Significance of maternal and infant serum antibodies to hepatitis B core antigen in hepatitis B virus infection of infancy

The significance of IgM and IgG class antibodies to hepatitis B virus (HBV) core component (anti-HBc) was investigated in a study of maternal-fetal HBV transmission. An IgM anti-HBc response was lacking in the majority (49/53) of HBV-infected infants. This antibody thus cannot be used as an indicator of transplacental infection. However, most infants who became HBsAg positive during the first 6 months of life acquire infection in the perinatal period rather than transplacentally. Passively transferred maternal IgG anti-HBc in the infant and additional IgM anti-HBc positively in the carrier mother have no modulating influence on HBV infection of infants born to HBV carrier women.     

Detection of hepatitis B virus DNA in serum and relation with the IgM class anti-HBc titers in hepatitis B virus infection

Sera from four groups of patients wtih different serologic markers of HBV infection were examined for HBV DNA using molecular hybridization technique and for IgM class anti-HBc using an ELISA based on the antibody capture principle. Results of HBV DNA assay were generally in good agreement with the presence of HBeAg. However, HBV DNA was found in 13% of anti-HBe+ sera and in one patient with anti-HBc as a sole marker. IgM anti-HBc was detected at high titers in acute hepatitis B patients and was also present during the "window-period." This marker was also found, though less frequently when other markers for HBV infectivity were absent, in chronic hepatitis B patients and healthy carriers. From these findings we conclude that the HBV DNA assay provides a reliable method of detecting the infectious agent, particularly in anti-HBe+ sera and sera with anti-HBc as a sole marker. The assay for IgM anti-HBc is useful for establishing the diagnosis of recent infection in patient with anti-HBc as a sole marker, and during acute hepatitis with very high aminotransferase values, a condition in which HBV DNA may be undetectable.     

Perinatal transmission of hepatitis B virus: role of maternal HBeAg and anti-HBc IgM

The development of hepatitis B surface antigen (HBsAg) carrier states in newborns of HBsAg-positive mothers was correlated to the presence of anti-HBc IgM and HBeAg in the mothers. There was a positive correlation between infection of the newborn and the presence of HBeAg, as shown previously, but no correlation with anti-HBc IgM.     

Intrauterine transmission of hepatitis B virus is closely related to placental leakage

Hepatitis B virus (HBV), transmitted by hepatitis B e antigen (HBeAg)-positive mothers by intrauterine infection, infecting newborns, is closely related to signs and symptoms associated with miscarriage. However, no correlation was observed between intrauterine infection of infants and the presence of antibodies of immunoglobulin M (IgM) class antibodies against hepatitis B core antigen (anti-HBc) in maternal blood, nor was HBeAg found in maternal or cord sera. These results indicate that contamination by the mother's blood, through placental leakage, plays an important role in HBV infection in utero. Without placental leakage, maternal blood could not pass through the placenta and enter fetal circulation, and so intrauterine infection would not occur, even if very high titers of hepatitis B surface antigen (HBsAg) and HBeAg were present in maternal blood.     

Relative functional affinity of specific anti-core IgG in different categories of hepatitis B virus infection

While resolution of hepatitis B virus (HBV) infection occurs in most cases, a carrier state can exist in which the HBV surface antigen (HBsAg) persists. Some carriers are also positive for the HBV “e” antigen (HBeAg), indicative of high viral replication. Others are HBV “e” antibody (anti-HBe)-positive carriers in whom there appears to be a fall in the level of viral replication with the appearance of antibodies against the “e” antigen. The former group of carriers is considered to be at a higher risk of transmitting HBV infection than the latter. In order that a carrier state may occur, some degree of tolerance to the infectious agent must exist. A study of the rate of increase of specific antibody avidity following infection provides a means of assessing the maturity of the immune response to an infectious agent. Since antibodies specific for the HBV core antigen (HBcAg) are produced in almost all cases of HBV infection and the HBeAg and HBcAg share a large number of amino acids and some B- and T-cell epitopes, the increase in the avidity of antibodies against the HBV core antigen (anti-HBc) in cases of acute, resolving HBV infection and in HBV carriers has, therefore, been studied. An increase in the avidity of specific antibody, similar to that seen in other viral infections, was observed following acute, resolving infection. However, low avidity antibody persisted longer in carriers who remained positive for HBeAg, whereas in cases where there were antibodies specific for HBeAg, the anti-HBc antibody was of high avidity. Analysis of sequential sera from carriers who seroconverted from HBeAg-positive to anti-HBe-positive showed that an increase in anti-core avidity could predate seroconversion from HBeAg-positive to anti-HBe-positive status. Thus, anti-HBc avidity studies may be of diagnostic and prognostic significance. J. Med. Virol. 51:189–197, 1997. © 1997 Wiley-Liss, Inc.     

