HBc Gene Research Articles

Prevalence of Hepatitis B Virus among Renal Dialysis Patients in Diyala Province, Iraq

Background: One of the main public health challenges in the globe is the prevalence of the hepatitis B virus (HBV). Objectives: The curent study aimed to determine the prevalence of hepatitis B virus in renal dialysis patients in Diyala province, Iraq. Methods: Ninety of renal dialysis patients attended Ibn-Sina Dialysis Center were screened for HBsAg, HBc IgG, HBc IgM and HBe Ab using ELISA technique, and then positive results were retested by conventional PCR for detection of HBs gene and HB core gene. Demographic data of study population were recorded. Simple statistical analysis was done using SPSS Version 25. Results: Among studied samples, the seroprevalence of HBsAg, Anti-HBc Ab, Anti-HBc IgM and Anti-HBe Ab were 4.4%, 17.8%, 2.2% and 5.6% respectively. The results of conventional PCR showed that only 1(1.1%) of HBs gene at 417 bp in renal dialysis patients were positive. Whereas, the HBc gene at 791 bp was not detected in all included study population. Conclusion: The prevalence of HBV was relatively high among renal dialysis in Diyala province/Iraq.

Most adults with severe HbSC disease are not treated with hydroxyurea.

Sickle cell hemoglobin SC (HbSC) disease is the second most frequent sickle cell disease (SCD) genotype after sickle cell anemia (HbSS). Globally, ∼55 000 newborns with HbSC are delivered annually, with the highest HbC gene frequency in West Africa. In Ghana, 40% of adults visiting the Ghana Institute of Clinical Genetics SCD clinic have HbSC. Unlike HbSS, hydroxyurea use is not routinely recommended for individuals with HbSC because of the perceived high-risk to benefit ratio. To test the hypothesis that at least 5% of adults with HbSC will meet the American Society of Hematology criteria for severe disease, we conducted a retrospective descriptive cohort study of all individuals with HbSC (≥18 years) who visited the clinic in 2019. Adults with HbSC aged from 18 to 45 years were selected. We identified a comparison group of 639 individuals with HbSS and matched the frequency based on the age and sex of individuals with HbSC. Severe disease was defined as a history of ≥3 SCD-associated moderate or severe pain episodes per year, history of acute chest syndrome, and severe symptomatic chronic anemia that interferes with daily activities or quality of life. The study end points were the proportion of individuals with SCD who met the definition of severe disease and were eligible for hydroxyurea. In total, 64 of 639 (10.0%) individuals with HbSC met the eligibility criteria for hydroxyurea therapy compared with 154 of 639 (24.1%) individuals with HbSS. Less than 1% and 3% of individuals with severe HbSC and HbSS, respectively, were routinely prescribed with hydroxyurea in this tertiary care medical center.

Prevalence of occult hepatitis B infection in Diyala province, Iraq

Background: Occult HBV infection (OBI) is the absence of hepatitis surface antigens (HBsAg) that is not apparent during detection by serological tests despite the presence of virus DNA. This study aimed to explore the prevalence of OBI infection among various populations in Diyala province, Iraq. Methods: A prospective cross-sectional study was conducted from 1st January to 30th September, 2021, at Ibn Sina Dialysis Center, Baquba Teaching Hospital, Iraq. Three hundred and sixty participants were equally involved (90 individuals for each) from the dialysis department, the thalassemia department, blood bank donation Centre, and the control group. Study populations were screened for HBV Ag, HBV c IgG, HBV c IgM, abusing the enzyme-linked immunosorbent assay (ELISA) test, and detecting HB core gene. Demographic data of the study group were recorded. Descriptive analysis was done using SPSS Version 25, and the P-value was considered significant wherever it was below 0.05. Results: The positivity rate of serological markers of OBI among the study population was (6.7%) of the participants were HBs Ag positive. Whereas 22 (6.1%) were anti-HBc IgG positive and 3 (0.8%) were anti-HBc IgM positive. The detection rates of the PCR products of 76 participants after amplification using specific primers for (core-gene) have been presented to the gel electrophoresis, which showed none of the 76 participants were positive for the HBc gene. Conclusion: The current study showed a medium percentage of anti-HBc IgG in the serum of the study groups without the presence of HBs Ag, which indicates the presence of a previous infection that was resolved or the occurrence of occult hepatitis B infection. The current study results also showed that the serum of any of the study groups was not positive for the core gene, which confirms the possibility of infection with OBI.

