Orthomyxovirus Orthomyxovirus and Paramyxovirus Paramyxovirus I

Orthomyxovirus and Paramyxovirus
I fl
Influenza,
Corona
C
SARS
SARS, avian
i flflu and
d other
h
respiratory
y viruses
Chao ZHAO(赵 超)
MOH&MOE Key Lab of Medical Molecular Virology
Shanghai Medical College,
College Fudan University
复旦大学上海医学院分子病毒学教育部/卫生部重点实验室
Nov 15,, 2013
TOPIC: what is the biggest challenge
•
•
•
•
•
War?
Food safety
Finance crisis
Natural disasters, eg earthquake…
acute
t infectious
i f ti
diseases,
di
esp respiratory
i t
viruses infection (RVI)
• Chronic disease & aging
• Biosafety & Bioterror(ism)
Why is RVI
•
•
•
•
•
Easy transmit
large population
Worldwide (Wide geographic spread)
Emergency
Variant/mutant
EXAMPLE:1918 Influenza Pandemic
1918 Influenza Pandemic
• Caused
C
d 40 million
illi deaths
d th worldwide
ld id
– Mainly the young!
• 80% of US Army deaths in World War I
resulted
lt d from
f
infection
i f ti with
ith influenza
i fl
virus
• We still do not understand fully why this
strain
t i off Influenza
I fl
A virus
i
was so
devastating to the younger population
High Mortality
of 1918 Influenza Pandemic
Spanish flu
Infectious Disease Mortality,
United States--20th Century
Armstrong, et al. JAMA 1999;281:61-66.
Recent
Outbreaks of
New
Influenza
2013 H7N9
2008 H5N1
H5N1 (Avian) Influenza
Attempt to control:
complete or partial slaughter of poultry population
in infected areas
† ASM News 70:154 (2004)
Then
h (Spanish
(
i h flu)
fl )
1918
What happened
1.8 billion
World population
Troop ships
Primary transportation
railroad
il d
mode
d
4 months
Time for virus to
circle globe
Gauze masks
Preventative measures
disinfectants
Bed rest
Treatments
aspirin
20+ million
Estimated dead
Now (Avian
( i flu)
fl )
2008
what could
6 billion
Jets
4 days
Vaccines
Some
antivirals
60 million?
Learning Objectives
At the end of this lecture, the students should be able to:
1
1.
O tli the
Outline
th distinguishing
di ti
i hi features
f t
off influenza
i fl
viruses.
i
2.
Outline the basic steps in the pathogenesis of influenza.
3. Discuss the potential complications of influenza infection.
4 Understand why a “flu”
4.
flu shot is needed every year
year.
5.
Understand how genome structure and viral polymerase impact on
appearance of new virus strains
strains.
6.
Outline the impact of animal reservoirs of viruses in the recurrence of
influenza.
Reference:
Jawetz, Melnick, & Adelberg's
g Medical Microbiology,
gy 25t
Influenza virus-an example of virus mutations. key notes on medical molecular virology.
Editors: Yu-mei Wen, et al. Fudan University Press, p64-75, 2005
Respiratory viruses
1 Orthomyxovirus
y
((~idae)) ：
influenza V
2 Paramyxoviruses (~idae) ：
measles
mumps
RSV (respiratory syncytial V)
3 others
Togaviridae:
i id Rubella
b ll V
Coronaviridae: SARS-CoV
Oth
Others:
adenovirus,
d
i
rhinovirus
hi i (Piconaviridae)….
