Different antibody responses against hepatitis B surface antigen among mouse strains transfected with mutant viral DNA.

BACKGROUND: Rapid seroconversion from hepatitis B surface antigen (HBsAg) to anti-HBs antibody is seen in most patients with fulminant hepatitis B. It is unclear whether viral mutation or host immune background is responsible for such enhanced host reaction to hepatitis B virus (HBV). To investigate interaction between virus mutation and host immune background, we established a mouse model of hepatitis B using liposome-mediated gene transfer. METHODS: A mixture of liposomes and full-length viral DNA derived from hepatitis B patients was injected into three strains of purebred mice intrahepatically. After injection, HBsAg and antibody in liver and serum were serially measured. RESULTS: Three days after transfection, viral transcript and antigen were detected in the liver and serum. Ten days after transfection with wild-type DNA, hepatitis B surface antibody was detectable in two of the three strains. Mice that did not produce antibody after transfection with wild-type DNA produced a high amount of serum antibody against surface antigen when transfected with fulminant hepatitis-associated DNA. CONCLUSIONS: The present results are consistent with previous clinical observations of rapid HBsAg seroconversion in patients with fulminant hepatitis B. Further studies are needed to determine which mutations are responsible for differences in immunogenicity between HBV strains.

Molecular analysis of antigenicity and immunogenicity of a vaccine-induced escape mutant of hepatitis B virus.

BACKGROUND: To analyze the mechanisms of mutant escape, we established a murine model of hepatitis B virus (HBV) infection and studied the interaction of the envelope protein of the virion with various kinds of anti-hepatitis B antibody. METHODS: Mutation from glycine to arginine at aa145 was introduced into replication-competent DNA of HBV. The resulting mutant HBV DNA was transfected into cultured hepatoma cells and livers of mice using liposome-mediated gene transfer. Then, interactions between the antigenic envelope protein (in culture or in circulation) and anti-hepatitis B antibody were examined. RESULTS: Mutant envelope protein escaped human hepatitis B immunoglobulin, rabbit polyclonal anti-hepatitis B surface antigen (HBsAg) antibody, and monoclonal anti-a antibody in vitro and in vivo. There was a difference in the degree of inhibition between hepatitis B immunoglobulin and the other two antibody types in vitro. Transfection with an HBV construct containing a mutation in the a-loop resulted in levels of HBsAg in circulation and seroconversion to anti-HBs antibody that were similar to those produced by a wild-type construct. CONCLUSIONS: The degree of escape by the mutant envelope protein differed according to antibody type. Of the three types of antibody used in this study, HBV immunoglobulin was least affected by mutation in the a-loop. There appears to be no correlation between antigenicity and immunogenicity of the escape mutant, and the a-loop mutant may cause hepatitis with the usual serum viral markers.

Configuration and replication competence of hepatitis B virus DNA in peripheral blood mononuclear cells from chronic hepatitis B patients and patients who have recovered from acute self-limited hepatitis.

Several studies have reported the presence of hepatitis B virus (HBV) DNA in peripheral blood mononuclear cells (PBMCs). However, the mode of existence, infectivity and replication competence of HBV DNA in PBMCs remain unclear. To clarify these questions, we assayed for covalently closed circular DNA (cccDNA) and integrated HBV DNA in PBMCs from ten patients who had recovered from acute self-limited hepatitis B (AHB) and 14 chronic hepatitis B (CHB) patients. HBV DNA was detected in all six CHB patients who were positive for hepatitis B e antigen (eAg), and cccDNA was detected in five. HBV DNA was detected in seven of the eight CHB patients who were negative for eAg, and cccDNA was detected in three. HBV DNA and cccDNA was also detected in five and two of the ten AHB patients, respectively. Integrated HBV was not detected in PBMCs of any patients. HBV DNA presence and replication competence in PBMCs are associated with eAg-positive phenotype. Sequence analysis revealed that the source of HBV DNA differed between PBMCs and serum. Even in patients who have recovered from AHB, replicable HBV may persist in PBMCs.

Genotypic analysis of hepatitis B virus from patients with fulminant hepatitis: comparison with acute self-limited hepatitis.

AIM/BACKGROUND: There is an increasing evidence that certain hepatitis B virus (HBV) strains may contribute to the pathogenesis of fulminant hepatitis B (FHB). Recently, we reported that genotypes of HBV influence the clinical course of acute self-limited hepatitis B (AHB). In this study, we compared clinical features of FHB between different HBV genotypes and compared the prevalence of each genotype between FHB and AHB patients. METHODS: The subjects consisted of seven patients with FHB and 25 patients with AHB. The core promoter and precore region were directly sequenced following polymerase chain reaction, and genotype was determined by restriction fragment length polymorphism analysis of the S gene. RESULTS: Of the seven FHB patients, one had genotype A, one had genotype B, four had genotype C, and one had genotype D. Six of the seven FHB patients were infected by heterosexual contact; one FHB patient who was not infected by heterosexual contact had genotype C. All four FHB patients with genotype C had a short duration clinical course. In one patient with genotype A, the time from onset of hepatitis to hepatic coma was 30 days. These results are similar to those of the patients with AHB, in which clinical course was longer in patients with genotype A than in patients with genotype C. CONCLUSION: Viral genotype can be used to predict the clinical course of both FHB and AHB.

Chronic hepatitis B with flare due to co-infection of hepatitis delta virus during lamivudine therapy.

In 1997, a 27-year-old homosexual man contracted acute hepatitis B that developed into chronic hepatitis. Because of repeated flares, administration of lamivudine was started in March 2002. Hepatitis B virus (HBV) DNA immediately decreased, but the serum level of alanine aminotransferase gradually increased. Drug-induced hepatitis due to lamivudine was excluded. It was suspected that the progression of liver damage was caused by hepatitis delta virus (HDV), because the patient was positive for both anti-HDV antibody and HDV RNA. Co-infection of HDV should be considered a possibility if liver injury is not improved by lamivudine therapy.

Repeated jaundice due to YMDD mutant in a patient with prolonged lamivudine therapy for chronic hepatitis B under prednisolone treatment for Still's disease.

A 50-year-old woman patient began receiving lamivudine because of acute exacerbation of chronic hepatitis B. She also suffered from adult-onset Still's disease and had received prednisolone for 5 years. Lamivudine was effective for treatment of the first flare. Fifteen months after lamivudine treatment was started, a breakthrough due to lamivudine-resistant strain M5521 occurred. Between 10 and 12 months after the breakthrough, flare with jaundice occurred 3 times. We decided interferon would not be suitable, because it could induce activation of Still's disease. Prolonged lamivudine therapy is only recommended in cases of hepatitis B in which there is no alternative treatment.