Transcript How the immune system targets influenza

Who Knew?
The Flu and YOU!
By: Christine Antler and Erin Boyle
COLD
FLU
Stuffy or runny nose
Fever
Sneezing
Headache
Sore Throat
Fatigue, extreme
exhaustion, weakness
Cough
Cough
The Influenza Virus
What the heck is a virus?
• NOT a bacterium
• Very, very small
• Simple: genetic material wrapped in protein shell
• Must have living cell (host) to survive and
replicate
Influenza Structure
Hemagglutinin
8 RNA
segments
Neuraminidase
Influenza Replication
HHMI movie
http://www.hhmi.org/grants/lectures/biointeractive/animations/
infection/inf_middle_frames.htm
Your Immune System: Under Attack!
• Keeps you healthy
• Defends your body
against invaders
• Can sense what’s
normal (self), and what
isn’t (non-self)
The Good Guys: B cells
How the immune system targets influenza
Lights Out for Influenza!
MACROPHAGE
Just like an elephant, B cells
remember!
• Immunity: stronger and faster response
It’s like an Army...
Influenza Can Hide From
the Immune System!
• Influenza alters its spike or knob proteins
• Memory B cells can’t recognize it anymore
old neuraminidase
old hemagglutinin
new neuraminidase
new hemagglutinin
How Influenza Changes Its Surface
Proteins
Small Changes = Drift
How Influenza Changes Its Surface
Proteins
Big Changes = Shift
Influenza Reassortment
HHMI movie
http://www.hhmi.org/grants/lectures/biointeractive/animations/
subunit/sub_middle_frames.htm
Prevention and Treatment of
Influenza
Vaccines...Ouch!
• Expose immune system to a defective virus
or viral component
• Immune system responds and is then ready
for next infection
IMMUNITY
Vaccine Production
Live virus is injected into fertilized hen’s egg
Virus replicates as embryo develops
Virus-containing fluid is harvested from egg
Vaccine Production
http://www.brown.edu/Courses/Bio_160/Projects1999/flu/vaccin
es.html
Killed Vaccines
• Also called inactivated vaccines
• Virus is killed by injecting a chemical into
the egg
• Immune system senses virus, but virus is
unable to replicate and spread
Live Vaccines
• Also called attenuated vaccines
• Virus is still alive, but can’t cause disease
Live Vaccines Cont’d
FluMist™ nasal spray (under development)
• Virus designed to grow best at colder
temperatures
• Flu virus weakened at body temperature
There must be a better way!!!
Subunit Vaccines
• H (spikes) and/or N
(knobs) proteins only
• Genetic engineering:
produce H and N
proteins using bacteria
or yeast
• H and N cause immune
response
DNA Vaccines
H gene (DNA)
Inject into human
Y
Y
Y
Y
Human cells produce H protein
Immune response to H protein
Why do you need to get a new
vaccine every year?
Influenza alters its H and N all the time!
Drugs
Drugs target either H or N and inactivate them
Inhibitors
NEURAMINIDASE (N)
HEMAGGLUTININ (H)
Virus can enter host cells
Virus cannot enter host cells
Virus cannot leave host cell
-
Decreased spread of infection
Decreased infection
Zanamivir and Oseltamivir
Amantadine and Rimantadine
Summary
• Influenza uses H and N proteins to infect cells
• Body develops immunity after fighting off the virus
• Influenza changes its H and N to avoid detection
• Vaccines trick body into developing immunity
• Antiviral drugs inhibit H and N
References and Resources
WEBSITES RELATED TO INFLUENZA:
http://www.niaid.nih.gov/publications/cold/sick.pdf
http://www.med.sc.edu:85/lecture/images/aviron.jpg
http://www.asap.unimelb.edu.au/hasn/no32/images/csleggs.jpg
http://www.glycoforum.gr.jp/science/word/gif0009/gd-a06e.jpg
http://medyred.sureste.com/fotos/influenza.jpg
http://www.sciam.com/2001/0201issue/IMG/working_2.gif
http://rex.nci.nih.gov/PATIENTS/INFO_TEACHER/immune_sys/Title.html
http://www.odomnet.com/vaccines/introduc.htm
http://www.uct.ac.za/depts/mmi/stannard/virarch.html
http://www.niaid.nih.gov/newsroom/focuson/flu00/background.htm
http://www.brown.edu/Courses/Bio_160/Projects1999/flu/vaccines.html
http://129.252.124.240:85/mhunt/flu.htm
www.accessexcellence.org/AE/AEC/CC/vaccines_how_why_html
References and Resources
WEBSITES RELATED TO INFLUENZA CONT’D:
http://www.tamiflu.com/
http://www.people.ku.edu/~jbrown/flu.html
http://www.people.ku.edu/~jbrown/virus.html
http://www.cdc.gov/ncidod/eid/vol4no3/webster.htm
http://www.hc-sc.gc.ca/pphb-dgspsp/fluwatch/index.html
OTHER WEBSITES:
http://www.allenshea.com/gifs/disguise.gif
http://www.hemophiliagalaxy.com/1_patients/encyclopedia/images/dna.gif
http://pbskids.org/lions/words/images/hen.gi
http://www.army.mil/
http://www.oaklandzoo.org/atoz/azeleph.html
http://www.leirpoll.com/rubber.htm
References and Resources
BOOKS:
Textbook of Influenza. K. G. Nicholson, R. G. Webster, and A. J. Hay. 1998.
Blackwell Science Ltd., London.
The Invisible Enemy: A Natural History of Viruses. D. H. Crawford. 2000.
Oxford University Press, Oxford.
The Transmission of Epidemic Influenza. R. E. Hope-Simpson. 1992. Plenum
Press, New York.