusion protein H Hemagglutinin N
Neuraminidase Structural/Assembly M Matrix Underlies lipid bylayer
Replication N nucleocapsid protein P Phosphoprotein L RNA dependent
RNA polymerase
Slide 18
Rhabdovirus Virion
Slide 19
Virus replication Machinery Proteins RNA-dependent
RNA-polymerase (RdRp) Transcription Replication Nucleocapsidprotein
(N) Encapsidates RNA Forms helical nucleocapsid P protein
Phosphoprotein - polymerase cofactor Forms complexes with N and L
Binds to RNA termini RNA Genome Proteins RNA-dependent
RNA-polymerase (RdRp) Transcription Replication Nucleocapsidprotein
(N) Encapsidates RNA Forms helical nucleocapsid P protein
Phosphoprotein - polymerase cofactor Forms complexes with N and L
Binds to RNA termini RNA Genome
Virus Coding Strategies Individual ORFs Multiple transcripts
with transcription attenuation Polyprotein processing Single
transcript to Large polyprotein: Proteolytic processing RNA Editing
Insertion/deletion of additional residues (at a specified site)
altering the reading frame Multiple ribosomal initiation sites Stop
codon read-through Individual ORFs Multiple transcripts with
transcription attenuation Polyprotein processing Single transcript
to Large polyprotein: Proteolytic processing RNA Editing
Insertion/deletion of additional residues (at a specified site)
altering the reading frame Multiple ribosomal initiation sites Stop
codon read-through
Slide 24
Virus Replication
Slide 25
RNA-dependent RNA Polymerase (RdRp L Protein) Catalytic subunit
of the polymerase complex Polymerization of nucleotides
Transcription of mRNA Capping Methylation Polyadenylation Genome
Replication Most conserved protein between the mononegavirales
virus families Catalytic subunit of the polymerase complex
Polymerization of nucleotides Transcription of mRNA Capping
Methylation Polyadenylation Genome Replication Most conserved
protein between the mononegavirales virus families
Slide 26
Source of the RNA-dependent RNA Polymerase Host cells do not
have a suitable one Therefore the virus must provide its own RNA
viruses use 2 different strategies to provide the RdRp: Synthesized
immediately upon entry and unpackaging of the virion into the cell
(positive-sense viruses) Therefore protein synthesis is the first
step in the replication process Packaged within the virion
(negative-sense viruses) Therefore mRNA transcription is the first
step in the replication process Host cells do not have a suitable
one Therefore the virus must provide its own RNA viruses use 2
different strategies to provide the RdRp: Synthesized immediately
upon entry and unpackaging of the virion into the cell
(positive-sense viruses) Therefore protein synthesis is the first
step in the replication process Packaged within the virion
(negative-sense viruses) Therefore mRNA transcription is the first
step in the replication process
Slide 27
VSV Transcription & Replication
Slide 28
(-) sense ssRNA virus Human Pathogens
Slide 29
Major Viral Target Tissues
Slide 30
Arenaviruses/Bunyaviruses
Slide 31
Arenavirus and Bunyavirus Disease Arenaviruses Mostly rodent
viruses Human zoonoses Junin virus Argentine hemorrhagic fever
Lassa Fever Bunyaviruses Large group of arthropod-borne viruses
Human pathogens hemorrhagic fever Hantaviruses Rodent-borne
Pulmonary Syndrome/Hemorrhagic fever Rift Valley Fever virus
Mosquito-borne virus Arenaviruses Mostly rodent viruses Human
zoonoses Junin virus Argentine hemorrhagic fever Lassa Fever
Bunyaviruses Large group of arthropod-borne viruses Human pathogens
hemorrhagic fever Hantaviruses Rodent-borne Pulmonary
Syndrome/Hemorrhagic fever Rift Valley Fever virus Mosquito-borne
virus
Slide 32
Filoviruses
Slide 33
Filovirus Disease
Slide 34
Rhabdoviruses
Slide 35
Slide 36
Rabies virus Pathogenesis
Slide 37
Paramyxoviruses
Slide 38
Slide 39
Human Respiratory Syncytial virus Major cause of lower
respiratory tract infections Rarely life-threatening Individuals
get repeat infections Highly infectious Spread is by exchange of
respiratory secretions Infection confined to respiratory tract
Globally: 100,000,000 infections/year 200,000 deaths/year In USA:
All infants by age of 4 years are infected 100,000
hospitalizations/year Estimated cost of $300,000,000/year (1985)
25-50% of hospital staff infected during outbreaks Major cause of
lower respiratory tract infections Rarely life-threatening
Individuals get repeat infections Highly infectious Spread is by
exchange of respiratory secretions Infection confined to
respiratory tract Globally: 100,000,000 infections/year 200,000
deaths/year In USA: All infants by age of 4 years are infected
100,000 hospitalizations/year Estimated cost of $300,000,000/year
(1985) 25-50% of hospital staff infected during outbreaks
Slide 40
Measles virus Extremely infectious Spreads through contact with
respiratory secretions Victims are infectious before symptoms are
evident Develops systemic infection Globally: 45,000,000
infections/year 1,000,000 deaths/year In USA: Infections are rare
Occasional epidemic in unvaccinated populations MMR (Measles,
mumps, and rubella) vaccine highly effective (2 shots) Extremely
infectious Spreads through contact with respiratory secretions
Victims are infectious before symptoms are evident Develops
systemic infection Globally: 45,000,000 infections/year 1,000,000
deaths/year In USA: Infections are rare Occasional epidemic in
unvaccinated populations MMR (Measles, mumps, and rubella) vaccine
highly effective (2 shots)
Slide 41
Acute Disseminated Encephalomyelitis Measles Inclusion Body
Encephalitis Subacute Sclerosing Panencephalitis Neurologic
Complications of Measles
Slide 42
Orthomyxoviruses
Slide 43
Influenza A: Mild to severe disease involving upper and
especially lower respiratory tract B: Similar spectrum of illness
to A but generally more mild C: Sporadic upper respiratory illness
in humans 96% of human adults have antibodies Thogotovirus Natural
host: Ticks Also infects: Humans, cattle, goats, waterfowl, etc.
