VARIABLE EXPRESSION OF PRES1 ANTIGEN IN SERUM DURING CHRONIC HEPATITIS-B VIRUS-INFECTION - AN ACCURATE MARKER FOR THE LEVEL OF HEPATITIS-B VIRUS-REPLICATION

The expression of the preSl antigen of hepatitis B virus in sera from chronic HBsAg carriers was studied using a specific monoclonal antibody F35.25 in an original, double‐immunoradiometric assay. The antibody F35.25 recognized an epitope located between amino‐acid residues 32 and 53 on the preSl sequence of the large HBsAg protein. This domain could be involved in the recognition of hepatitis B virus by hepatocyte receptors. PreS1 antigen detection by monoclonal antibody F36.25 closely correlated with the presence of complete virions in the serum of HBsAg carriers, as demonstrated by ultracentrifugation‐ gradient experiments and electron‐microscopical ex‐amination. Of the 19 HBsAg carriers with chronic liver disease, preSl antigen was detected in 17 (90%): all of the 11 HBeAg‐ and hepatitis B virus‐DNA‐positive cases (group 1) and six of eight anti‐HBe‐positive cases with low levels of hepatitis B virus replication (group 2). PreSl antigen/HBsAg ratios parallel to preS1 antigen titers were significantly higher in the HBeAg‐positive group (34% and 1:106) than in the anti‐HBe‐positive group (18% and l:lO2). In contrast, preSl antigen was not detected in 18 (90%) of the 20 HBsAg healthy carriers positive for anti‐HBe and negative for serum hepatitis B virus‐DNA (group 3). Our results show that in chronic HBsAg carriers the serum expression of preSl antigen correlates well with the level of hepatitis B virus replication (serum hepa‐titis B virus‐DNA and/or liver HBcAg) and that it may be useful in assessing the clinical importance of the chronic viral infection.(HEPATOLOGY 1990; 11:809‐814.) Copyright © 1990 American Association for the Study of Liver Diseases