Studies of HBV replication during acute hepatitis followed by recovery and acute hepatitis progressing to chronic disease

Infantile hepatitis B in immunized children: risk for fulminant hepatitis and long-term outcomes

BACKGROUND

Infantile hepatitis B after neonatal immunoprophylaxis is a rare yet distinct disease. This study aimed to analyze the long-term outcomes and risk factors in immunized infants with hepatitis B.

METHODS

The clinical parameters and outcomes of 41 infants born after universal immunization, and admitted for HBV-positive hepatitis were studied. All patients were followed for at least 6 months (median  = 4.4 years, range 0.6-18.1 years). Patient survival, changes of HBsAg and HBeAg status, and complications were analyzed.

RESULTS

Among the 41 cases (32 males, 9 females), 21 presented with fulminant hepatitis (FH), and 20 with non-fulminant hepatitis (NFH). Ninety-five percent (36/38) of the mothers were positive for hepatitis B surface antigen (HBsAg). Multivariate analyses revealed younger age of onset (age <7 months) and negative maternal hepatitis B e antigen (HBeAg) were associated with FH (p = 0.03 and p = 0.01, respectively). An infantile fulminant hepatitis B risk score using maternal/infant HBeAg positivity and onset age was proposed. Among the FH cases, the rate of mortality, HBsAg clearance, and chronic HBV infection were 47.6%, 38.1%, and 14.3%, respectively. Among the NFH cases, 35% developed chronic infection. Of the 9 chronically infected children received long-term follow-up, 8 had HBeAg seroconversion before 4 years of age. One case of FH developed hepatocellular carcinoma 14 years later.

CONCLUSIONS

Maternal HBsAg + /HBeAg- and early onset age were risk factors for FH in immunized infants. A significant portion of patients with FH or NFH evolve to chronic HBV infection, with HBeAg seroconversion in young childhood. Close surveillance for hepatocellular carcinoma is warranted in patients surviving infantile hepatitis B.

siRNA pool targeting different sites of human hepatitis B surface antigen efficiently inhibits HBV infection

The main objective was to determine whether a pool of small interfering RNAs (siRNAs) targeting different regions of hepatitis B virus surface antigen (HBsAg) efficiently inhibits hepatitis B virus (HBV) infection. siRNAs targeting different regions of HBsAg were transfected into HBV-producing HepG2.2.15 cells and at 72 h post-transfection, the culture medium was collected for ELISA to determine HBsAg, while total RNA was isolated from the cells for real-time PCR. Three siRNA sequences that efficiently inhibited HBV infection were converted into small hairpin RNAs (shRNAs) and then cloned into a single plasmid psiSTRIKE driven by a single U6 promoter. These shRNA expressing plasmids were tested for HBsAg gene silencing in HepG2.2.15 cells. A pool of siRNAs targeting HBsAg efficiently inhibited HBV replication and antigen expression when transfected into HepG2.2.15 cells, compared with the use of single siRNA. Similarly, the plasmid encoding three different shRNAs driven by a single U6 promoter was more effective in silencing HBsAg at DNA, mRNA and protein levels compared with the plasmid encoding single shRNA. No apoptotic change was observed in the cells when the plasmid was transfected at a dose of 0.5-2 microg/1 x 10(6) cells after complex formation with Lipofectamine LTX. Furthermore, transfection with siRNA or shRNA did not increase interferon-gamma (IFNs-gamma) release, suggesting no induction of IFN response. In conclusion, a pool of chemically synthesised siRNAs as well as the shRNA expression plasmid encoding multiple shRNAs targeting different regions of HBsAg showed high gene silencing in HepG2.2.15 cells.

