Immunology of hepatitis B virus infections

Autoimmune Kidney Diseases Associated with Chronic Viral Infections

Autoimmune kidney diseases triggered by viruses are an important cause of kidney disease in patients affected by chronic viral infection. Hepatitis B virus (HBV) infection is associated with membranous nephropathy and polyarteritis nodosa. Hepatitis C virus (HCV) infection is a major cause of cryoglobulinemic glomerulonephritis. Patients with human immunodeficiency virus (HIV) may develop HIV-associated nephropathy, a form of collapsing focal segmental glomerulosclerosis, or various forms of immune-complex-mediated kidney diseases. This article summarizes what is known about the pathogenesis, diagnosis, and management of immune-mediated kidney diseases in adults with chronic HBV, HCV, and HIV infections.

Concurrent HLA-related response factors mediate recombinant hepatitis B vaccine major adverse events

Recombinant hepatitis B (HB) vaccines have successfully reduced infection, cirrhosis and carcinoma, but questions have endured about causality of serious adverse events following vaccination. After an event in a pediatric patient an investigation reviewed HLA vaccine response effects and analyzed genetics in reported cases. There are apparent common causal immune mechanisms among reported adverse events. HLA class II alleles/haplotypes linked to HB vaccine cellular/non-response and Crohn's disease can create conditions that actively/passively amplify, respectively, all or other components of the immune response to the HB vaccine. Presence of the HLA class I allele A2 can result in heavy cytotoxic T-cell activation and vaccine/self-peptide presentation to immune cells. If HLA autoimmune susceptibility alleles/haplotypes are present that control other immune response components, the probability is elevated that these will activate cross-reactive immune cells; the cells, their inflammatory secretions and/or auto-antibodies may initiate adverse events reflecting those susceptibilities. Probable DRB1 amplifying alleles are noted. High-resolution DNA typing and results analysis are described to test the hypothesis in known HB vaccine adverse event patients. Possible practical applications stemming from hypothesis validation are described.

Characterization of minor and major antigenic regions within the hepatitis B virus nucleocapsid

Hepatitis B core antibodies (anti-HBc) appear very early during the course of the hepatitis B virus infection and often persist years after viral clearance. In order to characterize the immunodominant domain of the HBcAg, the human immune response against the HBV nucleocapsid (HBcAg) was analyzed by using 14 synthetic peptides. Anti-HBc antibodies were detected by an indirect enzyme-linked immunosorbent assay (ELISA) with HBc peptides. Results suggest that the anti-HBc response is heterogeneous and directed against the whole primary structure of the HBc protein. Results also indicate that the epitopes recognized by anti-HBc antibodies can vary with the stages of the disease. In most sera from patients with serological evidence of acute HBV infection, anti-HBc antibodies recognized all the HBc peptides; conversely, after the acute phase, anti-HBc antibodies recognized predominantly epitopes located within the central region of the HBc protein from residue 74 to 123. Our results suggest that the HBV core protein is made up of two antigenic regions: a major one expressing a family of immunodominant epitopes from residue 74 to 123, whereas the minor encompasses the rest of the protein. The concept of the conformational nature of the unique HBcAg determinant is discussed, suggesting numerous families of linear epitopes.

Absence or delayed appearance of hepatitis B core antibody in chronic hepatitis B surface antigen carrier children

An absence of the hepatitis B core antibody (anti-HBc) in hepatitis B surface antigen (HBsAg) carrier children has been reported before, but whether anti-HBc will ultimately appear is unknown. In a group of 420 HBsAg carrier children who were followed longitudinally, 10 (2.4%) had an absence or delayed appearance of serum anti-HBc. These 10 children were persistently seropositive for HBsAg, hepatitis B e-antigen, and hepatitis B virus DNA (HBV-DNA). Anti-HBc never appeared in 4, one of whom was a case of hepatitis B vaccine failure and became an HBsAg carrier. Three of the 4 were born to HBsAg carrier mothers. Liver biopsy in one revealed non-specific reactive hepatitis (NSRH). All 4 were asymptomatic during follow-up. Mothers of the other 6 children who had delayed appearance of anti-HBc were also HBsAg carriers. The children seroconverted to anti-HBc positivity between 2 and 8 years of age, and the titer of serum anti-HBc at the first appearance varied. There were no significant changes in liver function tests, HBV-DNA levels, or associated symptoms and signs before and after seroconversion. Liver biopsies were performed before anti-HBc seroconversion in 2 children and showed NSRH. All 10 children had a moderate to high replication of HBV as shown by the high titer of HBsAg and HBV-DNA. The absence of anti-HBc occurred almost exclusively in children who were infected perinatally.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence and type of pre-C HBV mutants in anti-HBe positive carriers with chronic liver disease in a highly endemic area

The sequence variability in the pre-C region of the hepatitis B virus (HBV) genome in the serum of 42 anti-HBe antibody positive carriers with chronic hepatitis B was studied by PCR and direct sequencing to determine prevalence and type of HBV pre-C mutants in a highly endemic area. Except for one, all patients were infected with viruses containing mutations in the pre-C region which prevent precore and e-antigen (HBeAg) expression: 33 were infected predominantly or exclusively with variants containing a stop codon; two had a mixture of wild-type and a pre-C stop codon mutant virus; three had precore variants with mutations of the pre-C initiation codon and two of them an additional stop codon; four had a frameshift mutation; and one had two stop codons. One patient was infected with viruses which contained a mutation creating an amino acid exchange which should not prevent precore and HBeAg expression. These data demonstrate that in an endemic area a higher prevalence and even broader spectrum of pre-C HBV mutants are found than has been recognized previously in anti-HBe positive patients with chronic hepatitis B.