Hepatitis C Virus Cirrhotic Patients Research Articles

Detection of high levels of S urvivin–immunoglobulin M immune complex in sera from hepatitis C virus infected patients with cirrhosis

The identification and surveillance of patients with liver dysfunctions and the discovering of new disease biomarkers are needed in the clinical practice. The aim of this study was to investigate on Survivin-immunoglobulin (Ig)M immune complex (IC) as a potential biomarker of chronic liver diseases. Serum levels of Survivin-IgM were measured using an enzyme-linked immunoassay that had been standardized and validated in our laboratory in 262 individuals, including healthy subjects and patients with chronic viral hepatitis, cirrhosis and hepatocellular carcinoma (HCC). Survivin-IgM IC was lower in healthy subjects (median, 99.39 AU/mL) than in patients with chronic viral hepatitis (median, 148.03 AU/mL; P = 0.002) or with cirrhosis (median, 371.00 AU/mL; P < 0.001). Among patients with cirrhosis, those with hepatitis C virus (HCV) infection showed the highest level of Survivin-IgM IC (median, 633.71 AU/mL; P < 0.001). The receiver-operator curve analysis revealed that Survivin-IgM accurately distinguishes HCV correlated cirrhosis from chronic viral hepatitis (area under the curve [AUC], 0.738; sensitivity, 74.5%; specificity, 70.7%). A multivariate logistic regression model, including Survivin-IgM IC, aspartate aminotransferase (AST) and AST/alanine aminotransferase (ALT) ratio increased the prediction accuracy for the identification of the cirrhotic HCV patients (AUC, 0.818; sensitivity, 87.2%; specificity, 65.9%). Conversely, Survivin-IgM IC significantly decreased in HCC patients (median, 165.72 AU/mL; P = 0.022). Our results suggest that Survivin-IgM immune complex may be used as a potential biomarker for liver damage, particularly for the identification of the HCV-related cirrhotic population.

Targeted metabolic profiling of hepatocellular carcinoma and hepatitis C using LC‐MS/MS

Hepatitis C virus (HCV) infection of the liver is a global health problem and a major risk factor for the development of hepatocellular carcinoma (HCC). Sensitive methods are needed for the improved and earlier detection of HCC, which would provide better therapy options. Metabolic profiling of the high-risk population (HCV patients) and those with HCC provides insights into the process of liver carcinogenesis and possible biomarkers for earlier cancer detection. Seventy-three blood metabolites were quantitatively profiled in HCC (n = 30) and cirrhotic HCV (n = 22) patients using a targeted approach based on LC-MS/MS. Sixteen of 73 targeted metabolites differed significantly (p < 0.05) and their levels varied up to a factor of 3.3 between HCC and HCV. Four of these 16 metabolites (methionine, 5-hydroxymethyl-2'-deoxyuridine, N2,N2-dimethylguanosine, and uric acid) that showed the lowest p values were used to develop and internally validate a classification model using partial least squares discriminant analysis. The model exhibited high classification accuracy for distinguishing the two groups with sensitivity, specificity, and area under the receiver operating characteristic curve of 97%, 95%, and 0.98, respectively. A number of perturbed metabolic pathways, including amino acid, purine, and nucleotide metabolism, were identified based on the 16 biomarker candidates. These results provide a promising methodology to distinguish cirrhotic HCV patients, who are at high risk to develop HCC, from those who have already progressed to HCC. The results also provide insights into the altered metabolism between HCC and HCV.

P.4.015 Long term therapy with methylphenidate induces modest effects on growth in ADHD children

A 24–48-week course of interferon-based therapy poorly tolerated in hepatitis C virus (HCV) cirrhosis patients with thrombocytopenia. Aim of the study was to identify patients at low-risk of liver-related complications over a 12-week course of interferon-based therapy.We assessed the rate of complications and death during the first 12 weeks of interferon-based therapy in HCV cirrhotics with thrombocytopenia (platelets ≤75 × 109/L) enrolled in the ENABLE-1 and -2 phase 3 randomised controlled trials.Overall, among 1441 patients, 89 complications (6.9%) and 10 deaths (0.7%) were observed within the first 12 weeks of therapy. At univariate analysis baseline albumin levels and Model for End Stage Liver Disease (MELD) score (≤35 g/L, p < 0.001, and ≥10, p < 0.001, respectively) were the only predictors associated with occurrence of complications and death. Of the 1026 patients with serum albumin >35 g/L (71.2%), one patient died (0.1%) and 17 experienced liver-related complications (1.7%). Among 667 patients with serum albumin >35 g/L and MELD score <10, no deaths occurred and 4 experienced liver-related complications (0.6%).Among HCV cirrhotic patients with thrombocytopenia, albumin levels and MELD score can identify patients who may safely receive a 12-week course of interferon-based therapy with a low risk of complications.

