Question

(a) (i) Give the full form of ‘ELISA’. Write the principle on which ELISA test is based.
(ii) Describe all the methods used to treat or cure Adenosine deaminase deficiency in humans.

Hint:

Malaria fever is due to haemozoin toxin released during RBC rupture.

Answer 1

(i) The full form of ELISA is Enzyme-Linked Immunosorbent Assay. It is a diagnostic tool used for detecting the presence of an antigen or antibody in a sample. The test is based on the principle of antigen-antibody interaction. In this method, an antigen is immobilized on a solid surface, and an antibody, which is linked to an enzyme, binds to the antigen. The enzyme is then used to catalyze a reaction with a substrate, generating a color change or signal that can be quantified. This principle allows for high sensitivity and specificity in detecting trace amounts of substances.

(ii) Adenosine deaminase (ADA) deficiency leads to Severe Combined Immunodeficiency (SCID). The treatments include:

1. Enzyme Replacement Therapy (ERT): Administration of PEG-ADA (pegylated ADA), a modified enzyme that compensates for the missing ADA enzyme. This method helps partially restore immune system functions. 
    
2. Bone Marrow Transplantation (BMT): The most common curative method. In this procedure, healthy bone marrow from a matched donor is transplanted into the patient to restore normal ADA function. It is especially effective in younger patients with a matched donor.
    
3. Gene Therapy: A revolutionary method where the patient's own stem cells are modified outside the body to include a functional copy of the ADA gene. These modified cells are then reintroduced to the patient to produce the necessary enzyme.