Occult hepatitis B infection among blood donors from Yaoundé, Cameroon

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.

Host immunity and HBV S gene mutation in HBsAg-negative HBV-infected patients

Background

Clinically, some patients whose HBsAg becomes negative owing to antiviral therapy or spontaneously still show a low level of HBV DNA persistence in serum. T-lymphocyte subsets, cytokine levels and HBV S gene sequences were analyzed in this study.

Methods

A total of 52 HBsAg-negative and HBV DNA-positive patients(HBsAg-/HBV DNA+ patients), 52 persistently HBsAg-positive patients(HBsAg+/HBV DNA+ patients) and 16 healthy people were evaluated. T-lymphocyte subsets of these patients were detected by flow cytometry, serum cytokines and chemokines were detected by the Luminex technique, and the HBV S region was evaluated by Sanger sequencing. T%, T-lymphocyte, CD8+ and CD4+T lymphocyte were lower in the HBsAg-negative group than in the HC group. Compared with the HBsAg-positive group, the HBsAg-negative group had lower levels in T lymphocyte %, CD8+T lymphocyte %, CD8+T lymphocyte and CD4/CD8. These difference were statistically significant (P<0.05). Serum IFN-γ, IFN-α and FLT-3L levels were significantly higher in the HBsAg-negative group than in the HBsAg-positive group (P<0.05). However, levels of many cytokines related to inflammation (i.e., IL-6, IL-8, IL10, IL-12, IL-17A) were lower in the HBsAg-negative group. Fifty-two HBsAg-negative samples were sequenced, revealing high-frequency amino acid substitution sites in the HBV S protein, including immune escape mutations (i.e., Y100C, S114T, C124Y, P127L, G130R, T131N, M133T, C137S, G145A) and TMD region substitutions (i.e., E2K/R/D, G7D/R, G10D, A17R, F20L/S, L21V, L22V).

Conclusions

According to the results of T-lymphocyte subsets and serum cytokines, it can be deduced that the cellular immune function of HBsAg-negative patients is superior to that of HBsAg-positive patients, with attenuation of liver inflammation. HBsAg-negative patients may show a variety of mutations and amino acid replacement sites at high frequency in the HBV S region, and these mutations may lead to undetectable HBsAg, HBsAg antigenic changes or secretion inhibition.

High Frequency Occult Hepatitis B Virus Infection Detected in Non-Resolved Donations Suggests the Requirement of Anti-HBc Test in Blood Donors in Southern China

Background

Most Chinese Blood Centers adopted mini pool (MP) nucleic acid testing (NAT) for HBV screening due to high cost of Individual donation (ID) NAT, and different proportions of MP-reactive but ID-non-reactive donations (MP+/ID-, defined as non-resolved donations) have been observed during daily donor screening process. Some of these non-resolved donations are occult HBV infections (OBIs), which pose potential risk of HBV transmission if they are not deferred. This study is aimed to further analyze these non-resolved donations.

Methods

The non-resolved plasma samples were further analyzed by serological tests and various HBV DNA amplification assays including quantitative PCR (qPCR) and nested PCR amplifying the basic core and pre-core promoter regions (BCP/PC; 295 base pairs) and HBsAg (S) region (496 base pairs). Molecular characterizations of HBV DNA+ non-resolved samples were determined by sequencing analysis.

Results

Of 17,226 MPs from 103,356 seronegative blood donations, 98 MPs were detected reactive for HBV. Fifty-six out of these 98 (57.1%) reactive MPs were resolved as HBV DNA+, but the remaining 42 pools (42.9%, 252 donations) were left non-resolved with a high rate (53.2%) of anti-HBc+. Surprisingly, among 42 non-resolved MPs, 17 contained one donation identified as OBIs by alternative NAT assays. Sequence analysis on HBV DNAs extracted from these OBI donations showed some key mutations in the S region that may lead to failure in HBsAg detection and vaccine escape.

Conclusion

A total of 53.2% of the non-resolved donations were anti-HBc+, and OBIs were identified in 40.5% of these non-resolved pools. Therefore, non-resolved donations with anti-HBc+ might pose potential risk for HBV transmission. Our present analysis indicates that anti-HBc testing in non-resolved donations should be used to identify OBIs in order to further increase blood safety in China.

Prevention of hepatitis B reactivation in patients requiring chemotherapy and immunosuppressive therapy

Hepatitis B virus (HBV) reactivation can lead to severe acute hepatic failure and death in patients with HBV infection. HBV reactivation (HBVr) most commonly develops in patients undergoing cancer chemotherapy, especially B cell-depleting agent therapy such as rituximab and ofatumumab for hematological or solid organ malignancies and that receiving hematopoietic stem cell transplantation without antiviral prophylaxis. In addition, the potential consequences of HBVr is particularly a concern when patients are exposed to either immunosuppressive or biologic therapies for the management of rheumatologic diseases, inflammatory bowel disease and dermatologic diseases. Thus, screening with HBV serological markers and prophylactic or pre-emptive antiviral treatment with nucleos(t)ide analogues should be considered in these patients to diminish the risk of HBVr. This review discusses the clinical manifestation, prognosis and management of HBVr, risk stratifications of cancer chemotherapy and immunosuppressive therapy and international guideline recommendations for the prevention of HBVr in patients with HBV infection and resolved hepatitis B.

Occult hepatitis B virus infection in Sudan: A systematic review and meta-analysis

In its occult form, hepatitis B virus infection can only be detected using molecular techniques such as polymerase chain reaction, increasing the cost of the screening process. Certain population subgroups are considered to have a higher risk of transmission and reactivation of occult hepatitis B virus infection (OBI). This review aims to estimate the prevalence of OBI among these high‐risk groups in Sudan. It was conducted under the PRISMA guidelines, targeting the literature available in MEDLINE/PubMed, ScienceDirect, Google Scholar, and Cochrane Library databases. Full‐text articles published in the last 10 years that provide prevalence estimates of OBI in Sudan were examined for fulfillment of eligibility criteria. Quality assessment of selected articles was performed using the critical appraisal tool reported by Munn et al. Publication bias was assessed by visual examination of the funnel plot. Meta‐analysis using the random‐effects model with 95% confidence interval was used to calculate the overall and subgroup pooled prevalence of OBI. Literature search yielded a total of 717 studies, of which only 11 articles fulfilled all selection criteria. The overall pooled prevalence of OBI was found to be 15.51%, with a high level of heterogeneity. Subgroup analysis demonstrated a prevalence of 16.48% among blood donors, 13.36% among hemodialysis patients, and 12.59% among febrile patients. Evidence for possible publication bias was detected. This review provides crucial evidence for health authorities in Sudan, outlining the necessity for re‐evaluation of the current screening strategies, especially among these high‐risk groups.