Use of the hepatitis B virus recombinant baculovirus-HepG2 system to study the effects of (-)-beta-2',3'-dideoxy-3'-thiacytidine on replication of hepatitis B virus and accumulation of covalently closed circular DNA

(-)-Beta-2',3'-Dideoxy-3'-thiacytidine (lamivudine [3TC]) is a nucleoside analog which effectively interferes with the replication of hepatitis B virus (HBV) DNA in vitro and in vivo. We have investigated the antiviral properties of 3TC in vitro in HepG2 cells infected with recombinant HBV baculovirus. Different types of information can be obtained with the HBV baculovirus-HepG2 system because (i) experiments can be carried out at various levels of HBV replication including levels significantly higher than those that can be obtained from conventional HBV-expressing cell lines, (ii) cultures can be manipulated and/or treated prior to or during the initiation of HBV expression, and (iii) high levels of HBV replication allow the rapid detection of HBV products including covalently closed circular (CCC) HBV DNA from low numbers of HepG2 cells. The treatment of HBV baculovirus-infected HepG2 cells with 3TC resulted in an inhibition of HBV replication, evidenced by reductions in the levels of both extracellular HBV DNA and intracellular replicative intermediates. The effect of 3TC on HBV replication was both dose and time dependent, and the reductions in extracellular HBV DNA that we observed agreed well with the previously reported efficacy of 3TC in vitro. As expected, levels of HBV transcripts and extracellular hepatitis B surface antigen and e antigen were not affected by 3TC. Importantly, the HBV baculovirus-HepG2 system made it possible to observe for the first time that CCC HBV DNA levels are lower in cells treated with 3TC than in control cells. We also observed that the treatment of HepG2 cells prior to HBV baculovirus infection resulted in a slight increase in the efficacy of 3TC compared to treatments starting 24 h postinfection. The treatment of HepG2 cells with the highest concentration of 3TC tested in this study (2 microM) prior to the initiation of HBV replication markedly inhibited the accumulation of CCC DNA, whereas treatment with the same concentration of 3TC at a time when CCC HBV DNA pools were established within the cells was considerably less effective. In addition, our results suggest that in HepG2 cells, non-protein-associated relaxed circular HBV DNA and particularly CCC HBV DNA are considerably more resistant to 3TC treatment than other forms of HBV DNA, including replicative intermediates and extracellular DNA. We conclude from these studies that the HBV baculovirus-HepG2 system has specific advantages for drug studies and can be used to complement other in vitro model systems currently used for testing antiviral compounds.

Induction of cytotoxic T lymphocytes with peptides in vitro: identification of candidate T-cell epitopes in hepatitis B virus X antigen

Cytotoxic T lymphocytes (CTL) have been suggested to contribute to viral clearance during hepatitis B virus (HBV) infection. To induce effective CTL against viral infection by peptide vaccination, it is essential to identify the epitope peptides recognized by CTL. Here, 15 peptide sequences that contain HLA-A2.1-restricted CTL binding consensus motif were identified on hepatitis B virus X (HBx) protein and synthesized for further characterization. In the binding assay, 8 of 15 synthetic peptides enhanced the expression of HLA-A2.1 molecules on the surface of T2 cells, a human transport-associated antigen processing-deficient cell line. This result implies that these eight peptides are able to bind to the HLA-A2.1 molecules. These peptides were further tested for their ability to activate CTL from peripheral blood mononuclear cells (PBMCs) isolated from HBV chronic carriers. Five of eight tested peptides activated PBMC-derived T cells, resulting in the lysis of the target T2 cells pulsed with the same peptide. Furthermore, the CTL responses to HBx antigen in HBV chronic carriers were shown to be polyclonal, multispecific, and mediated mainly by CD8+ T cells. In contrast, these responses were not detected in uninfected healthy blood donors. Although the five CTL epitope peptides identified in this study have not been proven to be the naturally processed epitopes in HBV-infected hepatocytes, they could be candidates for peptide-based immunotherapy against HBV infection.

