Enzyme Linked Immunosorbent Assay (ELISA), a technique for animal geneticists

In the field of immunology, many serological techniques, e.g. immunoassays, are used to detect the interaction of antigens with antibodies. Antibodies (also known as immunoglobulins and abbreviated Ig) are gamma globulin proteins that are found in blood and are used by the immune system to identify and neutralize foreign objects, such as bacteria and viruses. Antigens are substances that when introduced into the body stimulates the production of an antibody. The immunoassays are suitable for the detection and quantification of antibodies to infectious agents, microbial and non-microbial antigens.

Determination of either antigen or antibody in antigen-antibody interaction follows a general principle: A known antigen suspension or antiserum is used to detect and measure unknown
antibody or microbial antigen. There are different types of antigen-antibody interaction that include; Precipitation reaction, agglutination reaction, complement fixation reaction and Enzyme linked Immunosorbent Assay (ELISA). Therefore, Immunoassay is a laboratory technique that makes use of the binding between an antigen and its homologous antibody in order to identify and quantify the specific antigen or antibody in a sample.Preparation of blood samples for plasma extractionPreparation of blood samples for plasma extraction

Various specimens can be used for immunoassays test. These include serum, plasma and cerebrospinal fluid. Serum or plasma sample could be obtained from blood. To get serum or plasma sample, first 1.5-3 ml blood is collected using sterile syringe and needle from an animal. If serum is required, allow the whole blood to clot at room temperature for at least one hour and centrifuge the clotted blood for 10 minutes at 2000 rpm. Transfer the serum to a labeled tube using a pasture pipette. Plasma sample is obtained by treating fresh blood with an anticoagulant and centrifuging to get the supernatant (plasma) that is drained off into a new specimen tube free from hemolyzed blood. The specimen containing tube is appropriately labelled (e.g. Animal ID, Age, Sex, code no, etc) and sealed. Plasma extraction should be performed within hours after sample collection, otherwise the blood sample should be preserve it at - 200C for not more than 38 days after collection.

ELISA is used mainly in immunology to detect the presence of an antibody or an antigen in a sample. The principle of ELISA entails the use of an enzyme labeled antibody or enzyme labeled antigen conjugate for detection of antigens or antibodies, in an animal’s serum e.g. FMD antibody, SARs antigen.Various enzymes are employed in enzyme immunoassay. The most commonly used enzymes are peroxidase and alkaline phosphatase. In ELISA, a plastic bead or plastic plate is coated with antigen. The antigen reacts with antibody in the animal serum. The bead or plate is then incubated with an enzyme- labeled antibody conjugate, if antibody is present on the bead or plate. The enzyme activity is measured spectrophotometrically after the addition of the specific chromogeneic substrate (mostly TMB). Test result is calculated by comparing the spectrophotometer reading of animal serum to that of a control serum. One can use either Competitive, Sandwich (also called direct) and Indirect ELISA techniques.

ELISA technique can be used for quantification of immune proteins for geneticists. The quantification is of interest to iLINOVA fraternity as it will be used to provide insights into disease tolerance as exhibited by the indigenous livestock. with antibody in the animal serum. The bead or plate is then incubated with an enzyme- labeled antibody conjugate, if antibody is present on the bead or plate. The enzyme activity is measured spectrophotometrically after the addition of the specific chromogeneic substrate (mostly TMB). Test result is calculated by comparing the spectrophotometer reading of animal serum to that of a control serum. One can use either Competitive, Sandwich (also called direct) and Indirect ELISA techniques.

ELISA technique can be used for quantification of immune proteins for geneticists. The quantification is of interest to iLINOVA fraternity as it will be used to provide insights into disease tolerance as exhibited by the indigenous livestock.

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