Pathogens and The Immune System

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Pathogens and The Immune System
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What is a virus?

• Latin word for poison
• Segments of RNA or DNA surrounded by a protein
  coat.
• Tiny, non-living
• Invade living things

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Characteristics of life
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VIRUS STRUCTURE
Protein markers help virus recognize their host

• Envelope (part of the protein coat)
• Capsid right inside the envelope (part of the
  protein coat)
• Nucleic acid (either DNA or RNA)

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Retrovirus

• A virus that contains RNA instead of DNA
• Human Immunodeficiency Virus (HIV) is a
  retrovirus
• Genetic information is copied backwords, from RNA
  to DNA instead of DNA to RNA.

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Viruses Bacteriophage

• A virus that only infects bacteria

Aids in attachment
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Why do scientists consider viruses to be
non-living things?

• Do not grow
• Do not eat (metabolism)
• No homeostasis
• Do not breath
• Cannot reproduce on their own must infect a
  living cell.

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Viruses
Comparison of virus and living cells
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Viruses
Here are 3 virusesT4 Tobacco mosaic and HIVall
they have is a nucleic acid core and a protein
coat
Tobacco mosaic
T4
HIV
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The two life cycles of a virus

• Once inside a cell a virus can do one
• of two things
• LYTIC cycle enters cell, makes copies of itself
  and causes the cell to burst. Destroys host cell
• LYSOGENIC cycle slower cycle, virus integrates
  its DNA into the hosts DNA. Viral DNA is
  embedded in hosts DNA. hosts body triggers the
  virus into action takes a long time for the virus
  to take affect (like HIV)

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Viral Replication (virus reproduction)

• Attachment
• Injection of genetic material into the host
• Making of new parts
• Assembly of parts
• Release of new viruses

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Viral Disease in Humans

• Unlike bacterial diseases, viral diseases cant
  be treated with antibiotics. Vaccines are used
  for the prevention of some viral diseases. Once
  someone has contracted a viral disease, they can
  only treat the symptoms to make themselves feel
  better until the infection clears up on its own.
  Disinfectants can be used to kill viruses on
  household surfaces.

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SEM of a bacteriophage virus
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Bacteriophage infecting a bacteria
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Lytic cycle animation

• http//biology.about.com/gi/dynamic/offsite.htm?si
  tehttp//faculty.ccbcmd.edu/courses/bio141/lecgui
  de/unit3/viruses/adlyt.html

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A host cell in the lysogenic phase can suddenly
convert to the lytic stagethis happens with
HIVwhen it does, HIV becomes AIDS.
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Viral Disease in Humans

• Unlike bacterial diseases, viral diseases cant
  be treated with antibiotics. Vaccines are used
  for the prevention of some viral diseases. Once
  someone has contracted a viral disease, they can
  only treat the symptoms to make themselves feel
  better until the infection clears up on its own.
  Disinfectants can be used to kill viruses on
  household surfaces.

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Immune System
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Infectious and Non-infectious Disease

• Infectious can spread from person to person or
  from one body part to another, caused by a
  pathogen in the body
• Non-infectious does not spread - arthiritis

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DISEASE TRANSMISSION 5 ways to spread an
infectious disease

• Person to person contact- STDs, colds, strep
  throat
• Air-colds
• Food botulism (swollen cans)
• Water- infected with sewage
• Animal bites- mosquitos transmit malaria, dogs
  transmit rabies

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Disease Transmission

• Robert Koch established a procedure for
  diagnosing causes of infection.
• His 4 step procedure is called Kochs postulates.

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Disease Prevention and Protection

• Immunity resistance to a
• particular disease.
• Vaccination invented by Edward
• Jenner. Used to produce immunity.
• Vaccines contain a dead or
• weakened pathogen.

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Your Bodies Defenses chapter 40

• Body uses specific and nonspecific defense
  mechanisms to detect and destroy pathogens.
• 1st LINE OF DEFENSE SKIN nonspecific (do not
  target certain diseases, tries to kill anything)
  acts as a barrier, oil and sweat keep many
  diseases from growing.
• mucous membranes line entrances and exits of
  the body and trap pathogens when they enter.
• move to second line if the skin is broken.

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2nd LINE OF DEFENSE

• 4 important nonspecific.
• 1. Inflammatory response series of events
  that suppress infection and speed up recovery.
• Infected cells release histamine causing blood
  (including WBCs) to rush to the site.
• Causes swelling and redness. Pus contains
  WBCs, dead cells and dead pathogens.

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2nd LINE OF DEFENSE

• 2. Temperature response when the body is
  fighting a pathogen. Fever makes it harder for
  pathogens to grow, very high fever can be
  dangerous and even kill you.
• Proteins circulate in the blood and become
  active when they run into certain pathogens.

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2nd LINE OF DEFENSE

• White blood cells patrol the bloodstream and
  attack pathogens. 3 types
• 1. Neutrophil englufs and destroys. Most
  abundant type.
• 2. Macrophage ingest and kill pathogens,
  clear dead cells and debris from the body.
• 3. Natural Killer cells large WBC that
  attacks infected cells causing the cell to swell
  and burst. Kill cancer cells.

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• Walking macrophage"
• A major player in the body's immune system, this
  white blood cell is probing an airsac in a human
  lung with pneumonia. It was looking for debris,
  bacteria or other foreign matter that it would
  have ingested like a tiny vacuum cleaner. x7000

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• A large cancer cell surrounded by natural killer
  cells

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3rd LINE OF DEFENSE The Immune Response
SPECIFIC DEFENSES

• Occurs when bodies nonspecific defenses get
  overwhelmed.
• Army of individual cells that go to war for the
  body attacking specific pathogens.

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3rd LINE OF DEFENSE The Immune Response Cells
Involved

• 4 Different types of white blood cells
• 1. Macrophages- can attack any (not specific)
  consume pathogens.
• 2. Cytotoxic T cells attack and kill
• 3. B Cells remember and label invaders and
  instruct macrophages when to attack.
• 4. Helper T cells activate T and B cells.

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3rd LINE OF DEFENSE The Immune Response
Recognizing Invaders

• -The infected body cells have
• ANTIGENS on their surface.
• Antigens trigger the immune
• response. WBCs recognize and
• respond to the antigens
• -ANTIBODIES proteins that bind to antigens

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Oh no you have the flu- What happens?

• You just took a deep breath, the air contained
  the flu virus. Heres what happens
• Some were trapped in mucus, but a few slipped
  past.
• You now have infected cells.
• Macrophages begin engulfing and destroying the
  infected cells.

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2 Main parts of the Immune Response

• B cell response
• T cell response
• T and B cells are produced in the
• bone marrow.

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Disorders of the Immune system

• AUTOIMMUNE DISEASES immune system cannot
  distinguish between the bodys antigens and
  foreign antigens. Body begins fighting itself.
• Examples
• MS (Multiple Scelrosis)
• Arthritis
• Lupus
• Diabetes

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HIV - retrovirus

• Human immunodeficiency disorder
• HIV attacks helper T cells weakening the immune
  system.
• Transmitted by body fluids.
• Most commonly transmitted through sexual contact
  and needles.
• Mosquitos and ticks CANNOT transmit HIV.

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Allergies

• Inappropriate response by the immune system.
• Antigens bind to cells in the nose and release
  histamine.
• Histamine causes redness, swelling, runny nose,
  itchy eyes and congestion.
• Take antihistamines sudafed, etc, to fight
  allergies.