(Pi
i id )
influ B
vaccine
MMR,
measlesmumpsmumps
rubella
vaccine
Part I: Orthomyxovirus
-- Influ
fl V
• orthomyxoviridae ＃
Ortho, “standard, correct;” myxo, “mucus”
•
•
•
•
•
Pathogen causing viral influenza
3 subtypes（ABC）
I fl
Influenza
A lleads
d pandemic/epidemic
d i / id i
pandemic/epidemic ＃
1stt finding: in 1933, by a British Doctor Wilson
Smith，named H1N1
Influenza Types
• Type A
– Epidemics and pandemics
– Animals and humans
– All ages
• Type
T
B
– Milder epidemics
– Humans
H
only
l
– Primarily affects children
1. Properties of influ v
• -ss RNA, envelope
core：RNA（7～8， segmented）、
nucleoprotein（NP, A，B，C, category）、
RNA polymerase
Matix protein
Hemagglutinin, HA #,15
envelope
Neuraminidase, NA #, 9
General Properties
p
of Influenza A Virus
– Enveloped virus with helical symmetry
– ss-RNA (segmented) genome with negative
polarity
– 8 unique segments, 10 protein products
– All proteins but one (NS1) are structural
– Host nucleus required for replication
• Unusual for an RNA virus
2. Morphology & structure
• 80—120nm，envelope
glycoproteins-• Spikes: glycoproteins
Virion Structure - Diagram
Envelope glycoproteins (spikes):
Hemagglutinin (HA)
Neuraminidase (NA)
M1: matrix
M2: ion channel
NP: nucleoprotein
helical nucleocapsid
Polymerase complex
PA, PB1, PB2
Genome:
8 segments, SS, (-) sense
NS1, NS2: non-structural proteins (some NS2 also in virions)
3. Influenza Virus Composition
Nomenclature for Designation
g
of Subtypes
yp of Influenza
Type of nuclear
material
Neuraminidase
Hemagglutinin
A/Beijing/32/92
j g
(H3N2)
(
)
Virus
type
Geographic
origin
Strain
number
Year of
Isolation
Virus subtype
3.1 Hemagglutinin (HA)
1
1.
Integral membrane protein
2.
Responsible for binding of virions to host cell via sialic acid
p
receptors
3.
Responsible for fusion of virus envelope with endosomal
membrane
4.
Major antigen to which neutralizing (protective) antibodies
develop within the infected host
5.
HA0 cleaved into HA1 + HA2 by cellular protease, required for
fusion function
6
6.
HA binds
bi d to
t sialic
i li acid
id on the
th surface
f
off RBC (Red
(R d blood
bl d cell)
ll)
to cause the “hemagglutination” of RBC’s
Hemagglutinin (HA)
HA1
HA2
3.2 Neuraminidase, NA
• for subtype; catalytic site for neuraminic acid
• function
– Release of virion
– Promote
P
the
h virus
i spreadd
Structure of Neuraminidase
Sialic acid
Specific NA inhibitors as new anti-flu drugs (Tamiflu)
Site of cleavage by
Neuraminidase (NA)
( )
NA cleavage is required to release influenza
virions bound to SA on cells or other virions
(aggregation) in order to spread to other cells
N-linked Oligosaccharide
Chain of Glycoproteins
3.3 M1 & M2
M1: matrix, the structure
HA and M2 Collaborate in Releasing RNP from Endosome
M2: Ion Channel
The channel is specifically blocked by the antiviral drug Amantadine
3.4 Other proteins
• Non-structural proteins:
NS1: interferon (innate immunity) resistance
• H5N1 virus
• 1918 virus
• PA, PB1,PB2:
polymerase
• NP: nucleoprotein
4. General Scheme of Replication
mRNA
protein
p
( RNA)
(cRNA)
(vRNA)
= NP coating RNA
5 Antigenic drift & Antigenic shift
5.
Antigenic
g
variant,, occur in HA and NA
• Antigenic
g
drift ((minor change)
g )
mutation
• Antigenic shift (major change)
reassortment
Antigenic Shift
Appearance
pp
of Influenza
P d i
Pandemics
Influenza A Pandemics of the Past 100 Years
Year of Origin
1890
1900
1918
1957
1968
((1977))
Subtype in Circulation
H1N1 (Spanish flu)
H2N2 (A
(Asian
i fl
flu))
H3N2 (Hong Kong flu)
H3N2 and H1N1
(reintroduction of H1N1 into the population, but did not cause a pandemic)
2009
New H1N1 (Swine flu)
New H1N1
Development of a Pandemic-1
• Every new pandemic is accompanied by a
dramatic change in the HA protein
• NA may or may not change
• With a new pandemic, the HA changes and
th the
thus
th neutralizing
t li i antibodies
tib di no longer
l
react with the new HA molecule
Development of a Pandemic-2
How does the complete change of
HA molecule occur?
