Which one of the following is used as vector for cloning genes into higher organisms ?

Options

A. Baculovirus
B. Salmonella typhimurium
C. Rhizopus nigricans
D. Retrovirus

Answer

To determine which option is used as a vector for cloning genes into higher organisms, let's analyze each of the given options step by step:

### Step 1: Understand the concept of vectors in gene cloning
Vectors are DNA molecules used to deliver genetic material into cells. They can be plasmids, viruses, or other types of DNA that can replicate within a host organism.

### Step 2: Analyze each option
1. **Baculovirus**:
- Baculoviruses are primarily used as vectors for gene expression in insect cells. They are effective for producing proteins in insect systems but are not typically used for cloning genes into higher organisms like mammals.

2. **Salmonella typhimurium**:
- This bacterium is known for its role in vaccine development and can carry plasmids. However, it is not primarily used as a cloning vector for higher organisms. Instead, it is used to enhance immunogenicity when introducing antigens into hosts.

3. **Rhizopus nigricans**:
- This is a multicellular fungus. While fungi can be used in biotechnology, Rhizopus nigricans is not commonly utilized as a cloning vector for higher organisms.

4. **Retroviruses**:
- Retroviruses are RNA viruses that can integrate their genetic material into the host's DNA. They contain reverse transcriptase, which converts their RNA into DNA, allowing for stable integration into the host genome. This makes them suitable vectors for gene therapy and cloning genes into higher organisms.

### Step 3: Conclusion
Based on the analysis, the most suitable option for cloning genes into higher organisms is **retroviruses**. They can effectively deliver genetic material and integrate it into the host's genome.

### Final Answer:
**The correct answer is retroviruses.**

---