Incidence and significance of hepatitis B core antibody in a healthy blood donor population

To determine the current incidence of hepatitis B core antibody (anti-HBc) in a healthy blood donor population, 1,893 donors were screened for anti-HBc. Forty-one (2.16%) were found to be initially positive and 35 (1.85%) repeatably positive. Sera from the repeatably positive donors were further screened for hepatitis B surface antibody (anti-HBs), and hepatitis B virus DNA (HBV DNA) by dot hybridisation. The repeatably positive donors were subsequently recalled for further investigation, and their peripheral blood lymphocytes were also screened for HBV DNA by dot hybridisation. Eighteen (51.4%) of the anti-HBc-positive donors were also anti-HBs-positive. HBV DNA was not detected in the serum or the lymphocytes of any of the anti-HBc-positive donors.     

Selection of a precore mutant after vertical transmission of different hepatitis B virus variants is correlated with fulminant hepatitis in infants

The incidence of perinatal transmission of hepatitis B virus (HBV) depends on the HBeAg/anti-HBe status of the mother. While children of HBeAg-positive mothers have a 90% probability of acquiring a chronic hepatitis B virus carrier state, babies of anti-HBe-positive mothers are more likely to develop fulminant hepatitis within the first 3 to 4 months of life. There is evidence that precore (pre-C) mutations of the HBV can be associated with fulminant hepatitis. The pre-C region was therefore examined in sera from nine infants with fulminant hepatitis after vertical transmission, one HBeAg-positive and seven anti-HBe-positive mothers by polymerase chain reaction (PCR) and direct sequence analysis. In five mother/infant pairs the virus populations were characterized in addition by analysing clones of the amplified products. All mothers were infected with two or four variants of HBV with mutations at different positions of the preC genome including position 1896, which results in a stop codon. While the precore stop codon was detected in a portion of the virus populations of the HBeAg-positive and of four anti-HBe-positive mothers the dominating viral strain was represented by the wild type virus in three. In contrast, the virus populations of all babies showed the 1896 precore variant as the prevalent virus strain during the phase of active disease. In the surviving baby only wild type sequences were detected after recovery. Subtype ayw was found in all mothers and infants and adw2 was present in three mothers and in the surviving child. The findings suggest that all mothers carried a wild type HBV population with a certain number of different HBV variants. After transmission of the mixed virus population a selection process was started in the baby. The association of subtype ayw with the precore mutations and with the fatal outcome of the hepatitis B might be the result of a directed selection of this variant with a particular advantage in the viral life cycle. © Wiley-Liss, Inc.     

Comparison of hepatitis B core antigens derived from human liver or synthesized in Escherichia coli and evaluation of their use in diagnostic assays for anti-HBc IgM

Hepatitis B core antigen (HBcAg) synthesized in Escherichia coli (clone PR1-11) was compared with HBcAg purified from a liver obtained at autopsy of a patient with chronic active hepatitis B. The molecular weight determined by SDS-PAGE with subsequent transfer of the proteins to nitrocellulose paper, incubation with 125I anti-HBc and exposure to X-ray film, was about 21,000 for HBcAg synthesized in E. coli and was slightly lower for the liver-derived HBcAg. In CsCl density gradients the liver-derived HBcAg had one peak at 1.32 g/ml, and the HBcAg synthesized in E. coli had two peaks at 1.34 and 1.30 g/ml. In a comparison of the immunological activity of both antigen preparations in an enzyme immunoassay, the liver-derived HBcAg was detected only up to a dilution of 1:320, whereas the HBcAg synthesized in E. coli was detected in dilutions up to 1:100,000. With both antigens, the same percentage of sera were positive for anti-HBc IgM from patients with acute (100%), convalescent (61%), past (5%) and chronic active (29-37%) hepatitis. These results indicate that tests for anti-HBc IgM performed with HBcAg synthesized in E. coli are at least as sensitive and specific as those using liver-derived HBcAg.     