Severe adverse events during antiviral therapy in hepatitis C virus cirrhotic patients: A systematic review

To identify severe adverse events (SAEs) leading to treatment discontinuation that occur during antiviral therapy in hepatitis C virus (HCV)-infected cirrhotic patients. We identified all the articles published prior to December 2011 in the PubMed, Medline, Lilacs, Scopus, Ovid, EMBASE, Cochrane and Medscape databases that presented these data in cirrhotic patients. These studies evaluated the rate of SAEs leading to discontinuation of standard care treatment: Pegylated interferon (PegIFN) alpha 2a (135-180 μg/wk) or PegIFN alpha 2b (1 or 1.5 μg/kg per week) and ribavirin (800-1200 mg/d). Patients with genotype 1 + 4 underwent treatment for 48 wk, whereas those with genotypes 2 + 3 were treated for 24 wk. We included 17 papers in this review, comprising of 1133 patients. Treatment was discontinued due to SAEs in 14.5% of the patients. The most common SAEs were: severe thrombocytopenia and/or neutropenia (23.2%), psychiatric disorders (15.5%), decompensation of liver cirrhosis (12.1%) and severe anemia (11.2%). The proportion of patients who needed to discontinue their therapy due to SAEs was significantly higher in patients with Child-Pugh class B and C vs those with Child-Pugh class A: 22% vs 11.4% (P = 0.003). A similar discontinuation rate was found in cirrhotic patients treated with PegIFN alpha 2a and those treated with PegIFN alpha 2b, in combination with ribavirin: 14.2% vs 13.7% (P = 0.96). The overall sustained virological response rate in cirrhotic patients was 37% (95%CI: 33.5-43.1) but was significantly lower in patients with genotype 1 + 4 than in those with genotype 2 + 3: 20.5% (95%CI: 17.9-24.8) vs 56.5% (95%CI: 51.5-63.2), (P < 0.0001). Fourteen point five percent of HCV cirrhotic patients treated with PegIFN and ribavirin needed early discontinuation of therapy due to SAEs, the most common cause being hematological disorders.

Portal Pressure Predicts Outcome and Safety of Antiviral Therapy in Cirrhotic Patients With Hepatitis C Virus Infection

There are limited data on the efficacy and safety of antiviral therapy in patients with hepatitis C virus (HCV)-related cirrhosis, particularly on the impact of portal hypertension. We assessed hepatovenous pressure gradient (HVPG), liver stiffness (transient elastography), and interleukin (IL)-28B polymorphisms (rs12979860) in 90 cirrhotic patients with HCV infection (82% genotype 1 or 4) before antiviral therapy with pegylated interferon and ribavirin. Efficacy and safety were evaluated. Rates of sustained virologic response were significantly lower among patients with clinically significant portal hypertension (CSPH; HVPG ≥ 10 mm Hg; n = 50) than among patients without CSPH (HVPG <10 mm Hg; n = 40): 14% vs 51% (P = .0007). Seventy-nine percent and 83% of patients with CSPH and without CSPH, respectively, received more than 80% of planned dose (P = .647). The predictive value of HVPG (area under the curve [AUC], 0.743) was greater than that of liver stiffness (AUC, 0.647) or of baseline HCV RNA levels (AUC, 0.620). The IL-28B polymorphism was not associated significantly with a sustained virologic response. Multivariate analysis revealed that HVPG (odds ratio [OR], 14.3; P = .009), baseline HCV RNA levels (OR, 5.3; P = .019), and HCV genotype (OR, 6.5; P = .046) were independent risk factors for treatment failure. A trend toward higher incidence of anemia and neutropenia was observed for patients with CSPH. The incidence and grade of thrombocytopenia were significantly higher among patients with than without CSPH (94% vs 75%; P = .006). HVPG is an independent predictor of response to antiviral therapy, with better predictive value than liver stiffness, baseline HCV RNA levels, HCV genotype, or IL-28B polymorphism. The incidence and grade of thrombocytopenia during antiviral therapy are higher among patients with CSPH. In evaluating cirrhotic HCV patients for antiviral treatment, measurement of HVPG should be considered.