Multiple independent mutations do not occur
simultaneously
Rather, the reassortment of the segmented
genome of the virus
Reassortment of Influenza Virus Gene Segments
EMERGENCE OF NEW PANDEMIC STRAINS
Avian virus
1918 (H1N1), 1997 (H5N1)
H1 N1
raree
H2 N2
Peaceful
coexistence
Co - i n f e c t i o n
Re a sso r t m e n t
Pig is
Pi
i permissive
i i
for both avian
and human strains
Genetic reassortment
(mixing)
of genome segments
Human virus
N2
H2
Reassorted virus new HA and/ or
NA; other segments (green) enhance
replication/transmission in humans
Antigenic Drift
Appearance of Influenza
Epidemics
Antigenic
g
Drift
•
Explains the “local” epidemics that occur more frequently (every 1-2
yrs)
•
Occurs by point mutations in the HA gene that lead to altered antigenic
sites that are poorly recognized by the existing immune response
•
Viruses within a single subtype (H1N1 or H3N2) change with time
•
Can be measured by hemagglutination-inhibition; the number of
antibody units that block HA measures the degree off relatedness
between the two HA proteins. This correlates with neutralizing
antibody.
Summary of Antigenic Drift vs. Shift
Antigenic Drift
Antigenic Shift
GENETIC VARIATION IN INFLUENZA VIRUSES
ANTIGENIC DRIFT
Influenza A and B
Slow accumulation of mutations
in HA and/or NA genes
Escape from
antibody mediated
antibody-mediated
neutralization
HA
NA
viral transcriptase/
replicase
li
is
i
error-prone
ANTIGENIC SHIFT
Influenza A only
Complete replacement of
HA or NA genes
HA and NA
encoded in
different
genome
segments
Broad host range
Mixed co-infection
in pigs
6. Influenza pathogenesis
•
•
Transmission
Aerosoles
•
•
Infection
Epithelial cells
•
•
Replication cycle
4 –6 h
•
•
Cell death
Necrosis,apoptosis
•
•
Incubation
18 – 72 h
•
•
PBMC
Non-productive
7. Clinic: Influenza
(learn by yourself)
• Respiratory infection
• Transmission: contact with respiratory secretions
from an infected person who is coughing and sneezing
• Incubation period: 1 to 5 days from exposure to
onset of symptoms
• Communicability: Maximum 1-2 days before to 4-5
days after onset of symptoms
• Timing: Peak usually occurs December through
March in North America
DISEASE CAUSED BY INFLUENZA VIRUSES
INFLUENZA
CLINICAL PRESENTATION
Symptoms
Abrupt onset
Headache
Chill
Chills
Dry cough-rapidly followed
by high fever (38-41oC)
declines 2nd or 3rd day
Malaise
Significant myalgias
symptoms increase
as fever decreases
Respiratory
symptoms
due to
necrosis of
respiratory
epithelium
EPIDEMIOLOGICAL FORMS
Epidemic
every
1 2 years
1-2
Systemic
symptoms
due to release
of interferon
Pandemic
every
10 20 years
10-20
Uncomplicated Influenza is Limited to
Upper Respiratory Tract
S
S-S
HA precursor
( HA0)
No fusion
Mature HA
fusion
Tryptase
Clara
HA1
SS
S-S
Cleavage
site
HA2
HA0
Airway lumen
Nonciliated Clara cells in bronchial epithelia secrete the organ specific protease
COMPLICATIONS ASSOCIATED WITH INFLUENZA
PNEUMONIA
Primary Viral
Influenza A
Combined
Viral and Bacterial
Persons >65 years (30% fatalities)
Influenza A
Pregnant women in 2nd and 3rd trimester
P
Persons
with
ith cardiovascular
di
l disease
di
Immunodeficient individuals
Streptococcus pneumoniae
Infants and very young children
Hemophilis influenzae
Staphlococcus aureus
+
Bacterial
Invade after
loss of
Mucocilliary
bl k
blanket
Excreted bacterial p
proteases cleave HA0
Host inflammatory proteases cleave HA0
Influenza is a serious illness
• Annual deaths: 36,000*
• Hospitalizations: >200,000*
>200 000*
* Average annual estimates during the 1990’s
• Who is at greatest risk for serious complications?