Multiple optimizations of recombinant plasmid for improving expression of Hepatitis B core antigen in Escherichia coli

Hepatitis B core antigen (HBcAg) can self-assemble into virus-like particles (VLPs) when expressed in Escherichia coli. We optimized the different of the expression plasmid pBV220, including the ribosome bind site (RBS), spacer region, promoter and replication origin (ori), as well as the hbc gene dosage, to enhance HBcAg transcription and translation in E. coli. The optimized construct with a customized RBS6, 6 nt spacer, T7 promoter and pUCori significantly increased the levels of HBc36GFP fusion protein to 3.4-folds compared to the control. Thereafter, we substituted hbc36gfp gene with different copies of the hbc gene and tested the effects of gene dosage on HBcAg expression. The HBcAg-VLPs yield obtained using an engineered strain with three copies of hbc was 842.1 ± 46.8 μg/mL, which was 2.2-folds higher compared to that in the control strain. Thus, our study provides a simple and effective strategy for improving HBcAg expression in E. coli. Since the HBcAg-VLPs are promising carriers for presenting foreign antigen epitopes, an in vitro expression system that can generate high levels of HBcAg-VLPs can serve as a promising tool for developing novel HBV vaccines and drugs.

In Africa, a High Proportion of Adults with HbSC Meet American Society of Hematology's Eligibility Criteria for Severe Sickle Cell Disease and Starting Hydroxyurea Therapy in a Clinical Trial Setting