An Escalating Dose Regimen of Pegylated Interferon and Ribavirin in HCV Cirrhotic Patients Referred for Liver Transplant

To lessen the severity of recurrent hepatitis C virus (HCV) postliver transplantation (post-LT) by treating HCV patients with cirrhosis, we assessed the safety and efficacy of an escalating dose pegylated interferon (PEG-IFN)/ribavirin protocol in pre-LT patients. Ninety patients were treated with 90 microg PEG-IFN alpha-2a and 400 mg ribavirin and advanced to 180 microg and 800 to 1200 mg, respectively, over 8 weeks. Mean age was 55.3 years. Thirty-four percent of patients received prior interferon treatment, 77% had genotype 1 or 4. Mean Child's score was 6.7 and model for end-stage liver disease 11.2; 49% reached full-dose PEG-IFN and 85% ribavirin, 18% required dose reduction, 33% stopped treatment because of adverse effects, 9% had deterioration of liver function, and 7% died. Follow-up of 9.6 months showed sustained virological response in 13% of patients. The rate of serious complications was 16.3% in Child's class A, 48% in B, and 100% in C (P=0.005). Serum albumin was a significant predictor for worsening liver function (P=0.007). Using an escalating dose regimen of PEG-IFN alpha-2a and ribavirin, we achieved only a 13% sustained virological response in HCV cirrhotic pre-LT patients with an accompanying 9% risk of worsening liver function and 7% risk of death.

Proteomic Analysis of HCV Cirrhosis and HCV-Induced HCC: Identifying Biomarkers for Monitoring HCV-Cirrhotic Patients Awaiting Liver Transplantation

Progression from chronic hepatitis C virus (HCV) infection to cirrhosis and hepatocellular carcinoma (HCC) results in protein changes in the peripheral blood. We evaluated global protein expression in plasma samples of HCV-cirrhotic and HCV-cirrhotic-HCC patients. Plasma samples from 25 HCV-cirrhotic-HCC and 10 HCV-cirrhotic patients were quantitatively evaluated for protein expression. Tryptic peptides were analyzed using Thermo linear ion-trap mass spectrometer (LTQ) coupled with a Surveyor HPLC system (Thermo). SEQUEST and X!Tandem database search algorithms were used for peptide sequence identification. Protein relative quantification was performed using the area under the curve from the select ion chromatogram. A significant fold change between groups was based on controlling the false discovery rate (FDR) at less than 5%. We identified and quantified 2320 proteins from the analysis of the different protein pattern between HCV-cirrhosis and HCV-HCC samples. Gene ontology terms classified the more important biologic process related to these proteins as signal transduction, regulation of transcription DNA-dependent, protein amino acid phosphorylation, cell adhesion, transport, and immune response. Seven proteins showed significant expression changes with a FDR less than 5% between cirrhosis and tumor groups. Moreover, 18 proteins showed significant expression changes (FDR <5%) when plasma samples from HCV-cirrhosis were compared with early HCV-HCC. Differential protein expression was observed between samples from HCV patients with cirrhosis with and without HCC. Also, differences were observed between early and advanced HCV-HCC samples. This study provides important information for discovery of potential biomarkers for early HCC diagnosis in HCV cirrhotic patients.

Leukocyte Interferon Alpha Early Retreatment for Child A HCV Genotype 1b-Infected Cirrhotics Intolerant to Pegylated Interferons