Characteristics of the early phase of chronicity in acute hepatitis B infection

The mechanism of development of chronicity after acute hepatitis B infection has not been elucidated fully. Following a single source outbreak of hepatitis B among 79 adult women, three patients (4%) became chronic carriers of hepatitis B virus (HBV). We compared features of the virus and antibody response of the latter three patients with those of 12 HBeAg-positive cases with resolving infection. The virus genotype was D, antigenic subtype ayw2. Base sequence analysis of S- and C-gene regions revealed no differences between the two groups. During the acute illness the three patients who developed chronicity had a remarkable transient reduction of HBsAg, HBeAg, and HBV DNA levels at 14-20 weeks after infection, the time of HBeAg seroconversion in the patients who cleared the infection. One HBeAg-specific monoclonal antibody (HBOT.95A) used as solid-phase antibody in a sandwich enzyme immunoassay detected an increased HBeAg signal in 2 of the 3 patients that developed chronicity and in 1 of the 12 patients who recovered. The latter patient had an exceptional long period of HBsAg antigenemia. Standard HBeAg assays detected HBeAg in all cases. HBeAg and anti-HBe-positive serum samples from the patients who recovered could inhibit the HBOT.95A response. The results suggest that chronic hepatitis B develops after an interruption of immune clearance. Differentiation of the antibody response to HBeAg may help to find patients with an increased risk for this interrupted immune clearance who might be candidates for an early intervention therapy.

High levels of viral replication during acute hepatitis B infection predict progression to chronicity

To assess the pattern of development of serologic markers during acute hepatitis B, levels of HBsAg, HBeAg, and hepatitis B virus (HBV) DNA were assayed in stored serum samples obtained sequentially from 12 subjects infected with HBV during experimental studies conducted in the 1950s. Six patients developed acute self-limited hepatitis, three developed chronic hepatitis, and three had an asymptomatic infection without HBsAg. HBsAg was the first serologic marker detected (mean = 52 days after exposure), followed by HBeAg (62 days) and HBV DNA (72 days). Peak HBsAg levels occurred before onset of symptoms and correlated with peak titers of HBeAg and HBV DNA. Patients who developed chronic hepatitis had higher peak levels of viral markers than those with self-limited disease: HBsAg (30 versus 5.4 micrograms/ml), HBeAg (1:2,000 versus 1:60 titer) and HBV DNA (3,192 versus 444 pg/ml). Thus, chronic HBV infection is characterized by high levels of viral replication appearing early during the acute phase of infection.

Quantitative detection of hepatitis B virus DNA in sera from patients with acute hepatitis B

Two hundred forty-four serial serum samples from 30 adults hospitalized with benign (nonfulminant) acute hepatitis B were tested for the presence of hepatitis B virus (HBV) DNA by a quantitative solution hybridization assay using a 125I-labeled DNA probe complementary to HBV-DNA sequences. Acute hepatitis B was self-limiting in 28 and progressed to chronicity in the remaining two patients. Of the 28 patients with self-limiting hepatitis, 21 (75%) were hepatitis B e antigen (HBeAg) positive, 26 (93%) were HBV-DNA positive, and one patient (3.6%) was negative for both markers on admission to the hospital. HBV-DNA cleared after HBeAg clearance in 20 (71.4%), before HBeAg clearance in five (17.9%) and simultaneously with the loss of HBeAg in the remaining two (7.1%) of the 27 initially HBV-DNA- and/or HBeAg-positive patients. Moreover, HBV-DNA remained detectable in serum for 13.3 +/- 6.6 (range: 4-22) days after the appearance of anti-HBe in 71.4% of these patients. In contrast, HBV-DNA and HBeAg remained persistently positive in the two patients who developed chronic HBV infection. These data show that (1) viremia frequently persists after disappearance of HBeAg and (2) appearance of anti-HBe does not indicate the cessation of HBV replication in adults with acute self-limiting hepatitis B.

