Elevations in serum alpha-fetoprotein levels in patients with chronic hepatitis B

In a retrospective analysis of 166 patients with chronic hepatitis B followed for up to 8 years, 22 patients had 29 episodes of elevations in serum alpha-fetoprotein (AFP) levels. Twenty-five episodes were due to a transient exacerbation of the underlying hepatitis and 11 of these episodes were followed by a loss of hepatitis B e antigen (HBeAg) from serum and a remission in disease. Two patients were found to have hepatocellular carcinoma. No apparent cause could be found in a further two episodes of AFP elevation. In comparison to 144 patients with normal levels, the 22 with AFP elevations were more likely to have cirrhosis (61% versus 13%, P = 0.01), to die a liver-related death (27% versus 0.7%, P = 0.0007) and to have hepatocellular carcinoma (HCC) (9% versus 0%, P = 0.002). These findings confirm that AFP can be used to screen for HCC in high-risk patients with chronic hepatitis B. The majority of AFP elevations, however, will be found to be due to exacerbations of disease, with or without loss of HBeAg from serum, especially in white patients with severe disease and cirrhosis.     

Liver cell dysplasia and hepatitis B surface antigen in liver cirrhosis and hepatocellular carcinoma

Liver tissues of 223 autopsy cases of cirrhosis and hepatocellular carcinoma were examined for liver cell dysplasia in relation to hepatitis B surface antigen (HBsAg) detected with orcein stain. Liver cell dysplasia was found in 94 cases (42.2%): 37 were from cases of cirrhosis only, and 53 were from cases of cirrhosis with hepatocellular carcinoma. There was a significant difference in the overall incidence of HBsAg in cases with and without dysplasia (70.2%:32.6%). A similar difference was found in all groups, i.e., those with cirrhosis, cirrhosis with hepatocellular carcinoma, and hepatocellular carcinoma only, in which none of 11 cases of HBsAg negative had dysplasia. A good correlation was seen between the semiquantitative grade of dysplasia and the incidence of HBsAg. These findings suggest a close relationship of HBsAg with liver cell dysplasia.     

Transforming growth factor-alpha in human hepatocellular carcinoma and coexpression with hepatitis B surface antigen in adjacent liver.

BACKGROUND. Hepatitis B virus (HBV) infection is closely associated with the development of hepatocellular carcinoma (HCC) in many patients, but the mechanisms by which HBV contributes to HCC are not known. Transforming growth factor-alpha (TGF-alpha), a regulator of growth and regeneration in rat liver that can be found in high levels in some human cancers, theoretically could play such an intermediate role in the development of HCC. METHODS. The expression of TGF-alpha and its relation to the HBV antigens were evaluated in human HCC and adjacent nontumorous livers from 33 patients from the United States and China using immunoperoxidase staining of paraffin-embedded sections. RESULTS. TGF-alpha was detected in HCC from 27 of 33 (82%) patients; the frequencies were similar in patients from the United States and China. TGF-alpha was detected in HCC more frequently in patients whose adjacent nontumorous livers had detectable hepatitis B surface antigen (HBsAg) and/or hepatitis B core antigen (HBcAg) than in those whose adjacent livers lacked HBsAg and HBcAg. Detection of TGF-alpha was not affected by tumor size, histologic type, or grade. TGF-alpha was detected in adjacent nontumorous livers from 31 of 33 patients (94%). Coexpression at a high intensity of TGF-alpha and HBsAg in the same hepatocytes could be demonstrated by specific staining of consecutively cut sections for 17 of 33 patients (52%). CONCLUSIONS. TGF-alpha is expressed at a high level in 82% of human HCC. Localization of HBsAg within the same hepatocytes as TGF-alpha suggests a possible interaction between HBV and TGF-alpha during hepatocarcinogenesis in humans. Stimulation of TGF-alpha expression could be part of a chain of events by which HBV contributes to the development of HCC in some patients.     

Hepatitis B x antigen in hepatitis B virus carrier patients with liver cancer.

