HIV Human Immunodeficiency Virus

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HIV (Human Immunodeficiency Virus)
electron microscope picture of virus
particles (about 100,000x magnified)
cartoon
virology-online.com
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THE FUNDAMENTAL BASIS OF IMMUNE SYSTEMS
self versus non-self
(an "antigen" is any "non-self" entity that
will trigger an immune response)
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these are the organs of the vertebrate immune
system they are called "lymphoid organs" since
they produce lymphocytes (white blood cells) -
the key players in the immune response
http//press2.nci.nih.gov/sciencebehind/immune/imm
une05.htm
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the stem cells are found in the
bone marrow
they produce two different classes of immune
cells 1- includes monocytes (patrol cells) and
macrophages (clean up crew) 2- B cells and T
cells, involved in specific antigen recognition
and the mounting of an immune response
http//press2.nci.nih.gov/sciencebehind/immune/imm
une08.htm
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what happens when you get an infection?
1) first line of defense (non-specific immune
cells, enzymes, etc.) has failed to fight off an
invader. It multiplies. 2) a macrophage wanders
by and swallows one of the invading cells. It
chews up the invader, and presents bits
(antigens) of the consumed invader on its cell
surface. 3) this activates "helper T-cells,"
which, by lucky coincidence, have an antigen
that recognizes this antigenic bit presented on
the macrophage cell surface. The helper
T-cells then secrete substances (lymphokines)
that attract other immune cells to aid in the
defense process
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...continued
4) this "activated" helper T-cell then binds to B
cells that had previously taken up bits of the
destroyed invader cells 5) This then activates
antibody production. The B cells multiply, and
become one of two types of cells a) plasma
cells antibody-making factories. These
antibodies bind to the surfaces of the invading
cells, inactivating them. Macrophages then act
as a clean- up crew, digesting and destroying
these antibody- invader complexes b) memory
B-cells, which remain in your lymph
system, ready to be activated quickly in the
event of a second infection with the same
invader
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OVERVIEW OF THE ANTIGENIC RESPONSE
lymphokines
Campbell Reece (2002) Biology (6th Ed.) Fig.
43.13
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HIV (Human Immunodeficiency Virus)
electron microscope picture of virus
particles (about 100,000x magnified)
cartoon
virology-online.com
9
from Weiss (2001) Phil Trans Roy Soc. Lond. B
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from Freeman Herron Evolutionary Analysis
(1998)
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from Pantaleo G, Graziosi C, Fauci AS. 1993. New
concepts in the immunopathogenesis of human
immunodeficiency virus infection. N Engl J
Med328327-35
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comparison of mutation rates when copying the
genes of.
Humans Influenza A (flu) virus HIV virus
1 mistake in 1 billion nucleotides copied 1
mistake in 1 million nucleotides copied 1
mistake in 1 thousand nucleotides copied
from Freeman Herron Evolutionary Analysis
(1998)
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Phil Trans Roy Soc. Lond. B (2001)
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What's the evidence that HIV has evolved?
1. comparison of sequence types from last 50
years 2. growing resistance to once-effective
drugs (esp. AZT) 3. comparison of sequences in
newly infected HIV patient, with those in the
patient after he/she develops AIDS symptoms