Isolated antibody to hepatitis B core antigen in patients with chronic hepatitis C virus infection

AIM: To evaluate the prevalence of isolated anti-HBc in patients with chronic hepatitis C virus (HCV) infection, and its relation to disease severity. METHODS: We screened all patients with chronic HCV infection referred to King Faisal Specialist Hospital and Research Center for hepatitis B surface antigen (HBsAg), antibody to hepatitis B surface antigen (anti-HBs), and anti-HBc. One hundred and sixty nine patients who tested negative for both HBsAg and anti-HBs were included in this study. RESULTS: Pathologically, 59 had biopsy-proven cirrhosis and 110 had chronic active hepatitis (CAH). Of these 169 patients, 85 (50.3%) tested positive for anti-HBc. Patients with CAH had significantly higher prevalence of isolated anti-HBc than patients with cirrhosis, 71 (64.5%) and 14 (23.7%) respectively (P < 0.001). Twenty-five patients were tested for HBV DNA by qualitative PCR. The test was positive in 3 of them (12%; occult HBV infection). CONCLUSION: Isolated anti-HBc alone is common in Saudi patients with chronic HCV infection, and is significantly more common in those with CAH than those with cirrhosis. Therefore, a screening strategy that only tests for HBsAg and anti-HBs in these patients will miss a large number of individuals with isolated anti-HBc, who may be potentially infectious.     

Subcellular localization of hepatitis B core antigen in relation to hepatocyte regeneration in chronic hepatitis B

To test whether the dominant cytoplasmic expression of hepatitis B core antigen (HBcAg) in active chronic hepatitis B is secondary to liver damage and regeneration, the relationship between subcellular localization of HBcAg, liver inflammatory activity, and hepatocyte regeneration in chronic hepatitis B was studied. Correlation of the clinical and laboratory data with the topographical distribution of HBcAg was studied in 30 patients. The subcellular localization of HBcAg in relation to hepatocyte cell cycles was studied by double immunostaining of HBcAg and proliferating cell nuclear antigen. Patients with predominant cytoplasmic HBcAg had significantly higher levels of biochemical and histological activities and proliferating cell nuclear antigen expression than patients with predominant nuclear HBcAg. The levels of proliferating cell nuclear antigen expression correlated positively with biochemical and histological activities and degrees of cytoplasmic HBcAg expression but negatively with degrees of nuclear HBcAg expression. Proliferating cell nuclear antigen expression was shown in 49% of hepatocytes with cytoplasmic HBcAg but in only 2% of hepatocytes with nuclear HBcAg. These findings suggested that, following liver damage, the regeneration of surviving hepatocytes might cause the shift of intracellular HBcAg from nucleus to cytoplasm. As a result, the extent of nuclear HBcAg expression reduces with concomitant increase in cytoplasmic HBcAg expression.     

乙型肝炎病毒核心抗原在慢性乙型肝炎病毒感染者肝细胞内的分布及临床意义

目的 探讨HBcAg在慢性HBV感染者肝细胞内的分布情况及其临床意义.方法 对41例慢性HBV感染者进行肝组织穿刺,用免疫荧光组织化学技术在激光共聚焦显微镜下观察肝细胞内HBcAg的分布情况.计量资料采用Kruskal Wallis检验,计数资料采用卡方检验.结果 41例慢性HBV感染者中,36例肝细胞内HBcAg阳性表达,阳性率为87.8%,其中23例肝功能中度异常,10例肝功能轻度异常,3例肝功能正常.HBcAg有膜、胞质与核三种形式表达.在23例肝功能中度异常者中,6例呈明显膜型表达,无明显胞质型及核型,17例以胞质型与膜型混合表达,未发现核型表达.在10例肝功能轻度异常者中,以单纯胞质型为主,未见膜型与核型表达.在3例肝功能正常者中,以胞质型表达与少许核型表达为主,未见膜型表达.HBcAg表达类型与肝功能之间差异有统计学意义(χ2=10.60,P＜0.01).结论 慢性HBV感染者肝组织损伤与HBcAg的表达有直接联系,提示膜型表达的HBcAg是肝脏免疫损伤过程中的靶抗原.

