IMMUNOLOGY

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IMMUNOLOGY
Antibodies
ANTIGEN
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IMMUNITY

• Immunity is the resistance of a host to invasive
  pathogens or their toxic products.

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IMMUNOLOGY

• Our entire business is based on diagnosing the
  reaction of the immune system to foreign invaders
• The body has the ability to develop highly
  effective specific immunity against many foreign
  substances such as bacteria, viruses, toxins, and
  chemicals.
• These substances produce proteins called ANTIGENS
• All mammals make ANTIBODIES against Antigens to
  help eliminate the proteins and hence the foreign
  substance.
• In all SNAP assays, we either detect the
  antibodies against or the antigen from the
  foreign substances

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Antigen - AG

• Antigen is any substance foreign to the host and
  is capable of causing the body to produce
  specific antibodies that in turn have the express
  purpose of binding and ultimately destroying the
  antigen.
• The immune response - if micro-organism X invades
  the body, the immune system counterattacks with
  antibodies to X. For example, invasion by FIV
  triggers the production of anti FIV antibodies.

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Antibody - AB

• Antibody - protein molecules in serum or body
  fluids that are capable of uniting with an
  antigen molecule. Usually produced only in
  response to the presence of an antigen in the
  body.
• They are responsible for a variety of functions
  such as neutralizing toxins, helping monocytes
  perform phagocytosis and help antigens reduce the
  effectiveness of foreign invaders.

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The Battle Begins

• The body has an army of soldiers consisting of
  white cells and antibodies waiting for the
  invasion by the enemy (antigens).
• The antigen stimulates production of the
  antibody. When the antigen and antibody come
  into contact, the antibody locks on to the
  antigen. This process is called binding. The
  result is the antigen antibody immune complex.

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Serologic Reactions

• Using antigenantibody reactions, serologic
  tests can indicate whether antibody or antigen is
  present.
• Radioactive counting methods, fluorescence
  immunoassays, and ELISA (enzyme linked)
  immunosorbent assay are all at the core of
  laboratory testing.

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IMMUNOLOGY

• Serological testing attempts to identify either
  an unknown antigen or an unknown antibody.
• A Veterinarian suspects a puppy has Parvo but
  needs to confirm it.
• If the identity of an antigen is unknown,
  patients blood sample may be tested against an
  anti-serum with a known antibody content.
  (heartworm, FELV, PARVO).
• The Veterinarian will use the IDEXX Snap test
  which contains the known antibody for Parvo. The
  test will show positive if the dog has an antigen
  for Parvo.
• For antibody detection the patients blood is
  tested against a known antigen (FIV).

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Common Serologic Techniques

• ELISA (US)
• agglutination reactions (THEM)
• immunofluorescene (IFA) (THE LAB)

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How is a tests accuracy measured?
Sensitivity
Specificity
AND
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What is Sensitivity?

• Sensitivity of detected positives / of
  known positives a true positive.
• Example 100 known positive parvo dogs. If
  Snap test detects 95 positive dogs from the
  original 100 then Snap has 95 sensitivity. 5
  false negatives.
• We missed 5 samples that were true positives.

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What is Specificity?

• Specificity of detected negatives / of
  known negatives a true negative. If Snap
  called a true negative a positive false
  positive.
• For example, if 100 dogs are truly negative for
  the Parvo Virus but our test says that 5 are
  positive than our test is 95 specific.
• It falsely identified 5 dogs as positive even
  though they do not have Parvo.

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How is Accuracy Determined?

• Accuracy is presented in a percentage form based
  upon the sensitivity and specificity. The higher
  the sensitivity and specificity, the more
  accurate the assay. Accuracy sensitivity
  specificity / 2.
• Example 95(SENS) 100(SPEC) divided by 2
  97.5.

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Enzyme-Linked Immuno-Sorbent Assay
ELISA
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IDEXX Snap Device
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Why Snap?
Features and Benefits

• - Amplification of signal via enzyme reactions
  (ELISA)
• (increased sensitivity)
• - Bi-lateral flow (SNAP)
• - hits reactive spot twice, increasing signal
• - includes wash step for clear background
• (increased specificity)
• Simultaneous detection of Heartworm, Lyme and
  Ehrlichia
• canis as well as FIV with FeLV

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Signal Amplification

• The Snap device uses an enzyme to AMPLIFY the
  signal from one antigen or antibody molecule to
  100s of color molecules. Think of one blue
  bubble bursting onto 100 clear bubbles turning
  ALL the bubbles blue. This technology allows are
  tests to achieve the HIGHEST sensitivity

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The Wash Step

• The Snap device includes a wash step that
  removes non-specific binding. Think of the wash
  as a cleaner that clears away any of the blue
  that sticks to the wrong types of bubbles. This
  allows us to achieve the Highest specificity.

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SNAP Technology

• Only ELISA technology rapid test in the market
• Bilateral flow of samples and wash allows for
  efficient washing of the samples which removes
  any background noise. This makes the test
  easy to read even with bad samples.
• True blue color means the test spots amplify
  blue, not red (the color of blood) like the
  competitors
• Highest sensitivity due to the enzyme amplifier
  that is present in the conjugate
• Highest specificity due to wash step
• Patented technology
• Most used test in the Veterinary industry

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SNAP Technology

• Only ELISA technology rapid test in the market
• Bilateral flow of samples and wash allows for
  efficient washing of the samples which removes
  any background interference. This makes the
  test easy to read even when the sample is
  damaged.
• True blue color means the test spots amplify
  blue, not red (the color of blood) like the
  competitors (in US)
• Highest sensitivity due to the enzyme amplifier
  that is present in the conjugate
• Highest specificity due to wash step
• Patented technology

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Competitive Single Platform Tests
Competitive Product Parameters
Rapid Immunomigration Technology
Colloidal - type technologies
Lateral Flow Immunoassay