Hepatitis B virus subgenotype A1, occurrence of subgenotype D4, and S gene mutations among voluntary blood donors in Kenya

Molecular epidemiology of hepatitis B virus (HBV) in Ethiopia: A review article

Hepatitis B virus (HBV) belongs to the family Hepadnaviridae and is the smallest human DNA virus, with a genome that is only 3200 nucleotides long. The absence of proofreading function in HBV reverse transcriptase provides a wide range of genetic variants for targeted outgrowth at different stages of infection. A number of sub genotypes and ten HBV genotypes (A through J) have been identified through analyses of the divergence of HBV genomic sequences. Numerous clinical outcomes, including the emergence of chronicity, the course of the disease, the effectiveness of treatment, and the response to vaccination, have been related to differences in genotype between HBV isolates. There are just seven studies that have been done in Ethiopia that examine the molecular epidemiology of HBV. Moreover, these studies haven't been compiled and reviewed yet. In this review, we looked at the genetic diversity and molecular epidemiology of HBV, the relationship between HBV genotypes and clinical outcomes, the immunopathogenesis of HBV, and finally the molecular epidemiology of HBV in Ethiopia. PubMed, Embase, and Google Scholar search engines were used to find relevant articles for the review. By using HBV genotyping, clinicians can better tailor vaccination decisions and antiviral therapy for patients with chronic hepatitis B who are more likely to experience the disease's progression.

Seroprevalence of human immunodeficiency virus in African blood donors: a systematic review and meta-analysis

BACKGROUND

In developing countries, the safety of blood transfusions remains an important public health concern as it is associated with a higher risk of transfusion-transmissible infections (TTIs). In this study, we aimed to estimate the seroprevalence of HIV among blood donors in Africa and assess the temporal trends and regional differences within the continent through a systematic review and meta-analysis.

METHODS

Seven electronic databases (PubMed, Web of Science, Cochrane, Scopus, HINARI, Global Index Medicus and Clinical.

TRIAL

gov) were searched for relevant studies for our research. We included all primary studies that estimated the seroprevalence of HIV among blood donors in Africa with an age population from 16 to 65 years old, without language restrictions, from inception up to March 1st 2024. The pooled seroprevalence was estimated through the DerSimonian-Laird random effects model. The temporal trends and regional differences were assessed through subgroup and meta-regression analysis.

FINDINGS

We obtained 122 studies that met our inclusion criteria, comprising 7,814,996 blood donors tested for HIV. Sixty-six percent of the studies were from Western and Eastern Africa. The pooled seroprevalence of HIV among blood donors in Africa was 2.66% (95% CI: 2.17-3.20%; I2 = 99.80%, p < 0.01). The highest prevalence was observed in the Central African region, 3.28% (95% CI: 2.57%-4.06%), followed by the Eastern 3.21% (95% CI: 2.12%-4.52%), and the Western 2.66% (95% CI: 1.93%-3.49%) regions. Lower prevalences were observed in the Northern region, 0.57% (95% CI: 0.0%-2.10%), followed by the Southern African region with 0.45% (95% CI: 0.16%-0.86%). We observed a temporal decreased trend of HIV prevalence.

INTERPRETATION

The prevalence of HIV infection among African blood donors remains high and is not homogeneous across the continent. Efficient measures to strengthen HIV testing and prevent HIV transmission through blood transfusion are needed in Africa. Systematic review protocol registration: PROSPERO CRD42023395616.

FUNDING

This article was supported by National Funds through FCT - Fundação para a Ciência e a Tecnologia,I.P., within CINTESIS, R&D Unit (reference UIDP/4255/2020).

Genetic diversity, haplotype analysis, and prevalence of Hepatitis B virus MHR mutations among isolates from Kenyan blood donors

BACKGROUND

The rapid spread of HBV has resulted in the emergence of new variants. These viral genotypes and variants, in addition to carcinogenic risk, can be key predictors of therapy response and outcomes. As a result, a better knowledge of these emerging HBV traits will aid in the development of a treatment for HBV infection. However, many Sub-Saharan African nations, including Kenya, have insufficient molecular data on HBV strains circulating locally. This study conducted a population-genetics analysis to evaluate the genetic diversity of HBV among Kenyan blood donors. In addition, within the same cohort, the incidence and features of immune-associated escape mutations and stop-codons in Hepatitis B surface antigen (HBsAg) were determined.

METHODS

In September 2015 to October 2016, 194 serum samples were obtained from HBsAg-positive blood donors residing in eleven different Kenyan counties: Kisumu, Machakos, Uasin Gishu, Nairobi, Nakuru, Embu, Garissa, Kisii, Mombasa, Nyeri, and Turkana. For the HBV surface (S) gene, HBV DNA was isolated, amplified, and sequenced. The sequences obtained were utilized to investigate the genetic and haplotype diversity within the S genes.