Abstract：

Objective To explore the distribution and clinical significance of hepatitis B core antigen( HBcAg) in the hepatocytes of chronic hepatitis B virus infected patients. Methods Paraffin sections were made from 41 liver biopsy samples obtained from chronic hepatitis B virus infected patients. The immuno-fluorescence confocal technique was utilized to analyze the expression level and localization of HBcAg in hepatocytes. The data were analyzed by using Kruskal Wallis test and chisquare test. Results HBcAg expression were detected in 36 (87. 8%) patients, among whom 23 cases had moderate abnormal liver function, 10 with mild abnormal liver function and 3 with normal liver function. Among the cases with moderate abnormal liver function, 6 cases showed the simple membrane-type HBcAg expression, 17 cases showed mixed cytosolic-type and membrane-type HBcAg expression without the nuclear-type expression. Twelve cases with mild abnormal liver function only showed simple cytosolic-type HBcAg expression without membrane-type or nuclear-type expression. In the three patients with normal liver function, HBcAg was expressed in cytoplasm and nuclear but not on membrane. The correlation between HBcAg expression pattern and liver function was statistically significant (χ2 =10. 60, P＜0.01). Conclusion HBcAg expression is directly correlated with liver injury in chronic hepatitis B virus infected patients, which indicates that membrane expressed HBcAg is the target antigen during the immuno-attack of liver.     

Protection against hepatitis B virus infection by immunization with hepatitis B core antigen

Although antibody to the hepatitis B surface antigen usually provides protection against hepatitis B virus (HBV) infection, recent reports indicate that this is not always the case. To study the possible role of immune responses to hepatitis B core antigen in immunity to HBV infection, chimpanzees were immunized with chimpanzee liver-derived or genetically cloned hepatitis B core antigen and later challenged with known infectious HBV. Two chimpanzees, which received liver-derived or cloned hepatitis B core antigen in Freund's adjuvant and developed hepatitis B core antibody and low-titer hepatitis B e antibody, were completely protected against HBV infection following challenge. In contrast, another chimpanzee, which received liver-derived hepatitis B core antigen without adjuvant, developed hepatitis B core antibody only in serum and had a subclinical HBV infection when challenged. These findings demonstrate that protection against HBV infection can be induced by immunization with hepatitis B core antigen in adjuvant and that protection, in this case, is not solely dependent on hepatitis B surface antibody. This fact has important implications in our understanding of the biology of HBV infection and in the design of future hepatitis B vaccines.     

Cytoplasmic expression of hepatitis B core antigen in chronic hepatitis B virus infection: role of precore stop mutants

Abstract: Aims/Background: The cytoplasmic expression of HBcAg is a possible target of immune hepatocytolysis and it is important for the pathogenesis of hepatic injury in chronic hepatitis B virus (HBV) infection. Cytoplasmic HBcAg expression has been suggested to be related to the precore sequence of HBV, HBV DNA level or cell cycle of hepatocytes and the aim of this study was to understand its mechanism. Material/Methods: We studied the expression pattern of HBcAg and its relationship to serum HBV DNA levels, cell proliferation activity of hepatocytes and precore mutation using 66 patients' sera and biopsied liver specimens of chronic hepatitis B. Results: The expression patterns of HBcAg were cytoplasmic predominant (CP) in 17 cases, nuclear and cytoplasmic (NC) in 10 cases and nuclear predominant (NP) in 9 cases and negative in 30 cases. CP expression cases showed a higher grade of hepatitis activity than NP expression cases. Serum HBV DNA levels showed a wide range and there was no significant difference according to the expression pattern of HBcAg. Cell proliferation activity of hepatocytes, measured by Ki-67 (MIB-1) labelling index was higher in CP expression cases than in NP expression cases and it was also significantly higher in cases of high grade than in low grade hepatitis activity. The precore region was evaluated by primer extension assay in 51 cases and there were 16 cases of 1896 precore mutant, 23 cases of wild type, 12 cases of mixed infection of 1896 precore mutant type and wild type. CP expression of HBcAg was significantly more frequent in 1896 precore mutant cases (86%) than in wild type cases (26%). Conclusion: CP expression of HBcAg is the major pattern of 1896 precore mutant cases and it might be involved in the severe liver injury of precore mutants. One of the mechanisms regulating CP HBcAg expression is suggested to be precore mutation of HBV as well as cell cycle of hepatocyte.     