Hepatitis B virus DNA is frequently found in liver biopsy samples from hepatitis C virus-infected chronic hepatitis patients

Human hepatitis B virus (HBV) and hepatitis C virus (HCV) are two major etiologic agents of chronic hepatitis, which is closely related to the development of hepatocellular carcinoma (HCC). A possible involvement of HBV co-infection was investigated in ongoing HCV-related liver diseases in HCV-infected patients. A prevalence of anti-HBc in anti-HCV–positive/HBsAg-negative chronic hepatitis patients and a low copy number of HBV DNA were found in most of the liver biopsy samples of anti-HCV–positive/HBsAg-negative patients. The present data suggest that HBV co-infects frequently with HCV and may play an important role in the development of HCC in the anti-HCV–positive/HBsAg-negative patients with chronic hepatitis. J. Med. Virol. 54:249–255, 1998. © 1998 Wiley-Liss, Inc.     

Splenic replication of hepatitis B virus in the chimpanzee chronic carrier

Low levels of hepatitis B virus (HBV) replication and serum Dane particles have been commonly observed in chimpanzee chronic HBV carriers. To evaluate the possibility of extrahepatic sites of replication, DNA from various organs of a chimpanzee HBV carrier were evaluated by Southern blot analysis. With cloned, repurified HBV DNA of 3.2 kilobases (Kb) as a hybridization probe under stringent conditions, analysis of liver DNA revealed a diffuse hybridization pattern below 3.2 Kb and full-length double-stranded HBV genomes at 3.2 and 1.8 Kb, the latter representing the supercoiled (CCC) form found in the nucleus. No HBV DNA was found in pancreas, muscle, renal, or adrenal gland. Analysis of splenic DNA revealed diffuse hybridization below 3.2 Kb within the cytoplasmic subcellular fraction, and full-length HBV genomic forms in the nuclear fraction of splenic tissue. Use of (-) and (+) strand-specific HBV DNA and RNA probes demonstrated asymmetric viral replication within the spleen cytoplasm as previously demonstrated in liver. Northern blot analysis of total RNA from chimpanzee spleen and liver revealed HBV RNA sequences in both of these tissues, suggesting active viral gene expression and/or replication in chimpanzee spleen as well as in liver. Elucidation of the splenic cell type supporting viral propagation may serve as a basis for development of a tissue culture system to study molecular events of HBV replication.     

Isolated core antibody hepatitis B in sub-Saharan African immigrants

Chronic hepatitis B virus (HBV) infection is a major health problem in sub-Saharan Africa, where prevalence is > or =8%, and is increasingly seen in African immigrants to developed countries. A retrospective audit of the medical records of 383 immigrants from sub-Saharan Africa attending the infectious diseases clinics at the Royal Melbourne Hospital was performed from 2003 to 2006. The HBV, human immunodeficiency virus (HIV) and hepatitis C virus (HCV) serological results are reported, with a focus on the isolated core antibody HBV pattern (detection of anti-HBc without detection of HBsAg or anti-HBs). Two-thirds (118/174, 68%) of those tested had evidence of HBV infection with detectable anti-HBc. Chronic HBV infection (serum HBsAg detected) was identified in 38/174 (22%) and resolved HBV infection (both serum anti-HBs and anti-HBc detected) in 45/174 (26%). The isolated core antibody pattern was identified in 35/174 (20%), of whom only 1/35 (3%) had detectable serum HBV DNA on PCR testing, indicating occult chronic HBV (OCHB). Only 8/56 (14%) patients with negative anti-HBc had serological evidence of vaccination (serum anti-HBs detected). HIV infection was detected in 26/223 (12%). HCV antibodies were detected in 10/241 (4%), of whom 8 (80%) had detectable HCV RNA. Viral co-infection was detected in only 2/131 (1.5%) patients tested for all three viruses. The isolated core antibody HBV pattern was common among sub-Saharan African patients in our study. These patients require assessment for OCHB infection and monitoring for complications of HBV.     

Selective detection of IgM-antibody against core antigen of the hepatitis B virus by a modified enzyme immune assay.