▪Introduction: Sickle cell disease (SCD), HbSC, is the second most frequent hemoglobinopathy after HbSS. Worldwide, an estimated 54,736 babies are delivered annually with HbSC disease, with the highest HbC gene frequency in West Africa (Piel et al.2013). A retrospective study at the Ghana Institute of Clinical Genetics [(GICG), a sickle cell clinic] reported that 40% of the 3,000 SCD patients attending the clinic yearly are HbSC (Asare et al.2018). HbSC disease usually results in a comparatively milder form of SCD. However, rates of maternal-fetal morbidity, retinopathy, avascular necrosis (AVN) of the hip, priapism, and chronic kidney disease are increased (Powars et al.2002; Oppong et al.2018). While microalbuminuria is lower in HbSC than HbSS, it still occurs in >23% of adults (Drawz et al.2016). In addition, thrombosis, silent cerebral infarction, sensorineural hearing loss, and pulmonary hypertension may be higher than previously suspected (Sathi et al.2019). Unlike HbSS, hydroxyurea is not routinely recommended for HbSC patients because they are all perceived to have a milder phenotype, with improved life expectancy. Thus, HbSC individuals are often excluded from randomized controlled trials in children and adults with SCD (Luchtman-Jones et al.2016).Given the high proportion of adults with HbSC in Ghana, who may benefit from hydroxyurea therapy, we tested the hypothesis that at least 5% of adults with HbSC will meet the ASH criteria for severe disease and treatment. Data indicating that a significant proportion of adults with HbSC are eligible for hydroxyurea could potentially support pilot safety trials to determine the optimal hydroxyurea dose to ameliorate symptoms while limiting toxicity. Data can also facilitate government health policy decisions to subsidize hydroxyurea costs.Methodology: We conducted a medical chart review of all adults with HbSC disease (total: 639; 18-45years) who attended the SCD clinic, GICG (January 1, 2019, to December 31, 2019). We identified a comparison group of 639 adults with HbSS, age, and gender-matched to the HbSC patients from the same clinic. Severe complications were defined as a history of ≥3 sickle cell-associated moderate to severe pain episodes/year, a history of severe acute chest syndrome (ACS), and severe symptomatic chronic anemia that interferes with daily activities or quality of life (Hydroxyurea and Transfusion Therapy for the Treatment of Sickle Cell Disease.2014). We defined acute pain episode as new onset of pain that lasts at least 4 hours, for which there is no explanation other than vaso-occlusion, which requires therapy with parenteral opioids in a medical setting (Ballas et al.2010). Severe symptomatic chronic anemia was defined as a drop in hemoglobin by ≥2g/dL below the steady state. Data were analyzed using SPSS version 23 and summarized as simple descriptive statistics. Study endpoints were the proportion of individuals with SCD who met the definition of severe disease and were eligible for hydroxyurea. We also calculated the pain and ACS incidence rates.Results: The 639 HbSC participants had a mean age of 30.8years during the one-year study period, which was identical to that of the HbSS group. At least 8.5% of HbSC adults had ≥three acute pain episodes/ year, while 1.6% had ACS. No HbSC patient had severe symptomatic chronic anemia . In total, 10.0%(64/639) of patients with HbSC disease met the eligibility criteria for hydroxyurea therapy, compared to 24.1%(154/639) of patients with HbSS, p=<0.001. The pain and ACS incidence rates for the HbSC and HbSS individuals were [74.6; 95% CI(67.9-81.3) and 2.3; 95% CI(1.2-3.5)] events per 100 patient-years vs. [123.0; 95% CI(114.4-131.6) and 5.6; 95% CI(3.8-7.5)] events per 100 patient-years respectively. Also, 1.1%(7/639), 7.7%(49/639), 0.5%(4/639), and 4.4%(11/252) of patients with HbSC had papillary necrosis, AVN, stroke, and priapism, respectively while 8.5%(54/639) of patients with HbSS had proteinuria, Table 1. Only 0.9%(HbSC) and 2.3%(HbSS) took hydroxyurea during the study period.Conclusion: Based on ASH's evidence-based guidelines, in a large SCD clinic at an academic medical center in Ghana, 10.0% of HbSC adults meet the criteria for shared decision-making to consider starting hydroxyurea therapy in a clinical trial setting. The optimal dose of hydroxyurea that maximizes benefit and minimizes toxicity in adults with HbSC is yet to be determined. [Display omitted] DisclosuresAsare: ASH Global Research Award: Research Funding.

Mutations within the HBc Gene of the Hepatitis B Virus: A Study on Iranian Patients

Hepatitis B virus (HBV) is a serious risk factor for several severe liver diseases such as cirrhosis and hepatocellular carcinoma. HBV, like other viruses, uses several mechanisms to escape from specific immune responses including the use of mutations in the genome which lead to epitope variations. There are several immune responses, including T helper cells, cytotoxic T lymphocytes, and B cells, against the core antigen of HBV (HBcAg) that can lead to HBV eradication. Therefore, mutations within the HBc gene can lead to escape from immune responses by HBV and, hence, understanding the prevalence of HBc mutations among a specific population can be helpful for future treatment and vaccination. This review addresses the recent information regarding the prevalence of mutations within the HBc gene among Iranian HBV infected patients. The data presented here was collected gene sequences reported from Iran to the NCBI nucleotide Gen Bank. Results showed that the prevalence of HBc gene mutations is frequent in Iranian HBV infected patients. Based on our searches it seems that escape from immune responses is a plausible reason for the high prevalence of HBc gene mutations among Iranian HBV infected patients.

A Semliki Forest virus expression system as a model for investigating the nuclear import and export of hepatitis B virus nucleocapsid protein.