Significance of IgM antibody to hepatitis B core antigen in a Greek population with chronic hepatitis B virus infection

IgM antibody to hepatitis B core antigen (IgM anti-HBc) may indicate an active immune response to persistent infection with hepatitis B virus (HBV). We studied 186 Greek HBsAg carriers for IgM anti-HBc and attempted to correlate it with other HBV and hepatitis delta virus (HDV) markers. Overall, IgM anti-HBc was detected more frequently than HBV DNA in this population (50% vs 34, p less than 0.001); this was also true for the 149 of the 186 HBsAg carriers with antibody to hepatitis B e antigen (anti-HBe) (48% vs 22%, p less than 0.001). The opposite was found in the carriers positive for hepatitis B e antigen (HBeAg): HBV DNA was observed in 93% and IgM anti-HBc in 64% of the cases (p less than 0.05). The detection of these markers was independent of sex. Serum alanine aminotransferase (ALT) levels were significantly more elevated in patients with positive tests for IgM anti-HBc and HBV DNA than in patients positive only for HBV DNA (p less than 0.001) irrespective of their HBeAg or anti-HBe status. Moreover, the detection of elevated ALT was independent of the intensity of the HBV DNA hybridization signal. Antibodies to hepatitis delta antigen (HDAg) were only found in 4 (2.4%) of 167 patients tested.     

慢性乙型肝炎患者肝细胞内乙型肝炎核心抗原阳性的临床意义

目的探讨CHB患者肝组织HBcAg阳性的意义。方法对200例CHB患者应用荧光聚合酶链反应（FQ-PCR）法精确定量检测血清HBV DNA含量。患者均检测血清中HBeAg含量,同时进行肝活组织检查,应用免疫组织化学技术检测HBcAg情况,并进行相关性分析。结果按测定血清HBV DNA水平,分为A组（＜3 log10拷贝/ml）20例,B组（≥3 log10拷贝/ml-＜5 log10拷贝/ml）13例,C组（≥5 log10拷贝/ml～＜6 log10拷贝/ml）24例,D组（≥6 log10拷贝/ml～＜8 log10拷贝/ml）116例,E组（≥8 log10拷贝/ml）27例。肝组织HBcAg阳性者175例,占87．5％,A组HBcAg阳性率55．0％（11/20）,B组53．8％（7/13）,C组75．0％（18/24）,D组96．6％（112/116）,E组100．0％（27/27）,HBcAg阳性率与血清HBV DNA水平之间呈显著正相关（r=0．80,P＜0．01）。血清HBV DNA水平高低与HBeAg阳性率之间呈显著正相关（r=0．47,P＜0．01）。其中20例HBV DNA阴性者中（A组）,HBeAg阳性者5例（25％）,HBcAg阳性者11例（55％）；15例HBV DNA阴性且HBeAg阴性者中有7例HBcAg阳性,占46．7％。结论CHB患者肝组织HBcAg阳性能更可靠地反映肝细胞内HBV复制状态。检测肝组织内HBcAg对CHB患者疗效评价和对治疗反应性的预测更具有临床意义。     

Hepatitis B virus core and core-related antigen quantitation in Chinese patients with chronic genotype B and C hepatitis B virus infection

BACKGROUND AND AIMS: Hepatitis B virus (HBV) core-related antigen (HBcrAg) and HBV core antigen (HBcAg) assays were developed for the measurement of serum HBV load. The aim of this study was to assess the clinical utility of these assays in Chinese patients with chronic genotype B and C HBV infection. METHODS: One hundred and ninety-three chronic hepatitis B patients were enrolled. Serum HBcrAg and HBcAg were measured by chemiluminescence enzyme immunoassay, and HBV-DNA was measured by using a sensitive polymerase chain reaction assay. The data were analyzed in patients with HBV genotype B (HBV/B) and genotype C (HBV/C). The HBcrAg/HBcAg ratio was calculated and compared between patients with and without hepatitis B e antigen (HBeAg). RESULTS: The concentrations of HBcrAg and HBcAg showed significant positive correlation with the HBV-DNA concentration in both HBV/B (r = 0.79, P < 0.001, and r = 0.77, P < 0.001, respectively) and HBV/C (r = 0.87, P < 0.001, and r = 0.90, P < 0.001, respectively). The cut-off for a positive HBcAg corresponded to approximately 4.5 log copies/mL, and that for a positive HBcrAg result corresponded to 3-4 log copies/mL. The HBcrAg/HBcAg ratio was higher in patients with HBeAg than in those without HBeAg. CONCLUSIONS: The HBcrAg assay and HBcAg assay are clinically useful in viral quantitation of HBV/B and HBV/C. A combination of these assays would be a valuable tool for analyzing the clinical status of HBV infection.     

