[Study on a putative, proprotein convertase-cleaved product of HBV core protein in vitro].

OBJECTIVE: To investigate the cleavage of HBV core protein in vivo by proprotein convertase furin or its family members and observe the intracellular localization of the putative cleaved product. METHODS: Recombinant HBV core protein was incubated with furin under different conditions in vitro, and the reaction was checked with Western blotting. The recombinant vectors expressed the putative cleaved fragment and intact core protein (serves as control) were constructed. The stable expression cell lines were established by transfecting constructs into HepG2 cell line, for which indirect immunofluorescence staining was used by monoclonal anti-HBc against the region shared by core protein and its cleaved product .The confocal microscopy was carried out to observe the intracellular distribution. RESULTS: HBV core protein was cleaved by furin in vitro under different tested conditions. The molecular weight of the major cleaved product just about 15,000 was in concordance with the expectation. The expressed cleaved fragment could react to the monoclonal antibody against core protein, and mainly located in cytosol in particle style just like the intact core protein. CONCLUSION: HBV core protein can be cleaved by furin in vitro. The major cleaved product has similar antigenicity and subcellular distribution to core protein. These data suggest that proprotein convertase furin or its family members play important roles in HBV replication regulation, and the cleaved product may be involved in antiviral immunity of HBV infection. Further investigations are imperative.

Influence of a single nucleotide polymorphism in the P1 promoter of the furin gene on transcription activity and hepatitis B virus infection.

UNLABELLED: Hepatitis B e antigen (HBeAg) is a viral strategy of immune response evasion associated with hepatitis B virus (HBV) persistence. Spontaneous HBeAg seroconversion is usually accompanied by liver disease remission. Unfortunately, this goal is difficult to achieve and requires expensive and time-consuming treatment. Furin, a proprotein convertase, is involved in HBeAg maturation and is therefore a potential therapeutic target or indicator for predicting disease progression and antiviral response. Here we demonstrate that healthy Han Chinese from southern China (an endemic area of HBV infection) harbor a common single nucleotide polymorphism (SNP; -229 C/T) in a 1268-bp region of the P1 promoter of the furin gene [FES upstream region (Fur)]. A luciferase reporter gene assay showed that transcription activity is about 3 times higher in allele T carriers than in allele C carriers of this SNP. Allele T includes a suboptimal transcription factor NF-E2 [i.e., nuclear factor (erythroid-derived 2)]-binding motif according to bioinformatics and studies using site-directed mutagenesis. We also observed that individuals carrying allele T were more likely to become persistently infected. When persistently infected patients were divided into subgroups according to recent guidelines and HBeAg-defective virus infection was taken into account, patients with allele T or genotype TT had a decreased likelihood of HBeAg seroconversion or an increased likelihood of progressing to HBeAg-negative chronic hepatitis B or liver cirrhosis if accompanied by HBeAg-defective virus infection. CONCLUSION: The common SNP in the P1 promoter of the Fur gene affects furin transcription activity and HBV infection outcome, possibly by increasing furin messenger RNA expression, and this suggests that furin is a potential therapeutic target and that this SNP is a potential predictor of disease progression or therapeutic response.

[A simple scoring system to evaluate the severity of acute-on-chronic liver failure in hepatitis B].

OBJECTIVE: To establish an objective, simple and sensitive scoring system to evaluate the severity of acute-on-chronic liver failure in hepatitis B. METHODS: The clinical data of patients (194 survivals and 215 deaths) with acute-on-chronic liver failure in hepatitis B were collected and analyzed prospectively. 7 clinical indexes, including the hepatic encephalopathy, creatinine, prothrombin activity, serum total bilirubin, infection, the dimension of liver, the maximum depth of ascites, were scored objectively and simply from 0 to 4 points according to their severity. Then we calculated every patient's total score and divided the 409 patients into two groups: the one was 309 patients and the other is 100 patients. The first group was to establish the severity scoring system and define the cut-off-point, the second group was to test the severity scoring system. RESULTS: The total score of the 144 patients in the survival group was 6.9 +/- 3.2, 165 patients in the dead group was 15.8 +/- 4.0, respectively. There were significant differences (P < 0.01) between the two groups. The area under ROC curve was 0.953. The cut-off-point is 9.5. The sensitivity was 0.97, the specificity was 0.82. The second group patients' total score were divided into two groups: the one is > or = 10 score and the other is < or = 9 score. The prognosis of the first group was much worse than the second group, it's mortality rate was 87.5%; the second was 2.3%. There were significant differences between the two groups (P < 0.01). CONCLUSIONS: This scoring system was simple, sensitive and objective to evaluate the severity of acute-on-chronic liver failure in hepatitis B.