RESULTS

Among the blood donors, 74.74% were male, and the overall mean age was 25.36 years. HBV genotype A1 (88.14%) was the most common, followed by genotype D (10.82%), genotype C (0.52%), and HBV genotype E (0.52%). The phylogenetic analysis revealed twelve major clades, with cluster III comprising solely of 68 blood donor isolates (68/194-35.05%). A high haplotype diversity (Hd = 0.94) and low nucleotide diversity (π = 0.02) were observed. Kisumu county had high number of haplotypes (22), but low haplotype (gene) diversity (Hd = 0.90). Generally, a total of 90 haplotypes with some consisting of more than one sequence were observed. The gene exhibited negative values for Tajima's D (-2.04, p<0.05) and Fu's Fs (-88.84). Several mutations were found in 139 isolates, either within or outside the Major Hydrophilic Area (MHR). There were 29 mutations found, with 37.9% of them situated inside the "a" determinant. The most common mutations in this research were T143M and K122R. Escape mutations linked to diagnostic failure, vaccination and immunoglobulin treatment evasion were also discovered. Also, one stop-codon, W163STP, inside the MHR, was found in one sample from genotype A.

CONCLUSION

In Kenya, HBV/A1 is still the most common genotype. Despite limited genetic and nucleotide diversity, haplotype network analysis revealed haplotype variance among HBV genotypes from Kenyan blood donors. The virological properties of immune escape, which may be the source of viral replication endurance, were discovered in the viral strains studied and included immune-escape mutations and stop-codon. The discovery of HBsAg mutations in MHR in all isolates highlighted the need of monitoring MHR mutations in Kenya.

A systematic review of Hepatitis B virus (HBV) prevalence and genotypes in Kenya: Data to inform clinical care and health policy

The aim of this systematic review and meta-analysis is to evaluate available prevalence and viral sequencing data representing chronic hepatitis B (CHB) infection in Kenya. More than 20% of the global disease burden from CHB is in Africa, however there is minimal high quality seroprevalence data from individual countries and little viral sequencing data available to represent the continent. We undertook a systematic review of the prevalence and genetic data available for hepatitis B virus (HBV) in Kenya using the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) 2020 checklist. We identified 23 studies reporting HBV prevalence and 8 studies that included HBV genetic data published in English between January 2000 and December 2021. We assessed study quality using the Joanna Briggs Institute critical appraisal checklist. Due to study heterogeneity, we divided the studies to represent low, moderate, high and very high-risk for HBV infection, identifying 8, 7, 5 and 3 studies in these groups, respectively. We calculated pooled HBV prevalence within each group and evaluated available sequencing data. Pooled HBV prevalence was 3.4% (95% CI 2.7-4.2%), 6.1% (95% CI 5.1-7.4%), 6.2% (95% CI 4.64-8.2) and 29.2% (95% CI 12.2-55.1), respectively. Study quality was overall low; only three studies detailed sample size calculation and 17/23 studies were cross sectional. Eight studies included genetic information on HBV, with two undertaking whole genome sequencing. Genotype A accounted for 92% of infections. Other genotypes included genotype D (6%), D/E recombinants (1%) or mixed populations (1%). Drug resistance mutations were reported by two studies. There is an urgent need for more high quality seroprevalence and genetic data to represent HBV in Kenya to underpin improved HBV screening, treatment and prevention in order to support progress towards elimination targets.

The unexpected high prevalence of HBV subgenotype D4 in patients with chronic hepatitis B in Galicia, a northwestern Spanish region, reflects strong links with Latin America

BACKGROUND

Hepatitis B virus (HBV) comprises 9 genotypes and multiple subgenotypes that depict differences in geographic distribution, clinical outcome and response to antiviral therapy. However, the molecular epidemiology of HBV geno/subgenotypes is globally scarce. In Spain, HBV genotype D seems to be more prevalent in the northwestern regions compared to the rest of the country for unclear reasons.

METHODS

HBV genotyping was performed using geno2pheno on a S gene fragment amplified from plasma collected from all chronic hepatitis B individuals attended at one reference hospital in Santiago de Compostela, the Galicia's capital town. Phylogenetic and phylogeographic analyses using a fragment of 345 bp were performed in all viremic specimens. To avoid misleading allocation as consequence of short fragment analysis, several bioinformatic controls were used.

RESULTS

A total of 320 individuals with persistent serum HBsAg+ and detectable HBV-DNA were seen between 2000 and 2016 (male 68.4%; median age, 52 years-old; native Spaniards 83.8%). HBV genotype distribution was as follows: A 15.3%; B 1.6%; C 2.5%; D 71.6%; E 3.1%; F 2.2%; G 3.1%; and H 0.6%. HBV genotype D was mostly represented by D4 and D2 subgenotypes (33.4% and 15% of total, respectively). Compared to chronic hepatitis B patients with genotypes B, C, E and G, HBV-D4 carriers tended to be older (54.2% had >50 years-old) and HBeAg-negative (85%). Moreover, 43% were female, 4.7% had cirrhosis, 10.2% hepatitis C and 6.4% HIV coinfection. Phylogenetic analyses could be performed on 82 HBV-D4 specimens; and 79 were confirmed as HBV-D4 using PhyML. Phylogeography using FasTree suggested at least two distinct introductions of HBV-D4 in Galicia, one from the Caribbean and South America, and another from India.

CONCLUSIONS

HBV subgenotype D4 is the most prevalent HBV variant in chronic hepatitis B patients living in the northwest of Spain, representing 33.4% (107/320) of all chronic hepatitis B infections. This rate of HBV-D4 is among the highest reported worldwide. Epidemiological and phylogenetic analyses suggest a strong association with historical migrant exchanges with Latin America, and especially with the Caribbean basin.