Formalin-fixed, paraffin-embedded specimens from 110 cases of primary hepatocellular carcinoma were stained for hepatitis B x antigen (HBxAg), hepatitis B surface antigen (HBsAg), and hepatitis B core antigen (HBcAg). Eighty-four % of these patients were HBxAg positive in their tumor cells. Among the 110 cases studied, 80 had adjacent nontumorous tissue in the same block, and 65 of these nontumorous liver tissues stained positive for HBxAg (81%). HBsAg was positive in 19% of cases within tumor tissue and 61% in surrounding nontumorous tissue. HBcAg was positive in 11% of cases within tumor tissue and 26% in surrounding nontumorous tissue. These findings show that HBxAg is a common marker in the liver of patients with hepatitis B virus (HBV)-associated primary hepatocellular carcinoma and that it is closely associated with tumor cells in these individuals. In addition, the finding of HBxAg in the absence of detectable HBsAg and HBcAg in the liver tissues of many HBsAg carriers suggests that HBxAg could be expressed independent of HBV replication and implies that the synthesis of this antigen may be directed from integrated HBV DNA templates. The finding of HBxAg in the nucleus of hepatocytes from primary hepatocellular carcinoma patients with dysplasia, combined with the known trans-activating properties of HBxAg, implies that HBxAg plays one or more important roles in hepatocarcinogenesis. The finding of HBxAg in bile duct epithelium and cholangiocarcinoma tissues is compatible with the hypothesis that HBV may contribute to this other primary tumor type in the liver. Together, these results further implicate HBxAg in the pathogenesis of primary liver cancers.     

Primary liver cell carcinoma in the presence or absence of hepatitis B antigen.

The clinical course and pathological patterns of a group of 13 patients with both primary liver cell carcinoma and Hepatitis B surface antigen (HBsAg) are described and contrasted with those of 43 patients with primary liver cell carcinoma but without HBsAg. HBsAg-positive carcinoma patients demonstrated a higher incidence of splenomegaly, transudative ascites, and the presence of alpha-fetoprotein, although none of these reached statistical significance. Serum bilirubin was significantly higher in patients with HBsAg. HBsAg-positive carcinoma patients most frequently originated from countries where the presence of HBsAg is high in the general population. Survival time from the diagnosis of primary liver cell carcinoma was shorter in patients with HBsAg.     

Recombinant hepatitis B virus surface antigen formulated with B-type CpG oligodeoxynucleotide induces therapeutic immunity against hepatitis B virus surface antigen-expressing liver cancer cells in mice

To develop a therapeutic vaccine against hepatitis B virus surface antigen (HBsAg)-expressing liver cancer, we tried to prepare a vaccine by formulating recombinant HBsAg with BW006, a B type CpG oligodeoxynucleotide (ODN) with Th1-biasing activity, and examined its potency of inducing therapeutic immunity against HBsAg-expressing liver cancer cells in mice. When applied therapeutically, BW006 could assist HBsAg to induce vigorous immune responses capable of inhibiting the growth of HBsAg-expressing liver cancer cells and prolonging the survival of mice bearing HBsAg-expressing liver cancer cells. In vivo and in vitro experiments showed that the BW006-adjuvanted HBsAg enhanced the production of IgG2a antibodies, interferon-γ, and interleukin-12 and facilitated the generation of specific cytotoxic T lymphocyte that killed the HBsAg-expressing liver cancer cells. These results suggest that the BW006-adjuvanted HBsAg might be developed into a candidate tumor vaccine for the treatment of HBsAg-expressing liver cancer.     

Carcinoembryonic antigen, alpha-fetoprotein and carcinoplacental alkaline phosphatase in gastric carcinoma metastatic to the liver.

Carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), and carcinoplacental alkaline phosphatase (CPALP) were detected simultaneously in the sera and body fluids of two male patients with gastric carcinoma matestatic to the liver. At autopsy, widely disseminated gastric cancer of Borrmann III type with liver metastases was revealed in both bases. Histologically, they were moderately differentiated tubular and papillary adenocarcinomas with marked cellular atypia and necrosis. In Case 1, the properties of CPALP were identical to Nagao type CPALP, and in Case 2 the Variant type CPALP. Using immunofluorescence, CEA and CPALP were demonstrated in both primary and metastatic cells. However, only in Case 2 was AFP observed in some of the primary tumor cells.     

Additive effect modification of hepatitis B surface antigen and e antigen on the development of hepatocellular carcinoma.

