Transcript N.S. 100 Lecture 6 - PPT Viruses HIV AIDS Assignment Page

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N.S. 100 Lecture 6 – Viruses, HIV, AIDS
SARS virus causes Severe
Acute Respiratory Syndrome
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Fluid build up
http://www.rsvmd.com/virus.jpg
Influenza Virus
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Viruses infect all species of life
Viruses infect all tissues in all organisms
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http://www.anatomy-resources.com/human-anatomy/images/sb200-t8.gif
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Viruses are not living
Nucleic acid
(DNA or RNA)
Protein coat
= Capsid
Virus structure = nucleic acid core
surrounded by protein coat
(a)
Adenovirus causes respiratory infections
Capsid with
antenna-like
fibers
DNA inside
capsid
Virus Example
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DNA inside capsid
Head (Capsid)
Tail (capsid)
Tail
Fibers
(capsid)
Virus Example
Bacterial virus –
one of best known viruses
Fig. 23.01c
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Virus Cycle:
1. Virus enters cell
2. Viral genetic material takes over ribosomes
3. Ribosomes viral proteins
4. Viral genetic material replicates itself
5. Viral proteins wrap up genetic material
6. New viruses emerge from cells to infect other cells.
Lytic Cycle
Virus DNA
enters cell and
immediately
makes more
viruses
Virus attaches
to host cell
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Viral DNA enters
host cell
New viruses
Host cell
assembles
new virus
Viral DNA takes
over host cell
protein
synthesis
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Virus capsid
(tail fibers)
proteins match
up with host
cell membrane
proteins
http://www.mediaq.net/_borders/Virus.jpg
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Viruses attacking cell
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Injection of DNA
Cell
membrane
Viral DNA
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http://www.slic2.wsu.edu:82/hurlbert/micro101/images/101PhageLife.gif
Lysogenic Cycle
1. Virus attaches to host cell.
Virus DNA enters cell
and forms provirus
2. Virus DNA
enters the cell.
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Provirus
Provirus
3. Virus DNA integrates into
cell DNA as a provirus.
4. Integrated provirus
replicates when cell
DNA replicates.
HIV
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Human Immunodeficiency Virus
AIDS
Acquired Immune Deficiency Syndrome
The number of people living with HIV rose from around 8
million in 1990 to 38.6 million in 2005, and is still
growing. Around 63% of people living with HIV are in
sub-Saharan Africa.
Regional statistics for HIV & AIDS, end of 2005
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Structure of HIV (retroviruses)
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Viral Protein
Plasma membrane
capsid #2
capsid #1
RNA
Reverse transcriptase
HIV
Viral protein (spike)
Plasma membrane
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Capsid
Better look at
HIV structure
from previous
page
RNA
http://www.zoobotanica.plus.com/GIF%20files/Medical/HIV.gif
Reverse
transcriptase
and other
enzymes
White
blood
cell
Red
blood
cell
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HIV
HIV attacks White blood cells (lymphocytes)
which are needed to fight disease
http://www.beyondbooks.com/lif71/images/00016305.jpg
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HIV on surface of human lymphocyte
http://evolution.unibe.ch/images/AIDS-virus72.jpg
1. HIV (retrovirus) enters cell
2. Reverse Transcriptase (AZT)
makes DNA copy of RNA
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3. Viral DNA forms provirus with
host DNA
Viral DNA makes mRNA
mRNA makes HIV proteins
HIV proteins become HIV capsid
mRNA is collected inside of HIV
capsid forming new HIV
New HIV leaves cell and wraps itself
in host membrane (envelope)
Example of
previous page
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HIV emerging from
cell – notice that
new HIV becomes
surrounded by cell
membrane and viral
proteins
HIV entering and leaving a human cell
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A
C
B
D
HIV
Proteins match on
up on virus and cell
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Cell
Research to stop
HIV involves
stopping this
match up
HIV
Cell
Relationship between HIV
infection and AIDS symptoms
Relative
#s
AIDS
symptoms
start
Immune
cells
HIV
Time
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Kaposi’s Sarcoma – Secondary AIDS complication – type of
cancer that can occur anywhere in the body and can cause
internal bleeding. Before AIDS this was primarily a disease
of older persons.
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Lung with cavities caused by Mybacterium
tuberculosis; secondary AIDS infection
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Bird flu virus
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Virus is harbored in birds, but they may not be sick
Virus has RNA which mutates
Mutation makes new viral antigens (proteins) at a fast rate
Human immune system does not recognize new viral antigen
Virus can jump from birds to pigs and from birds to humans, but not
human to human - yet
Human viral infection results in extreme version of the flu
Therefore, avoidance of infected birds will prevent spread for now
Vaccine does not work because virus mutates too fast