What is the ImmunoComb?

For the detection and measurement of antibodies for a wide range of infectious diseases

One of the major arms of the immune defense system are antibodies, specific proteins that bind to a foreign entity and are capable of neutralizing it and calling other arms of the immune system to join the fight. Given most animals’ lifestyles, it comes as no surprise that they are under constant threat of microbial invasion, their antibodies working extra hours trying to fight off foreign entities that have entered the body. These antibodies can also serve as diagnostic markers that indicate previous exposure to a specific pathogen, a disease-causing agent. Depending on the combined information on the amount of antibodies, clinical signs and the pet’s vaccination history the result can indicate vaccine protection, recent infection or past infection.

Introducing Biogal’s ImmunoComb

Biogal’s ImmunoComb® diagnostic test looks for specific antibodies in the pets’ blood. The ImmunoComb assay is similar in principle to what is called ELISA, an Enzyme Linked Immuno-Sorbent Assay. Yet, it is much easier to operate. The ImmunoComb kit contains all the necessary reagents for developing the test in the veterinary office, without the need for any equipment required for classic ELISA like special dispensers, an automatic washer or an electronic reader.

The ImmunoComb is based on two components, the comb and the plate. The comb’s twelve teeth are activated with specific antigens localized to dots. Antigens are “building blocks” elements of the tested disease agents.

The plate contains 6 wells filled with different formulated reagents that enable the development of the assay. Similarly to the classic ELISA, these reagents have common functions. However, as they are contained within the development plate, they enable a simple free assay development.

How it Works?

The first step of the assay is to add a sample into well A in the plate. The comb is then inserted into this well. If a single patient is tested, one tooth can be cut out of the twelve teeth comb. The tooth, partial comb or the complete comb (depending on the number of patients) is then incubated in well A for several minutes subject to the tested disease and the kit in use.

During the incubation, specific antibodies, if present in the sample, bind to the deposited antigens on the comb. This binding is unique and similar to a key and keyhole mechanism. Non-specific antibodies will bind weakly and will be removed throughout the next steps.

During the second step, the comb is transferred from well A to well B. During the incubation in well B, a special wash solution removes the non-specific bound antibodies leaving the specific antibodies that were present in the sample bound to the comb’s antigen.

Next, the comb is transferred from well B to well C. In this well, there is a conjugation between a secondary antibody with a chemically tied enzyme. This conjugation recognizes natural antibodies specific to the tested animal. During the incubation in well C, the conjugates bind to the antibodies that remain bound to the antigens on the comb.

To put in simpler terms, imagine a human tower competition made up of a father balancing his son on his shoulders while the boy balances his younger sister. The father is likened to the antigen, the boy to the specific antibodies while the sister is the conjugate.

In the next two steps the comb is moved to two additional wash wells, similar to well B, removing non-specific bound materials.

In the last step, the comb is moved to a substrate solution for short incubation. The substrate formulation contains a colorless chemical that is digested by the conjugate from well C. The digestion carried out by the enzymatic part of the conjugate creates a dark gray product. This digested colored product will be deposited on the comb only if the conjugate is present. The conjugate’s digested products will be localized to the antigens dots on the comb only if there are specific antibodies in the blood sample.

In the human tower competition analogy, the winners are those whose youngest participant managed to pull a flag from a tall pole. Only a complete tower will enable them to reach this height. Therefore, waving the flag, like the colored reaction in the ImmunoComb indicates that all the essential previous steps took place. Indirectly, a flag means that a boy holding his sister up must be present in the tower and a gray spot on the ImmunoComb means that specific antibodies to a certain disease agent must be present; hence the patient has been exposed to the disease agent.