To assess the role of hepatitis B e antigen (HBeAg) and its interaction with hepatitis B surface antigen (HBsAg) on the development of hepatocellular carcinoma (HCC), this case-control study included 361 age- and sex-matched pairs of patients with histologically proven HCC and healthy control subjects. HBsAg, HBeAg and antibody to HBeAg (anti-HBe) were detected by radioimmunoassay. Antibodies to hepatitis C virus (anti-HCV) were detected by second-generation enzyme immunoassay. The prevalences of HBeAg (20.2%), HBsAg (80.3%) and anti-HCV (29.5%) in cases were higher than in controls (1.9%, 20.7%, and 2.7% respectively; each P < 0.0001). Using patients negative for HBsAg, HBeAg and anti-HBe as a referent group, univariate analysis indicated that HBsAg alone or HBsAg and HBeAg were risk factors for HCC (P for trend < 0.0001). Calculation of incremental odds ratio indicated that there was additive interaction between HBsAg and HBeAg. Multivariate analysis indicated that HCC development was strongly associated with the presence of HBeAg (odds ratio, 8.1; 95% confidence interval, 2.4-27.1), HBsAg (odds ratio, 68.4; 95% confidence interval, 20.5-227.8) and anti-HCV (odds ratio, 59.3; 95% confidence interval, 13.6-258.4). In conclusion, HBsAg, HBeAg and anti-HCV are independent risk factors for HCC. There is additive and independent effect modification between HBsAg and HBeAg on the development of HCC.     

Elevation of circulating immune complexes and its relationship to alpha-fetoprotein levels in patients with hepatitis B surface antigen-positive hepatocellular carcinoma.

In an attempt to evaluate the relationship between circulating immune complexes (CIC) and alpha-fetoprotein (AFP), CIC and AFP were detected in 93 hepatitis B surface antigen-positive (HBsAg+) patients with hepatocellular carcinoma (HCC) and 54 healthy controls. The median level of 3% PEG (polyethylene glycol)-CIC and Clq-CIC were higher in patients than in controls (p less than 0.001). In patients with HCC, the prevalence of elevated 3% PEG-CIC, Clq-CIC, and AFT was 27.9%, 55.9%, and 77.4%, respectively. There was association between AFP and 3% PEG-CIC positivity (p less than 0.01). The median level of 3% PEG-CIC and Clq-CIC increased as AFP levels elevated (p less than 0.05), but decreased as AFP exceeded 1599 ng/ml (p less than 0.05). For adjusting the effect of impaired liver function on the level of CIC, multivariate analysis with stepwise logistic regression revealed that 3% PEG-CIC was associated, in a dose-related fashion, with an increased risk for developing HCC (odds ratio = 1.003, p less than 0.001). These results imply that elevation of 3% PEG-CIC may be related to tumor mass. Additionally, 3% PEG-CIC is a useful marker to monitor therapy with transcatheter arterial embolization in patients with HBsAg+ HCC.     

Expression of hepatitis B virus surface antigen in 120 Hodgkin's lymphoma patients

Background and Objective: Little is known about the incidence of hepatitis B virus (HBV) infection in Hodgkin's lymphoma patients. This study was to evaluate the impact of HBV infection on the survival of Hodgkin's lymphoma patient. Methods: Clinical data of 120 Hodgkin's lymphoma patients treated at the Sun Yat-sen University Cancer Center between January 2004 and October 2007 were collected. The impact of prognostic factors including HBV infection on survival was examined by univariate and multivariate an...     

乙肝病毒表面抗原浓度与恶性肿瘤患者肝功能损伤的相关性

目的:探讨乙肝病毒表面抗原(HBsAg)浓度与α-L-岩藻糖苷酶(AFU)、甲胎蛋白(AFP)、丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)、γ-谷氨酰基转移酶(γ-GGT)、碱性磷酸酶(ALP)及乳酸脱氢酶(LDH)在恶性肿瘤中的相关性。方法:收集2019年06月01日到2020年05月31日期间我院81例HBsAg阳性住院肿瘤患者及同期81名健康体检者肝功能检测指标。应用SPSS 20.0统计学软件分析HBsAg阳性在恶性肿瘤中的意义。结果:HBsAg阳性组与对照组AFU、AFP、ALT、AST、γ-GGT、ALP及LDH比较差异有统计学意义(P＜0.05)。HBsAg浓度在性别、肿瘤类型中差异无统计学意义(P＞0.05),在年龄和分期中存在统计学差异(P＜0.05)。根据HBsAg浓度将肿瘤组分为0.03~25.00 IU/mL、25.01~250.00 IU/mL、250.01~2 500.00 IU/mL及>2 500.00 IU/mL四组,0.03~25.00 IU/mL组AFP、AST与HBsAg呈正相关(r=0.654,0.501,P＜0.05),>2 500.00 IU/mL组AFU、AFP、AST与HBsAg呈正相关(r=0.527,0.524,0.476,P＜0.05),25.01~250.00 IU/mL、250.01~2 500.00 IU/mL组各项与HBsAg浓度之间无相关性(P＞0.05);各组AFP阳性率随HBsAg浓度升高无升高趋势(P＞0.05),而AFU阳性率随HBsAg浓度升高呈升高趋势(P＜0.05)。HBsAg、HBeAg和HBcAb三项阳性组与AFU呈正相关(r=0.516,P＜0.05),HBsAg和HBcAb两项阳性组与ALP呈正相关(r=0.567,P＜0.05)。结论:HBsAg阳性在肿瘤患者肝功能损伤及疾病的严重程度或进展评估方面有一定的临床参考价值。     