IgM antibody against core antigen of the hepatitis B virus (anti-HBc IgM) was selectively determined by a new enzyme immunoassay (EIA). Microtiter plates were coated with anti-human micro chain immunoglobulin. On addition of serum IgM is bound by a factor of about 4,000 more than IgG. After removing the sample, HBcAg is added to the IgM-coated surface. Binding takes place if the IgM contained anti-HBc and was demonstrated by the aid of a conjugate made from anti-HBc IgG and horse radish peroxidase. Quantitation may be achieved without testing a dilution series. The assay was not disturbed by a large excess of anti-HBc IgG in the sample and rheumatoid factor did not produce false-positive results, provided the sample was diluted in an excess of aggregated IgG. The diagnostic relevance of the assay was demonstrated in selected cases of acute hepatitis B. Rapid diagnosis of acute hepatitis B infection is therefore now possible in those cases whihc are HBsAg-negative but anti-HBc-positive.     

Age- and sex-related study of hepatitis B virus chronic carrier state in infants from an endemic area (Senegal)

This report concerns hepatitis B virus (HBV) infections observed in 155 infants from Senegal, studied with a view to determining the factors involved in development of the chronic carrier state. A chronic carrier state was observed in 50.3% of the infants. This study confirms that the risk of chronic carriage is linked to age. This risk declines very rapidly with age, falling from 82% in infants under 6 months old, to 15% in children between the ages of 2 and 3 years. Spontaneous elimination of hepatitis B surface antigen (HBsAg) is uncommon in HBsAg carriers during childhood. The difference observed in chronic carriage between males and females is due to a difference in susceptibility of the two sexes to the development of the chronic carrier state: HBV infections (before 2 years of age) lead to a chronic carriage in 77% of males as against 50% of females. These conclusions are important in view of the immunisation programs being carried out against hepatitis B virus in endemic areas. For a maximum efficacy, vaccination must be carried out at birth, or shortly afterwards.     

Baseline seroepidemiology of hepatitis B virus infection in children in Taipei, 1984: a study just before mass hepatitis B vaccination program in Taiwan

Hepatitis B virus (HBV) markers were studied by radioimmunoassays in serum samples of 1,200 (647 male, 553 female) apparently healthy children under 15 years of age in Taipei between June and October 1984. The prevalence rate of hepatitis B surface antigen (HBsAg) was 5.1% in infancy, increased to 10.7% between 1 and 2 years of age, and then remained constant at about 10% thereafter. The prevalence rate of surface antibody (anti-HBs), core antibody (anti-HBc), and seropositivity (at least one marker of hepatitis B detectable) were 39.0, 30.5, and 52.5%, respectively, in infancy, then decreased to 10.7, 14.3, and 17.9%, respectively, between 1 and 2 years of age. Thereafter, the antibody prevalence increased in parallel with age. By the age of 13-14 years, nearly half of the children were infected by HBV. The results suggested that in our children, most HBsAg carriers resulted from infections before 3 years of age, and HBV infections after 3 years of age infrequently resulted in a carrier state. One hundred (83.3%) of the 120 HBsAg-positive children had hepatitis B e antigen (HBeAg), indicating high prevalence in young asymptomatic HBsAg carriers. The prevalence rate of HBeAg tended to decrease with age and a reversed trend was observed with anti-HBe. Our study, just before our government extends mass hepatitis B vaccination program from newborns to children, provides background seroepidemiologic data of HBV infections in the healthy children in Taiwan.     

Nucleotide sequence of hepatitis B virus isolated from subjects without serum anti-hepatitis B core antibody

The nucleotide sequences of the precore/core and X open reading frames (ORFs) of hepatitis B virus (HBV) were studied in four subjects who were serologically negative for anti-hepatitis B core antibody. These subjects were positive for serum hepatitis B surface antigen and were considered to be asymptomatic HBV carriers. Sequencing of the precore/core ORF revealed precore wild type and 3 to 8 nucleotide substitutions (replacing 0 to 2 amino acids) in the core region compared with the sequence of subtype adr. These substitutions were not considered to have changed the epitope of the core antigen, resulting in the absence of anti-HBc as determined by a conventional diagnostic kit. The X ORF showed 1 to 5 nucleotide substitutions (replacing 1 to 3 amino acids) and the structure of the X protein and the core promoter/enhancer II complex appeared to be conserved. These findings strongly suggest that the absence of serum anti-HBc is not due to mutation of the HBV DNA but to an aberrant immune reaction of the host to HBV. © 1995 Wiley-Liss, Inc.     

