Detection of occult HBV infection by nested PCR assay among chronic hepatitis C patients with and without hepatocellular carcinoma

Genetic diversity and occult hepatitis B infection in Africa: A comprehensive review

BACKGROUND

Occult hepatitis B infection (OBI) is a globally prevalent infection, with its frequency being influenced by the prevalence of hepatitis B virus (HBV) infection in a particular geographic region, including Africa. OBI can be transmitted through blood transfusions and organ transplants and has been linked to the development of hepatocellular carcinoma (HCC). The associated HBV genotype influences the infection.

AIM

To highlight the genetic diversity and prevalence of OBI in Africa.

METHODS

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and involved a comprehensive search on PubMed, Google Scholar, Science Direct, and African Journals Online for published studies on the prevalence and genetic diversity of OBI in Africa.

RESULTS

The synthesis included 83 articles, revealing that the prevalence of OBI varied between countries and population groups, with the highest prevalence being 90.9% in patients with hepatitis C virus infection and 38% in blood donors, indicating an increased risk of HBV transmission through blood transfusions. Cases of OBI reactivation have been reported following chemotherapy. Genotype D is the predominant, followed by genotypes A and E.

CONCLUSION

This review highlights the prevalence of OBI in Africa, which varies across countries and population groups. The study also demonstrates that genotype D is the most prevalent.

Prevalence of occult hepatitis B virus infection in Egypt: a systematic review with meta-analysis

BACKGROUND

Occult hepatitis B virus (HBV) infection (OBI) is a major public health problem. The clinical importance of OBI stems from the fact that it can be transmitted to healthy individuals at extremely low viral load levels. Additionally, immunosuppression has the potential to trigger viral replication, which can result in life-threatening liver decompensation. Despite several studies examining the prevalence of OBI, the pooled prevalence of OBI in Egypt remains unknown, particularly among blood donors and high-risk individuals, to whom intervention should be targeted.

METHODS

A comprehensive literature search of the following databases was conducted from inception to October 2022 using the following keywords: occult hepatitis B virus infection or occult HBV infection or OBI and Egypt in MEDLINE [PubMed], Scopus, Google Scholar, and Web of Science. The review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement. I-squared and Cochran's Q were used to measure the heterogeneity between the studies, and based on the random effects model, results were reported as proportions (%) with a 95% confidence interval (CI). Analyses of subgroup analyses were conducted based on the target population. Sensitivity analyses were conducted using the leave-one-out approach to test the robustness of the results.

RESULTS

A total of 50 studies with 62 estimations of OBI were included, 19 in patients who were HBsAg-negative and anti-HBc-positive and 43 in patients who were HBsAg-negative. The highest prevalence (41%) was among multi-transfused patients according to  studies that report occult hepatitis B virus prevalence in an HBsAg-negative population, while the pooled prevalence of OBI among patients on hemodialysis, patients with chronic hepatitis C infection, patients with hepatocellular carcinoma (HCC), and patients with liver cirrhosis was 17%, 10%, 24%, and 13%, respectively. On the other hand, among studies that report OBI prevalence in HBsAg-negative and anti-HBc-positive individuals, the pooled prevalence of OBI among blood donors, patients with chronic hepatitis C infection, and patients with HCC was 12%, 15%, and 31%, respectively. Also, the majority of studies examining the genetic background of OBI have found that genotype D is the most prevalent.

CONCLUSION

 This study highlights the high prevalence in OBI among blood donors and high-risk populations in Egypt. The implementation of HBV nucleic acid amplification testing (NAT) may increase the safety of blood transfusions by excluding all HBV DNA-positive donations. However, the cost-effectiveness of these tests should be investigated.

Prevalence of occult hepatitis B virus infection among patients receiving haemodialysis in Sana'a city

BACKGROUND

Occult hepatitis B virus infection (OBI) is a challenging entity. Due to the increase in invasive procedures, blood transfusions, and difficulties in diagnosing OBI, patients are more likely to acquire OBI. This cross-sectional study was conducted to assess the prevalence of OBI by hepatitis B virus (HBV)-DNA detection, the prevalence of HBV infection by total hepatitis B core antibody (HBcAb) detection, and the potential risk factors for HBV infection in patients receiving haemodialysis regularly.

METHODS

This study included 80 patients receiving haemodialysis regularly, without acute or chronic HBV infection. They were selected from the dialysis units in Sana'a city, Yemen from June 2016 to June 2017. Patients who were positive for hepatitis B surface antigen and hepatitis B surface antibody were excluded from this study. Blood samples were taken prior to each haemodialysis session, and serological markers of HBV were included. HBcAb was measured by enzyme-linked immunosorbent assay, and HBV-DNA was measured by polymerase chain reaction.

