Transcript Influenza Virus

Respiratory Virus
Medically important members
RNA Orthomyxoviridae
Virus Paramyxoviridae
Togaviridae
Picornaviridae
Coronaviridae
Reoviridae
DNA Adenoviridae
Virus
Influenza virus
Measles virus
Mumps virus
Respiratory syncytial virus
Parainfluenza virus
Rubella virus
Rhinovirus
Coronavirus, SARS Cov
Reovirus
Adenovirus
Influenza Virus
Avian
Influenza
• Orthomyxovirdae
• 3 types
H9N2
Russian
Influenza
H5N1
H7N7
H5N1
H1N1
Spanish
Influenza
H1N1
1918
Asian
Influenza
H2N2
H3N2
Hong Kong
Influenza
1957 1968 1977
1997 2003/4
1998/9 2005
Type A
Type B
Type C
Human
+
+
+
Animal
reservoir
Antigenic
drift
Antigenic
shift
Human
epidemics
Human
pandemics
+
+
-
+
+
-
+
-
-
+
+
-
+
-
-
Biological properties
• Size and Shape
– highly pleomorphic
• mostly spherical: 80 - 120nm
• long filamentous particles
– Structure
• nucleocapsid
• Envelop
NA
• Function
– Hemagglutination
– Attachment and penetration
– Antigenicity
NA
• Function
– Release
– Antigenicity
Replication
Typing and Variation
• Typing
– NP, M1, and M2: type A, B, and C
– HA and NA: subtypes only in type A
• Influenza A viruses: H1-H15, N1-N9
• Avian: H1~H15, N1~N9
• Human: H1, H2, H3, H5 and N1, N2
Typing and Variation
• Variation
– Antigenic drift抗原漂移: minor antigenic changes of HA
and NA due to point mutations, belonging to quantitative
changes, causing annual epidemics of influenza viruses.
– Antigenic shift抗原转变: major antigenic changes of HA
and NA due to genetic reassortment between human and
animal influenza viruses, belonging to qualitative changes,
resulting in new subtype and may causing periodic
pandemics.
Emergency hospital during 1918 influenza epidemic
What is avian influenza (bird flu)?
Avian influenza
• What is the avian influenza A (H5N1) virus
• How do people become infected with avian
influenza viruses?
• Does the current seasonal influenza vaccine
protect me from avian influenza?
• Is there a vaccine to protect humans from
H5N1 virus?
• Is there a risk for becoming infected with
avian influenza by eating poultry?
• What changes are needed for H5N1 or
another avian influenza virus to cause a
pandemic?
Resistance
• Weak
– Sensitivity
•
•
•
•
•
Heat
Drying
Ultraviolet
Acid
formalin
– Resistance
• Cold
Pathogenicity
• Source
– Patients
• transmission
– Aerosols or droplets
• Pathogenesis
– surface infection without entering blood
generally.
Clinical findings
• Uncomplicated influenza
–
–
–
–
–
Fever (38 - 40℃)
myalgia (or muscle ache)
Headache
photophobia, tears
Dry cough, nasal discharge
• Complications
– Pneumonia
– Reye’s syndrome
Immunity
• short and re-infection
– No viremia
– Many subtypes
– High variation
Microbiologic diagnosis
• haemagglutination inhibition test
Prevention and treatment
• Prevention
– inactivate (most)
– live attenuated (new)
• Treatment
– Rimantadine金刚乙胺 and amantadine金刚烷
胺
– Oseltamivir达菲
II. Paramyxoviridae
Morbillivirus:
measles virus cause systemic symptoms
Paramyxovirus:
mumps virus
parainfluenza virus
Pneumovirus:
cause infant & young
respiratory syncytial virus children local LRT infections
(RSV)
II. Paramyxoviridae
Common properties:
Size: 150~300nm in diameter.
Shape: spherical or pleomorphic.
Structure: enveloped; -ssRNA
non-segmented; genetically stable
spikes: fusion protein;
attachment protein
1. Measles virus
About 10d incubation period
V→
respiratory
epithelial cells
→
replicate in LC
regional lymphoid → Blood (first Viremia)
tissue
↓ reticuloendothelial system
Blood (second Viremia)
↓
epithelial surface of body
↓
respiratory tract, eye conjunctiva, mouth, skin, small blood vessels, etc
Typical symptoms ↓
high fever, photophobia, rhinitis, cough, Koplik’s spots, maculopapular skin rash
eye conjunctivitis
(diagnostic signification)
prodrome
Main complications
encephalitis; pneumonia; SSPE (subacute sclerosing panencephalitis).
B. Immunity: lifelong
C. Treatment and prevention:
live attenuated vaccine;
Immunoglobulin-γ/placenta immunoglobulin for emergency;
Presence of
viremia
Types of Ag
Ag stability
Influenza V
No viremia
Labile
Measles V
Two viremia
Many
subtypes
Single type
Stable
Infectious
characteris
tic
Local
mucosa
systemic
2. Mumps virus
A patient
with parotitis
2. Mumps virus
V respiratory epithelial cells facial lymph nodes blood
viremia parotid glands, the other tissues
Disease manifestation:
Typical symptom:
unilateral or bilateral non-suppurative parotitis, fever
Severe complications:
testitis, ovaritis, pancreatitis, aseptic meningitis
Immunity: permanent
Prevention: live attenuated vaccine
MMR(Measles-Mumps-Rubella) is used in US;
Monovalent form (only attenuated mumps virus S97)
--program of immunization.
3. Respiratory syncytial virus (RSV)
The most important cause of LRT infection in infants and
young children.
Diseases:
Infants: bronchiolitis(50%), pneumonia(25%);
Young children & adults: common cold, rhinitis.
Immunity: not strong & long, re-infection.
Ab cannot prevent babies from RSV, aggravate disease.
Ⅲ.Other respiratory viruses
1. Rhinovirus
the most important virus that cause common cold)
Picornaviridae.
Spherical, 28-30nm in diameter;
+ssRNA
many serotypes(>100);
Diseases: mild URT infection,
bronchitis and pneumonia.
Ⅲ.Other respiratory viruses
2. Coronaviridae:

Coronavirus:
~10-30% common cold;
bronchitis and pneumonia.

o
SARS-CoV:
80-140nm
osymptom:
high fever, cough, headache,
general malaise and aches, dry cough,
dyspnea;
Respiratory distress cause death