Cytoplasmic expression of hepatitis B core antigen in chronic hepatitis B virus infection: role of precore stop mutants.

AIMS/BACKGROUND: The cytoplasmic expression of HBcAg is a possible target of immune hepatocytolysis and it is important for the pathogenesis of hepatic injury in chronic hepatitis B virus (HBV) infection. Cytoplasmic HBcAg expression has been suggested to be related to the precore sequence of HBV, HBV DNA level or cell cycle of hepatocytes and the aim of this study was to understand its mechanism. MATERIAL/METHODS: We studied the expression pattern of HBcAg and its relationship to serum HBV DNA levels, cell proliferation activity of hepatocytes and precore mutation using 66 patients' sera and biopsied liver specimens of chronic hepatitis B. RESULTS: The expression patterns of HBcAg were cytoplasmic predominant (CP) in 17 cases, nuclear and cytoplasmic (NC) in 10 cases and nuclear predominant (NP) in 9 cases and negative in 30 cases. CP expression cases showed a higher grade of hepatitis activity than NP expression cases. Serum HBV DNA levels showed a wide range and there was no significant difference according to the expression pattern of HBcAg. Cell proliferation activity of hepatocytes, measured by Ki-67 (MIB-1) labelling index was higher in CP expression cases than in NP expression cases and it was also significantly higher in cases of high grade than in low grade hepatitis activity. The precore region was evaluated by primer extension assay in 51 cases and there were 16 cases of 1896 precore mutant, 23 cases of wild type, 12 cases of mixed infection of 1896 precore mutant type and wild type. CP expression of HBcAg was significantly more frequent in 1896 precore mutant cases (86%) than in wild type cases (26%). CONCLUSION: CP expression of HBcAg is the major pattern of 1896 precore mutant cases and it might be involved in the severe liver injury of precore mutants. One of the mechanisms regulating CP HBcAg expression is suggested to be precore mutation of HBV as well as cell cycle of hepatocyte.     

联合检测HBV前S1抗原和核心抗原的临床意义

探讨联合检测血清HBV前s1抗原（preSl）和核心抗原（HBcAg）（均为HBV核酸相关抗原，nucleic acids related antigen，HBV NRAg）的意义及临床价值。方法：采用ELISA法对393份HBsAg、HBV DNA双阳性的血清和612份HBsAg阴性血清进行HBV NRAg检测，所有标本均采用多区段巢式PCR确认阳性、阴性，采用荧光定量PCR法进行HBV DNA定量分析。结果：393份HBsAg、HBV DNA双阳性血清中，HBV NRAg阳性为382份，其阳性率为97．2％；612份HBsAg阴性的血清标本中，609份确认为HBV DNA阴性，其中检出2份HBV NRAg阳性，607份为阴性，其HBV NRAg的阴性率为99．7％（607／609），另3份HBsAg阴性血清HBV DNA阳性者，其HBV NRAg均为阳性。结论：联合检测preSl和HBcAg的HBV NRAg可作为临床HBV感染的筛选及判断HBV复制的有意义的补充项目。     

HLA class I antigen display on hepatocyte membrane in chronic hepatitis B virus infection: its role in the pathogenesis of chronic type B hepatitis