Isavirus Infectious salmon anemia virus Influenza A: Mild to severe
disease involving upper and especially lower respiratory tract B:
Similar spectrum of illness to A but generally more mild C:
Sporadic upper respiratory illness in humans 96% of human adults
have antibodies Thogotovirus Natural host: Ticks Also infects:
Humans, cattle, goats, waterfowl, etc. Isavirus Infectious salmon
anemia virus
Slide 44
G Neumann et al. Nature 000, 1-9 (2009) doi:10.1038/nature08157
Schematic diagram of influenza A viruses
Slide 45
Involved in virion uncoating Highly conserved Target for
amantadine Involved in virion uncoating Highly conserved Target for
amantadine M2 Ion Channel
Slide 46
Hemagglutinin
Slide 47
Virion release from cell membrane Cleavage of sialic acid from
cell membrane thus preventing binding by HA Target for Oseltamavir
(Tamavir) and Zanamivir (Relenza) Virion release from cell membrane
Cleavage of sialic acid from cell membrane thus preventing binding
by HA Target for Oseltamavir (Tamavir) and Zanamivir (Relenza)
Neuraminidase
Slide 48
Influenza virus Variation and evolution
Slide 49
Influenza Virus Variation Antigenic drift Amino acid changes
Antigenic shift Reassortment/exchange of genome segments between
strains Recombination Detected but rare Antigenic drift Amino acid
changes Antigenic shift Reassortment/exchange of genome segments
between strains Recombination Detected but rare
Slide 50
Reassortment
Slide 51
G Neumann et al. Nature 000, 1-9 (2009) doi:10.1038/nature08157
Genesis of swine-origin H1N1 influenza viruses
Slide 52
Why Pigs? Susceptible to infection by influenza virus Express
both human- and avian-like influenza virus receptors on their
tracheal epithelial cells Swine may therefore be acting as a mixing
vessel for the production, replication, and transmission of novel
influenza virus reassortments Susceptible to infection by influenza
virus Express both human- and avian-like influenza virus receptors
on their tracheal epithelial cells Swine may therefore be acting as
a mixing vessel for the production, replication, and transmission
of novel influenza virus reassortments
Slide 53
US Influenza Surveillance 2004- 2008
Slide 54
US Influenza Surveillance 2008- 2009
Slide 55
US Influenza Surveillance 2010- 2011
Slide 56
Fighting back Antiviral drugs Neuraminidase inhibitors
Oseltamavir (Tamavir) and Zanamivir (Relenza) Active against
influenza A and B Ion channel blockers Amantidine and rimantidine
Prevent release and subsequent transport of the virus RNP Active
only against Influenza A Vaccines Inactivated Live attenuated
Antiviral drugs Neuraminidase inhibitors Oseltamavir (Tamavir) and
Zanamivir (Relenza) Active against influenza A and B Ion channel
blockers Amantidine and rimantidine Prevent release and subsequent
transport of the virus RNP Active only against Influenza A Vaccines
Inactivated Live attenuated
Vaccine Development Inactivated vaccine (TIV) Produced from
seed stocks in eggs Live-attenuated vaccine (LAIV) Administered as
a nasal spray Vaccines contain three viruses H3N2; H1N1; B Exact
strains used change each year Strain choice determined by data
collected by WHO on currently circulating strains Decision on
composition made in February and September Inactivated vaccine
(TIV) Produced from seed stocks in eggs Live-attenuated vaccine
(LAIV) Administered as a nasal spray Vaccines contain three viruses
H3N2; H1N1; B Exact strains used change each year Strain choice
determined by data collected by WHO on currently circulating
strains Decision on composition made in February and September
Slide 59
Vaccine Strains for the 2009-2010 and 2010-2011 Seasons 2009
2010 Seasonal Vaccine A components unchanged from 2008-2009 B
component changed toB/Brisbane/60/2008 Related to B/Victoria 2009
Supplementary Vaccine A/California/7/2009 (H1N1) 2009 pandemic
influenza A (H1N1) virus 2010 2011 AND 2011 2012 influenza A (H1N1)
virus A/California/7/2009 (H1N1)-like virus (99.8% of 2010-2011
viruses match) A/Perth/16/2009 (H3N2)-like (96.8% of 2010-2011
viruses match) B/Brisbane/60/2008 (94% of 2010-2011 viruses match)
2009 2010 Seasonal Vaccine A components unchanged from 2008-2009 B
component changed toB/Brisbane/60/2008 Related to B/Victoria 2009
Supplementary Vaccine A/California/7/2009 (H1N1) 2009 pandemic
influenza A (H1N1) virus 2010 2011 AND 2011 2012 influenza A (H1N1)
virus A/California/7/2009 (H1N1)-like virus (99.8% of 2010-2011
viruses match) A/Perth/16/2009 (H3N2)-like (96.8% of 2010-2011
viruses match) B/Brisbane/60/2008 (94% of 2010-2011 viruses
match)
Slide 60
And finally, how is influenza spread between humans and
pigs?