RESULTS

HBV-DNA was detected in four patients (5%) and HBcAb was detected in 38 patients (47.5%). There was a significant association between HBV-DNA and HBcAb in patients receiving haemodialysis regularly.

CONCLUSIONS

Patients who test positive for HBcAb should undergo additional HBV-DNA testing to allow accurate HBV screening and prevent infection of other patients.

Epidemiology of occult hepatitis B and C in Africa: A systematic review and meta-analysis

BACKGROUND

Occult hepatitis B (OBI) and C (OCI) infections lead to hepatic crises including cases of liver cirrhosis and even hepatocellular carcinoma (HCC). OBI and OCI also pose a significant problem of their transmissibility. This study aimed to assess the overall prevalence of OBI and OCI in the African continent, a region highly endemic for classical hepatitis B and C viruses.

METHODS

For this systematic review and meta-analysis, we searched: PubMed, Web of Science, African Journal Online and African Index Medicus for published studies on the prevalence of OBI and OCI in Africa. Study selection and data extraction were performed by at least two independent investigators. Heterogeneity (I²) was assessed using the χ² test on the Cochran Q statistic and H parameters. Sources of heterogeneity were explored by subgroup analyses. This study was registered in PROSPERO, with reference number CRD42021252772.

RESULTS

We obtained 157 prevalence data for this meta-analysis, from 134 studies for OBI prevalence; 23 studies on OCI prevalence, and a single study on the OBI case fatality rate. The overall estimate for the prevalence of OBI was 14.8% [95% CI = 12.2-17.7] among 18579 participants. The prevalence of seronegative OBI and seropositive OBI was 7.4% [95% CI = 3.8-11.8] and 20.0% [95% CI = 15.3-25.1] respectively. The overall estimate for the prevalence of OCI was 10.7% [95% CI = 6.6-15.4] among 2865 participants. The pooled prevalence of seronegative OCI was estimated at 10.7% [95%CI = 4.8-18.3] and that of seropositive OCI at 14.4% [95%CI = 5.2-22.1]. In Sub-group analysis, patients with malignancies, chronic hepatitis C, and hemodialysis had a higher OCI prevalence. While those with malignancies, liver disorders, and HIV positive registered highest OBI prevalence.

CONCLUSION

This review shows a high prevalence of OBI and OCI in Africa, with variable prevalence between countries and population groups.

Occult Hepatitis (B) Infection in Hepatitis (C) Virus Infection Patients after the Treatment with Direct Acting Antiviral Drugs

Background: The prevalence of occult hepatitis B ranges widely in patients with hepatitis C. This may have an impact on treatment of hepatitis C. Aims: The current study aimed to evaluate the prevalence of occult hepatitis B infection in chronic hepatitis C patients who finished the course of treatment with direct acting antiviral drugs and it’s correlation with treatment failure. Setting: Outpatient Clinic of Internal Medicine Department, Faculty of Medicine, Menoufia University, Egypt. Patients and methods: This study was conducted on 900 Egyptian patients chronically infected with HCV. All patients tested positive for serum real time polymerase chain reaction for HCV- RNA and received DAAs therapy for 12 weeks. Patients were categorized to:  Group I: 450 patients with chronic hepatitis C after direct antiviral treatment who responded to treatment. Group II: 450 patients with chronic hepatitis C after direct antiviral treatment who didn’t respond to treatment. All patients were submitted to clinical examination, laboratory investigations and abdominal ultrasonography. Detection of HBV- DNA and HCV- RNA was performed by PCR. Results: The prevalence of OBI detected in sera of HCV patients was 10.6 % (96/900). The present study showed no significant correlation between prevalence of OBI and virologic failure (p-value: 0.084).  There was no statistically significant difference (p-value > 0.05) between the studied groups as regard prevalence of OBI. Conclusion: The prevalence of OBI was 10.6% in patients chronically infected with HCV. OBI doesn't affect the anti-HCV DAAs outcomes.

Epidemiology, risk factors, and molecular characterization of occult hepatitis B infection among anti-hepatitis B core antigen alone subjects

OBJECTIVES

Features of occult hepatitis B virus (HBV) infection among the anti-hepatitis B core antigen (anti-HBc) positives have yet to be described in more details. This study aimed to determine the molecular prevalence of occult HBV infection (OBI), and association to risk factors among seropositives for anti-HBc.