Disproportionate Distribution of HBV Genotypes A and D and the Recombinant Genotype D/E in the High and Low HBV Endemic Regions of Uganda: A Wake-Up Call for Regional Specific HBV Management

BACKGROUND

Hepatitis B virus (HBV) is the leading cause of liver-related diseases. In Uganda, there is a regional disparity in the HBV burden. Our study was aimed at establishing the circulating genotypes in a low and a high endemic region to give plausible explanations for the differences in regional burden and guide the future management of the disease.

METHODS

A total of 200 HBsAg-seropositive subjects were recruited into the study by convenience sampling. The HBsAg Rapid Test Strip (Healgen Scientific Limited Liability Company, Houston, TX77047- USA) was used to screen for HBsAg while the Roche machine (Roche, Basel Switzerland/Abbot Technologies (USA)) was used to determine the viral load. The Chemistry Analyzer B120 (Mindray, China) was used for chemistry analysis. For HBV genotyping, total DNA was extracted from whole blood using the QIAamp® DNA extraction kit. Nested PCR amplification was performed using Platinum Taq DNA Polymerase (Invitrogen Corporation, USA) to amplify the 400 bp HBV polymerase gene. Purification of nested PCR products was performed using Purelink PCR product purification kit (Life Technologies, USA). Automated DNA sequencing was performed using BigDye Terminator v3.1 Cycle Sequencing Kit on 3130 Genetic Analyzer (Applied Biosystems, USA). The NCBI HBV genotyping tool (https://www.ncbi.nlm.nih.gov/projects/genotyping/formpage.cgi) was used for determination of genotype for each HBV sequence. Pearson's chi-square, multinomial logistic regression, and Mann-Whitney U tests were used for the analysis. All the analyses were done using SPSS version 26.0 and MedCalc software version 19.1.3 at 95% CI. A p < 0.05 was considered statistically significant.

RESULTS

Majority of our study subjects were female (64.5%), youth (51.0%), and married (62.0%). Overall, genotype A was the most prevalent (46%). Genotype D and the recombinant genotype D/E were proportionately more distributed in the high endemic (38.2%) and low endemic (36.5%) regions, respectively. Genotype D was significantly more prevalent in the high endemic region and among the elderly (p < 0.05). Genotype D was significantly associated with elevated viral load and direct bilirubin (p < 0.05). The recombinant genotype D/E was significantly associated with elevated viral load (p < 0.05). Similarly, genotype A was significantly associated with elevated AST and GGT, lowered viral load, and normal direct bilirubin levels (p < 0.05).

CONCLUSION

There is disproportionate distribution of genotypes A and D and the recombinant genotype D/E in the low and high endemic regions of Uganda. This probably could explain the differences in endemicity of HBV in our country signifying the need for regional specific HBV management and control strategies.

Seroprevalence and genotypic characterization of HBV among low risk voluntary blood donors in Nairobi, Kenya

Background

Hepatitis B virus (HBV) causes significant morbidity and mortality globally primarily due to its ability to cause hepatitis, liver cirrhosis and hepatocellular carcinoma. The Kenya National Blood Transfusion Services screens for Hepatitis B antibodies using the chemiluminescent microparticle immunoassay method. This test does not inform on the genotypic characteristics of the virus or the actual presence of the virus in blood. This study therefore sought to determine the serologic and genotypic profiles of HBV circulating among the voluntary blood donors in Nairobi.

Methods

Blood samples were collected in plain and EDTA vacutainers and tested for the Hepatitis B surface antigen (HBsAg). HBV DNA was then extracted from plasma, its overlapping P/S gene amplified and sequenced. The resulting sequences were used to analyze for the circulating genotypes and mutations within the P and S genes. Bivariate statistical analysis was used to determine the association between demographic factors and HBV infection.

Results

A seroprevalence of 2.3% (n = 7) was reported. The age group 19–28 years was significantly associated with HBV infection. Nine samples were positive for HBV DNA; these included 2 HBsAg positive samples and 7 HBsAg negative samples. Genotype A, sub genotype A1 was found to be exclusively prevalent while a number of mutations were reported in the “a” determinant segment of the major hydrophilic region of the S gene associated with antibody escape. RT mutations including mutation rt181T in the P gene conferring resistance against Lamivudine and other ʟ-nucleoside drugs were detected.

Conclusion

There is a high prevalence of occult HBV infections among these blood donors and therefore the testing platform currently in use requires revision.

Reconstruction of the spatial and temporal dynamics of hepatitis B virus genotype D in the Americas

Hepatitis B virus (HBV) genotype D (HBV/D) is globally widespread, and ten subgenotypes (D1 to D10) showing distinct geographic distributions have been described to date. The evolutionary history of HBV/D and its subgenotypes, for which few complete genome sequences are available, in the Americas is not well understood. The main objective of the current study was to determine the full-length genomic sequences of HBV/D isolates from Brazil and frequency, origin and spread of HBV/D subgenotypes in the Americas. Complete HBV/D genomes isolated from 39 Brazilian patients infected with subgenotypes D1 (n = 1), D2 (n = 10), D3 (n = 27), and D4 (n = 1) were sequenced and analyzed together with reference sequences using the Bayesian coalescent and phylogeographic framework. A search for HBV/D sequences available in GenBank revealed 209 complete and 926 partial genomes from American countries (Argentina, Brazil, Canada, Chile, Colombia, Cuba, Haiti, Martinique, Mexico, USA and Venezuela), with the major circulating subgenotypes identified as D1 (26%), D2 (17%), D3 (36%), D4 (21%), and D7 (1%) within the continent. The detailed evolutionary history of HBV/D in the Americas was investigated by using different evolutionary time scales. Spatiotemporal reconstruction analyses using short-term substitution rates suggested times of the most recent common ancestor for the American HBV/D subgenotypes coincident with mass migratory movements to Americas during the 19^th and 20^th centuries. In particular, significant linkages between Argentina and Syria (D1), Brazil and Central/Eastern Europe (D2), USA and India (D2), and Brazil and Southern Europe (D3) were estimated, consistent with historical and epidemiological data.