Immunohistochemical study of HBV antigens in 338 liver cell carcinomas

Tumor tissue (n = 338) and liver parenchyma (n = 276) from patients of Asian (n = 31) and European descent (n = 307) with hepatocellular carcinoma (HCC, n = 299), cholangiocellular carcinoma (CCC, n = 16) and combined HCC/CCC (n = 23) were screened with immunohistochemical methods for HBV antigens (HBs, preS1, preS2, HBc, HBe and HBx). Of the HCC cases nine were of the fibrolamellar type (FLC). All cases of HCC/CCC and CCC were from Western European patients. HBV antigens could be demonstrated more frequently in HCC cases of Asian descent (59.09% in liver parenchyma and 66.67% in tumor tissue) compared to Western European HCC cases (23.11% and 30.77%; chi-square test, p = 0.0003 and p = 0.0001, respectively), HCC/CCC (26.32% and 30.43%), CCC (7.14% and 20%) and FLC (0% and 25%). Results for HBx were not considered here due to questionnable HBV specificity of the antibodies employed. Immunohistochemical detection mainly HBs, whereas HBc, HBe and preS antigens played only a minor part. Comparing the results obtained with a rabbit and a goat polyclonal HBs antibody and a cocktail of seven monoclonal HBs antibodies showed statistically significant superior sensitivity for the goat antibody. Reactivity of tumor tissue for HBc and/or HBe as observed in twelve cases is suggestive of virus replication within tumor tissue. These data plus the demonstration of HBV antigens within so-called proliferated bile ducts, which represent metaplastic hepatocytes, underscore the nature of CCC as malignant counterpart of proliferated bile ducts. Consequently, it is proposed to divide the entity liver cell carcinoma (LCC) into the subcategories HCC and CCC in contrast to adenocarcinomas arising from bile ducts or peribiliary glands. In conclusion, HBV seems to play a part in the pathogenesis of LCC in Asian and in Western European patients. Further factors like HCV and other chronic inflammatory processes may be employed here.

Human hepatitis B virus X protein is detectable in nuclei of transfected cells, and is active for transactivation

Subcellular localization and transactivation of human hepatitis B virus X protein (HBx), a plausible causative factor for hepatocellular carcinogenesis, were studied in transiently transfected cells. The transactivation was detected not only by the cis-element driven chloramphenicol acetyltransferase (CAT) assay but also by immunostaining of CAT protein cotransfected into human hepatoma cell line HepG2. Scanning fluorescence microscopy showed the majority of immunological signals of HBx to be at the perinuclear region of transfected cytoplasm. HBx was also clearly detectable in the nucleus, though less intensely expressed. This was confirmed by Western analysis and coimmunoprecipitation of HBx with transcription factor IIB (TFIIB) in subcellular fractionations. The percentage of HBx-positive cells coincided with that of CAT-positive cells, and confocal laser microscopy revealed the coexistence of CAT signals in GFP-HBx positive cells. The SV40 large T antigen nuclear localization signal (NLS) appended HBx, regardless of whether NLS was added to the N- or C-terminus, transactivated all the examined X-responsive elements (XRE) similarly as did wild-type HBx. Similar results were obtained in p53 negative Saos-2 cells. The detected nuclear HBx may be involved in modulating the transcription at the promoter level whereas the HBx in cytoplasm may be working through signal transduction pathways.

[Detection of viral markers in liver tissue dually infected with hepatitis B and C viruses by double labelling]

OBJECTIVE

To study the distribution and mutual relation of HBV and HCV in dually infected liver tissue.

METHODS

Detected HBV and HCV nucleic acids and their antigens by immunohistochemistry and in situ hybridization, the cases with HBcAg and HCV RNA positive were tested further on single section by double labeling.

RESULTS

On the section tested by double labeling we could see that positive hepatocytes infected with HBV or HCV were mostly present in different liver lobules, even if the two viruses were seen in the same lobule, most of them were not seen within a single cell.

CONCLUSIONS

In most of hepatocytes, there was no direct interference or suppression of each other in the liver tissue dually infected with HBV and HCV. Double labeling method is useful to analyze the coinfection of two viruses in the same tissue.