预防性抗病毒治疗对乙型肝炎表面抗原阳性非小细胞肺癌患者肝功能及乙型肝炎病毒再激活的影响

目的 探讨预防性抗病毒治疗对乙型肝炎表面抗原(HBsAg)阳性非小细胞肺癌患者肝功能及乙型肝炎病毒(HBV)再激活的影响.方法 根据是否采用预防性抗病毒治疗将80例HBsAg阳性非小细胞肺癌患者分为观察组(n=40)和对照组(n=40),两组患者均进行抗肿瘤治疗,观察组患者同时服用抗病毒治疗药物,对照组患者未服用抗病毒...     

Putative roles of hepatitis B x antigen in the pathogenesis of chronic liver disease

Under most circumstances, hepatitis B virus (HBV) is noncytopathic. However, hepatocellular regeneration that accompanies each bout of hepatitis appears to be associated with increased integration of HBV DNA fragments expressing the virus encoded hepatitis B x antigen (HBxAg). Intrahepatic HBxAg staining correlates with the intensity and progression of chronic liver disease (CLD), and additional work has shown that HBxAg blocks immune mediated killing by Fas and by tumor necrosis factor alpha (TNFα). This is not only associated with the blockage of caspase activities by HBxAg, but also by the constitutive stimulation of hepatoprotective pathways, such as nuclear factor kappa B (NF-κB), phosphoinositol 3-kinase (PI3K), and beta-catenin (β-catenin). HBxAg also appears to promote fibrogenesis, by stimulating the production of fibronectin. HBxAg also stimulates the production and activity of transforming growth factor beta1 (TGFβ1) by several mechanisms, thereby promoting the profibrogenic and tumorigenic properties of this important cytokine. In addition, HBxAg appears to remodel the extracellular matrix (ECM) by altering the expression of several matrix metalloproteinases (MMPs), which may promote tumor metastasis. Hence, HBxAg appears to promote chronic infection by preventing immune mediated apoptosis of infected hepatocytes, by promoting the establishment and persistence of fibrosis and cirrhosis preceding the development of HCC, and by promoting the remodeling of EMC during tumor progression.     

Alpha-fetoprotein synthesis in human hepatocellular carcinoma: correlation with hepatitis B surface antigen expression.

We analyzed the pattern of alpha-fetoprotein (AFP) synthesis in 40 consecutive human hepatocarcinomas (HCC) in relation to hepatitis B viral (HBV) infection. In addition, histopathological characteristics of liver parenchyma and the tumor itself were examined. Elevated AFP (> 20 ng/ml) were found in 90% of HCC patients and in none of the controls. In 35% of HCC cases, serum AFP was above 100,000 ng/ml. AFP levels were significantly higher in patients seropositive for hepatitis B surface antigen (HBsAg) compared with their negative counterparts (mean log[AFP]: 4.28 +/- 1.67 vs. 3.28 +/- 1.96, respectively; geometric mean (GM): 19,322.6 ng/ml and 1939.5 ng/ml, respectively; p < 0.05). Furthermore, serum AFP levels were higher in HCC patients with liver cirrhosis than in those without (log[AFP]: 4.43 +/- 1.58 vs. 3.23 +/- 1.98, respectively; p < 0.05). However, the relationship of cirrhosis with AFP was confounded by the high prevalence of HBsAg in cirrhotic HCC patients. There was no correlation of AFP with either liver necrosis (abnormal AFP in 45% of cases; mean log[AFP]: 3.99 +/- 1.91 vs. 3.75 +/- 1.85 for HCC with and without necrosis, respectively; 0.05 < p < 0.68, not significant (NS)), or inflammation (abnormal AFP in 25%; mean log[AFP]: 4.33 +/- 1.62 vs. 3.70 +/- 1.93 for HCC with and without inflammation, respectively; 0.05 < p < 0.39, NS). A vast majority of HCC (75%) were moderately (grade 2-3) or poorly differentiated tumors (grade 3, grade 4, or combined grade 3-4). Serum AFP did not correlate with tumor grade. Immunohistochemical analysis of HBsAg and AFP confirmed the serological findings, and confirmed earlier observations of elevated AFP in HBsAg-positive patients. These results may reflect pathogenic and biological differences between HBsAG-secreting and nonsecreting HCC.     