An enzyme-linked (alkaline phosphatase) oligonucleotide probe for the detection of serum hepatitis B virus DNA

Serum HBV-DNA detection represents a new and important diagnostic tool for the hepatologist, as well as a prognostic and therapeutic guide. Though most laboratories use genomic radioactive probes, the appearance of commercially available enzyme-linked oligonucleotide probes, which simplify the method, represents an advance in HBV-DNA detection. In order to verify the value of an enzyme-linked (alkaline phosphatase) oligonucleotide probe in HBV-DNA detection, we have first compared the results of the detection of serum HBV-DNA in 46 patients at different serological stages of HBV infection using this probe and with those obtained using a genomic P32-labeled probe. Fisher's test analysis of the results shows statistical significance; this indicates a high correlation between methods. Secondly, we have tested 296 sera of patients at different serological stages of HBV infection with the enzyme-linked probe; we have found HBV-DNA in 8 patients with acute hepatitis (61.54%), 61 HBeAg (70.12%), and 7 anti-HBe (12.07%) chronic hepatitis. These results show the value of this probe for routine survey of serum HBV-DNA using a simple method which avoids the use of radioactivity.

Prognostic significance of pre-S2 antigen and antibody in fulminant hepatitis B. Evidence for heterogeneous serological responses

Serial sera were collected prospectively and from early on in the clinical course of ten patients with fulminant hepatitis B. These were analysed for HBV DNA (dot-blot technique), HBsAg, HBeAg, pre-S2-Ag and their respective antibodies. Two patterns emerged in nine of the patients. The first and well-recognised pattern of rapid clearance of antigens and appearance of antibodies was seen in four patients, all of whom survived. The second pattern seen in five patients was one of persistence of HBsAg and pre-S2 antigen and failure to detect antibodies but only one patient survived. The first pattern may reflect a more rapid cessation of virus replication and this may favour liver cell regeneration and recovery. In contrast, the second pattern may indicate continuing virus replication and liver cell damage which could contribute to the high mortality in some patients with fulminant hepatitis B.

The affinity of anti-HBc antibodies in acute and chronic hepatitis B infection

Antibodies to hepatitis B core antigen (anti-HBc) are found in the sera of all individuals infected with hepatitis B virus. A role for these antibodies has been suggested in determining the outcome of infection. In this study, the affinity of anti-HBc antibodies in asymptomatic virus carriers was compared with that of antibodies present in the sera of patients with chronic liver disease. Persistently infected individuals with no evidence of clinical disease were found to have anti-HBc antibodies of greater affinity, compared with the chronic liver disease group. Sera from patients with chronic hepatitis contained high levels of low-affinity antibody whereas antibody levels in asymptomatic carriers were significantly lower. These findings are discussed in relation to the predicted role of anti-HBc antibodies in mediating hepatitis B virus-related hepatocellular injury.

Subclasses of antibodies to hepatitis B core antigen in chronic HBV infection: changes during treatment with alpha interferons and predictors of response

Response to interferon therapy in chronic hepatitis B virus (HBV) carriers is preceded by the appearance of IgM class anti-HBc (antibody to hepatitis B core antigen). The temporal relationship and magnitude of the IgM anti-HBc response is variable suggesting that the antibody is not directly involved in hepatocyte lysis, but is merely a marker of a changed state of immunity to the nucleocapsid proteins, induced by interferon. IgG 1, 2, 3, and 4 class anti-HBc did not change during therapy, but IgG 3 anti-HBc was significantly lower in responders than non-responders. IgG anti-HBc of all subclasses was absent in two Chinese HBV carriers. Lower than normal titres of anti-HBc (p less than 0.001) were detected in human immunodeficiency virus antibody positive (anti-HIV) HBV carriers. These data indicate the presence of altered immunity to the nucleocapsid antigens in these two types of chronic HBV carrier that are known to respond poorly to antiviral therapy.

