Elimination of hepatitis B virus surface antigen and appearance of neutralizing antibodies in chronically infected patients without viral clearance

Abstract

Seroconversion from hepatitis B surface antigen (HBsAg) to antibodies against HBsAg (anti-HBs) usually indicates resolution of hepatitis B virus (HBV) infection. Here, two HBV-infected patients with seroconversion to anti-HBs were found to be persistently positive for HBeAg and HBV DNA. Immunohistology of liver biopsies confirmed the expression of HBV proteins in the liver of one patient. The neutralizing ability of anti-HBs in patient sera was demonstrated by blocking HBV infection of primary tupaia hepatocytes. Analysis of the HBsAg-encoding region of HBV isolates from patients indicated the coexistence of heterogeneous HBV genomes in patients. The majority of recombinant variant HBsAg was reactive in HBsAg assays and was able to bind to anti-HBs. Circulating immune complexes (CIC) of HBsAg in patient sera could be detected by polyethylene glycol precipitation and trypsin digestion. Thus, neutralizing anti-HBs may appear in chronic HBV carriers for long periods but does not necessarily lead to complete viral clearance.

A novel general and efficient technique for dissociating antigen in circulating immune complexes

“…In the dissociation, the isotonic state was assured during the dissociation, neutralization and measurement, which assures that the antigens are not influenced by the measurement. This has never been reported in previous studies . In addition, glycine‐HCl was found as the best buffer system.…”

“…The tolerance of antigens in different CICs to pH is different. Thus, the traditional HCl dissociation method, trypsin digestion method and Immune Complex Transfer method are only used in the measurement after dissociation of HBsAg‐IC, HCV Core‐IC and HIV P24‐IC . However, the values determined with these methods were also lower than those determined with our new method.…”

“…HCl Dissociation , Trypsin Digestion and Immune Complex Transfer (three methods used for the detection of CICs with specific antigen) as well as our technique were employed to separate, dissociate or trypsinize HBsAg‐IC (five HBV‐M patterns; n = 335), HCV core‐IC ( n = 32), HIV P24‐IC ( n = 12), Ins‐IC ( n = 35) and TG‐IC ( n = 56). Different antigens were detected using ELISA HCV core antigen assay kit, ELISA HIV P24 antigen assay kit and ELISA‐anti‐Clq capture assay kit.…”

“…Immune complexes were degraded by the trypsin digestion method of Zhang et al. (2011) with slight modification. In short, the above sediment tubes (test and control; n = 2) was mixed with 100 μL of trypsin (10 mg/mL) or 0.9% NaCl.…”

Prevalence of occult hepatitis B in a population from the Brazilian Amazon region

“…One explanation for the lack of detection of HBsAg by enzyme immunoassays would be the occurrence of mutations in the “a” determinant, which is located after amino acids 124‐147 within the major hydrophilic region (MHR) of the S gene . Some mutations have been shown to reduce the circulation of HBsAg in serum and others can cause structural changes in the surface protein that prevent it from being recognized by commercial assays …”