Elevated concentrations of serum alpha-fetoprotein in rats with chemically induced liver tumors.

The study was undertaken to determine whether aflatoxin B1 (AFB1)-induced liver tumors in rats produced alpha1-fetoprotein (AFP) and whether the age of the animals would influence such as appearance, a finding suggested by data seen in man. Other liver carcinogens (N-hydroxy-N-2-fluorenylacetamide, N-2-fluorenylacetamide, and diethylnitrosamine) were tested for their ability to induce liver tumors producing AFP. The presence of AFP. The presence of AFP in the serum was determined by double diffusion in agarose and by comparison also by quantitative radioimmunoassay. Using double diffusion, AFP was detected in the majority of tumor-bearing rats that had received either N-2-fluorenylacetamide or N-hydroxy-N-2-fluorenylacetamide. Sera of diethylinitrosamine-treated rats with liver tumors were all positive, whereas sera of rats bearing AFB1-induced tumors were positive in only a few cases. However, all sera of tumor-bearing rats examined had elevated AFP levels by radioimmunoassay. Nonetheless, the average level of AFP in the sera of rats bearing AFB1-induced tumors was considerably lower, compared to the sera of rats with tumors caused by diethylnitrosamine, N-2-fluorenylacetamide, or N-hydroxy-N2-fluorenylacetamide. Rats started on AFB1 when 6 weeks old had more mixed liver tumors with neoplastic hepatocytes and bile ducts and higher AFP levels than did rats started at 26 weeks of age. However, the histological grade of differentiation of inducted tumors did not seem to influence the AFP level.     

Safety and immunogenicity of a DNA vaccine encoding carcinoembryonic antigen and hepatitis B surface antigen in colorectal carcinoma patients.

Despite an abundance of preclinical data, relatively little is known regarding the efficacy of DNA vaccination in humans. Here, we present results from a dose-escalation clinical trial of a dual expression plasmid encoding carcinoembryonic antigen (CEA) and hepatitis B surface antigen (HBsAg) in 17 patients with metastatic colorectal carcinoma. CEA was selected as a prototypic tumor-associated self-antigen, and the HBsAg cDNA was included as a positive control for immune response to the DNA vaccine without relying upon breaking tolerance to a self-antigen. Groups of 3 patients received escalating single i.m. doses of the DNA vaccine at 0.1, 0.3, and 1.0 mg. Subsequent groups of 3 patients received three repetitive 0.3- or 1.0-mg doses at 3-week intervals. A final group of 2 patients received three repetitive 2.0 mg doses at 3-week intervals. Toxicity was limited to transient grade 1 injection site tenderness, fatigue, and creatine kinase elevations, each affecting a minority of patients in a non-dose-related manner. Repetitive dosing of the DNA vaccine induced HBsAg antibodies in 6 of 8 patients, with protective antibody levels achieved in four of these patients. CEA-specific antibody responses were not observed, but 4 of 17 patients developed lymphoproliferative responses to CEA after vaccination. No objective clinical responses to the DNA vaccine were observed among this population of patients with widely metastatic colorectal carcinoma. Nevertheless, this pilot trial has provided encouraging human immune response data in support of this vaccine technology.     

