Download Viral pathogenicity and Immunity

General characteristics
of Viruses
Introduction
I.
I. Conception
1. Virus: Viruses are obligate intracellular parasites at
the genetic level.
2. Virion: The entire infectious unit or the complete virus
particles
3. Atypical virus like agents (subvirus)
1) Viroid: Viroids consist solely of a single molecule of
circular RNA without a protein coat or envelope.
Introduction
I. Conception
2) Prion (unconventional virus) Prion are infectious
protein particle that are composed solely of protein, i.e.
they contain no detectable nucleic acid.
CJD
Kuru
Fatal Familial Insomnia
Scrapie of sheep and goat
Bovine spongiform Encephalopathy (BSE)
3) Satellites: virusoid
Satellites
Introduction
II. Developing history
III. Medical Virology
Basic properties of viruses
I . Structure and Chemical composition of viruses
1. Size and shape
Measuring the size of viruses.
A . Direct observation in the electron microscope
B . Filtration through membranes of graded
C . Sedimentation in the ultracentrifuge
D . Comparative measurements
1. Size and shape
Basic properties of viruses
2. Basic structure
1) Nonenveloped virion
Nonenveloped virion
Basic properties of viruses
2) Enveloped virion
Enveloped virion
Basic properties of viruses
3) Types of symmetry
A . Cubic symmetry
B . Helical symmetry
C . Complex structure
Types of symmetry
Basic properties of viruses
3. Chemical composition
1) Nucleic acid
DNA: dsDNA; ssDNA
RNA:+ssRNA; -ssRNA; dsRNA; +ssRNA
Retroviridae
Nucleic acid 3-1
Nucleic acid 3-2
Nucleic acid 3-3
Basic properties of viruses
2) proteins
3) lipids
4) carbohydrates
Basic properties of viruses
II. Viral Replication
1. Replication
2. Steps in Viral replication
1) Recognition and attachment to the target cell
2) Penetration
3) Uncoating
4) Gene expression & genome replication
5) Assembly & release
Steps in Viral replication
Replication: example 1
Replication: example 2
Replication: example 3
Basic properties of viruses
Abnormal multiplication
A. Defective virus: A virus particle that is
functionally deficient in some aspect of
replication.
B. Abortive infection: Infection in which
some or all virus components are synthezised
but no infective virus is produced.
Viral pathogenicity and Immunity
In this section, you will learn:
$ Viral Pathogenicity
$ Immunity for viral infection
Viral pathogenicity and Immunity
I. Viral Pathogenicity
Viral Pathogenicity
Viral pathogenicity and Immunity
1. modes of transmissions
1) Horizontal transmission: Transmission
between person of any age after birth, usually
excluding via the maternal milk.
modes of transmissions
1) Horizontal transmission 2-1
modes of transmissions
1) Horizontal
transmission
Viral pathogenicity and Immunity
2) Vertical transmission: Spread of
infection parent to the young via the placenta or
genital tract.
Transmission via the maternal milk is
sometime included.
Vertical
transmission
Viral pathogenicity and Immunity
2. Types of viral infections
1) inapparent infections
2) apparent infections
A. Acute infection
B. Persistent infection
a) chronical infection: HBV
b) latent infection: HSV
Varicella--zoster virus
latent infection: HSV
Viral pathogenicity and Immunity
C) slow virus infection （HIV. kuru)
D) delayed complication after acute viral infection.
SSPE
Viral pathogenicity and Immunity
3.Viruses-host interaction
1) cell level
A. lytic infection (Cytocidal infection) : cytopathic
effect ( CPE ) Alternation in the Microscopic apperance of cell
in culture following infection with a virus.
B.
steady state infection : fusion of cells, new
antigen.
C. integration
D. apoptosis
E.
inclusion body: An area of abnormal staining in a
virus- infected cell.
F.
Cell transformation : alternation in cell
morphology and / or behaviour, …….
Viral pathogenicity and Immunity
3.Viruses-host interaction
2) Host immune response
A. inflammatory reaction
Bacteria : inflitration of polymophonuclear leukocyte
Viruses : inflitration of mononuclear cell and
lymphocytes.
B. Immune pathology
a. Cell-mediated immunity : measles virus , HIV
b. Antibody-mediated immunity : dengue virus :
ab+RBC+C----hemolysis, HBV
Viral pathogenicity and Immunity
II. Immunity for viral infection
1. non-specific immune
NK , IFN
1) Interference phenomenon
A. Definition : prevention of the replication of
one virus by another.
B. Types of interference
C. Mechanisms of interference
Viral pathogenicity and Immunity
2) Interferon (IFN)
A. Definition: Interferons(IFNs) are host-coded
proteins of the large cytokine family that inhibit viral
replication; they are produced by intact animals or cultured
cells in response to viral infection or other inducers.
B. types of IFN
C. antiviral activity
Antiviral activity
Viral pathogenicity and Immunity
2. Specific immune
1) humoral immune
A. Neutralization antibodies
B. Hemagglutination antibodies
C. CF antibodies
2) Cellular immunity
Laboratory Diagnosis of Viral Disease
In this section, you will learn:
$ Introduction
$ Procedure
Laboratory Diagnosis of Viral Disease
Introduction
Object
Procedure
I. Specimens
1. Kinds of specimen
2. Time
Laboratory Diagnosis of Viral Disease
II. Methods
1. Cytology
2. Electron microscopy
3. Viral isolation
1) animals
2) chicken embryo
3) Tissue culture
A. Definition: The growth or maintenance
of living tissue in a liquid or soft gel medium in vitro.
Laboratory Diagnosis of Viral Disease
B. Types of cell culture
a. Primary cell culture
b. Cell line
C. Detection of virus-infected cells
a. CPE
b. Adsorption of RBC
c. Interference
d. PCR
Detection of virus-infected cells: CPE
Detection of virusinfected cells: CPE
Laboratory Diagnosis of Viral Disease
D. Quantitation of viruses
a. TCID50(50% Tissue culture infected dose ): Infections
dose of 50% CPE of tissue cultures caused by viral minimum
infected dose is called TCID50
b. PFU : under controlled condition,single plague can
arise from a single infection virus particle, termed a plagueforming unit.
Laboratory Diagnosis of Viral Disease
4. Serologic methods
1) complement fixation
2) Hemagglutination inhibition
3) Neutralization
4) Fluorescent antibody
5) Radioimmunoassay
6) Enzyme-linked Immunosorbent Assay (ELISA)
Laboratory Diagnosis of Viral Disease
5. Detection of viral genetic material
1) nucleic acid hybridization technique :
a. Southern blot
b. Northern blot
2) polymerase chain reaction (PCR), RT-PCR
6. Western blot
7. Biochip/DNA microarray/gene chip
Antiviral Therapy and Immune prophylaxis
In this section, you will learn:
$ The treatment with and prevention from viral diseases
Antiviral Therapy and Immune prophylaxis
I. Antiviral Agent
II. Immunoglobulins
III. Immunomodulators
Immunomodulators
Antiviral Therapy and Immune prophylaxis
IV. Gene therapy
a. Antisense oligonucleotide, ASON
b. Short interfering RNA, siRNA
C. Ribozyme
V. Vaccine
1. Inactivated vaccine
2. Attenuated vaccine
3. Genetic engineering vaccine
4. DNA Vaccine