Hepatitis D is caused by infection with which virus?

• A. Hepatitis C
• B. HIV
• C. Hepatitis A
• D. Hepatitis B

Answer: (D)

Hepatitis D is a satellite virus that can only infect people who are also infected with Hepatitis B. It’s a defective RNA virus that lacks its own envelope proteins, so it relies on the Hepatitis B surface antigen to assemble and enter liver cells. Because of this dependency, infection with Hepatitis B is necessary for Hepatitis D to occur. It can present as a coinfection with Hepatitis B or as a superinfection in someone already chronically infected with Hepatitis B, and it often leads to more severe liver disease. The other viruses listed do not cause Hepatitis D: Hepatitis C is a different hepatotropic virus, HIV is not a hepatitis virus, and Hepatitis A is an enteric virus that does not enable HDV infection.