Microsatellite alterations in human hepatocellular carcinoma infected with hepatitis B virus: associated with the elevation of serum alpha-fetoprotein

Identification of the basic genetic changes in human hepatocellular carcinoma (HCC) is very important for the understanding of this cancer. In this study, genomic DNA from 29 pairs of HCC and corresponding non-tumour tissues infected with hepatitis B virus (HBV) was prepared. Five CA-repeated microsatellite markers, including D8S277, D3S1029, D5S409, D2S123, and TP53, were used to analyse microsatellite alterations and their subtypes in these patients by polymerase chain reaction (PCR) amplification and denatured polyacrylamide gel electrophoresis. Microsatellite alterations were found in 15 of the 29 HCC patients (51.72%), implying that microsatellites are unstable in genomic DNA of HBV-infected HCC. It was found that frequency of microsatellite alterations in these HCC patients was not associated with patients' age, sex, status of tumour differentiation, and tumour size. Frequency of microsatellite alterations in HCC patients with cirrhosis tended to be less than that in patients without cirrhosis, but Fisher's exact test, 2-tailed, showed that this difference was not significant. Significantly more microsatellite alterations in serum alpha-fetoprotein (AFP)-positive cases were observed than those in serum AFP-negative ones, implying that the elevation of AFP in HBV-infected HCC may be associated with microsatellite stability.     

Clinical significance of serum alpha-fetoprotein in patients with liver cirrhosis

The clinical significance of serum alpha-fetoprotein (AFP) was studied in 114 patients with liver cirrhosis, who were followed for more than one year. Out of 114 patients, serum HBs antigen (HBsAg) was positive in 49 (43%). The mean follow-up period was 4.3 years (from 1 to 13 years). Serial determinations of AFP by RIA were performed once a month in all patients. The pattern of serial changes of AFP levels could be divided into three characteristic types: 1) fluctuation of AFP levels to greater than 20ng/ml was observed in 39 cases (Type I); 2) a transient rise of AFP levels to greater than 50ng/ml was observed in 20 cases (Type II); 3) in the remaining 55 cases, AFP levels were always less than 20ng/ml. During the follow-up period, liver cell carcinoma (LCC) developed in 29 cases (25%) and hepatic failure in 11 cases (10%). The incidence of LCC was significantly higher in Type I (18/39, 46%) than in Type II (3/20, 15%) and Type III (8/55, 15%). It is concluded that cirrhotic patients with fluctuation of AFP levels should be included in the high-risk group for LCC.     

The effect of chronic habitual alcohol intake on the development of liver cirrhosis and hepatocellular carcinoma: relation to hepatitis B surface antigen carriage

To study the effects of habitual alcohol intake on the latency period for the development of liver cirrhosis and hepatocellular carcinoma (HCC), 158 patients with cirrhosis and 79 with HCC were analyzed with respect to age at the time of diagnosis. They were classified into four groups based on hepatitis B surface antigen (HBsAg) in serum, and the history of intake of more than one small bottle of Japanese "sake" or an equivalent per day for more than 10 years. The average age of HBsAg positive male cirrhotics with a drinking habit (n = 10) was 38.8 years, 10.5 years younger than that of those without a drinking habit (n = 8) (P less than 0.05). The average age of HBsAg negative cirrhotics with a drinking habit (n = 97) was 47.9 years, eight years younger than that of those not drinking (n = 36) (P less than 0.001). There was no significant difference in the laboratory data between these groups. The average age of the HBsAg positive HCC patients with a drinking habit (n = 20) was 48.9 years, nine years younger than that of those without a drinking habit (n = 12) (P less than 0.05). The average age of HBsAg negative male HCC cases with habitual intake of more than 126 ml of ethanol per day was 51.0 years (n = 8), ten years younger than that of nondrinking male HCC cases (n = 11) (P less than 0.05). These data suggest that habitual alcohol intake may promote the development of liver cirrhosis and HCC, especially in HBsAg carriers.     

Epitope mapping of recombinant hepatitis B surface antigen by murine monoclonal antibodies

Hepatitis B surface antigen (HBsAg) induces a potent protective antibody response in immunized healthy individuals. The antibody response in humans is largely directed to a restricted conformational immunodominant region of HBsAg, identified as "a" determinant. Our aim was generation and characterization of murine monoclonal antibodies (MAbs) against recombinant HBsAg and their use for epitope mapping of the antigen. Hybridoma cells were established from Balb/c mice immunized with recombinant HBsAg of the "adw" subtype and cloned by limiting dilution. Specificity of MAbs was studied by indirect ELISA and immunoblotting. Topology of the epitopes was analyzed by competitive and inhibition ELISA. Eight hybridoma clones producing MAbs specific for the immunogen were established. Five of the MAbs recognized overlapping conformational epitopes, whereas the remaining three MAbs were found to identify linear epitopes. Cross-inhibition studies suggest recognition of mutually exclusive epitopes by these MAbs. Our data suggest that, similar to the human system, the mouse antibody response is largely directed to restricted conformational overlapping epitopes of HBsAg.