The expression of insulin-like growth factor II, hepatitis B virus X antigen and p21 in experimental hepatocarcinogenesis in tree shrews

The purpose of this paper was to study the mechanism of synergistic effect in hepatocarcinogenesis induced by hepatitis B virus (HBV) infection and aflatoxin B1 (AFB1) intake. Immunohistochemical staining was used in formalin-fixed, paraffin-embedded sections of cancer and liver tissues. The incidence of hepatocellular carcinomas (HCCs) was 52.9% in experimental tree shrews that received both HBV and AFB1. It was significantly higher than that of animals exposed to HBV (11.1%, Group B), or (AFB1) (15.8%, group C) alone. HCC was not found in the control animals (group D). The expressions of insulin-like growth factor II (IGF-II) were 82.4%, 22.2%, 26.3% and 0 in groups A, B, C and D, respectively. The significant differences of IGF-II were observed between groups A and B, C and D (P < 0.05). The expressions of p21 were 29.4%, 11.1%, 15.8% and 0 in group A, B, C and D, respectively. The positive rate of hepatitis B x antigen (HbxAg) was significantly higher in the group A than that in the group B (52.9% vs. 11.1%, P < 0.05). The parallel relations between the incidence of HCC and the overexpressions of these genes protein have been found in each group. On the other hand, the expressions of these genes in tumour-bearing tree shrews were significantly higher than that in nontumour-bearing animals. These findings suggest a synergistic effects of HBV and AFB1 in activation of these genes in tree shrews. Overexpressions of these genes may take an important role in the course of hepatocarcinogenesis in tree shrews.

Fibrosing cholestatic hepatitis after living related-donor renal transplantation

A 43-year-old man underwent living related-donor renal transplantation because of chronic renal failure in 1991. During the transplant period, both donor and recipient were seronegative for hepatitis B surface antigen (HBsAg). The donor was seropositive for antibody to hepatitis B surface antigen (anti-HBs) due to hepatitis B virus (HBV) vaccination. After transplantation, FK506 and methylprednisolone had been administered to the patient as immunosuppressants. In 1993, HBsAg appeared in his serum. His alanine aminotransferase level elevated gradually during 1995 and then in 1996, general fatigue, ascites and jaundice developed. At this time his serum was positive for hepatitis B e antibody, contained more than 100000 Meq/mL HBV-DNA and 100% precore mutant. Despite subsequent intensive therapy, liver dysfunction progressed and this patient died of hepatic failure 2 months following admission. At autopsy, the liver exhibited cholestasis, fibrosis extending from the portal tracts, mild inflammation and hepatocytes with a ground-glass appearance. In addition, HBsAg and hepatitis B core antigens had accumulated in the hepatocytes. Consequently, the final diagnosis was fibrosing cholestatic hepatitis (FCH) due to precore mutant HBV infection contracted after renal transplantation. It is unclear when and where the recipient liver became HBV infected. Nevertheless, after renal transplantation, while receiving immunosuppressive drugs, HBV appeared to have the potential to cause hepatic failure and FCH may have been a fatal complication for the recipient.

[Pretreatment with prednisolone enhances the effect of human lymphoblastoid interferon in chronic hepatitis B]

Patients (n = 213) with chronic hepatitis B were randomised to prednisolone (two weeks of 0.6 mg/kg/day, one week of 0.45 mg/kg/day and one week of 0.25 mg/kg/day) or placebo followed by two weeks rest, and were then given human lymphoblastoid interferon 10 MU daily for five days followed by 10 MU thrice weekly for 11 weeks. There were statistically significant effects of prednisolone pre-treatment on both HBeAg disappearance and HBeAg to anti-HBe seroconversion (log rank test statistics 5.43; p = 0.02 and 4.75; p = 0.03). HBeAg disappearance and HBeAg to anti-HBe seroconversion rates were 28 vs. 44% and 23 vs. 38% (placebo vs. prednisolone). Fifteen patients (7.5%) lost HBsAg. Three out of 22 cirrhotic patients (14%), one of whom received prednisolone pre-treatment, developed hepatic decompensation with a fatal outcome. Prednisolone pre-treatment, enhances the effect of lymphoblastoid interferon in chronic hepatitis B. Interferon treatment (with and without prednisolone) should be used with caution in patients with cirrhosis and avoided in patients with evidence of hepatic decompensation.

