IMMUNOLOGY

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

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

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.

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.

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.

Serologic Reactions Using antigen~antibody 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.

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, patient’s 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 patient’s blood is tested against a known antigen (FIV).

Common Serologic Techniques ELISA (US) agglutination reactions (THEM) immunofluorescene (IFA) (THE LAB)

How is a test’s accuracy measured? AND

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.

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.

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%.

Enzyme-Linked Immuno-Sorbent Assay

IDEXX Snap® Device

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 Why Snap®?

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

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.

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

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

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