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Hepatitis B and Hepatitis D Viruses: A Comprehensive Update with an Immunological Focus
Daniel G Sausen1, Oren Shechter1, William Bietsch2
1School of Medicine, Eastern Virginia Medical School, Norfolk, VA 23507, USA.
Insights
Hepatitis B (HBV) and hepatitis D (HDV) viruses cause severe liver disease. Understanding their interaction and immune response is key to developing new therapies for these widespread infections.
Area of Science:
- Virology
- Immunology
- Hepatology
Background:
- Hepatitis B virus (HBV) and hepatitis D virus (HDV) infect millions globally.
- HDV relies on HBV for infection, and co-infection leads to severe liver disease, including cirrhosis and cancer.
- These viruses are a major cause of global mortality.
Purpose of the Study:
- To provide a comprehensive overview of HBV and HDV, including their life cycles, structures, and infection patterns.
- To elucidate the complex interplay between HBV DNA and HDV RNA during chronic infections.
- To detail the immune responses to hepatitis B surface antigens and hepatitis D antigen.
Main Methods:
- Review of existing literature on HBV and HDV.
- Analysis of viral life cycles, structures, and pathogenesis.
- Examination of host immune responses to viral antigens.
- Discussion of recent therapeutic advancements.
Main Results:
- HDV requires HBV envelope proteins for replication and spread.
- Co-infection with HBV and HDV exacerbates liver damage and disease progression.
- Immune responses target specific viral antigens, including HBV surface antigens (small, middle, large) and HDV antigens (small, large).
Conclusions:
- A deep understanding of HBV and HDV biology and immunology is crucial for effective disease management.
- Recent therapeutic strategies show promise in combating these viral infections.
- Further research into viral interplay and immune modulation is essential.
Abstract:
Hepatitis B virus (HBV) and hepatitis delta virus (HDV) are highly prevalent viruses estimated to infect approximately 300 million people and 12-72 million people worldwide, respectively. HDV requires the HBV envelope to establish a successful infection. Concurrent infection with HBV and HDV can result in more severe disease outcomes than infection with HBV alone. These viruses can cause significant hepatic disease, including cirrhosis, fulminant hepatitis, and hepatocellular carcinoma, and represent a significant cause of global mortality. Therefore, a thorough understanding of these viruses and the immune response they generate is essential to enhance disease management. This review includes an overview of the HBV and HDV viruses, including life cycle, structure, natural course of infection, and histopathology. A discussion of the interplay between HDV RNA and HBV DNA during chronic infection is also included. It then discusses characteristics of the immune response with a focus on reactions to the antigenic hepatitis B surface antigen, including small, middle, and large surface antigens. This paper also reviews characteristics of the immune response to the hepatitis D antigen (including small and large antigens), the only protein expressed by hepatitis D. Lastly, we conclude with a discussion of recent therapeutic advances pertaining to these viruses.
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