Serological assessment of HBcAg and HBV DNA: its prognostic relevance in acute hepatitis B

The Origin of Capsid-Derived Immune Complexes and Their Impact on HBV-Induced Liver Diseases

Over 240 million people worldwide are chronically infected with Hepatitis B Virus (HBV), a hepatotropic DNA virus with an evolutionary root of over 400 million years. Persistent HBV infection exhibits distinct and diverse phases of disease, from minimal liver pathology to fulminant Hepatitis, that vary in duration and severity among individuals. Although huge progress has been made in HBV research which has yielded an effective prophylactic vaccine and potent antiviral therapy, our understanding of its virology and immunobiology is still far from complete. For example, the recent re-discovery of serum HBV RNA in chronic Hepatitis B (CHB) patients has led to the proposal of noncanonical viral particles such as RNA virion and capsid-derived immune complex (Capsid-Antibody-Complexes, CACs) that contradict long-established basic theory. Furthermore, the existence of capsid-derived immune complex may hint at novel mechanism of HBV-induced liver disease. Here, we summarize the past and recent literature on HBV-induced immune complex. We propose that the release of capsid-derived particles by HBV has its deep evolutionary origin, and the associated complement activation serves as an indispensable trigger for intrahepatic damage and a catalyst for further cell-mediated immunopathology.

Therapy of acute and fulminant hepatitis B

Although new hepatitis B virus (HBV) infections are decreasing due to improving vaccination coverage, patients without vaccination coverage can still suffer from manifestation of acute hepatitis B with jaundice and (although rarely) liver failure. No treatment is indicated for mild acute hepatitis B; however, antiviral therapy should be initiated for patients showing signs of significant liver impairment as exemplified by deterioration of prothrombin time to an equivalent of 1.5 or 50% of the 'Quick test'. For fulminant hepatitis, there is no complete agreement on whether antiviral treatment would alter the course, but it should still be started, as it would reduce the risk of reinfection in case there is a need for liver transplantation. Patients in danger of progression towards acute liver failure should be referred to transplant centers as early as possible.

Management of severe acute to fulminant hepatitis B: to treat or not to treat or when to treat?

Despite a decline in cases of acute hepatitis B and the low hepatitis B virus (HBV) chronicity rates in adults, still some patients progress to HBV-related fulminant liver failure. In this review, we discuss treatment options that may prevent the progression of severe acute hepatitis B to fulminant liver failure and death. In severe acute HBV with prolonged prothrombin time and increased bilirubin, interferon failed to be effective while antiviral treatment, particularly with lamivudine, appears to improve survival (mean survival almost 80%). Outcome without antiviral therapy has remained considerably poor, whereas there is no convincing evidence of amelioration of HBV-targeted immunity. Of note, most patients who died or required transplantation despite lamivudine therapy, were started on lamivudine at advanced stages compared with those survived. This suggests that prompt and timely antiviral therapy is crucial. Owing to the abovementioned results the design of randomized placebo-control trials in the setting of severe acute hepatitis B seems unethical. On the contrary, the design of multicentre double-blind randomized trials to compare the efficacy between lamivudine and entecavir or even tenofovir in acute severe HBV cases is ideally needed, but these studies appear to be very difficult to perform considering that these cases are not frequent and therefore, it is almost impossible to have two arms adequately numerous and homogenous for statistical evaluation. Thus, in the absence of solid evidence based data, the hepatologists could treat their patients with severe acute hepatitis B with lamivudine or the most potent antivirals entecavir or tenofovir.

HBcAg expressed on the surface of circulating Dane particles in patients with hepatitis B virus infection without evidence of anti-HBc formation

Circulating immune complexes composed of HBcAg and anti-HBc have been demonstrated recently in patients with hepatitis B virus replication. After dissociation of immune complexes by chaotropic ions, HBcAg was quantified radioimmunologically. In the present study, we describe 10 patients with hepatitis B virus replication, absent or delayed anti-HBc formation and exposed HBcAg in serum. Four of the 10 patients had acute hepatitis, and six patients had chronic persistent hepatitis. In seven of 10 patients, a secondary immune defect was apparent due to acquired immunodeficiency syndrome, leukemia, histiocytosis X, sarcoidosis or end-stage renal disease. Electron microscopy demonstrated that Dane particles from anti-HBc-negative patients were agglutinated after addition of monoclonal anti-HBc antibodies, whereas Dane particles from anti-HBc-positive sera did not show agglutination. Monoclonal HBsAg-specific antibodies aggregated Dane particles independent of the presence of anti-HBc. Circulating HBcAg was always associated with the Dane particle fraction after density gradient separation. Hepatitis B virus core proteins from patients with and without anti-HBc studied by immunoblotting after sodium dodecyl sulfate-gel electrophoresis showed identical patterns. Hepatocytes from anti-HBc-negative patients were positive for HBcAg but negative for immunoglobulin G by immunofluorescence technique. The data indicate that HBcAg may also be expressed on the surface of Dane particles, where it is commonly masked by anti-HBc.