HBV core protein (HBc), the major component of nucleocapsid is known to have an essential role in the virus life cycle as the transporter of virus genome to the host nucleus; however, molecular details of the intracellular transport of HBc remain unknown. In this study, we investigated the intracellular distribution of the HBc protein resulting from Semliki Forest virus (SFV)-driven HBc gene and HBV RNA pregenome (pgRNA) expression in BHK-21 cells. Fluorescent confocal microscopy revealed extensive HBc protein synthesis in the cytoplasm 12 hr post infection (p.i.) with recombinant pSFV1/HBc or pSFV1/HBVpgRNA viruses. Twenty-four hr p.i., the HBc protein showed asymmetric, predominantly nuclear localization in most cells. However, 42 hr p.i., the number of cells containing intranuclear HBc protein, dramatically decreased to ~ 5%, while cytoplasmic HBc protein was detected in all cells. Remarkably, 24 hr p.i. with pSFV1/HBVpgRNA virus, cytoplasmic HBc protein colocalized with HBs protein. We conclude that a HBs-HBc interaction partially prevents the transport of HBc from the cytoplasm to nucleus. The SFV-driven system can be used for identification of new factors involved in the HBV nuclear import and export.

Highly efficient production of phosphorylated hepatitis B core particles in yeast Pichia pastoris

Virus-like particles (VLPs) of the recombinant hepatitis B virus (HBV) core protein (HBc) are routinely used in HBV diagnostics worldwide and are of potential interest as carriers of foreign peptides (e.g., immunological epitopes and targeting addresses, and/or as vessels for packaged diagnostic and therapeutic nanomaterials). Despite numerous reports exploiting different expression systems, a rapid and comprehensive large-scale methodology for purification of HBc VLPs from yeast is still lacking. Here, we present a convenient protocol for highly efficient production and rapid purification of endotoxin-free ayw subtype HBc VLPs from the methylotrophic yeast Pichia pastoris. The HBc gene expression cassette along with the geneticin resistance gene was transferred to the P. pastoris genome via homologous recombination. A producer clone was selected among 2000 transformants for the optimal synthesis of the target protein. Fermentation conditions were established ensuring biomass accumulation of 163 g/L. A simple combination of pH/heat and salt treatment followed by a single anion-exchange chromatography step resulted in a more than 90% pure preparation of HBc VLPs, with a yield of about 3.0 mg per 1 g of wet cells. Purification is performed within a day and may be easily scaled up if necessary. The quality of HBc VLPs was verified by electron microscopy. Mass spectrometry analysis and direct polyacrylamide gel staining revealed phosphorylation of HBc at at least two sites. To our knowledge, this is the first report of HBc phosphorylation in yeast.

Hepatitis B virus core protein inhibits TRAIL-induced apoptosis of hepatocytes by blocking DR5 expression

Hepatitis B virus (HBV) causes chronic hepatitis in hundreds of millions of people worldwide, which can eventually lead to hepatocellular carcinoma (HCC). The molecular mechanisms underlying HBV persistence are not well understood. TRAIL, the TNF-related apoptosis-inducing ligand, has recently been implicated in hepatocyte death during HBV infection. We report here that the HBV core protein (HBc) is a potent inhibitor of TRAIL-induced apoptosis. Overexpressing HBc significantly decreased TRAIL-induced apoptosis of human hepatoma cells, whereas knocking-down HBc expression in hepatoma cells transfected with HBV genome enhanced it. When present in the same cell, HBc blocked the pro-apoptotic effect of the HBV X protein (HBx). The resistance of HBc-expressing cells to TRAIL-induced apoptosis was associated with a significant reduction in death receptor 5 (DR5) expression. Upon transfection, HBc significantly repressed the promoter activity of the human DR5 gene. Importantly, HBc gene transfer inhibited hepatocyte death in a mouse model of HBV-induced hepatitis; and in patients with chronic hepatitis, DR5 expression in the liver was significantly reduced. These results indicate that HBc may prevent hepatocytes from TRAIL-induced apoptosis by blocking DR5 expression, which in turn contributes to the development of chronic hepatitis and HCC. They also call into question the potential side effects of HBc-based vaccines.