Clearance of hepatitis B virus DNA and pre-S surface antigens in patients with markers of acute viral replication

To clarify the relationship between the pre-S antigens and other serological markers of hepatitis B virus (HBV) replication, we followed up 27 patients: 21 presented with symptoms of acute hepatitis (two progressed to chronicity) and six suffered from chronic hepatitis. Pre-S1, pre-S2, HBV DNA, IgM antihepatitis core antigen (HBc), hepatitis B e antigen (HBeAg), and anti-HBe were detected in about 200 sera serially collected at different times for at least 6-12 months from the onset of clinical observation. In the early symptomatic phase of acute hepatitis, the pre-S1 and pre-S2 antigens were present in 95% of the cases and correlated well with high levels of alanine-transferase (ALT) and IgM anti-HBc, while HBV DNA was present in the sera of only six (28.6%) patients (P less than 0.0001). This was the first marker to disappear (1 month after the initial stage). All of the HBV DNA-positive patients were also HBeAg positive, whereas no HBeAg-negative subjects were found with serum HBV DNA. In the six chronic patients, pre-S antigens were always present independently of the HBeAg/anti-HBe status; HBV DNA was detected in three of them, even if transiently, and in two of these it reappeared together with pre-S2 epitope. The follow-up data suggest that, in acute hepatitis, the clearance of pre-S antigens can be considered as a prognostic index of clinical resolution and that, in chronic hepatitis, the persistence of pre-S antigens seems to indicate progression of the disease. In particular, pre-S2, in patients in whom it is intermittent, can be considered as an index of reactivation.

Hepatitis B virus replication in hepatitis B and D coinfection

The clinical course, changes in liver function tests and the behaviour of viral markers over the course of time have been examined in 45 patients with acute hepatitis B and 14 patients with acute hepatitis caused by B and D viruses coinfection. There were no significant differences either in the clinical course or in the liver function tests, in the two groups. The changes in serum viral markers were as follows: HBV-DNA was the first marker to disappear; this was closely followed by HBeAg, and HBsAg was the last marker to become negative, during convalescence. This pattern was not altered by Delta coinfection. When we quantified serum HBV-DNA in both groups of patients, we found that Delta virus infection led to parital inhibition of HBV replication, so that serum HBV-DNA levels were significantly lower in those patients with acute hepatitis B who were simultaneously infected with Delta virus.

Changes of serum HBV-DNA in relation to serum transaminase level during acute exacerbation in patients with chronic type B hepatitis

To examine the relationship between changes of serum hepatitis B virus-dexoyribonucleic acid (HBV-DNA) and transaminase levels during acute exacerbation of chronic type B hepatitis, serial serum specimens from 74 patients were assayed for HBV-DNA by slot blot hybridization with 32P-labeled cloned HBV-DNA as probe. Of these patients, serial serum specimens were obtained with an interval of 2-7 days in 22 patients (Group I), 8-14 days in 30 patients (Group II) and 15-30 days in 22 patients (Group III). The peak of serum HBV-DNA was reached shortly before or simultaneously with the maximum elevation of serum alanine transaminase (ALT) in most (greater than 90%) of the acute exacerbations. In contrast, the peak of serum ALT was reached before maximum elevation of serum HBV-DNA in only 13.6% of Group I, 3.3% of Group II and 13.6% of Group III (9.5% of whole series). The results suggest that the increase of serum HBV-DNA is an event preceding, rather than the result of, hepatocytolysis in most of the acute exacerbations occurring in patients with chronic type B hepatitis.

Serological assessment of HBcAg and HBV DNA: its prognostic relevance in acute hepatitis B

