viral pathogenesis - scholar.cu.edu.eg adaptive (acquired) immunity. •show the evidence of...
TRANSCRIPT
4/12/2020 Vaccinology-Ausama 1
Introduction to immunology:
It’s a dangerous matter.
VIR-3178
Ausama A. YousifDVM, MSc, PhD
Professor of Virology
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Disclaimer
• The classical view slides were privided by Dr. Nancy L.
Haigwood, Ph.D. [[email protected]]
• Additional resources were added from a lecture by Marie
Lipoldová. Institute of Molecular Genetics. Academy of
Sciences of the Czech Republic. www.img.cas.cz/mci/
• I have chosen to present the lecture as is, with added
information bearing both virology logos. This is to get a
sense of the current paradigm in immunology.
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Learning objectives
• Overview the components of the immune systems.
• Describe the names and functions of the key players of adaptive (Acquired) immunity.
• Show the evidence of specificity, memory and self limitation.
• Show the immunological goal of vaccination and how to improve the animal’s chances of surviving infection with a virulent virus.
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Is the immune system
Functional or Anatomical?
Just protection against pathogens? NO.
• Elimination of tissues and cells that have been damaged, infected or killed.
• DOES THE IMMUNE SYSTEM RECOGNIZE ANTIGENS THE SAME WAY IN THE DIFFERENT COMPARMENTS OF THE BODY?
• Remember this question. We will get back to it later
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The Classical View
Innate
Immunity
Acquired
Immunity
Nancy L. Haigwood, Ph.D.
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The Classical View of how
the adaptive immune system works
• Discrimination between pathogens/self.• Antigen specificity.• Diversity of responses. • Self-limiting.• Produces immunologic memory.
• WHY DON’T IMMUNE CELLS RECOGNIZE SELF ANTIGENS?!!
• This is a trick question.
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Post-infection immune responses
Viral
titers CTLAntibody
Days post-infection
7 14 28 350
Illness
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Specificity, memory, self-limitation
X-s
pe
cifc
An
tibo
dy tite
rs
Weeks
Antigen
X
Antigen
X
2 4 6 8 10 12
IgM response
IgG response
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The Classical View of how
the adaptive immune system works
• Discrimination between pathogens/self.
• Antigen specificity.
• Diversity of responses.
• Self-limiting.
• Produces immunologic memory.
• WHY DON’T IMMUNE CELLS RECOGNIZE SELF ANTIGENS?!!
• Review selection in the thymus.
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Goal of vaccination
Reduction of Illness Vs Reduction of Replication
CTLAntibody
Vaccine Infection
CTLAntibody
Illness
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In order to achieve this goal we
need to think a little bit more
about the specifics of the adaptive
immune response.
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Exogenous (MHCII) and Endogenous (MHCI) Pathways of Antigen Presentation
HS
P 7
0
This is not the
complete pictureWhy does the immune system recognize self tissue that has been
damaged (like testicular tissue for instance, or the endocardium during
certain bacterial infections)?
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BIC 2005 - Introduction to Artificial Immune Systems - Dr. Leandro Nunes de Castro14
The Immune System (XVII)
◼ Danger Theory
after Matzinger, 1994
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DC activation and
Th activation and polarization
Nature Reviews Immunology 3, 984-993 (December 2003)
If the immune system works so well
how come the virus maintains itself
in immunocompetent populations?
Refer to the answers we discussed in
Advanced General Virology
Last semester
Email me if you have questions
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Don’t you think that this kind of immune
evasion will also influence the outcome of
infection of vaccinated animals?
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Take home messages1. The immune system responds to danger signals; even if it is
associated with self antigens.
2. The nature of the antigen and cytokine environment determine the
immune system polarization towards Th1- or Th2-type responses.
3. Exposure to antigen in the correct context results in the
development of immunological memory.
4. The immune system responds differently to antigens in different
compartments.
5. Viruses are able to evade host cell immunity by manipulation of
antigen presentation or cell signaling pathways.
6. Successful protection against viral infection can only work if the
immune response worked in the correct time and location, with the
correct type and level, and if the animal has a correct feed back
mechanism. (TTLLF)
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• WHY DOES THE IMMUNE SYSTEM RECOGNIZE ANTIGENS DIFFERENTLY IN THE DIFFERENT COMPARTMENTS OF THE BODY?
TAKE HOME QUESTION