Researchers find that even though the current recombinant hepatitis B vaccine is immunogenic, about 10% of immunocompetent individuals do not develop high enough levels of anti-HB antibodies to confer immunity despite receiving the recommended 3 doses of the vaccine. To increase the vaccine immunogenicity, they use a lipopolysaccharide derivative as a vaccine adjuvant. The new vaccine induces an exaggerated immune response in previous nonresponders, which results in high antibody titers and, possibly, lifelong protection. Universal vaccination with the new vaccine would most likely lead to eradication of which of the following conditions?
Hepatitis D virus (HDV) is a small, enveloped RNA virus that does not contain a replicase or RNA polymerase. Therefore, the virus is completely reliant on host cell machinery for transcription and translation. In addition, HDV is considered a replication-defective virus because it does not encode for viral envelope proteins, which are necessary to generate viral progeny. HDV can only finish its replication cycle in the setting of coinfection with hepatitis B virus (HBV). HBV encodes for several envelope proteins (HBsAg) that are used to generate the envelope of HDV. Therefore, universal vaccination against HBV would completely eliminate HDV.
HDV infection can occur as an acute coinfection with hepatitis B or as a superinfection in a chronic HBV carrier. Infection with HDV dramatically increases the already elevated risk of cirrhosis and hepatocellular carcinoma seen with HBV.
(Choice A) Fulminant viral hepatitis is rare but can occur with any of the hepatitis viruses (A, B, C, D, or E). Therefore, vaccination against HBV would not eliminate fulminant viral hepatitis.
(Choice B) There is currently no vaccine against hepatitis C virus (HCV). Vaccinating a patient against HBV would not prevent HCV infection.
(Choice D) Hepatocellular carcinoma is most commonly associated with HCV or HBV infection. Although universal vaccination against HBV would reduce the incidence of hepatocellular carcinoma, it would not eradicate the condition.
(Choices E and F) HBV and HCV can cause extrahepatic manifestations such as membranous glomerulopathy and mixed cryoglobulinemia due to the formation of circulating immune complexes. Although vaccination against HBV would reduce the incidence of these extrahepatic manifestations, it would not completely eliminate them.
Educational objective:
Hepatitis D virus (HDV) is a replication-defective RNA virus that is capable of causing infection only in the setting of coinfection with hepatitis B virus (HBV). HBV provides hepatitis B surface antigen for the HDV envelope.