[The determination of the viral markers of the hepatitis B virus and protein p53 in liver biopsy samples]

The X gene product of the hepatitis B virus (HBV) genome functions as a transactivating element and it is considered as an essential factor for establishing chronic infection as well as for hepatocarcinogenesis. Its interaction with the product of the p53 tumor suppressor gene could be responsible for the intensification of cellular proliferation. We assessed the presence of X protein in biopsy samples of chronic hepatitis (CH), cirrhosis (CiH) and hepatocellular carcinoma (HCC) tissues comparing to the presence of other viral markers (HBcAg, HBsAg) using immunohistochemical methods. We sought the expression of p53 gene in the same tissue samples and analysed the possibility of its accumulation in detectable quantity at different stages of the disease. Our results indicate a higher positivity for the X protein than for HBs and HBc antigens (p < 0.05). HBx expression in liver cells during chronic HBV infection may be a prognostic marker for the development of HCC. The p53 protein was not detectable in the majority of non-malignant tissues; thus its inactivation seems to be more likely a late event in carcinogenesis.

Interferon treatment in hepatitis B surface antigen-positive hepatitis B e antibody-positive chronic hepatitis B: role of hepatitis B core antibody IgM titre in patient selection and treatment monitoring

Chronic hepatitis B infection with the hepatitis B e antigen (HBeAg)-negative variant is associated with a severe clinical course and a low response rate to interferon (IFN). In an attempt to improve the chances of sustained response to interferon we designed a pilot study, using titres of IgM antibodies to hepatitis B core antigen (HBcAb IgM) to guide treatment initiation. Eighteen adults who were HBeAg-negative with biopsy-proven chronic active hepatitis (seven with cirrhosis) entered the study. They were followed-up bimonthly with routine liver function tests, and HBcAb IgM titres were also determined. Treatment (lymphoblastoid IFN 5 million units (MU) m(-2) three times weekly for 6 months) was started when the HBcAb IgM titre was increasing. Fifteen (83.3%) patients had normal alanine aminotransferase (ALT) levels and undetectable HBV DNA at the end of treatment. HBcAb IgM decreased in all responders. We observed a relapse in four patients (three with cirrhosis), in the first year after treatment, with an increase in ALT, HBV DNA and titre of HBcAb IgM. Eleven patients (61.1%) had a sustained response and eight of these 11 patients were followed-up for more than 18 months; two responders cleared hepatitis B surface antigen (HBsAg). Hence, the rate of sustained response to IFN in HBeAb-positive patients with chronic hepatitis is improved if treatment is started when HBcAb IgM levels are increasing.

Lack of colocalization of HBxAg and insulin like growth factor II in the livers of patients with chronic hepatitis B, cirrhosis and hepatocellular carcinoma

To evaluate the possibility that HBxAg is related to an enhanced expression of IGF-II, immunohistochemical staining was performed for distribution and colocalization of HBxAg and IGF-II in liver tissues from 40 chronic active hepatitis (CAH-B), 51 cirrhosis and 46 hepatocellular carcinoma (HCC) patients using polyclonal rabbit anti HBxAg raised against full length-recombinant HBxAg and monoclonal mouse anti IGF-II. HBxAg in CAH-B, cirrhosis and HCC tissues was detected in 95%, 39% and 17%, whereas IGF-II in the same tissues was seen in 0%, 92% and 100%, respectively. There was a gradual decrease in the prevalence of HBxAg expression in cirrhosis and HCC, as compared to CAH-B tissues. All of the cirrhosis and HCC samples with positive staining for HBxAg expressed IGF-II. However, 55% of cirrhosis and 100% of HCC samples without HBxAg staining also expressed IGF-II. Moreover, colocalization at neighboring sections, even in both HBxAg and IGF-II positive samples, was not regularly observed. It is concluded that HBxAg expression in CAH-B may play a role in the pathogenesis of CAH-B. Although HBxAg may be related to the expression of IGF-II in some cirrhotic and HCC tissues, IGF-II expression in a large majority of these cases may be related to other factor(s) than HBxAg.