METHODS

This was part of a community-based screening project that included 5234 cases. All participants completed a questionnaire on demographic and socio-epidemiological information. Then, the blood samples were collected and tested for anti-HBc and HBsAg using ELISA method. To identify OBI, nested-polymerase chain reaction (PCR) assays were performed for HBV-S and X genes, and viral load was determined using an in-house real-time PCR. Sequencing and phylogenetic analysis have been implemented for genotyping.

RESULTS

Overall, 596 cases, positive only for anti-HBc were included in the study. OBI was detected among 61 cases (10.2%). The genotype and subgenotype of HBV among all of them was D1, except one that was D4. Most of them had low viral loads ranged from 1.2 × 10² to 1.34 × 10 ³  copies/mL; 19.6% had undetectable viral loads. Important mutations in surface protein and reverse transcriptase were sI92T, sQ129H, rtL80I, rtS85F, rtL91I. The prevalence of OBI was related to some risk factors, such as tattooing (P = 0.02), sexual activities (P = 0.009), and diabetes (P = 0.031).

CONCLUSION

Our study suggests that OBI should be considered among anti-HBc seropositive subjects. This form of HBV infection was accompanied with some mutations, risk factors, and diseases. However, further investigations are needed to determine virological importance of documented mutations.

Effectiveness of PCR primers for the detection of occult hepatitis B virus infection in Mexican patients

BACKGROUND

Occult hepatitis B infection (OBI) is defined as the presence of hepatitis B virus (HVB) DNA in the liver of HBsAg negative individuals with or without detectable viral DNA in serum. OBI is a diagnostic challenge as it is characterized by a very low viral load, intermittently detectable through time. Individuals with OBI can develop chronic hepatic disease, including liver cirrhosis and hepatocellular carcinoma. The aim of this work was to produce tools to improve OBI detection of the HVB genotypes prevalent in Mexico.

METHODS

We designed and tested primers to detect OBI in serum samples by nested and real-time PCR. Conserved sites in the viral genome were determined by alignment of the most frequent HBV genotypes in Mexico (H, G/H, F and D) and primers spanning the entire viral genome were designed for first round and nested PCR. Primers were tested in serum samples of 45 patients not co-infected with hepatitis C virus or with HIV, out of a group of 116 HBsAg (-)/anti-HBc (+) individuals. Primers were also tested in a control group with chronic HBV. Nested PCR products obtained from HBsAg (-)/anti-HBc (+) were sequenced and used to design primers for real-time PCR (SYBR Green).

RESULTS

The most effective primer pairs to detect HBV products by nested PCR targeted ORF regions: PreS2/P, S/P, X/PreC, and C; while by real-time PCR they targeted ORF regions PreS2/P, S/P, X, and C. Out of the 45 HBsAg (-)/anti-HBc (+) patients tested, the viral genome was detected in 28 (62.2%) and 34 (75.5%), with nPCR and real-time PCR respectively.

CONCLUSION

Primers designed for real-time PCR detected up to 75.5% of suspected OBI Mexican patients, with or without liver disease, which represents an improvement from previous PCR strategies.

Integrating nested PCR with high-throughput sequencing to characterize mutations of HBV genome in low viral load samples

Due to the low viral load of hepatitis B virus (HBV) in plasma samples, conventional techniques have limitations to the detection of antiviral resistance mutations. To solve the problem, we developed a fast, highly sensitive, and accurate method to sequence the HBV whole-genome sequencing in plasma samples which had various viral loads from very low to high.Twenty-one plasma samples were collected from patients who were carriers of HBV from the Hangzhou First People's Hospital. Two pairs of conserved, overlapping, nested primers were used to amplify and sequence the whole HBV genome in 8 plasma samples with different viral loads. High-throughput sequencing was performed on Illumina MiSeq platform. Concomitantly, 3 samples were directly sequenced without PCR amplification. We compared amplicon-sequencing with direct sequencing to develop a method for amplifying and characterizing the whole genome of HBV.HBV genome was amplified from all samples and verified by Sanger sequencing, regardless of the viral loads. Sequencing results revealed that only a few reads were mapped to the HBV genome following direct sequencing, while the amplicon-sequencing reads had a good coverage and depth. We identified 50 intrahost single nucleotide variations (iSNVs), 14 of which were low frequency mutations. Interestingly, iSNVs were more common in low viral load samples than in high viral load samples, and mutations in the reverse transcriptase (RT) region were most prevalent.We conclude that amplicon-sequencing is not only a practical method to detect HBV infection with a high sensitivity and accuracy but also enables to detect mutations in the HBV genome in low viral load samples from HBV-infected patients. Thus, our findings provide a new diagnosis method of HBV infection, which is capable of detection of low frequent mutations in low viral load samples.