The pegylated interferon (PEG-IFN)/ribavirin combination has been shown to be effective for hepatitis C virus (HCV)-related compensated cirrhosis, but it frequently causes adverse events, leading to premature termination. In this open study we evaluated the safety and efficacy of early retreatment with leukocyte IFN-alpha in Child A HCV genotype 1b-infected cirrhotics intolerant to PEG-IFNs. 61 patients were treated with PEG-IFN (either alpha-2b 1.2-1.5 lg/kg weekly or alpha-2a 180 lg/weekly) plus ribavirin (1,000 mg/day) for 48 weeks. During the first 6 months, patients who discontinued treatment because of side effects were retreated with leukocyte IFN-alpha (6 MU/three times weekly) plus ribavirin (1,000 mg/day) for 48 weeks after a 1-month wash-out. The primary end points were safety and efficacy in terms of sustained virological response (SVR). At intention-to-treat analysis of the 61 patients receiving PEG-IFNs plus ribavirin revealed that 18 (29.5%) obtained a SVR. 16 patients (26.2%) prematurely discontinued treatment and were retreated with leukocyte IFN-alpha plus ribavirin. The switch was well tolerated, and all but one patient completed the treatment period. As a result of the switch, 4 of these 16 (25%) patients also obtained a SVR. Thus, the overall SVR rate of this study was 22/61 (36.1%). These results suggest that an early retreatment with leukocyte IFN-alpha may be a safe and valid therapeutic option among difficult-to-treat HCV cirrhotic patients who cannot tolerate PEG-IFNs.

Natural history of hepatitis-related hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an important cause of cancer death in the world. It has great regional differences in the pathology and epidemiology. The variation is greatly influenced by the aetiologies of the disease. Hepatitis B and C infection are the most important risk factors. HCC incidence rates are higher but in decreasing trend in developing countries. However, the figures in the developed countries are contrary. Successful hepatitis B virus (HBV) vaccination programs, better food hygiene, increased global hepatitis C virus (HCV) prevalence and population migration are the possible explanations. A number of clinical and pathogenic differences exist between HBV- and HCV-related HCC. HBV infection leads to the development of HCC through direct and indirect pathways as it has the ability to integrate into the host genome affecting cellular signaling and growth control. HCV causes HCC mainly through indirect pathways: chronic inflammation, cell deaths and proliferation. As a result, HCC is almost exclusively found in cirrhotic HCV patients while HCC is sometimes found in HBV patients without significant liver cirrhosis. Due to the different severities of liver cirrhosis and HCC extent, therapeutic strategies from resection, liver transplantation to symptoms palliation are available. Poorly differentiated histology, lack of fibrous capsule, large tumour size, early vascular invasion and elevated serum levels of alpha fetoprotein (AFP) are the features for more aggressive disease. Combined with markers of liver reserve and performance status, accurate scoring systems and models have been developed to predict patients' survival and match best treatment option.

Extracellular Branched-Chain Amino Acids, Especially Valine, Regulate Maturation and Function of Monocyte-Derived Dendritic Cells

The functions of dendritic cells (DCs) are impaired in patients with liver cirrhosis. It is well-known that cirrhotic patients show decreased levels of plasma branched-chain amino acids (BCAA). Although amino acids are associated with maintaining the cell structure and function in many organs, limited data are available regarding the role of amino acids including BCAA in the immune system. We aimed to investigate the roles of BCAA in the function of human monocyte-derived DCs (MoDC). CD14-positive monocytes (CD14 (+)) were isolated from PBMC from healthy volunteers and hepatitis C virus (HCV) cirrhotic patients. In medium deprived of BCAA or valine, monocytes were able to differentiate into immature, but not into mature, DCs and showed weak expression of CD83. The deprivation of leucine or isoleucine did not affect this process. The MoDC allostimulatory capacity was significantly decreased in medium deprived of BCAA or valine (p = 0.017, p = 0.012, Bonferroni's analysis, respectively). Annexin V(FITC)/propidium iodide staining showed that the DC yield and viability were not significantly different under any medium. Immunoblotting demonstrated that depletion of valine or leucine decreased phospho-S6 kinase expression. Valine increased dose-dependently the allostimulatory capacity and IL-12 production of MoDC from both healthy volunteers and HCV cirrhotic patients. An elevated extracellular concentration of valine could improve the DC function in cirrhotic patients. These data provide a rationale for nutrition therapy that could be beneficial to patients with cirrhosis.