Molecular epidemiology of hepatitis B virus in Central America reflected in the genetic variability of the small S gene

The S genes of 31 Central American hepatitis B virus (HBV) strains belonging to genotypes A, C, D, and F (4, 1, 4, and 22 strains, respectively) were compared with 104 published S genes. According to the deduced S gene product, 21 genotype F strains encoded adw4, while 1 encoded ayw4. Three clusters were revealed within genotype F, which correlated with substitutions at residue 45. In a cluster of 18 Central American and 1 Alaskan strain, all had Thr45. One cluster included 2 Central American strains and 6 strains from South America and Europe, which had Leu45. Two Nicaraguan strains differed by five substitutions, including a Pro45 in the S gene product from other F strains. In conclusion, the dominating HBV genotype was F, which might be the reason for a low prevalence of HBV in the area, despite high prevalence of hepatitis A. These infections otherwise vary in parallel and are considered to reflect socioeconomic conditions.

[Pathological features of hepatocellular carcinoma carrying hepatitis C virus antigen]

OBJECTIVE

To analyze the pathological features of hepatocellular carcinomas (HCCs) carrying different hepatitis virus antigens histopathologically and systematically.

METHODS

PAP and ABC kits were used in the immunohistochemical study, and CAS-200 System was applied in the image cytometry.

RESULTS

As compared with HCCs carrying HBV marker(s), the HCCs carrying HCV marker showed more cases of clear cell type (7/9 vs 4/33), better differentiation of cancers, less necrosis of hepatocytes, milder lymphocyte infiltration in the hepatic sinuses or periportal areas (P < 0.01), higher incidence of bile ductule damages, and bore a close relation to the formation of lymphoid follicle in the surrounding tissues (P < 0.05). These patients were elder, with lower grade of symptoms and better prognosis after operation.

CONCLUSION

HCCs carrying only HCAg have different pathological features and clinical characteristics from which carrying HBV marker(s). The results of image cytometry are in accordance with the biological behaviour of HCC.

Hepatitis B: diagnosis, prevention, and treatment

Hepatitis B virus (HBV) infection occurs worldwide and is an important cause of acute and chronic viral hepatitis in the US. In this review, I describe the virus, risk factors for infection, clinical features of infection, results of laboratory tests during infection, and standard and emerging treatment for chronic infection. Although 95% of adult patients recover completely from HBV infection, 90% of children < or = 4 years of age develop chronic infection. Active vaccination is highly efficacious.

Hepatitis C virus is frequently coinfected with serum marker-negative hepatitis B virus: probable replication promotion of the former by the latter as demonstrated by in vitro cotransfection

Patients with hepatitis C have been reported occasionally to be coinfected with serum marker-negative (silent) hepatitis B virus (HBV). The frequency and significance of such coinfection were investigated. Thirty patients with hepatitis C virus (HCV) infections (10 acute, 10 chronic, 10 cirrhotic) were selected randomly; the acute cases were without serum hepatitis B surface antigen (HBsAg) and anti-hepatitis B core IgM, and the chronic cases were without HBsAg. A nested polymerase chain reaction for the X open reading frame was used to amplify HBV DNA in serum, and immunoperoxidase staining was carried out on liver biopsy specimens. Nucleotide sequencing was carried out to characterize the amplified HBV DNAs. In order to clarify the possibility that the silent HBV mutant promotes HCV replication in the liver, the full-length HCV RNA and the cloned silent HBV DNA dimer were cotransfected into an established cell line, HuH-7, and the amount of secreted HCV RNA was quantified serially. The target HBV DNA was amplified in 26 (86.7%) of the 30 patients. Subsequent direct nucleotide sequencing in 9 selected patients revealed an 8-nucleotide deletion, characteristic of a silent HBV mutant. Immunostaining revealed hepatitis B surface antigen in 15 (50.0%). Cotransfected silent HBV DNA augmented the secretion of HCV RNA by up to 5-fold in comparison with HCV RNA transfection alone. In conclusion, HCV is coinfected frequently with the silent HBV mutant and the latter probably promotes the replication of the former in the liver.