High Prevalence of Hepatitis B Subgenotype D4 in Northeast Brazil: an Ancient Relic from African Continent?

INTRODUCTION

Hepatitis B virus (HBV) infection leads to a chronic liver disease that is distributed worldwide. The characterization of HBV into genotypes/subgenotypes is not only a mere procedure for distinguishing different HBV strains around the world because determining their geographic distribution is crucial to understanding their spread across the world.

MATERIAL AND METHODS

We characterized different HBV genotypes and subgenotypes in five municipalities located in northeastern Maranhão, in the Brazilian north Atlantic coast. 92 HBsAg-positive individuals were submitted to PCR (polymerase chain reaction). Fifty samples were sequenced using automated Sanger sequencing and classified by phylogenetic methods.

RESULTS

Subgenotypes D4 and A1 were found in 42 (84%) and eight (16%) samples, respectively. To our knowledge, this is the first study to describe a high frequency of subgenotype D4 in any population. Subgenotype A1 is frequently found across Brazil, but D4 has been rarely detected and only in a few Brazilian states. This study shows the characterization of HBV subgenotypes from a population based study in the state of Maranhão, particularly in populations that do not have frequent contact with populations from other regions of the world.

CONCLUSION

Our findings showed a HBV subgenotype profile that probably reflect the viruses that were brought with the slave trade from Africa to Maranhão. This study also reinforces the need to evaluate the status of HBV dispersion not only in large urban centers, but also in the hinterland, to enable the implementation of effective control and treatment measures.

Genotyping and sero-virological characterization of hepatitis B virus (HBV) in blood donors, Southern Ethiopia

Hepatitis B virus (HBV) prevalence is highest in Sub-Saharan Africa including Ethiopia. HBV genotypes have distinct geographic distributions and play a role in course of infection and treatment management. However, in Ethiopia there is paucity of information about distribution of HBV genotypes. This study was done to determine genotype, mutation and sero-virological profiles of HBV isolates in Southern Ethiopia. Cross-sectional, laboratory based study was conducted on 103HBsAg sero-positive samples from a total of 2,237 screened blood donors. HBV serological markers and biochemical assays were done. Serum viral load was measured using quantitative real-time PCR. Partial HBV S-gene was amplified with nested PCR and sequenced. Bioinformatics tools were utilized to determine genotypes, serotypes and mutations. Of 103 HBsAg reactive serum samples, 14.6% and 70.9% were sero-positive for HBeAg and HBeAb, respectively. Ninety-eight samples gave detectable viral load with a median of 3.46(2.62-4.82) log IU/ml. HBeAg sero-positive donors carried elevated levels of viral load. Eighty five isolates were successfully amplified, sequenced and genotyped into 58 (68.2%) genotype A (HBV/A) and 27 (31.8%) genotype D (HBV/D). HBV serotypes found were adw2 (74.1%), ayw2 (24.7%), and ayw3 (1.2%). In twenty-four (28.2%) samples mutations in the major hydrophilic region (MHR) were observed. Donors infected with HBV/A had higher viral load and more frequent MHR mutation than HBV/D infected donors. This study illustrated distribution of HBV genotype A and D among blood donors in southern Ethiopia. It also demonstrated occurrence HBV variants that may influence clinical aspects of HBV infection. The study contributes in narrowing the existing gap of HBV molecular study in Ethiopia.

Genetic and phylogenic characterization of hepatitis B virus in the eastern part of the Democratic Republic of Congo

Hepatitis B virus (HBV) genotypes show a distinctive geographical distribution worldwide and genotypes A, D, and E are the most frequently found in Africa. There are only limited studies on HBV genotype distribution in Democratic Republic of Congo (DRC), all done in the western part showing a vast majority of genotype E. In our study, HBV strains from South Kivu, an eastern province of the DRC, were analyzed. Sequencing of 41 serum samples from HBV infected patients revealed strains of genotype A in 40/41 (97.6%) and genotype E in 1/41 (2.4%). The phylogenetic analysis showed that nearly all genotypes A (38/40) were closely related to A1 subgenotype strains found in Rwanda, Haiti, and Martinique while only two strains attached to the A2 subgenotype cluster were isolated. The remaining genotype E case was linked to the western African E crescent. Only the I169T nucleotide substitution was observed in two genotype A samples. In conclusion, the genotype A seems to be the most predominant genotype in eastern DRC with the majority belonging to the Afro-Asian subgenotype (A1). This contrasts with the western part of DRC where genotype E is predominant. These results support the hypothesis of an East-West genotypic demarcation.