–
–
–
–
–
persons 65 and older
persons with chronic diseases
infants
pregnant women
nursing home residents
8. Diagnosis, Treatment and Immunization
Clinical Grounds
Symptoms
Epidemic
periods
virus isolation
and typing;
antibody testing
for epidemiology
Killed Vaccine
Reformulated yearly
Three antigenic types
circulating the previous
year
2 type A
1 type B
Vaccinate
Sept. to
mid-Nov.
70-90%
effective
against
epidemic
strains
contained
in vaccine
Also, live flu vaccine (nasal spray)
Influenza - diagnosis
•Specimens:
p
throat swabs, nasal aspirates,
p
sputum
p
•Culture: conventional, rapid
•Direct detection (EIA, IF, PCR)
•Serologic response: 4
4-fold
fold or greater
rise in IgG titers
Antivirals Against Influenza
Stocking
Resistance
De eloping
Developing
“Universal” Flu Vaccine in Development
Elicit antibodies targeting the highly
conserved, “fusion peptide” of HA,
instead of its variable, receptor-binding
region.
region
Potentially active against multiple subtypes.
Vaccine Development (current)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
WHO/CDC)
surveillance
select strains
prepare reassortants
standardize antigen
WHO/CDC/FDA
CDC/FDA
FDA
FDA
assign potency
review/license
formulate/test/package
vaccinate
FDA
manufacturers
clinic
Pandemic Flu Today
y
Despite
p ...
– Expanded global and national surveillance
– Better healthcare, medicines, diagnostics
– Greater vaccine manufacturing capacity
N risks:
New
ik
–
–
–
–
–
Increased global travel and commerce
G t population
Greater
l ti density
d it
More elderly and immunosuppressed
More daycare and nursing homes
Bioterrorism
PART II.
other
h respiratory
i
viruses
i
• Paramyxoviruses
P
i
and
dR
Rubella
b ll V
measles
•
•
•
•
•
•
Paramyxoviruses
y
-ssRNA
One serotype (antigen stable)
Inclusion body in cell
Human being is the only host
Cellular immune
measles
l patient
i
K lik
Koplik
Mumps V
•
•
•
•
paramyxovirueses
+ RNA
+ssRNA
One serotype
yp
vaccine
Corona virus
• SARS
SARS-corona
corona virus
• +ssRNA
SARS host
SARS-CoV
Rubella V
• Togaviridae,
g
, cause rubella,, Germen
Measles
• +ssRNA
+ RNA
• One serotype
yp
• Congenital rubella syndrome (CRS)
Questions
• Why influenza virus is so easy to spread over the
world? (Why is the influenza virus easy to
produce variant?) (1.everyone is easy to be
infected 2.
infected,
2 vaccine failure due to antigen change,
change
3. RNA, mutation; segmented, reassortment)
• What is antigen reassortment? Antigen shift?
Antigen drift?
• Plz describe the functions of hemagglutinin and
neuraminidase?
• What should you do when you face to a
suspicious outbreak of respire infectious
pp
yyou as a virologist,
g ,a
diseases? Supposed
general physician, a infectionalist
(physician in dept of infection),
infection) an
epidemiologist, or the editor in chief of a
f
famous
virology
i l
journal
j
l respectively.
ti l