It has been suggested that cytotoxic T cells are involved in the recognition and lysis of the infected hepatocytes in chronic hepatitis B virus infection, and that the target antigen is probably HBcAg which is displayed on the hepatocyte membrane during active viral replication. However, studies in other viral infection have demonstrated that cytotoxic T cells recognize viral antigen on the infected cells only in the context of HLA class I antigens. To test whether this mechanism is also operative in chronic hepatitis B virus infection, we studied the expression of HLA class I antigens in livers from 35 patients with chronic hepatitis B virus infection by indirect immunofluorescence using monoclonal antibody against HLA class I antigens. The blocking effect of monoclonal antibody against HLA class I antigens on the in vitro T cell cytotoxicity to autologous hepatocytes was also studied. The results revealed that HLA class I antigen was undetectable on the hepatocyte membrane in all of 10 HBeAg-positive carriers with minor hepatitic activity, whereas it was demonstrated in 15 (88%) of the 17 HbeAg-positive patients with chronic active liver disease and in 7 (87%) of the 8 anti-HBe-positive "normal" carriers. The in vitro T cell cytotoxicity to autologous hepatocytes in six HBeAg-positive patients with chronic active liver disease was significantly inhibited by preincubation of hepatocytes with monoclonal antibody (10 to 40 micrograms per ml) against HLA class I antigen, but not by monoclonal antibody against HLA class II antigens and non-HLA-associated surface molecules (Leu 11).(ABSTRACT TRUNCATED AT 250 WORDS)     

The natural history of chronic hepatitis B virus infection

Three stages of chronic hepatitis B virus (HBV) infection are recognized: the immune tolerant phase, the chronic hepatitis B phase, and the inactive hepatitis B carrier phase. Active liver disease is most often found in persons with elevated aminotransferase levels and HBV DNA levels >10(5) copies/mL. Possible risk factors for developing liver disease include older age, male gender, presence of hepatitis B e antigen (HBeAg), HBV genotype, mutations in the precore and core promoter regions of the viral genome, and coinfection with hepatitis D (delta) virus. All persons chronically infected with HBV should be followed every 6 to 12 months with aminotransferase levels. Those with elevated levels should be tested for HBeAg and its antibody (anti-HBe) as well as HBV DNA levels to determine if they are in need of further evaluation with a liver biopsy and are candidates for antiviral therapy. Future research will help clarify the outcome of chronic HBV infection.     

Latent hepatitis B virus infection in healthy individuals with antibodies to hepatitis B core antigen

Several recent reports have shown that hepatitis B virus (HBV) could be frequently transmitted to the recipients from donors who have antibodies to hepatitis B core antigen (anti-HBc) through liver transplantation. We provide here the molecular evidence of latent HBV infection accompanied with ongoing viral replication in the liver tissue of anti-HBc-positive healthy individuals. HBV DNA was detectable in 13 of 14 healthy donors who were positive for both anti-HBc and antibodies to hepatitis B surface antigen (anti-HBs), but in none of 3 who were positive for anti-HBs alone. The detected HBV genomes from these subjects included covalently closed circular DNA and pregenomic RNA, the replication intermediate of HBV. Notably, 5 of 7 cases tested were predominantly infected with wild type HBV strains without any mutations in the precore and core promoter regions under the presence of circulating antibody to hepatitis B e antigen. Interestingly, a predominant clone detected in one donor showed a 63-nucleotide deletion in the precore region including an encapsidation signal sequence. Our findings indicate that the majority of healthy individuals positive for anti-HBc, which had been assumed to denote a past history of transient HBV infection, were latently infected with the episomal form of HBV accompanied by ongoing viral replication and few nucleotide mutations in the precore and core regions.     

Role of hepatitis C virus infection in spontaneous hepatitis B surface antigen clearance during chronic hepatitis B virus infection.

To examine the role of hepatitis C virus (HCV) infection in spontaneous hepatitis B surface antigen (HBsAg) clearance during the course of chronic hepatitis B virus (HBV) infection, serum specimens from 32 asymptomatic HBsAg carriers and 22 patients with chronic hepatitis type B who underwent spontaneous HBsAg clearance were studied for antibody to HCV (anti-HCV) using commercial EIAs. The results were compared with those of control groups matched for age, sex, hepatitis B e antigen, antibody to hepatitis delta virus, and cirrhosis. Eight (25%) of the asymptomatic carriers and 9 (41%) of the patients with chronic hepatitis were seropositive for anti-HCV in contrast to 1.6% and 9.1% of their respective control groups (P less than .01). Serum alanine aminotransferase level was persistently abnormal after HBsAg clearance in one asymptomatic carrier and in four patients with chronic hepatitis. These patients were seropositive for anti-HCV and at least one of them was negative for HBV-DNA by polymerase chain reaction. The data suggest that HCV superinfection may not only suppress HBV or terminate the HBsAg carrier state but may also assume the role of HBV as the cause of persistent hepatitis or transaminase elevation.     