Molecular epidemiology of hepatitis B virus infection in Tanzania

Despite the significant public health problems associated with hepatitis B virus (HBV) in sub-Saharan Africa, many countries in this region do not have systematic HBV surveillance or genetic information on HBV circulating locally. Here, we report on the genetic characterization of 772 HBV strains from Tanzania. Phylogenetic analysis of the S-gene sequences showed prevalence of HBV genotype A (HBV/A, n=671, 86.9 %), followed by genotypes D (HBV/D, n=95, 12.3 %) and E (HBV/E, n=6, 0.8 %). All HBV/A sequences were further classified into subtype A1, while the HBV/D sequences were assigned to a new cluster. Among the Tanzanian sequences, 84 % of HBV/A1 and 94 % of HBV/D were unique. The Tanzanian and global HBV/A1 sequences were compared and were completely intermixed in the phylogenetic tree, with the Tanzanian sequences frequently generating long terminal branches, indicating a long history of HBV/A1 infections in the country. The time to the most recent common ancestor was estimated to be 188 years ago [95 % highest posterior density (HPD): 132 to 265 years] for HBV/A1 and 127 years ago (95 % HPD: 79 to 192 years) for HBV/D. The Bayesian skyline plot showed that the number of transmissions 'exploded' exponentially between 1960-1970 for HBV/A1 and 1970-1990 for HBV/D, with the effective population of HBV/A1 having expanded twice as much as that of HBV/D. The data suggest that Tanzania is at least a part of the geographic origin of the HBV/A1 subtype. A recent increase in the transmission rate and significant HBV genetic diversity should be taken into consideration when devising public health interventions to control HBV infections in Tanzania.

A novel hepatitis B virus subgenotype D10 circulating in Ethiopia

Hepatitis B virus (HBV) is genetically highly divergent and classified in ten genotypes and forty subgenotypes in distinct ethno-geographic populations worldwide. Ethiopia is a country with high HBV prevalence; however, little is known about the genetic variability of HBV strains that circulate. Here, we characterize the complete genome of 29 HBV strains originating from five Ethiopian regions, by 454 deep sequencing and Sanger sequencing. Phylogenetically, ten strains were classified as genotype A1 and nineteen as genotype D. Fifteen genotype D strains, provisionally named subgenotype D10, showed a novel distinct cluster supported by high bootstrap value and >4% nucleotide divergence from other known subgenotypes. In addition, the novel D10 strains harboured nine unique amino acid signatures in the surface, polymerase and X genes. Seventy-two per cent of the genotype D strains had the precore premature stop codon G1896A. In addition, 63% genotype A and 33% genotype D strains had the basal core promoter mutations, A1762T/G1764A. Furthermore, four pre-S deletion variants and two recombinants were identified in this study. In conclusion, we identified a novel HBV subgenotype D10 circulating in Ethiopia, underlining the high genetic variability of HBV strains in Africa.

The hepatitis delta genotype 8 in Northeast Brazil: The North Atlantic slave trade as the potential route for infection

Hepatitis Delta virus (HDV) is not well known, even though HDV and Hepatitis B virus (HBV) co-infection leads to severe forms of acute and chronic liver diseases. HDV is endemic in the Western Amazon region. Recently, the HDV genotype 8 was found in chronic patients followed at the center for liver studies in the Northeast Brazil, Maranhão. Previous studies suggested that this genotype was introduced in Maranhão during the slave trade. The presence of HDV in that study, which was done outside the Amazon region, led us to investigate whether the virus is found infecting individuals in other regions of Maranhão as well. Thus, we screened ninety-two HBsAg positive individuals from five Municipalities of Maranhão for anti-HD antibody and eight were found positive (8.7%). These eight positive individuals were submitted to polymerase chain reaction (PCR) to investigate active HDV infection. Half of them were positive for a fragment sequence of the delta antigen; their sequence samples were submitted to genotype characterization by phylogenetic analysis. All sequences clustered in a unique branch of the tree separated from the other branch described in Africa. Our study confirmed the presence of HDV-8 in Maranhão. These infected individuals had no evidence of contact with African people. Furthermore, we found individuals infected with HDV-8 in two more different municipalities. More studies like ours are urgent because the co-infection HBV/HDV is more difficult to treat. Identification of the endemic regions and implementation of healthy policies for preventing this infection are urgent in this region.

Hepatitis B infection is highly prevalent among patients presenting with jaundice in Kenya

BACKGROUND

Viral hepatitis is a major concern worldwide, with hepatitis A (HAV) and E (HEV) viruses showing sporadic outbreaks while hepatitis B (HBV) and C (HCV) viruses are associated with chronic hepatitis, cirrhosis and hepatocellular carcinoma. The present study determined the proportion, geographic distribution and molecular characterization of hepatitis viruses among patients seeking medical services at hospitals throughout Kenya.

METHODS

Patients presenting with jaundice at four selected hospitals were recruited (n = 389). Sera were tested for the presence of antibody to hepatitis viruses A through E, and HBV surface antigen (HBsAg). Nucleic acid from anti-HAV IgM antibody and HBsAg positive samples was extracted, amplified and sequenced.

