What are DNA vaccines typically composed of?

• A. Live attenuated forms of the virus
• B. Protein extracts from pathogens
• C. Circular plasmids with viral protein genes
• D. Conventional viral DNA without modifications

Answer: (C)

DNA vaccines are composed of circular plasmids that contain genes encoding specific proteins from a virus or pathogen. These plasmids are used to induce an immune response by delivering the genetic material into host cells, which then transcribe and translate the viral genes into proteins. The host's immune system recognizes these proteins as foreign and mounts a response against them, training the immune system to recognize and combat the actual pathogen if encountered in the future.

This method harnesses the body's own cellular machinery to produce the antigen, which is a significant advantage of DNA vaccines. The plasmid nature allows for stability and ease of production compared to live attenuated forms or protein extracts. Unlike live virus vaccines that can carry a risk of infection, or protein extracts that require the immune system to recognize entire proteins without prior genetic instruction, DNA vaccines generate specific immune responses effectively.

The focus on using plasmids makes DNA vaccines innovative in vaccine technology, promising for their safety, longevity of immunity, and potential for rapid development in response to emerging infectious diseases.