Which of the following is the most common gene delivery system for ‘In-vivo’ gene therapy?
**Core Concept**
The underlying principle being tested is the method of delivering genetic material into cells for therapeutic purposes, specifically focusing on **in-vivo gene therapy**. This approach involves directly introducing the therapeutic gene into the patient's body, where it can produce the desired effect. **Gene delivery systems** are crucial for the success of gene therapy.
**Why the Correct Answer is Right**
Although the specific correct answer choice is not provided, generally, **viral vectors** are the most common gene delivery system for in-vivo gene therapy. They can efficiently transduce a wide range of cell types and express the therapeutic gene at high levels. Viral vectors, such as **adenoviruses**, **retroviruses**, and **lentiviruses**, have been engineered to be safe and effective for gene delivery.
**Why Each Wrong Option is Incorrect**
**Option A:** Without the specific details, it's challenging to provide a precise reason, but typically, non-viral methods like naked DNA or liposomes are less efficient than viral vectors for in-vivo gene therapy.
**Option B:** Similarly, without specifics, it's hard to comment, but generally, physical methods of gene delivery are not as commonly used for in-vivo therapy as viral vectors.
**Option C:** Again, lacking details, but often, bacterial vectors are not the primary choice for in-vivo gene therapy due to potential immune responses and lower efficiency compared to viral vectors.
**Option D:** Assuming it's another non-viral or less common method, it would be incorrect because it doesn't match the most common and effective approach used in in-vivo gene therapy.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that the choice of gene delivery system depends on the specific application, including the type of cells being targeted and the duration of gene expression required. Viral vectors are preferred for many applications due to their high transduction efficiency.
**Correct Answer:** D. Viral vectors.