RESULTS

Chronic HBV infection was the leading cause of morbidity among patients with symptoms of liver disease seeking medical help. Incident HCV, HEV and HDV infection were not detected among the patients in this study, while the proportion of acute HAV was low; HAV IgM positivity was observed in 6.3 % of patients and sequencing revealed that all cases belonged to genotype 1B. HCV seropositivity upon initial screening was 3.9 % but none were confirmed positive by a supplementary immunoblot assay. There was no serological evidence of HDV and acute HEV infection (anti-HEV IgM). HBsAg was found in 50.6 % of the patients and 2.3 % were positive for IgM antibody to the core protein, indicating probable acute infection. HBV genotype A was predominant (90.3 %) followed by D (9.7 %) among HBV DNA positive specimens. Full genome analysis showed HBV/D isolates having similarity to both D4 and D6 subgenotypes and D/E recombinant reference sequences. Two recombinant sequences demonstrated > 4 % nucleotide divergence from other previously known D/E recombinants.

CONCLUSIONS

HBV is highly prevalent among patients seeking care for symptoms consistent with hepatitis, compared to the general population. Molecular characterization of HBV isolates indicated recombinant strains that may give rise to new circulating variants. There is a need to document the prevalence, clinical manifestation and distribution of the variants observed. HAV genotype 1B, prevalent in Africa, was observed; however, the absence of HCV, HDV and acute HEV in this study does not rule out their presence in Kenya.

Molecular epidemiology and genetic diversity of hepatitis B virus in Ethiopia

Although hepatitis B virus (HBV) infection is hyperendemic in Ethiopia and constitutes a major public health problem, little is known about its genetic diversity, genotypes, and circulation. The aim of this study was to determine the molecular epidemiology and genetic diversity of HBV in Ethiopia, using 391 serum samples collected from HBsAg-positive blood donors living in five different geographic regions. The HBV S/pol gene was amplified, sequenced, and HBV genotypes, subgenotypes, serotypes, and major hydrophilic region (MHR) variants were determined. Phylogenetic analysis of 371 samples (95%) revealed the distribution of genotypes A (78%) and D (22%) in Ethiopia. Further phylogenetic analysis identified one subgenotype (A1) within genotype A, and 4 subgenotypes within genotype D (D1; 1.3%, D2; 55%, D4; 2.5%, and D6; 8.8%). Importantly, 24 isolates (30%) of genotype D formed a novel phylogenetic cluster, distinct from any known D subgenotypes, and two A/D recombinants. Analysis of predicted amino-acid sequences within the HBsAg revealed four serotypes: adw2 (79%), ayw1 (3.1%), ayw2 (7.8%), and ayw3 (11.6%). Subsequent examination of sequences showed that 51 HBV isolates (14%) had mutations in the MHR and 8 isolates (2.2%) in the reverse transcriptase known to confer antiviral resistance. This study provides the first description of HBV genetic diversity in Ethiopia with a predominance of subgenotypes A1 and D2, and also identified HBV isolates that could represent a novel subgenotype. Furthermore, a significant prevalence of HBsAg variants in Ethiopian population is revealed.

Epidemiology of HBV infection in a cohort of Ugandan HIV-infected patients and rate and pattern of lamivudine-resistant HBV infection in patients receiving antiretroviral therapy

BACKGROUND

Many HIV-infected patients in sub-Saharan Africa are not routinely screened for hepatitis B virus (HBV) infection and are on antiretroviral therapy (ART) regimens containing only lamivudine as anti-HBV active drug.

METHODS

In 2009-2011, we screened for hepatitis B surface antigen (HBsAg) in 2820 HIV-infected adults patients at the Mbarara Hospital Uganda and investigated risk factors for HBV infection. Using samples of dried plasma or blood spots, we tested for HBV viral load and HBV drug resistance mutations in all HBsAg-positive patients on ART for ≥ 12 months.

RESULTS

In this study, 109 patients tested HBsAg positive (3.9%; 109/2820). HBsAg-positive patients were more likely to have had >4 lifetime sexual partners (p<0.01). Of the 55 HBsAg-positive patients on ART for ≥ 12 months, 53 were only on lamivudine as anti-HBV active drug and two were on tenofovir and lamivudine. HBV-DNA was detected in 30 patients (54.5%; 30/55), all on lamivudine-monotherapy. Of the 23 patients in whom HBV-DNA sequencing was successful, 17 had lamivudine-resistant HBV strains harbouring rtM204V/I mutations accompanied by secondary/compensatory mutations.

CONCLUSIONS

Our study suggests that sexual transmission may represent a major mode of spread of HBV in southwest Uganda and confirms the importance of screening for HBV and of using ART regimens containing tenofovir in HIV/HBV co-infected patients.

Hepatitis B virus sero-profiles and genotypes in HIV-1 infected and uninfected injection and Non-injection drug users from coastal Kenya

Background

Information about HBV sero-markers, infection stages and genotypes in HIV-1 infected and uninfected injection and non-injection drug users (IDUs) in Kenya remains elusive.

Methods

A cross-sectional study examining HBV sero-marker, infection stages and genotypes was conducted among HIV-1 infected and uninfected, respectively, IDUs (n = 157 and n = 214) and non-IDUs (n = 139 and n = 48), and HIV-1 uninfected non-drug using controls (n = 194) from coastal, Kenya. HBV sero-marker and infection stages were based on HBV 5-panel rapid test plasma sero-reactivity. DNA was extracted from acute and chronic plasma samples and genotypes established by nested-PCR and direct sequencing.

