Nervous tissue Rabies vaccines are usually manufactured from
**Core Concept**
The question requires knowledge of rabies vaccine production, specifically the source of nervous tissue used in its manufacture. Rabies vaccines are typically produced using a strain of the rabies virus grown on a substrate, which can be either a nervous tissue or a cell line.
**Why the Correct Answer is Right**
The correct answer is a nervous tissue, specifically the brain tissue of sheep or other animals. This tissue is used as a substrate to grow the rabies virus, which is then harvested and inactivated to produce the vaccine. The use of nervous tissue allows for the replication of the virus in a complex environment that mimics its natural host, resulting in a more effective vaccine.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is too vague. While it is true that some vaccines are produced using cell lines, this is not the primary source of nervous tissue used in rabies vaccine manufacture.
**Option B:** This option is incorrect because it refers to a type of virus, not a substrate used in vaccine production.
**Option C:** This option is incorrect because it refers to a type of vaccine, not a source of nervous tissue.
**Clinical Pearl / High-Yield Fact**
It's worth noting that the use of nervous tissue in rabies vaccine manufacture has raised concerns about the risk of transmitting neurodegenerative diseases such as Creutzfeldt-Jakob disease. However, the risk is considered to be extremely low, and the benefits of the vaccine in preventing rabies far outweigh the risks.
**Correct Answer:** D. Sheep brain tissue.