Evidence for limited humoral immunoglobulin M antibody response to hepatitis B core antigen during acute and chronic hepatitis B virus infections

The periods of persisting immunoglobulin M class antibodies to hepatitis B core antigen in 28 patients with acute hepatitis B infections and in 134 patients with chronic hepatitis B infections were studied by using an enzyme-linked immunosorbent assay and an indirect immunofluorescence technique. We showed that the clearance of antibodies to hepatitis B core antigen is independent of the degree of viremia in both forms of hepatitis.     

Hepatitis A and hepatitis B virus infection in children and adolescents in north-east Italy

The sera of 722 children and adolescents without overt liver disease were tested for hepatitis B surface antigen (HBsAg), antiHBs and anti-hepatitis B core anti-HBc; 658 of the sera were also tested for anti-hepatitis A virus anti-HAV. Except for the "passive" antibody peak observed in babies, the anti-HAV age-specific prevalence was negligible until the age of 3; it then increased, reaching 35% by the age of 15. Serological evidence of HBV was present in 16% of the subjects: this prevalence was almost constant at all ages. The HBsAg carrier rate was highest in children under 5 years of age (7.6%) and decreased with age. However, only one HBsAg carrier was under 1 year of age. Anti-HBs age-specific prevalence increased progressively from 2.7% to 11.4%. Anti-HBc alone was present in 4.1% of the subjects. No significant sex differences were found in the prevalence of HBV serum markers or in the HBsAg carrier rate. Neither HAV nor HBV infection was significantly influenced by place of residence or socioeconomic status. It is concluded that in this area both HAV and HBV are endemic, but while HAV is mainly acquired at school, most of the HBV infections occur within the household. The results suggest that not only perinatal transmission, but also intrafamilial horizontal infection, plays a role in HBV spread among infants.     

The IgM antibody responses to the core antigen of hepatitis B virus

Little is known about the immunoglobulin class of antibodies to HBcAg. In the present study sera containing anti-HBc were fractionated by sucrose density-gradient centrifugation, and all serum fractions were tested against HBcAg by immunoelectro-osmophoresis. In addition selected fractions were examined by complement fixation test, immune adherence hemagglutination and immune electron microscopy. Anti-HBc activity in IgG serum fractions was demonstrated by all four techniques used, but HBcAg-specific IgM was detected only by immunoelectro-osmophoresis and by immune electron microscopy. In acute hepatitis B, HBcAg-specific IgM was detected for up to eight weeks after the onset of jaundice. It was also found transiently in two patients who developed chronic hepatitis B without an icteric episode and in one out of thirteen patients with HBsAg-positive chronic liver disease, but in none of eight healthy HBsAg carriers. The results suggested that HBc Agspecific IgM is formed transiently in response to primary HBV infection but is generally undetectable in established HBsAg carriers.     

Specific deletions in the hepatitis B virus core open reading frame in patients with chronic active hepatitis B

The polymerase chain reaction (PCR) and DNA sequencing were used to examine genomic variation in the pre-core/core open reading frame of the hepatitis B virus (HBV) in chronically infected patients. Gel electrophoresis of amplification products showed the presence of shortened forms of the core gene in addition to the full length product. These shortened forms were seen only in patients with chronic active hepatitis (CAH) seropositive for HBeAg and not in patients with chronic persistent hepatitis (CPH) or HBeAg minus CAH. Cloning and DNA sequencing revealed the presence of a number of overlapping deletions within the core gene, the majority being in-frame, which were clustered within aa 81-114 of the core gene product. These deletions were found in patients with CAH from different racial and geographical backgrounds, whereas PCR analysis of the surface and ×open reading frames showed no shortened forms suggesting deletions to be specific to the core gene in these patients. Because the product of the core gene-the HBV core antigen–is believed to be the major target for T-cell-mediated liver damage, it seems likely that the products of core genes carrying deletions will alter immune recognition and may be of importance in the progression of inflammatory liver damage.