The paradox of hemoglobin SC disease

Homozygous HbC gene results only in mild hemolytic anemia. In HbSC disease red cells contain equal levels of HbS and HbC. It is a paradox that HbSC exhibit a moderately severe phenotype in spite of being a mixture of HbS trait and HbC trait, neither of which has significant pathology. Why does the combination of these two Hbs result in a serious disease? The short answer is that HbC enhances, by dehydrating the SC red cell, the pathogenic properties of HbS, resulting in a clinically significant disorder, but somewhat milder that sickle cell anemia (SCA). Nevertheless, retinnitis proliferans, osteonecrosis, and acute chest syndrome have equal or higher incidence in HbSC disease compared to SCA. This pathogenic trick is accomplished by HbC inducing, by mechanisms not fully understood, an increase in the activity of K:Cl cotransport that induces the lost of K + and consequently of intracellular water. This event creates a sufficient increase of MCHC, so that the lower levels of HbS found in SC red cells can polymerize rapidly and effectively. This situation offers a unique opportunity: if we could inhibit the effect of HbC on K + transport we can cure the disease.

Immune response induced by immunization with Hepatitis B virus core DNA isolated from chronic active hepatitis patients

There are many mutations in the gene encoding Hepatitis B virus (HBV) core antigen of chronic active hepatitis patients, and such mutations are most likely to be related to the severity of disease. Here, we constructed plasmids containing wild-type and deletion type of HBV core gene (HBc) to develop an experimental DNA vaccine and to compare immunogenicity of two types of HBc vaccine. Twenty-nine wild-types and seven deletion types of HBc were detected in sera of 32 Korean patients with chronic active hepatitis. Four wild-types (W1, W2, W4, W6) and two deletion types (D3, D4) of HBc were cloned into the pcDNA3 vector. Intramuscular immunization with wild-type HBc efficiently increased serum anti-HBc antibody response in a dose-dependent manner. Anti-HBc antibody response in mice injected with W6 increased 14 days after immunization, and peaked after 30 days and was maintained at least up to 50 days. W6 immunization induced a specific cytotoxic T lymphocyte response to W6-transfected 3LL (3LL-W6), and reduced the sizes of tumor mass of mice challenged with 3LL-W6 or 3LL transfected with D4. However, intramuscular immunization with D3 and D4 did not show antibody response at all. D3 and D4 have 157 bp (from 331 to 491 bp) and 122 bp (from 327 to 448 bp) gene deletion, respectively, and these encode class II MHC-restricted T-cell epitope. Altogether, these results suggest that mutant virus that has deleted HBc gene may evade immune systems due to loss of T-cell epitope.

DNA immunization with fusion genes containing HCV core region and HBV core region

The eucaryotic expression plasmids were constructed to express the complete (HCc191) or the truncated (HCc69 and HCc40) HCV core genes, solely or fused with the HBV core gene (HBc144). These constructions were transiently expressed in COS cells under the control of the CMV promoter. The antigenicity of HBc and HCc could be detected in the expression products by ELISA and Western blot. The mice immunized with these expression plasmids efficiently produced the anti-HCc antibodies, and also anti-HBc antibodies when the plasmids contained the fusion genes. In addition, the antibodies induced by the fusion genes were more persistent than those induced by the non-fusion HCV core genes. These indicate that the fusion of HCc genes to HBc gene is in favor of the immunogenicity of HCc, while the immunogenicity of HBc is not affected.

A comparison of the incidence of severe malaria in Malian children with normal and C-trait hemoglobin profiles

Although a protective effect against malaria has been demonstrated for several hemoglobin variants, no selective factor is established for the high incidence of HbC in regions of West Africa. Here we report a survey of hemoglobin profiles among children admitted with symptomatic and severe malaria to the Gabriel Touré Hospital in Bamako, Mali, where the frequency of the HbC gene is 8–10%. Children with AC and AA profiles presented with severe malaria at comparable rates, indicating lack of protection by the heterozygous state. Two admitted children, one of whom presented with cerebral malaria, were found to have SC profiles. No CC homozygotes were detected in the study cohort.