Preoperative serum levels of wild-type and hepatitis B e antigen-negative hepatitis B virus (HBV) and graft infection after liver transplantation for HBV-related hepatocellular carcinoma

Allograft infection in hepatitis B surface antigen (HBsAg)-positive patients undergoing liver transplant (OLT) is still significant, despite post-transplant prophylaxis with high doses of immunoglobulin to HBsAg. Baseline status and post-OLT levels of viraemia and wild-type and hepatitis B e antigen (HBeAg)-negative hepatitis B virus (HBV) were correlated with the clinical course of 16 consecutive HBsAg carriers. positive for hepatitis B e antibody, with hepatocellular carcinoma who underwent OLT and received permanent post-OLT prophylaxis with antibody to HBsAg (HBsAb). Fourteen patients had less than 10(3) HBV genome equivalents ml(-1) (eq ml[-1]) at baseline and remained HBV free after a median of 36 months following OLT. Two patients with mean pre-OLT viraemia higher than 10(5) genome eq ml(-1) and prevalent HBeAg-negative HBV viraemia before OLT suffered a severe graft hepatitis. Interferon-alpha2b (3 MU m(-2) per day) was able to reduce viraemia in both patients and to revert the clinical course of the infection in one, who remained infection-free 22 months after IFN treatment. Fourteen patients had less than 10(3) HBV genome eq ml(-1) at baseline and remained HBV free, after a median of 36 months following OLT, with permanent HBsAb immunoprophylaxis. These observations suggest that the quantitative analysis of HBV pre-OLT viraemia levels may provide a very useful tool for predicting the ideal time of liver replacement. Clinical trials on the use of antiviral drugs capable of inhibiting HBV serum levels before liver transplantation should be pursued on this premise.

[Clinical experience with changing type I diabetics from animal to human insulin administered by the NovoPen 3 applicator]

The objective of the study was to assess the safety of changing ambulatory patients from animal insulin produced in the Czech Republic administered by classical insulin syringes to human insulins of the Danish firm Novo Nordisk, using a NovoPen 3 applicator. Furthermore antibody levels against hog, bovine and human insulin were assessed. Forty-seven patients with diabetes type I stabilized on an intensified insulin regime were after a four-day preparatory period divided at random into two groups. Patients in group A (n = 22) were after randomization changed to human insulin, patients in group B (n = 25) eight weeks later. From the onset of treatment with human insulins up to the end of the study the mean daily dose of insulin in both groups increased (in group A by 1.51 IU/day, in group 1.35 IU/day). This is not statistically or clinically significant. During the same period a statistically significant decline of the mean value of the daily 8-point glycaemic profile was recorded (in group A by 0.85 mmol/l, in group B by 0.51 mmol/l). Glycosylated haemoglobin declined also significantly in the course of the study (in group A by 1.64%, p = 0.00004, in group B by 1.02%, p = 0.0077). The greatest drop occurred during the preparatory period. Despite the increased daily insulin dose and improved compensation the number of hypoglycaemic events declined significantly in both groups (in group A by 0.78%, p = 0.0102, in group B by 0.74%, p = 0.0134). Hypoglycaemic coma was not recorded in either group. A significant drop of insulin antibodies was found in both group after the onset of treatment with human insulins. From the results of the study ensues that metabolically compensated type I diabetics with a mean daily insulin dose of 0.6 IU/kg body weight can be changed without any complications, in the ambulatory department, to human insulins with the same dosage. Concurrently a gradual decline of antibodies can be expected.

Further observations on the immune response to recombinant hepatitis B vaccine after administration to aboriginal and Torres Strait Island children

OBJECTIVE

To determine the prevalence of markers of hepatitis B virus (HBV) immunity and infection at 5 years of age in Aboriginal and Torres Strait Island children who were fully vaccinated in infancy, and to examine the response to a booster dose of hepatitis B vaccine in those children who had no detectable immunity despite vaccination.

METHODOLOGY

A cross-sectional study of serological markers to HBV in a sample of 239 Aboriginal and Torres Strait Island children, with a mean age of 5.7 years, who were fully vaccinated in infancy. The antibody response to a booster dose of hepatitis B vaccine was determined in those children in the sample who had no markers of either immunity to HBV or infection with HBV.

RESULTS

Of the 239 children, 6% (95% CI 4-10%) had been infected and, of these, four were HBV surface antigen (HBsAg) positive. Of the remaining 224 children, only 41% (95% CI 35-48%) had evidence of immunity (i.e. an antibody to HBV surface antigen (anti-HBs) level of > or = 10 miu/mL) to HBV. Of the children with no detectable immunity (i.e. anti-HBs < 10 miu/mL), 113 were followed up after receiving a booster dose of hepatitis B vaccine. Of these, 84% (95% CI 76-90%) had an anamnestic response (i.e. anti-HBs < 10 miu/mL following the booster dose). Therefore 16% (95% CI 10-24%) still had no detectable immunity following the booster dose.