Safe use of pegylated interferon/ribavirin in hepatitis C virus cirrhotic patients with hypersplenism after partial splenic embolization

Partial splenic embolization (PSE) is a non-surgical alternative for the treatment of hypersplenism. Thrombocytopenia precludes the use of pegylated interferon (peg-IFN) and ribavirin in cirrhotic patients with hepatitis C virus (HCV). We aimed to evaluate the role of PSE as a procedure allowing combined HCV therapy in this setting. A retrospective analysis of the safety and rate of sustained virological response (SVR) after a full-dose course of peg-IFN plus ribavirin in eight HCV cirrhotic patients with severe hypersplenism undergoing PSE at a tertiary centre in Madrid, Spain, from May 2002 to August 2004. Six patients (75%) were in Child-Pugh class B (median score 7). PSE significantly improved the mean platelet (P = 0.012), leucocyte (P = 0.017) and haemoglobin (P = 0.035) levels, and prothrombin activity (P = 0.012). After a mean of 20 weeks after PSE all patients started weight-adjusted ribavirin plus peg-IFN-alpha2b (n = 6) or 180 microg/week of peg-IFN-alpha2a (n = 2). Six subjects (75%) completed therapy with no peg-IFN dose reductions; the dose of ribavirin was reduced in two patients reaching haemoglobin levels of less than 10 g/dl (one also received erythropoietin and granulocyte colony-stimulating factor because of neutrophil counts < 300 cells/microl). Three patients (38%) achieved SVR. Portal vein thrombosis was observed in 50% of patients, but did not preclude antiviral therapy. The pathogenic mechanism was multifactorial. It was successfully managed with anticoagulant therapy in two cases. PSE allowed the safe use of peg-IFN plus ribavirin in HCV cirrhotic patients with severe cytopenias who otherwise would never have been treated. The rate of SVR was 38%.

Peginterferon and Ribavirin in Patients With HCV Cirrhosis After Liver Transplantation

The objective of the study was to assess the efficacy of antiviral therapy in patients with hepatitis C virus (HCV) recurrence after liver transplantation (OLT). We included 30 patients of mean age 56 years, who experienced HCV recurrence after OLT. Mean time from OLT to the beginning of therapy was 57 months (median: 43 months). All of them were on monotherapy: tacrolimus ( n = 21), cyclosporine ( n = 6), and mycophenolate mofetil ( n = 3). Fourteen had previously been diagnosed with allograft HCV cirrhosis. Patients were treated with peginterferon alpha 2b (1.5 μg/kg/weekly SC) and ribavirin (10.6 mg/kg/d) for 48 (genotypes 1, 4) or 24 weeks (genotypes 2, 3). After a mean follow-up of 20 months, two patients had died due to biliary sepsis (while on therapy) and acute myocardial infarction (7 months after the end of therapy). End of treatment virological response was achieved in 19 patients (63.3%) and sustained virological response (SUR) in 14 (46.7%). Comparing cirrhotic and noncirrhotic patients, SVR was achieved in seven patients in both groups (50% vs 43.8%; P = .732). Every patient had some adverse event; in 11 patients (36.7%) it was withdrawn (seven cirrhotic and four noncirrhotic; P < .05), and in 12 the starting dose was decreased (40%). There were neither rejection episodes nor cirrhotic complications during therapy, but infections were more common in cirrhotic patients (57% vs 25%; P < .05). In HCV cirrhotic transplanted patients the sustained virological response to combined antiviral therapy was similar to that in noncirrhotic patients, but severe adverse events including infections were much more common.

Insulin resistance impairs sustained response rate to peginterferon plus ribavirin in chronic hepatitis C patients

We evaluated the effect of insulin resistance and viral factors on sustained virological response in patients with chronic hepatitis C treated with peginterferon plus ribavirin. Patients (n=159; 94 men; age, 41.7 +/- 11.1 years) with chronic hepatitis C (genotype 1, n=113; non-1 genotype, n=46) received treatment with interferon plus ribavirin. Serum levels of leptin and insulin were measured, and the insulin resistance index (HOMA-IR: homeostasis model of assessment) and body mass index were calculated. A sustained virological response was associated with lower age, insulin resistance index, body mass index, and gamma-glutamyltranspeptidase and serum leptin levels. There was no association with viral load, sex, type of interferon, or cholesterol levels. A sustained virological response was achieved in 43.4% (46/113) of genotype 1 and 89% (32/36) of genotype 2 and 3 (P=.0001) patients. Necroinflammatory activity and steatosis were not associated with the sustained virological response rate. Multivariate regression analysis indicated that the independent variables related to sustained virological response were genotype (odds ratio, 3.57; 95% confidence interval, 1.49-8.3; P=.001), insulin resistance index (odds ratio, 1.82; 95% confidence interval, 1.08-3.06; P=.012), and fibrosis (odds ratio, 1.36; 95% confidence interval, 1.01-1.84; P=.029). A sustained virological response in patients with genotype 1 and insulin resistance (HOMA-IR > 2) occurred in 23 of 70 (32.8%; 95% confidence interval, 21.9%-43.9%) patients, vs. 26 of 43 (60.5%; 95% confidence interval, 45.9%-75.1%) genotype 1 patients without insulin resistance (P=.007; odds ratio, 3.12, 95% confidence interval, 1.42-6.89). Insulin resistance, fibrosis, and genotype are independent predictors of the response to antiviral therapy in chronic hepatitis C patients treated with peginterferon plus ribavirin.