Results

HBsAg positivity was higher in HIV-1 infected IDUs (9.6 %) relative to HIV-1 uninfected IDUs (2.3 %), HIV-1 infected non-IDUs (3.6 %), HIV-1 uninfected non-IDUs (0.0 %) and non-drug users (2.6 %; P = 0.002). Contrastingly, HBsAb positivity was higher in HIV-1 uninfected IDUs (14.6 %) and non-IDUs (16.8) in comparison to HIV-1 infected IDUs (8.3 %), and non-IDUs (8.6 %), and non-drug users (8.2 %; P = 0.023). HBcAb positivity was higher in HIV-1 infected IDUs (10.2 %) compared to HIV-1 uninfected IDUs (3.3 %), HIV-1 infected non-IDUs (6.5 %), HIV-1 uninfected non-IDUs (2.1 %) and non-drug users (4.6 %; P = 0.038). Acute (5.7 %, 1.4 %, 0.0 %, 0.0 % and 1.5 %) and chronic (5.1 %, 0.9 %, 3.6 %, 0.0 % and 1.5 %) stages were higher in HIV-1 infected IDUs, compared to HIV-1 uninfected IDUs, HIV-1 infected and uninfected non-IDUs and non-drug users, respectively. However, vaccine type response stage was higher in HIV-1 uninfected IDUs (15.4 %) relative to HIV-1 infected IDUs (6.4 %), and HIV-1 infected (6.5 %), and uninfected (10.4 %) non-IDUs, and non-drug users (5.7 %; P = 0.003). Higher resolved infection rates were also recorded in HIV-1 uninfected IDUs (11.2 %) compared to HIV-1 infected IDUs (8.3 %), and HIV-1 infected (7.2 %), uninfected (6.3 %) non-IDUs, and non-drug users (6.7 %; P = 0.479), respectively. Only A1 genotype showing minimal diversity was detected among the study participants.

Conclusion

HBV sero-markers and infection staging are valuable in diagnosis and genotyping of HBV infections. Among IDUs, higher HBsAg and HBcAb positivity in HIV-1 infected and higher HBsAb positivity in HIV-1 negative IDUs suggests frequent exposure. Additionally, HBV genotype A is the dominant circulating genotype in both high and low risk populations of Kenya.

Epidemiology of HBV subgenotypes D

The natural history of hepatitis B virus infection is not uniform and affected from several factors including, HBV genotype. Genotype D is a widely distributed genotype. Among genotype D, several subgenotypes differentiate epidemiologically and probably clinically. D1 is predominant in Middle East and North Africa, and characterized by early HBeAg seroconversion and low viral load. D2 is seen in Albania, Turkey, Brazil, western India, Lebanon, and Serbia. D3 was reported from Serbia, western India, and Indonesia. It is a predominant subgenotype in injection drug use-related acute HBV infections in Europe and Canada. D4 is relatively rare and reported from Haiti, Russia and Baltic region, Brazil, Kenya, Morocco and Rwanda. Subgenotype D5 seems to be common in Eastern India. D6 has been reported as a rare subgenotype from Indonesia, Kenya, Russia and Baltic region. D7 is the main genotype in Morocco and Tunisia. D8 and D9 are recently described subgenotypes and reported from Niger and India, respectively. Subgenotypes of genotype D may have clinical and/or viral differences. More subgenotype studies are required to conclude on subgenotype and its clinical/viral characteristics.

Hepatitis B virus infection in post-vaccination South Africa: occult HBV infection and circulating surface gene variants

BACKGROUND AND OBJECTIVE

The aim of this study was to investigate the prevalence of occult hepatitis B virus (HBV) infection and the HBV surface (S) gene variants circulating in the South African population after nearly two decades of universal hepatitis B vaccination.

STUDY DESIGN

From a previous serosurvey, 201 serum samples with serological evidence of exposure to HBV were identified and these were stratified into post- and pre-vaccine introduction populations. For all samples, HBV DNA was screened and quantified using a real-time PCR assay and results analysed together with HBV serological markers. Where HIV results were available, subset analysis was performed. The HBV S gene was PCR-amplified and sequences analysed for a total of 37 isolates.

RESULTS

The prevalence of occult HBV infection reduced from 70.4% in the pre-vaccine introduction era to 66.0% post-vaccine introduction. There was an association between HIV infection and an increase in prevalence of occult HBV infection within the post-vaccine introduction population, although this was not statistically significant. Furthermore, sequence analysis revealed the following HBV subgenotypes; A1 (n=34), A2 (n=2) and a rare D4 isolate. HBV S gene variants, including diagnostic escape mutants were isolated.

CONCLUSION

There was a decline in the prevalence of occult HBV infection in post-vaccination South Africa, although the disease burden remains significant in the HIV co-infected population. After nearly two decades of a universal hepatitis B vaccination programme, no positive selection of vaccine escape mutants were observed.

A rare HBV subgenotype D4 with unique genomic signatures identified in north-eastern India--an emerging clinical challenge?

BACKGROUND/AIMS

HBV has been classified into ten genotypes (A-J) and multiple subgenotypes, some of which strongly influence disease outcome and their distribution also correlate with human migration. HBV infection is highly prevalent in India and its diverse population provides an excellent opportunity to study the distinctiveness of HBV, its evolution and disease biology in variegated ethnic groups. The North-East India, having international frontiers on three sides, is one of the most ethnically and linguistically diverse region of the country. Given the paucity of information on molecular epidemiology of HBV in this region, the study aimed to carry out an in-depth genetic characterization of HBV prevailing in North-East state of Tripura.

