Transcript Response to Pathogens

Response to Pathogens
An introduction to the homeostatic
mechanisms of the immune system
Questions to consider…
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Is a fever always bad?
Should you use alcohols to rid your skin of bacteria?
Why do cuts get “pus”?
What is an allergy?
Do antibodies kill bacteria?
Can you get chicken pox twice? Or do you become
“immune”?
• How does a vaccine activate your immune system?
Mechanisms for Defense
Innate Immunity
rapidly response to
common pathogens
VS.
Adaptive Immunity
responses slower with
a vast array of
receptors
(vertebrates only)
Emergence of Function
• Where does your immune system hang out?
White Blood
Cells can leak
out of blood
vessels, collect
in lymphatic
vessels
Types of White Blood Cells
Become
macrophages
and dendritic
cells both of
which are
phagocytes
Nonspecific cellular defense
• Why not have a specific defense? Why is this
useful?
Activating Specific Defense
• Pathogens carry antigens on their surfaces
that must be recognized by lymphocytes
– Humoral Response - B-cells and antibodies
– Cellular Response - cytotoxic T-cells
Overview
T-cells vs. B-cells
• T-cells (thymus)
– Cytotoxic—directly kill
bad cells
– Helper—activate B-cells
• B-cells (bone marrow only)
– Produce antibodies
Activating Specific Defense
• MHC-I: Virus infected; cancerous cells
• MHC-II: Macrophages that have eaten
bacteria
Cytotoxic T
• Perforin
• CD8 Binding with Class I MHC
Helper T
• Interleukins and cytokines (chemical signals)
• CD4 Binding with MHC II
The first time you get sick!
• Takes a while
for your body to
Respond!
What happens the next time?
• Chicken pox example
Not all antibodies
are the same
• What would
someone with
allergies have an
elevated number
of?
• How does the fetus
get passive
immunity?
Antibody Structure meets Function
Why this works—Clonal Selection
How antibodies help
Overactive
antibodies
• Autoimmune disease
and inflammatory
repsonse
• Allergies
Putting it all together
HIV—A virus that destroys the body’s
ability to specifically respond to pathogens
What could an HIV test look for?
• How could a
virusinfected
person test
negative?
Molecular Biology of HIV
• Reverse
Transcriptase
• Envelop proteins
• Why don’t we
have an HIV
Vaccine?
Can you be immune to HIV?
HIV vs. AIDS
• HIV (Virus)
infection
can cause
AIDS
(disease)
Slowing HIV
progression
• Stop virus from
making copies!
Evolution of
HIV
• SIV—Simian
immunodeficiency
virus
• What does this
cladogram show?
Why West Africa in the early 1900s?
Ecology of Virus Podcast:
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