利用单个细胞RT-PCR法克隆全人源性HBV单克隆抗体的探讨

目的建立外周血单个抗体分泌细胞分离和单个细胞RT-PCR系统,高效快速克隆高度特异性、全人源性的HBV单克隆抗体。方法选择3例HBV感染恢复期患者,从外周血中富集B淋巴细胞,加入HBcAg Peptide pool活化B淋巴细胞,流式分选出记忆性抗体分泌细胞(CD19~+CD10~-IgG~+CD27~+),通过有限稀释法获得单个细胞,单细胞RT-PCR反转出cDNA,巢式PCR扩增抗体重链恒定区序列片段,将PCR产物纯化并克隆至pEASY~-T1 simple克隆载体,进行测序鉴定。结果 ELISA结果显示,3例HBV感染恢复期患者血浆中均检测到较高水平IgG,与健康志愿者相比,差异均有统计学意义(P值均0.05)。流式结果显示,B淋巴细胞比例均高于94%,且均可分离出记忆性抗体分泌细胞。从分离的抗体分泌细胞中挑选出24个含有1个形态完好的细胞,经鉴定,其中有14个扩增成功,且条带在200 bp左右,与预期片段大小相符。对抗体重链序列分析显示成功扩增出抗体恒定区片段。结论成功构建了单个抗体分泌细胞分离和单个细胞RT-PCR系统,获得了抗体重链序列,为后期全人源性乙型肝炎单克隆抗体的高通量生产打下了坚实的基础。     

Long-term clinical impact of occult hepatitis B virus infection in chronic hepatitis B patients

BACKGROUND/AIMS: Long-term clinical outcomes of occult hepatitis B virus (HBV) infection were studied. METHODS: Fifteen chronic hepatitis B patients were monitored for a median of 4.4 years (range 0.9-15.3) after hepatitis B surface antigen (HBsAg) seroclearance. Serum HBV DNA was measured by real-time detection polymerase chain reaction. Thirteen patients underwent liver biopsies at the end of follow-up and liver histology was evaluated by Ishak score. Liver HBV DNA was also measured for 12 patients. RESULTS: At the end of follow-up, HBV viremia was absent in 13 (87%) patients, and antibody titers to hepatitis B core antigen showed an inverse correlation with time from HBsAg seroclearance (r=-0.554; P=0.0040). However, all patients retained liver HBV DNA and tested positive for the covalently closed circular HBV DNA replicative intermediate. The hepatic HBV DNA loads had no relation to liver histology. Paired biopsies from 11 patients disclosed that each necroinflammatory score significantly improved after HBsAg seroclearance. Amelioration of liver fibrosis was also evident in eight (73%) patients (P=0.0391 by signed rank test). CONCLUSIONS: A long-standing but strongly suppressed HBV infection may confer histological amelioration after HBsAg seroclearance.     

Low rate of YMDD motif mutations in polymerase gene of hepatitis B virus in chronically infected patients not treated with lamivudine

Background Lamivudine is used for the treatment of chronic hepatitis B (CH-B), and exhibits excellent antiviral activity. However, longterm administration increases the likelihood of the emergence of resistant viruses, with an accompanying relapse of hepatitis. However, recent studies have reported lamivudine-resistant viruses in patients with CH-B before such treatment. The aim of this study was to investigate whether YMDD mutants occur in nature.Methods The existence of lamivudine-resistant viruses was examined in 20 asymptomatic carriers of hepatitis B virus (ASC), 10 patients who lost hepatitis B surface antigen (HBsAg) during follow-up and in 20 lamivudine-treated patients with and without breakthrough hepatitis. Both polymerase chain reaction (PCR) restriction fragment length polymorphism and SMITEST hepatitis B virus (HBV)-YMDD mutation detection methods were used to detect resistant viruses.Results No YMDD mutants were detected in the sera of the 20 ASC at the initial and final medical examinations, nor were YMDD mutants detected in sera collected at the initial medical examination, about 6 months before, or immediately after the loss of HBsAg in the 10 patients. In the 20 patients treated with lamivudine, YMDD mutants were not detected in any of them before treatment, whereas mutants were detected in the sera of 10 patients during treatment.Conclusions Our results suggest that lamivudine-resistant YMDD mutant viruses were present in a few patients with HBV infection who before they have been treated with lamivudine.     