132例家族聚集性慢性乙型肝炎病毒感染者影响自然病程进展的相关因素分析

目的探讨慢性乙型肝炎病毒感染者自然病程进展规律及其与感染持续时间、血清HBV DNA载量、HBe Ag状态和脾脏厚度的关系。方法 2007年1月至2010年8月就诊于中国医科大学附属盛京医院感染病科的家族聚集性慢性乙型肝炎病毒感染者132例,常规行肝组织活检病理学检查,采用化学发光法检测血清HBV标记物;采用荧光定量PCR法检测血清HBV DNA;使用西门子S200二维彩超诊断仪测量脾脏厚度。结果在132例慢性乙型肝炎患者中,年龄≥30岁患者肝组织炎症评分≥5分和纤维化评分≥3分发生率分别为33.3%和38.4%,显著高于年龄30岁组(14.9%和14.8%,P0.05);肝功能正常组肝组织炎症评分≤4分和纤维化评分≤2分发生率分别为92.0%和92.0%,肝功能异常组为53.6%和16.74%(P0.05);肝功能反复异常1年的患者肝组织炎症评分≥5分和纤维化评分≥3分发生率分别为42.8%和51.5%,显著高于肝功能异常≤1年组(31.9%和31.9%,P0.05);血清HBV DNA载量为3~5 lg copies/ml组肝组织炎症评分为≤4分和纤维化评分为≤2分发生率分别为50.0%和27.8%,显著高于病毒载量3 lg copies/ml组(P0.05);血清HBe Ag阴性组纤维化评分在3~4分和≥5分发生率分别为23.1%和20.5%,显著高于HBe Ag阳性组的11.8%和9.7%(P0.05);血清HBe Ag阳性与否与肝组织炎症无显著相关性(P0.05);脾脏厚度≥4 cm组肝组织炎症≥5分和纤维化评分≥5分发生率分别为76.9%、7.7%和76.9%,显著高于脾脏厚度4 cm组的16.0%、3.4%和5.9%(P0.05);多因素分析发现脾脏厚度与肝组织炎症(t=2.153)和纤维化程度(t=4.654)呈显著独立正相关(P=0.033);血清HBV DNA载量与肝组织纤维化程度(t=-2.826)也呈独立相关(P=0.005)。结论家族聚集性的慢性乙型肝炎病毒感染者肝组织炎症和纤维化程度与感染持续时间成正相关,年龄大于30岁时更易出现肝脏疾病的进展。肝功能异常时间越长肝脏炎症和纤维化改变越显著。脾脏厚度与肝组织炎症和纤维化程度具有独立正相关。血清HBV DNA载量为1×103~105copies/ml时肝组织炎症和纤维化改变更显著。     

Low-molecular-weight IgM antibody to hepatitis B core antigen in chronic infections with hepatitis B virus

IgM antibody to hepatitis B virus core antigen (IgM anti-HBc) develops during acute hepatitis B but frequently persists in chronic infections. To characterize persistent IgM anti-HBc better, 7-8S and 19S immunoglobulin fractions were prepared by rate-zonal centrifugation of sera from 17 patients with persistent hepatitis B (chronic active hepatitis) and were tested for IgM anti-HBc by a specific radioimmunoassay. In 16 sera peak activity was found in 7-8S fractions, although in 11 sera a minor peak was also present in 19S fractions. The low molecular weight of the predominant IgM anti-HBc was confirmed by gel filtration. In competition experiments, the binding of 7-8S antibody to an anti-IgM-coated solid phase was blocked more effectively by purified IgM than by purified IgG. These findings indicate that hepatitis B carriers with chronic active hepatitis have predominantly 7-8S IgM anti-HBc and represent a novel demonstration of naturally occurring 7-8S IgM with defined antiviral specificity.