A functional ADA cDNA can be introduced into cells of the patients receiving gene therapy by using vector constituted by-

Options

A. E. coli
B. Reovirus
C. Retrovirus
D. Agrobacterium

Answer

To answer the question regarding the introduction of functional ADA cDNA into the cells of patients receiving gene therapy, we can follow these steps:

### Step 1: Understand the Role of ADA
Adenosine deaminase (ADA) is an enzyme that plays a crucial role in the purine salvage pathway. A deficiency in ADA can lead to severe combined immunodeficiency (SCID), as it results in the accumulation of toxic metabolites that are harmful to lymphocytes.

**Hint:** ADA is essential for the proper functioning of the immune system.

### Step 2: Identify the Need for Gene Therapy
Gene therapy aims to correct or replace defective genes responsible for disease development. In the case of ADA deficiency, introducing a functional copy of the ADA gene can restore the enzyme's activity.

**Hint:** Gene therapy is used to treat genetic disorders by introducing functional genes.

### Step 3: Use of Vectors in Gene Therapy
Vectors are vehicles used to deliver genetic material into cells. Common types of vectors include viral vectors (like retroviruses, adenoviruses) and non-viral vectors (like plasmids).

**Hint:** Vectors are crucial for delivering therapeutic genes into target cells.

### Step 4: Choose the Appropriate Vector
For ADA gene therapy, a viral vector, particularly a retroviral vector, is often used. Retroviruses can integrate their genetic material into the host genome, allowing for stable expression of the ADA gene.

**Hint:** Retroviral vectors are commonly used in gene therapy due to their ability to integrate into the host genome.

### Step 5: Introduction of Functional ADA cDNA
The functional ADA cDNA is cloned into the chosen vector. Once the vector is introduced into the patient's cells (often through methods like transduction), it allows the cells to produce the ADA enzyme.

**Hint:** The cDNA must be properly cloned into the vector for successful gene therapy.

### Final Answer
A functional ADA cDNA can be introduced into the cells of patients receiving gene therapy by using a vector constituted by a retroviral vector.