Replicative efficiency and pathogenicity of hepatitis B virus e-minus precore variant

Abstract To study the replicative efficiency and pathogenicity of hepatitis B virus precore variant (A1896), anti-hepatitis B virus e antigen (HBe) titre was studied in naturally occurring wild-type virus infection, A1896 variant infection and dual infection. Higher titre of anti-HBe was found in patients with no virus replication and in patients coinfected with the wild-type virus and A1896 variant, which suggest that anti-HBe may either act as an inhibitor of virus replication or as selective pressure for the A1896 variant. Three site-directed mutants were constructed in the duck hepatitis B virus (DHBV) precore region. A frame shift in the encapsidation signal region abolished replication of DHBV; mutation in the initiation codon of the precore and mutation to generate a termination codon at the distal region of the precore resulted in decreased replication in the duck model. More significant pathological changes were found in the liver tissues of ducks infected with the mutant which mimicked the HBV A1896 variant.     

Impact of acute hepatitis C virus superinfection in patients with chronic hepatitis B virus infection

BACKGROUND & AIMS: Superinfection in patients with chronic hepatitis B virus (HBV) infection is not uncommon. Acute hepatitis delta virus (HDV) superinfection is associated with severe and/or progressive liver disease. The natural course following acute hepatitis C virus (HCV) superinfection has not been well studied. The aim of this study was to investigate the impact of acute HCV superinfection. METHODS: The clinical features during acute phase and long-term outcomes of acute HCV superinfection were studied and compared with a cohort of acute HDV superinfection and a matched control group of active chronic hepatitis B. RESULTS: Acute HCV superinfection typically occurs as acute icteric hepatitis. The severity is similar to acute HDV superinfection in that hepatic decompensation developed in 34% of patients, hepatitis failure occurred in 11%, and 10% died. During a follow-up period of 1-21 years, patients with acute HCV superinfection had a significantly higher cumulated incidence of cirrhosis (48% at 10 years) and hepatocellular carcinoma (14% at 10 years, 21% at 15 years, and 32% at 20 years) than acute HDV superinfection or active chronic hepatitis B. Hepatitis B surface antigen (HBsAg) seroclearance occurred earlier in HCV superinfected patients. Continuing hepatitis after HBsAg seroclearance was observed only in HCV superinfected patients. CONCLUSIONS: Acute HCV superinfection in patients with chronic HBV infection is clinically severe during its acute phase. The long-term prognosis following acute HCV superinfection is much worse than that following HDV superinfection or active hepatitis B in terms of continuing hepatitis activity after HBsAg loss and the development of cirrhosis or hepatocellular carcinoma.     

Basal core-promoter mutant of hepatitis B virus and progression of liver disease in hepatitis B e antigen-negative chronic hepatitis B.

BACKGROUND/AIMS: The long-term outcomes in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B are distinct from those in HBeAg-positive chronic hepatitis. However, the molecular virological factors that contribute to the progression of liver disease in this special clinical setting remain largely unknown. We thus investigated the association of hepatitis B virus (HBV) genotypes as well as precore/basal core-promoter mutations with the clinical and virological characteristics of patients with HBeAg-negative chronic hepatitis B in Taiwan. METHODS: HBV genotypes and sequences of precore and basal core-promoter regions of the HBV genome were determined in 174 HBeAg-negative chronic HBV infection patients including 62 inactive carriers and 112 with different stages of liver disease. RESULTS: HBV carriers with older age (> 50 years) (odds ratio, 9.09; 95% confidence interval (CI), 3.22-25, P < 0.001) and basal core-promoter mutant of HBV (odds ratio, 4.12; 95% CI, 1.41-12.03, P = 0.01) were associated with the development of liver cirrhosis and hepatocellular carcinoma (HCC). The gender-related risk factors associated with the development of liver cirrhosis and HCC were further analyzed, and basal core-promoter mutant was only associated with the development of liver cirrhosis and HCC in male carriers (odds ratio, 4.35; 95% CI, 1.30-14.52, P = 0.02). CONCLUSIONS: The risk of development of liver cirrhosis and HCC is significantly increased in patients with advanced age as well as with basal core-promoter mutant of HBV. In addition, basal core-promoter mutant might contribute to the gender difference of the progression of liver disease in HBeAg-negative chronic hepatitis B in Taiwan.     

Therapeutic implications of hepatitis B virus genotypes.

