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Neonatal hepatitis B infection: clinical and immunologic considerations
1Department of Pediatrics, University of California Los Angeles.
Insights
Newborns are highly susceptible to chronic hepatitis B infection due to immature immune responses. This review covers why infants struggle to clear the hepatitis B virus and supports universal infant vaccination.
Area of Science:
- Immunology
- Virology
- Pediatrics
Background:
- Hepatitis B virus (HBV) infection leads to chronic disease in most newborns, unlike adults.
- Infant susceptibility is linked to an immature immune system's inability to clear the virus.
- Maternal factors may also influence the infant immune response to HBV.
Purpose of the Study:
- To review the epidemiological, virological, and immunological factors contributing to chronic hepatitis B in infants.
- To discuss the rationale for universal hepatitis B vaccination in newborns.
Main Methods:
- Review of existing literature on newborn hepatitis B infection.
- Analysis of immune system defects in infants.
- Examination of epidemiological and virological data.
Main Results:
- Newborns exhibit diminished cytokine production, reduced cytotoxic activity, and generalized immune suppression.
- Incomplete viral clearance by the infant immune system leads to chronicity.
- Maternal hepatitis B antigens/antibodies can negatively modulate the infant immune response.
Conclusions:
- Infant immune system immaturity is the primary driver of chronic hepatitis B.
- Understanding these factors supports the recommendation for universal hepatitis B vaccination in newborns.
Abstract:
A chronic infection develops in the vast majority of newborn infants infected with the hepatitis B virus, compared with fewer than 10% of infected adults. The reason is probably related to the immaturity of the newborn immune response to infection, resulting in failure to completely eradicate the virus from hepatocytes. Studies of the newborn immune system demonstrate a variety of defects that may predispose infants to chronic hepatitis B infection, including diminished cytokine production, decreased cytotoxic activity, and a generalized suppression of the immune response. In addition, there is evidence that exposure of the fetus to certain maternal hepatitis B antigens and antibodies may adversely modulate the newborn immune response. This article reviews the epidemiologic, virologic, and immunologic aspects of newborn hepatitis B infection, and discusses the reasoning behind the recent recommendations for universal hepatitis B vaccination of newborn infants.