New Employee Orientation

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Chapter 20
Viruses Associated with Respiratory Infections
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Categories of respiratory viruses
p257

• Myxovirus
  orthomyxovirus
• paramyxoviruses
• SARS coronavirus(SARS Cov)
• Other respiratory viruses

(influenza virus)
(measles virus,so.on.)
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Influenza Virus
???????
orthomyxovirus(????) pathogen of influenza
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Outline

• Biological Properties
• Pathogenicity and Immunity
• Laboratory Diagnosis
• Prophylaxis and Treatment

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?.Biological Properties
1.Shape and structure
? Shape
d80-120 nm,spherical
? Structure

• segmented ?ssRNA
• Nucleoprotein(NP)
• RNA-dependent RNA polymerase

(???????)
Viral core
(?????, Ag???)
(nucleocapsid)
Viral envelope
matrix protein (M1) lipid bilayer
(?????, Ag???)
HA and NA ???????
??????
Ag??????
membrane protein(M2) spikes
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Structure of influenza virus

segmented ssRNA
M1
(negative sense, 8 or 7 segments)
M2
Viral envelope
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1
2
4
3
5
6
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matrix protein
viral core
RNA-dependent RNA polymerase
PB2
lipid bilayer
PB1
PA
HA
RNA
NA
NP
RNPi.e. nucleocapsid
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Viral core ---- helical nucleocapsid
structure of virion
(RNA NP RNP)
Viral envelope
(MPlipid bilayerspike)

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Spikes

• glycoprotein
• surface antigen of virus
• 2 types HA and NA

subtype-specific
labile and variable in antigenicity
HA1, HA2 function
Hemagglutinin (HA)
Neuraminidase (NA)
????? ???????????
function
?????? ?????? ?????
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2.Typing and Variation

• Typing
  type A,B,C
  subtypesH1H15 and N1N9
• ?Labile and much variable in
• antigenicity of HA and NA
• ? Form of variation

antigenic drift ? median or small epidemic
of influenza

antigenic shift ? pandemic of influenza
(point mutation?variant)
(reassortment?form new subtype)
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3.Cultivation

• Embryonated eggs inoculation
• Tissue culture

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?.Pathogenicity Immunity

• 1.Pathogenicity

?route of transmission ?influenza and
complication
2.Immunity
?anti-HA (SIgA important) ?specific CMI
(CD4T/CD8T cell) ?subtype-specific immunity
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?.Laboratory Diagnosis

• 1.Isolation of viruses
• 2.Detection of antibody (hemagglutination
  inhibition test)
• 3.Quick diagnosis
  (Immunolabelling technique,PCR)

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Hemagglutination
inhibition test
a.virusRBC?agglutination of RBC
HA
receptoe
(hemagglutination)
b.(virusserum)RBC
?
?,????
absence of agglutination
(hemagglutination inhibition)
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?.Principle of Prophylaxis and Therapy

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Paramyxovirus (????)

• Inclusion measles virus, mumps virus,
  parainfluenza virus and respiratory syncytial
  virus (RSV)
• Differ from orthomyxoviruses

larger diameter different
spikes (HN, H, G and F protein) nonsegmented
ss-RNA
obvious CPE
d150-300nm
(????????)
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1.Biological properties
Measles Virus
????
(spherical,enveloped virus)

• Spikes HA and HL (haemolysin)
• ? Nonsegmented ss-RNA (negative sense)
• ? Single serotype
• ? Typical CPE in cell culture

HA---??????,????? HL---???????
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2.Pathogenicity and immunity
? Pathogenicity
feature of infection pathogen of measles
complication
(viral receptor----CD46 )
(pneumonnia, encephalitis and SSPE)
? Immunity
(lifelong immunity)
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? Specific provention
? Laboratory diagnosis

• Artificial active immunity (live attenuated
  vaccine or MMR)
• Artificial passive immunity

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Mumps Virus
?????
(pathogen of mumps)
?Single serotype ?Mumps complications ?lifelong
immunity ?Artificial active immunity
(live attenuated vaccine , MMR)
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Parainfluenza Viruses
?????

• 5 types
• Causes of croup (type 1,2)
• Also cause pneumonia in children and common cold
  in adults

??---?????????

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Respiratory Syncytial Virus
(RSV)
???????

• Spike G and F protein
• Pathogenicity
  cause bronchiolitis, pneumonia in infants
  
  cause common cold in adults and young children
  
  important pathogen of hospital infection

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(SARS Cov)
SARS coronavirus
SARS ????
---pathogen of severe acute respiratory
syndrome(SARS)
1.Shape and structure 2.Pathogenicity and
immunity
d60220nm, ss-RNA,enveloped virus and spike
source of infection route of transmission
cause SARS immunity
patient
????????? ????????????
3.Diognosis and prophylaxis
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Other Respiratory Viruses
1.Adenovirus
? naked virus with ds-DNA and cubic
nucleocapsid ? typical CPE and pathogenicity
(p207???????????????)
2.Rubella virus
? single antigen type ? cause rubella and
congenital rubella syndrome
(MMR)
3.Rhinovirus
?gt114 type ?The most important pathogen of
common cold