BACKGROUND/AIMS: Hepatitis B virus (HBV) is a global health problem. In addition to the implementation of universal hepatitis B vaccination, effective and individualized treatment of chronic hepatitis B to prevent progression into end-stage liver diseases and hepatocellular carcinoma is still needed. HBV has been designated eight genotypes (A-H) based on genome sequence divergence. The epidemiology of HBV genotypes and their implications on the responses to antiviral therapy have become increasingly recognized in both Asian and Western countries. METHODS: Published data are thus reviewed. Results: Each genotype has its distinct geographical and ethnic distribution. Genotypes A and D occur frequently in Africa, Europe, and India, while genotypes B and C are prevalent in Asia. Genotype E is restricted to West Africa, and genotype F is found in Central and South America. The distribution of genotypes G and H is less clear. Accumulating evidence indicates a better sustained response to conventional interferon in patients with genotype B than those with C, and in patients with genotype A than those with D. In contrast, conflicting results exist regarding the response to pegylated interferon. On the other hand, the therapeutic responses to nucleoside/nucleotide analogues are comparable among patients with different HBV genotypes. The impact of HBV subgenotypes, mixed genotype infections, and recombinants of different genotypes on the response to antiviral treatments awaits further examinations. CONCLUSION: Remarkable clinical and pathogenic differences do exist among HBV genotypes; however, researches on molecular and virologic mechanisms underlying the clinical phenotypes of different HBV genotypes are urgently needed.     

Changes in levels of hepatitis B virus markers in patients positive for low-titer hepatitis B surface antigen

Aim: Recently, patients positive for the low-titer hepatitis B surface antigen (HBsAg) have been found occasionally owing to the increase in the accuracy of detection methods. The aim of this study is to clarify the clinical status of acute hepatitis B virus (HBV) infection in patients positive for low-titer HBsAg. Method: Eight patients, who were positive for HBsAg at low titers and diagnosed as having acute HBV infection, were enrolled in this study. Assays of HBsAg, hepatitis B core antibody (anti-HBc), hepatitis B e-antigen (HBeAg), hepatitis B e-antibody (anti-HBe), hepatitis B surface antibody (anti-HBs) and HBV DNA, and biochemical tests were basically conducted every 4 weeks for at least 24 weeks. Result: The average cut-off index of HBsAg was 8.7 ± 9.6 (range, 1.0–25.7). All the patients were negative for anti-HBc, HBeAg, anti-HBe and HBV DNA on their initial visit. The genotype of HBV could be determined in four patients: two were infected with genotype B/HBV, one was infected with genotype A/HBV, and the remaining patient was infected with genotype C/HBV. Although HBsAg clearance was observed within 4 months in all the patients, none of the other HBV markers seroconverted during the observation period. Conclusion: HBV infection terminating with seronegativity for HBV markers may occur in transient HBV infection.     

Development of transient autoimmune hepatitis during interferon treatment of chronic hepatitis B

Summary A 42-year-old man was treated with interferon- for chronic hepatitis B; during the fourth week of treatment he developed an exacerbation of liver disease, and nuclear and smooth muscle autoantibodies, which were previously negative, were detected in very high titers. After discontinuation of interferon therapy, ALT values subsided promptly and autoantibodies disappeared within a few months. This sequence of events strongly suggests a direct relationship between IFN treatment and a self-limited hepatitis with autoimmune markers in this case.     

Antiretroviral treatment change among HIV, hepatitis B virus and hepatitis C virus co-infected patients in the Australian HIV Observational Database

OBJECTIVES: To assess the impact of highly active antiretroviral therapy (HAART) on rates of change of antiretroviral treatment among patients co-infected with hepatitis B virus (HBV) and/or hepatitis C virus (HCV) in the Australian HIV Observational Database (AHOD). METHODS: Analysis was based on 805 of the 2218 patients recruited to the AHOD by March 2003, who had commenced HAART after 1 January 1997, who had recorded test results for HBV surface antigen and anti-HCV antibody, and who had follow-up of more than 3 months. The effect of hepatitis co-infection on the rate of antiretroviral treatment change after commencing HAART was assessed using a random-effect Poisson regression model. RESULTS: Among those included in the analyses, the prevalences of HBV and HCV were 4.8% and 12.8%, respectively. The overall rate of combination antiretroviral treatment change was 0.74 combinations per year. Factors independently associated with an increased rate of change of combination antiretroviral treatment were: prior AIDS-defining illness; prior exposure to double combination antiretroviral therapy; and antiretroviral treatment class. Co-infection with HBV and/or HCV was not found to be significantly associated with the rate of combination antiretroviral treatment change. CONCLUSIONS: While both HBV and HCV co-infections are relatively common in the AHOD, they do not appear to be serious impediments to the treatment of HIV-infected patients.