Different effects of a CD14 gene polymorphism on disease outcome in patients with alcoholic liver disease and chronic hepatitis C infection

Clinical and experimental data suggest that gut-derived endotoxins are an important pathogenic factors for progression of chronic liver disease. Recently, a C-T (-159) polymorphism in the promoter region of the CD14 gene was detected and found to confer increased CD14 expression and to be associated with advanced alcoholic liver damage. Here, we investigated this polymorphism in patients with less advanced alcoholic liver disease (ALD) and chronic hepatitis C virus (HCV) infection. CD14 genotyping was performed by PCR-RFLP analysis in (a) 121 HCV patients, (b) 62 patients with alcohol-associated cirrhosis (Alc-Ci), (c) 118 individuals with heavy alcohol abuse without evidence of advanced liver damage (Alc-w/o Ci), and (d) 247 healthy controls. Furthermore, serum levels of soluble CD14 (sCD14) and transaminases were determined. The TT genotype was significantly more frequent in Alc-Ci compared to Alc-w/o Ci or controls (40.3% vs 23.7% or 24.0%, respectively). In Alc-w/o Ci, serum levels of transaminases did not differ significantly between patients with different CD14 genotypes. In HCV patients, TT-homozygotes had significantly higher sCD14 levels and sCD14 serum levels were significantly higher in patients with advanced fibrosis or cirrhosis. However, no association was found between CD14 genotypes and histological staging or grading. Considering serum transaminases as surrogate markers for alcoholic liver damage, the CD14 polymorphism seems to exhibit different effects during the course of ALD. Differences in genotype distribution between cirrhotic HCV patients and alcoholics and the known functional impact of this polymorphism on CD14 expression levels further indicate differences in the pathophysiological role of CD14 and CD14-mediated lipopolysaccharides signal transduction with regard to the stage as well as the type of the underlying liver disease.

Prevalence of type 2 diabetes mellitus in Brazilian liver transplant candidates: Negative association with HCV status

Recently, an epidemiological association between hepatitis C virus (HCV) infection and type 2 diabetes mellitus (DM) has been reported in several studies, although many of them did not consider known risk factors in the pathogenesis of type 2 DM. The aim of this study was to assess the prevalence of type 2 DM among Brazilian HCV (+) and HCV (−) liver transplant candidates, analyzing known confounding factors for the development of type 2 DM. We conducted a cross-sectional study to evaluate the prevalence of type 2 DM among 106 liver transplant adult candidates, comparing 36 HCV (+) cirrhotic patients with 70 HCV (−) patients who developed cirrhosis from other causes. Type 2 DM was diagnosed after two consecutive fasting glucose values ≥126 mg/dL. The age, sex, and race distribution, severity of liver disease (Child-Pugh score), and family history of DM were similar in both groups, but the mean body mass index (BMI) was higher in the HCV (−) subjects (26.81 ± 5.29 vs 24.0 ± 4.71, P < .01) Most of the patients were Caucasians (70.75%). Type 2 DM was detected in 36.11% of HCV (+) group and in 25.71% of the HCV (−) ( P = .27). A multivariate analysis revealed that family history of DM was the only significant independent predictor for DM (odds ratio = 2.55, 95% CI = 1.03 to 6.31, P = .04). In conclusion, our study did not show an association between HCV infection and Type 2 DM in Brazilian liver transplant candidates. It confirmed that the family history of DM was a determinant factor for the development of type 2 DM.

Occult HBV infection—both hidden and mysterious

Occult HBV infection—both hidden and mysterious