Clinical significance of low or negative titer of antibody to hepatitis B core antigen during the course of chronic hepatitis B virus infection in adolescents

New Strategies for Blood Donor Screening for Hepatitis B Virus

Serologic testing for hepatitis B virus (HBV) surface antigen (HBsAg) and antibody to HBV core antigen (anti-HBc) has historically been the foundation of blood screening, while HBV nucleic acid testing (NAT) was recently developed to detect HBsAg-negative, anti-HBc-negative blood units donated during early acute infection. Comparison data on seroconversion panels using HBsAg assays of varying sensitivities and pooled- or single-sample NAT, along with viral load estimates corresponding to HBsAg assay detection limits, have provided information on the theoretical benefits of NAT relative to HBsAg. Model-derived estimates have generally been predictive of the yields of DNA-positive, HBsAg-negative window period blood units detected in a number of studies from Europe, Japan, and the US. Studies indicate that the added benefit of pooled-sample NAT is relatively small in areas of low endemicity, with greater yields in areas highly endemic for HBV. Single-sample NAT would offer more significant early window period closure and could prevent a moderate number of residual HBV transmissions not detected by HBsAg assays; however, no fully automated single-sample HBV NAT systems are currently available.Even single-sample HBV NAT may not substitute for anti-HBc screening, as indicated by studies of donors with isolated anti-HBc who have extremely low DNA levels undetectable by standard single-sample NAT and who have been associated with transfusion-transmitted HBV. Moreover, HBsAg testing may still be needed even in the setting of combined anti-HBc and NAT screening. HBsAg-positive units from donors in the chronic stage of infection may contain very low or intermittently detectable DNA levels that single-sample NAT would miss. Although such donors are usually anti-HBc reactive and would be interdicted by anti-HBc screening, some lack anti-HBc. Extensive parallel testing will be needed to determine whether single-sample NAT in combination with anti-HBc might be sufficient to detect all the infectious donors currently interdicted by HBsAg testing. In countries that do not screen for anti-HBc, HBsAg testing would be the only means of detecting donations from chronically infected individuals with low/intermittently detectable DNA, since even single-donor NAT would not identify these potentially infectious blood units. In the future, the current fully automated HBsAg assays may incorporate significant sensitivity improvements, and automated single-sample HBV NAT may become a reality. Each country will need to develop its blood screening strategy based on HBV endemicity, yields of infectious units detected by different serologic/NAT screening methods, and cost effectiveness of test methods in ensuring blood safety.

Full-length sequence and functional analysis of hepatitis B virus genome in a virus carrier: a case report suggesting the impact of pre-S and core promoter mutations on the progression of the disease

In chronic hepatitis B virus (HBV) infection, the quiescent immunotolerant phase evolves into the immunoactive phase. The aim of the present study was to clarify the virological alterations relevant to progression. Serial serum samples obtained from a patient with HBV during long-term follow-up were analysed by sequencing of the full-length HBV-DNA using polymerase chain reaction (PCR). In addition, PCR products of HBV genome from each serum sample were transfected into HuH-7 human hepatoma cells for the functional analysis of the transfected viral genomes. Based on the HBV-DNA sequence analysis, the patient had the genotype C virus, and the mutant HBV with common core promoter mutations (T(1762)A(1764)) and deletion of the pre-S region responsible for large surface protein transcription emerged before the onset of hepatitis. When the vigorous host immune response developed (indicated by the flare-up of hepatitis), the mutant HBV containing common core promoter mutations and another pre-S deletion causing lack of the surface protein promoter became predominant. The HBV-DNA sequences, other than pre-S and core promoter regions were identical to the wild-type sequence throughout the study. Transfection of PCR products containing the mutant HBV sequences resulted in increased amounts of intracellular replicative intermediates but the decreased secretion of HBsAg and HBeAg into culture media, suggesting accumulation of nonenveloped viral core particles within the cells. These results indicate that pre-S deletion and core promoter mutations may participate cooperatively in progression of the disease.

Long-term follow-up of hepatitis B virus carrier infants

One hundred twenty-two hepatitis B surface antigen (HBsAg) carrier infants were followed-up for 8-10 years. One hundred eleven had antibody to hepatitis B core antigen (anti-HBc; 83 had been vaccinated) and the remaining 11 were without anti-HBc (7 had been vaccinated). During the follow-up period, 29 (26.1%) carrier infants with anti-HBc had one or more episodes of alanine aminotransferase (ALT) elevation and up to 32.8% (21/64) of the carriers in this group lost their hepatitis B e antigen (HBeAg) before the age of 10. In addition, 2 (1.8%) carriers lost their HBsAg at the age of 3 and 8, respectively. No significant symptom or sign was noted during HBeAg seroconversion. In contrast, all the carrier infants without anti-HBc were still positive for both HBeAg and hepatitis B virus (HBV) DNA and none displayed abnormal ALT levels or any symptom related to liver disease. One became anti-HBc positive at the age of 9, and 5 other carriers had inconsistent borderline or weakly positive titers of anti-HBc. The episodes of ALT elevation and the prevalence of HBeAg seroconversion were not significantly different between immunized carrier infants. In conclusion, HBeAg seroconversion may occur in about one third of the anti-HBc-positive carrier infants during the first decade. On the other hand, the anti-HBc-negative HBsAg carrier infants' immune incompetence to the HBV antigens could persist for more than 10 years. Hepatitis B immunization did not have significant effect on the clinical course in carriers.