Population genetics of abnormal haemoglobins in Burkina Faso, West Africa

The gene frequencies of haemoglobin A (HbA), HbS and HbC were studied in Burkina-Faso (BF) and in a neighbouring region of Niger, Ayorou. The frequency of HbS was higher in the Sahel region, (northern part of BF and Ayorou) than in the Savanna region. The reverse was true for the HbC gene. The major findings of this study are: (a) confirmation of a peak of HbC gene frequency in the central region of BF (Mossi plateau); (b) a possible negative correlation between the frequencies of HbS and HbC-Cavalli-Sforza and Bodmer have observed that this correlation is at a significantly different level from that expected because of the allelic relationship between HbS and HbC; (c) comparison with the data collected by Livingstone shows a modification in the fitness of the different genotypes in the last thirty years: AS individuals have a lower and AA and SS a higher fitness. Our data favour a partial selection relaxation in this region.

Homology between HBV-DNA and a sequence regulating the interferon-induced antiviral system: possible mechanism of persistent infection.

Treatment of hepatitis B virus (HBV)-infected hepatocytes with lymphoblastoid alpha-interferon (IFN) leads to an increased expression of the core antigen (HBcAg) and reduced expression of surface antigen (HBsAg). We have identified the presence of a nucleotide sequence at the start of the HBc gene in the hepatitis B virus genome similar to a consensus sequence known to occur upstream from genes induced by IFN in mammalian cells. It is possible that interferon influences the expression of the viral genes because of the presence of this homologous sequence. This sequence in the viral genome may determine the site of integration of the virus and could influence the ability of the cell containing the integrated viral sequence to respond to interferon. This "neutralisation" of the interferon system by viral integration might not only facilitate persistent infection but might also adversely affect response to alpha-interferon therapy.

Induction of hepatitis B virus core gene in human cells by cytosine demethylation in the promoter.

A recombinant human cell line constructed by transfection of epithelial cells with a plasmid containing the hepatitis B virus core gene (HBc) was used to study the regulation of HBc gene expression. Methylation of a single Hpa II site 280 base pairs upstream from the structural gene was found to regulate the expression of the core gene. Expression increased in cells treated with 5'-azacytidine as a result of cytosine demethylation at this site, and there was a fivefold increase in the number of HBc gene transcripts in total cellular messenger RNA. The varied life cycle of hepatitis B virus in disease such as viral hepatitis and liver cancer may therefore be attributable to the site-specific regulation of the gene involved in replication of the viral DNA and to the cytophathic effects elicited by this gene in human cells.

High-frequency transfection and cytopathology of the hepatitis B virus core antigen gene in human cells.

A protoplast fusion method was developed to stably transfect human cells with pSV2-derived plasmids at frequencies greater than 10(-3). This procedure made it possible to test the biological effect of a hepatitis B virus (HBV) gene independent of the viral structures required for infection. A pSV2gpt+ plasmid constructed to carry a subgenomic fragment of HBV that contained the core antigen gene (HBc gene) was transfected into human cells. A human epithelial cell line was stably transfected with the HBc+ gene by selecting recipient cells for expression of guanine phosphoribosyl transferase expression. With this gpt+/HBc+ cell line it was shown that growth in serum-free medium or treatment with 5'-azacytidine stimulates the production of the HBV core antigen. A hepatocellular carcinoma carrying the entire HBV genome was stimulated to produce the HBc gene product in response to the same factors that stimulated HBcAg production in the gpt+/HBc+ cell line constructed by transfection. The temporal relation between the cytopathologic response and HBc gene expression was similar for both cell types, indicating a primary role for HBc gene expression in the cytopathology of HBV-infected human liver.