CONCLUSIONS

This study provides further evidence that Aboriginal and Torres Strait Island children have a suboptimal response to recombinant hepatitis B vaccine. It also indicates that a considerable number of Aboriginal and Torres Strait Island children in the study age cohort have been exposed to HBV. However, despite these concerns, this study and historical data provide strong evidence that there has been a marked reduction in the prevalence of HBV infection and carriage in previously 'high risk' Aboriginal and Torres Strait Island children since the introduction of hepatitis B vaccines. Aboriginal and Torres Strait Island children who have been fully vaccinated in infancy do not require a booster dose of hepatitis B vaccine at school entry.

Integrity of p53 in hepatitis B x antigen-positive and -negative hepatocellular carcinomas

Inactivation of the tumor suppressor p53 seems to be important to the pathogenesis of hepatocellular carcinoma (HCC) associated with chronic hepatitis B virus infection. Although this inactivation may be due to mutations in the p53 gene, recent evidence suggests that the hepatitis B virus-encoded X antigen (HBxAg) binds to and inactivates wild-type p53. Hence, experiments were designed to test the hypothesis that there is a low frequency of p53 mutations in HBxAg-positive HCC. HBxAg and p53 were assayed by immunohistochemistry (IHC) in HCC and nontumor liver from 16 Chinese patients, half of whom were hepatitis B surface antigen carriers. HBxAg was detectable in tumor and/or nontumor cells from all patients by IHC; six of these samples also had detectable p53. To determine whether p53 detection by IHC, and hence stabilization, is associated with mutation, sequencing of p53 exons 5-8 was performed with each patient sample. Wild-type sequences were found in 13 of 16 HBxAg-positive cases (81%). Hence, HBxAg is a common marker of HCC that correlates with the persistence of wild-type p53 among both carriers and noncarriers. The low frequency of p53 mutations in HCC in these patients implies that p53 inactivation may occur predominantly by complex formation with HBxAg.

Pathogenesis of chronic liver disease in patients with chronic hepatitis B virus infection without serum HBeAg

Chronic hepatitis B in patients lacking hepatitis B e antigen has been attributed to a hepatitis B virus variant (G-to-A mutation at nucleotide 1896 in the precore region of the genome). We therefore assessed the frequency and significance of this variant among 43 United States patients (10 with chronic hepatitis B seropositive for e antigen, 19 seronegative for e antigen, and 14 healthy carriers). Sera were tested for HBV DNA by polymerase chain reaction and branched DNA assay. The A1896 variant was detected by direct sequencing and ligase chain reaction. Serum HBV DNA was more frequently found among patients with e antigen-positive than e antigen-negative chronic hepatitis B. Viral titers were generally higher in those with e antigen. None of the e antigen-positive and only 24% of e antigen-negative patients harbored the A1896 variant. Patients infected with the variant were more often Asian, had had hepatitis B for longer and had higher levels of viral DNA than HBeAg-negative patients with the wild-type virus. The A1896 variant was found exclusively in patients infected with HBV genotypes C and D. Thus, the A1896 variant is uncommon in the United States. The activity of liver disease appears to be more closely related to the level of HBV replication than the presence of mutations at nucleotide 1896 in the genome.

A comparison of amino acid sequences of hepatitis B virus S gene in 46 children presenting various clinical features for immunoprophylaxis

We compared amino acid sequences of hepatitis B virus (HBV) S protein deduced from analyzed DNA sequence in 46 children who received immunoprophylaxis to prevent mother-to-child transmission of HBV. They were classified into 6 groups by their clinical features. The antibody escape mutants were found in 8 cases among 46 cases. We studied the difference in clinical features in these cases and speculated that 126 Ser or 140 Ser-strain may have a different behavior in relation to antibody to hepatitis B surface antigen from 126 Asn or 145 Arg-strain.