METHODS

From sera of chronically HBV infected patients biochemical/serological tests, HBV DNA quantification, PCR-amplification, sequencing of PreS/S or full-length HBV genomes were done. HBV genotype/subgenotype determination and sequence variability were assessed by MEGA5-software. The evolutionary divergence times of different HBV subgenotypes were estimated by DNAMLK/PHYLIP program while jpHMM method was used to detect any recombination event in HBV genomes.

RESULTS

HBV genotypes D (89.5%), C (6.6%) and A (3.9%) were detected among chronic carriers. While all HBV/A and HBV/C isolates belonged to subgenotype-A1 and C1 respectively, five subgenotypes of HBV/D (D1-D5) were identified including the first detection of rare D4. These non-recombinant Indian D4 (IndD4) formed a distinct phylogenetic clade, had 2.7% nucleotide divergence and recent evolutionary radiation than other global D4. Ten unique amino acids and 9 novel nucleotide substitutions were identified as IndD4 signatures. All IndD4 carried T120 and R129 in ORF-S that may cause immune/vaccine/diagnostic escape and N128 in ORF-P, implicated as compensatory Lamivudine resistance mutation.

CONCLUSIONS

IndD4 has potential to undermine vaccination programs or anti-viral therapy and its introduction to North-East India is believed to be linked with the settlement of ancient Tibeto-Burman migrants from East-Asia.

A rare HBV subgenotype D4 with unique genomic signatures identified in north-eastern India--an emerging clinical challenge?

Background/Aims

HBV has been classified into ten genotypes (A–J) and multiple subgenotypes, some of which strongly influence disease outcome and their distribution also correlate with human migration. HBV infection is highly prevalent in India and its diverse population provides an excellent opportunity to study the distinctiveness of HBV, its evolution and disease biology in variegated ethnic groups. The North-East India, having international frontiers on three sides, is one of the most ethnically and linguistically diverse region of the country. Given the paucity of information on molecular epidemiology of HBV in this region, the study aimed to carry out an in-depth genetic characterization of HBV prevailing in North-East state of Tripura.

Methods

From sera of chronically HBV infected patients biochemical/serological tests, HBV DNA quantification, PCR-amplification, sequencing of PreS/S or full-length HBV genomes were done. HBV genotype/subgenotype determination and sequence variability were assessed by MEGA5-software. The evolutionary divergence times of different HBV subgenotypes were estimated by DNAMLK/PHYLIP program while jpHMM method was used to detect any recombination event in HBV genomes.

Results

HBV genotypes D (89.5%), C (6.6%) and A (3.9%) were detected among chronic carriers. While all HBV/A and HBV/C isolates belonged to subgenotype-A1 and C1 respectively, five subgenotypes of HBV/D (D1–D5) were identified including the first detection of rare D4. These non-recombinant Indian D4 (IndD4) formed a distinct phylogenetic clade, had 2.7% nucleotide divergence and recent evolutionary radiation than other global D4. Ten unique amino acids and 9 novel nucleotide substitutions were identified as IndD4 signatures. All IndD4 carried T¹²⁰ and R¹²⁹ in ORF-S that may cause immune/vaccine/diagnostic escape and N¹²⁸ in ORF-P, implicated as compensatory Lamivudine resistance mutation.

Conclusions

IndD4 has potential to undermine vaccination programs or anti-viral therapy and its introduction to North-East India is believed to be linked with the settlement of ancient Tibeto-Burman migrants from East-Asia.

Hepatitis B virus subgenotype A1: evolutionary relationships between Brazilian, African and Asian isolates

Brazil is a country of low hepatitis B virus (HBV) endemicity in which the genotype A of HBV (HBV/A) is the most prevalent. The complete nucleotide sequences of 26 HBV/A isolates, originating from eight Brazilian states, were determined. All were adw2. Twenty-three belonged to subgenotype A1 and three to A2. By phylogenetic analysis, it was shown that all the 23 HBV/A1 isolates clustered together with isolates from Bangladesh, India, Japan, Nepal, the Philippines and United Arab Emirates, but not with those of Congo, Kenya, Malawi, Rwanda, South Africa, Tanzania, Uganda and Zimbabwe. Four amino acid residues in the polymerase (His138 in the terminal protein domain, Pro18 and His90 in the spacer, and Ser109 in the reverse transcriptase), and one (Phe17) in the precore region, predominated in Latin American and Asian HBV/A1 isolates, but were rarely encountered in African isolates, with the exception of those from Somalia. Specific variations of two adjacent amino acids in the C-terminal domain of the HBx protein, namely Ala146 and Pro147, were found in all the Brazilian, but rarely in the other HBV/A1 isolates. By Bayesian analysis, the existence of an 'Asian-American' clade within subgenotype A1 was supported by a posterior probability value of 0.996. The close relatedness of the Brazilian, Asian and Somalian isolates suggests that the HBV/A1 strains predominant in Brazil did not originate from the five million slaves who were imported from Central and Western Africa from 1551 to 1840, but rather from the 300-400,000 captives forcibly removed from southeast Africa at the middle of the 19th century.