Physicochemical heterogeneity of hepatitis B e antigen detected in asymptomatic carriers and carriers in a hemodialysis unit

Synthesis of hepatitis B virus e antigen in E. coli

Hepatitis B virus core antigen (HBcAg) gene was deleted at some unique restriction enzyme sites, or at random, and inserted into the expression plasmids of E. coli which had the tryptophan promoter. E. coli transformants with the plasmids, synthesized materials with many kinds of antigenicity of HBcAg, HBeAg, or both HBcAg and HBeAg. HBeAg-specific material smaller than native HBeAg was produced in a stable condition.

Immunochemical characterization of hepatitis B e antigen subtypes, HBeAg/1 and HBeAg/2, in sera of hepatitis B virus carriers

The interrelation between HBeAg subtypes, HBeAg/1 and HBeAg/2, in sera was examined immunochemically. The detection of HBeAg subtypes in immunodiffusion (ID) depended upon the amount of HBeAg determined by reversed passive haemagglutination (RPHA), ie, the titres of HBeAg in sera positive for both HBeAg/1 and HBeAg/2, positive for only HBeAg/1 and negative for both HBeAg/1 and HBeAg/2 were 2(9.8) +/- 1.5, 2(7.0) +/- 1.6, and 2(5.6) +/- 1.3, respectively. When the sera belonging to the latter two groups were concentrated up to 2(10) RPHA titre, the precipitin line corresponding to that of HBeAg/2-anti-HBeAg/2 was visualized in ID. Monoclonal anti-HBeAg antibody that absorbed only the precipitin line of HBeAg/1-anti-HBeAg/1 in ID was prepared for the characterization of HBeAg subtypes. A linear correlation (r = 0.91) between titres of HBeAg determined by the RPHA cells prepared with monoclonal and polyclonal antibodies was found in almost all HBeAg-positive sera. The reactivities of this monoclonal anti-HBeAg antibody to both HBeAg/1 and HBeAg/2 were demonstrated in affinity chromatography experiments using a Sepharose 4B column conjugated with this antibody. These results suggest that both HBeAg/1 and HBeAg/2 are constantly present in HBeAg-positive sera and that they are closely associated. Based upon these results, a hypothetical model for the elucidation of the immunological relationship between HBeAg/1 and HBeAg/2 is proposed.

Prevalence of Williams e1 antigen in comparison with e2 antigen in hepatitis B antigen carriers and patients in hemodialysis unit

The prevalence of both e1 and e2 antigens in 1,158 sera of asymptomatic HBsAg carriers, carriers in hemodialysis units, and HBsAg-negative blood donors was examined. The detection rate of e1 antigen was as high as 80% in asymptomatic carriers, 95% in hemodialysis patients, and even 13.1% in HBsAg-negative donors. All of the e1 antigen-positive specimens in such HBsAg-negative sera were found to have both or either anti-HBs and anti-HBc, suggesting the past history of Hepatitis B virus (HBV) infection of the donors. In the HBsAg-positive serum, the detection rate of e2 antigen (17%) was lower than that of e1 (80%), and all sera having e2 antigen were positive for e1 antigen. The titers of HBsAg, HBcAg, and anti-HBc in e2 antigen-positive sera were higher than that of sera detecting only e1 antigen. The appearance of e1 antigen and e2 antigen in the course of post-transfusion hepatitis B was studied with five cases. Retrospective study showed that three of them each received one unit of HBsAg-positive blood, and the other two received HBsAg-negative blood but with high-titered anti-HBc. In four cases out of five, in which e2 antigen was detected during the course of infection, the initial detection of e2 antigen occurred at or just before the elevation of liver enzyme levels. On the other hand, e1 antigen was detected relatively early after transfusion, and the time of onset. Moreover, the detection period of e1 antigen persisted longer, even after the disappearance of HBsAg antigenemia. These two separate studies suggest that not only e2 antigen but also e1 antigen are associated with the infection of HBV, but they are distinct from each other; the e2 antigen may have the properties of a signal of the viral activity in the patient as suggested by many others, but e1 antigen does not seem to bear such diagnostic values.

The separation and analysis of hepatitis B e antigen

A solid-phase radioimmunoassay has been used successfully for detecting hepatitis B e antigen in fractionated hepatitis B virus-containing serum. Ammonium sulphate precipitation followed by gel filtration through a column of Sepharose CL-6B resulted in two fractions of antigen-containing material with molecular weights of 220,000 and 130,000. The smaller of these two fractions was found to possess an average isoelectric point of 4.9 and consisted of two major polypeptide species with estimated molecular weights of 66,000 and 17,000 respectively. Affinity chromatography on Blue Sepharose showed that e antigen was not retained under conditions which bound serum albumin. These results are discussed in relation to the immunopathogenesis of hepatitis B.