X antigen/antibody Markers in Hepadnavirus Infections. Presence and Significance of Hepadnavirus X Gene Product(s) in Serum

Gastroenterology. 1990 Apr;98(4):1071-8. doi: 10.1016/0016-5085(90)90035-y.


The finding that X antigen is associated with hepatitis B core antigen particles and that serum hepatitis B e antigen derives from the cleavage of one or more core associated polypeptides raises the question as to whether core associated X antigen could be similarly generated and released into serum. To test this hypothesis, antisera raised to X antigen peptides were used to construct an enzyme-linked solid-phase immunoassay to detect X antigen in sera from patients infected with hepatitis B virus and from woodchucks infected with woodchuck hepatitis virus. X antigen was present in more than half of the individuals tested. There was a significant association between X antigen and markers of viral replication. Most individuals destined to become surface-antigen carriers had X antigen appearing before surface antigen, as did a smaller proportion of individuals transiently positive for surface antigen. A high frequency of X antigen was observed only in sera from human populations with a high frequency of other hepatitis B virus markers. These results suggest that X is a newly identified serum marker of viral replication that often appears before surface antigen in productive infections.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Enzyme-Linked Immunosorbent Assay
  • Hepatitis Antibodies / analysis
  • Hepatitis B / immunology*
  • Hepatitis B Core Antigens / immunology
  • Hepatitis B virus / immunology*
  • Hepatitis Viruses / immunology*
  • Hepatitis, Viral, Animal / immunology*
  • Humans
  • Marmota*
  • Sciuridae*
  • Trans-Activators / analysis*
  • Viral Fusion Proteins / analysis*


  • Hepatitis Antibodies
  • Hepatitis B Core Antigens
  • Trans-Activators
  • Viral Fusion Proteins
  • X antigen, viral infections
  • hepatitis B virus X protein