Treatment of serum precipitates with sodium thiocyanate in patients with hepatitis B virus (HBV) replication results in liberation of circulating hepatitis core antigen (HBcAg) which can be demonstrated radioimmunologically. Follow-up investigations were performed in 80 patients with acute hepatitis B. Sera were examined for HBcAg. HBV DNA and conventional HBV markers. At the time of admission to hospital 34 of 80 (42%) patients were HBeAg positive. Twenty-six (76%) of the 34 HBcAg positive patients were HBV DNA positive, and circulating HBcAg was detectable in 25 of 34 (73%) HBcAg positive cases. In patients with uncomplicated courses of acute hepatitis B the serological HBcAg assay and HBV DNA became negative 1 to 8 weeks before elimination of HBeAg and up to 12 weeks earlier than the sera became negative for HBsAg. Five patients (6%) showed transition to chronic hepatitis B with persistence of HBsAg, HBeAg, HBV DNA and HBcAg in serum. One patient with acute hepatitis B and development of chronic hepatitis suffered from acquired immunodeficiency syndrome and showed delayed formation of anti-HBc. In this case uncomplexed HBcAg was demonstrable during the acute phase of hepatitis B. With the appearance of anti-HBc HBcAg circulated in a complexed form. The data indicate that serological determinations of HBcAg and HBV DNA can serve as prognostic markers in the early phase of acute hepatitis B. The demonstration of uncomplexed HBcAg in serum of a patient with inadequate formation of anti-HBc supports the hypothesis that circulating HBcAg is usually complexed by specific antibodies.

Hepatitis B virus replication in acute hepatitis B, acute hepatitis B virus-hepatitis delta virus coinfection and acute hepatitis delta superinfection

To evaluate the effect of hepatitis delta virus on the level of replication of hepatitis B virus and to assess the clinical significance that such an effect might have on the final outcome of the infection, the serological profile of hepatitis B virus DNA was investigated in 153 patients with acute or chronic hepatitis B virus infection with or without associated delta infection. Serum hepatitis B virus DNA was detected in 57% of patients with acute hepatitis B, 67% of those with acute hepatitis B virus-hepatitis delta virus coinfection and 25% of HBsAg carriers with hepatitis delta virus superinfection during the first week after the onset of symptoms. Patients with acute hepatitis B and those with acute hepatitis B virus-hepatitis delta virus coinfection did not differ significantly with respect to the serological profile of hepatitis B virus DNA and final clinical outcome. Within the group of HBsAg carriers with hepatitis delta virus superinfection, all patients who were initially negative for hepatitis B virus DNA developed chronic hepatitis delta virus infection, whereas 3 of the 4 patients with active hepatitis B virus infection at the time of superinfection showed transient inhibition of hepatitis B virus replication followed by termination of hepatitis delta virus infection in two patients. Therefore, although delta virus may inhibit the replication of hepatitis B virus among chronic HBsAg carriers, this effect is not readily apparent among patients with hepatitis B virus-hepatitis delta virus coinfection.

Cytotoxic T-cell responses to the nucleocapsid proteins of HBV in chronic hepatitis. Evidence that antibody modulation may cause protracted infection

The nucleocapsid antigens (HBc and HBe) are present on the membranes of HBV-infected hepatocytes from HBV carriers. In autologous cytotoxicity experiments we demonstrate that cytotoxic T cells sensitised to the nucleocapsid proteins of hepatitis B are present in HBe antigen-positive HBV carriers with chronic hepatitis and can be blocked by monoclonal anti-HBc and anti-HBe. Passive immunisation of chimpanzees with monoclonal anti-HBc and anti-HBe offers no protection against HBV infection but in both cases leads to an unusually prolonged hepatitis probably by modulation of HBc and HBe antigen display on the hepatocytes. High-titre anti-HBc in the circulation of HBe antigen-positive patients probably modulates the former protein making HBe the important target antigen for cytotoxic T cells mediating liver damage in chronic carriers. These data also support the hypothesis that passive transfer of IgG anti-HBc across the placenta may be one major factor promoting development of persistent infection in neonates infected from carrier mothers.

Identification of a dominant immunogenic epitope of the nucleocapsid (HBc) of the hepatitis B virus

Four monoclonal antibodies to hepatitis B core antigen are described. The antibodies bind to the same or a very closely related epitope. Antibodies to this dominant epitope are present in the sera of patients with either acute or chronic hepatitis B virus (HBV) infection. A high percentage of inhibition of the binding of these antibodies to the core antigen by these four monoclonal antibodies suggests that the core antigen has a restricted antigenicity in man. Radiolabeled or peroxidase labeled forms of these monoclonal antibodies can be used to assay IgM and total anticore in serum.