Scrapie of sheep and Cruetzfeldt - Jacob nervous disease of humans are caused by

Options

A. Prions
B. Viroids
C. RNA-viruses
D. DNA-viruses.

Answer

**Step-by-Step Solution:**

1. **Identify the Diseases**: The question mentions two diseases: Scrapie in sheep and Creutzfeldt-Jakob disease in humans.

2. **Understand the Nature of the Pathogens**: Both diseases are associated with neurodegenerative conditions. To answer the question, we need to identify the type of pathogen responsible for these diseases.

3. **Evaluate the Options**: The options provided are:
- Prions
- Viroids
- RNA viruses
- DNA viruses

4. **Analyze Each Option**:
- **Prions**: These are misfolded proteins that can induce other proteins to misfold, leading to neurodegenerative diseases. Scrapie and Creutzfeldt-Jakob disease are both known to be caused by prions.
- **Viroids**: These are small, circular RNA molecules that lack a protein coat and primarily infect plants. They do not cause Scrapie or Creutzfeldt-Jakob disease.
- **RNA viruses**: These are viruses that have RNA as their genetic material. They are responsible for various diseases (like HIV causing AIDS) but are not responsible for the diseases mentioned.
- **DNA viruses**: These viruses contain DNA and cause diseases such as hepatitis and herpes, but again, they do not cause Scrapie or Creutzfeldt-Jakob disease.

5. **Conclusion**: Based on the analysis, the correct answer is **prions**, as they are the infectious agents responsible for both Scrapie in sheep and Creutzfeldt-Jakob disease in humans.

**Final Answer**: Scrapie of sheep and Creutzfeldt-Jakob nervous disease of humans are caused by **prions**.

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