[Prognosis in acute viral hepatitis B in children]

Epidemiological evaluations indicate an increase of acute viral hepatitis B in children. In this study authors performed an analysis of disease prognosis in retrospective trial in children hospitalized in the Pediatric Department of Infectious Diseases from 1983 to 1993 because of acute viral hepatitis B. It was documented that a risk of persistent hepatitis B may be related to the age of patients with acute viral hepatitis B in the past. In 64% of analyzed patients below 1 year old and in 20% over 6 years-persistent hepatitis was diagnosed, especially in male subjects.

Detection of alpha-fetoprotein and hepatitis-B surface antigen in blood spotted on filter paper: use as a screen for hepatocellular carcinoma in Alaska Natives

A program of twice yearly testing of Alaska Native carriers of hepatitis-B surface antigen (HBsAg), for alpha-fetoprotein elevations as an indicator of early hepatocellular carcinoma has been established in Alaska. Because many HBsAg carriers live in remote regions of Alaska, logistical and cost considerations complicate the efficiency of this program. We evaluated the feasibility of using blood spotted onto mail-in cards as a system of blood collection and commercial assays for alpha-fetoprotein and HBsAg testing. We compared alpha-fetoprotein levels and the detection of HBsAg in both plasma and blood spots from HBsAg-positive carriers, normal volunteers, and pregnant females. There was good correlation between serum and blood spot AFP levels (r = 0.94, p < 0.001) over a wide range of serum alpha-fetoprotein levels. alpha-fetoprotein and HBsAg remained detectable in blood spots stored at room temperature for more than 8 weeks. The sensitivity of detection of HBsAg in blood spots was not as great in blood spots when compared to plasma levels. This system has been incorporated into the hepatocellular carcinoma screening program in Alaska. It should also prove feasible and economical for such screening to be undertaken in developed countries and possibly make alpha-fetoprotein screening affordable in those developing countries where the prevalence of hepatitis-B virus infection is high.

Maternal and neonatal prevalence of toxoplasma and cytomegalovirus (CMV) antibodies and hepatitis-B antigens in an Egyptian rural area

To determine the seroprevalence of maternal and neonatal toxoplasmosis and cytomegalovirus (CMV) antibodies and hepatitis-B (HB) antigenaemia in a rural Egyptian area, a prospective serological study was done on a randomly selected sample of pregnant women (n = 150) and their newborn infants (n = 150). Sera were collected from the mothers during the first antenatal visit, and at the time of delivery and cord blood specimens (paired samples) taken from their infants to be tested for toxoplasma-IgG and IgM antibodies, CMV-IgG and IgM antibodies surface antigen (HBsAg) and HBe antigen (HBeAg). Maternal infection was indicated in cases where specific IgM antibody was present or where an initial maternal specimen gave negative result for IgG antibody, but the second blood specimen gave positive result. Specific IgM antibody in a cord blood specimen indicated fetal infection. Out of the 150 pregnant women, 64 (43 percent) were toxoplasma immune at their first antenatal visit and their newborns were toxoplasma IgG positive. Toxoplasma specific IgM antibody was detected in only three mothers at the time of deliver. The rate of maternal infection in susceptible pregnancies was 4 percent and the maternal-fetal transmission rate was estimated to be 33 percent, as only one newborn infant had toxoplasma-IgM antibody at birth. This denoted a prevalence of congenital toxoplasma infection = < 1.0 percent to non-immune mothers. There were no clinical features of congenital infection in the infant with toxoplasma-IgM antibody, but he will require long-term follow-up. All the mothers infected during pregnancy had known risk factors for toxoplasma infection. One-hundred-and-forty-three (96 percent) of the pregnant women were CMV-IgG seropositive at their first antenatal visit. At the time of delivery 143 (96 percent) of the mothers and their newborn infants were CMV-IgG seropositive. None of the mothers or their infants was CMV-IgM seropositive. HBsAg was detected in 8 per cent of pregnant mothers (n = 12) and in two (17 percent) of their newborn infants. None of the mothers was HBeAg positive. In conclusion, the prevalence of toxoplasma infection during pregnancy and its transplacental transmission rate in a rural Egyptian area are high compared to other countries. A toxoplasmosis antenatal screening and public education programmes for pregnant mothers is justifiable in rural Egypt. However, it appears that an antenatal screening programme for CMV is, at present, not warranted.