New pieces on genetic diversity and evolutionary history of hepatitis B virus: Characterization of the novel subgenotype F6

First Detection of Hepatitis B Virus Subgenotype A5, and Characterization of Occult Infection and Hepatocellular Carcinoma-Related Mutations in Latin American and African Immigrants in Brazil

This study aims to characterize the molecular profile of the hepatitis B virus (HBV) among socially vulnerable immigrants residing in Brazil to investigate the introduction of uncommon HBV strains into the country. Serum samples from 102 immigrants with positive serology for the HBV core antibody (anti-HBc) were tested for the presence of HBV DNA by PCR assays. Among these, 24 were also positive for the HBV surface antigen (HBsAg). The full or partial genome was sequenced to determine genotype by phylogenetic analysis. Participants were from Haiti (79.4%), Guinea-Bissau (11.8%), Venezuela (7.8%), and Colombia (1%). Of the 21 HBV DNA-positive samples, subgenotypes A1 (52.4%), A5 (28.6%), E (9.5%), F2 (4.8%), and F3 (4.8%) were identified. Among the 78 HBsAg-negative participants, four were positive for HBV DNA, resulting in an occult HBV infection rate of 5.1%. Phylogenetic analysis suggested that most strains were likely introduced to Brazil by migration. Importantly, 80% of A5 sequences had the A1762T/G1764A double mutation, linked to an increased risk of hepatocellular carcinoma development. In conclusion, this study is the first report of HBV subgenotype A5 in Brazil, shedding new light on the diversity of HBV strains circulating in the country. Understanding the genetic diversity of HBV in immigrant communities can lead to better prevention and control strategies, benefiting both immigrants and wider society.

A review of epidemiology and clinical relevance of Hepatitis B virus genotypes and subgenotypes

BACKGROUND

Hepatitis B virus (HBV) infection is a global public health burden, affecting nearly 300 million people around the world. Due to HBV population is considered to be represented as a viral quasispecies with genetic diversity, some reports showed that different genotypes of HBV have different viral effects, though the emergence of antiviral drugs that effectively inhibit viral replication, however, HBV infection has still not been eradicated and further research is needed.

SUMMARY

HBV has been classified into at least ten genotypes (A-J)  and more than 40 subgenotypes based on an intergroup or intragroup nucleotide difference across the whole genome, respectively. Inter genotypic recombinants were also observed during the HBV evolution. HBV genotypes and subgenotypes have distinct ethno-geographical distributions, as well as evident differences in their biological characteristics. HBV genotypes and subgenotypes also have close association with disease severity, long-term clinical outcomes, and response to antiviral therapy.

KEYMESSAGES

In this review, we up-dated the epidemiological characteristics, clinical features and prognosis of HBV infection with dissimilar genotype/subgenotypes, to better understanding and developing individualized prevention and treatment strategies.

The Hepatitis B Virus Genotypes E to J: The Overlooked Genotypes

Hepatitis B virus (HBV) genotypes E to J are understudied genotypes. Genotype E is found almost exclusively in West Africa. Genotypes F and H are found in America and are rare in other parts of the world. The distribution of genotype G is not completely known. Genotypes I and J are found in Asia and probably result from recombination events with other genotypes. The number of reported sequences for HBV genotypes E to J is small compared to other genotypes, which could impact phylogenetic and pairwise distance analyses. Genotype F is the most divergent of the HBV genotypes and is subdivided into six subgenotypes F1 to F6. Genotype E may be a recent genotype circulating almost exclusively in sub-Saharan Africa. Genotype J is a putative genotype originating from a single Japanese patient. The paucity of data from sub-Saharan Africa and Latin America is due to the under-representation of these regions in clinical and research cohorts. The purpose of this review is to highlight the need for further research on HBV genotypes E to J, which appear to be overlooked genotypes.

Mapping hepatitis B virus genotypes on the African continent from 1997 to 2021: a systematic review with meta-analysis

Hepatitis B virus (HBV) has ten genotypes (A-J) and over 40 sub-genotypes based on the divergence of ≥ 8% and 4 to < 8% in the complete genome respectively. These genotypes and sub-genotypes influence the disease prognosis, response to therapy and route of viral transmission. Besides, infection with mixed genotypes and recombinant genotypes has also been reported. This study aimed at mapping the de novo genotypes and correlate them with the immigration trends in order to inform future research on the underlying reasons for the relative distribution of HBV genotypes from a large sample size pooled from many primary studies. Data was extracted from 59 full research articles obtained from Scopus, PubMed, EMBASE, Willy library, African Journal Online (AJOL) and Google Scholar. Studies that investigated the genotypes, sub-genotypes, mixed genotypes and recombinant were included. The Z-test and regression were used for the analysis. The study protocol is registered with PROSPERO under the registration number CRD42022300220. Overall, genotype E had the highest pooled prevalence significantly higher than all the other genotypes (P < 0.001). By region, genotype A posted the highest pooled prevalence in eastern and southern Africa, E in west Africa and D in north Africa (P < 0.0001). Regarding the emerging genotypes B and C on the African continent, genotype B was significantly higher in south Africa than C (P < 0.001). In contrast, genotype C was significantly higher in east Africa than west Africa (P < 0.0001). The A1 and D/E were the most diverse sub-genotypes and genotype mixtures respectively. Finally, we observed a general progressive decrease in the prevalence of predominant genotypes but a progressive increase in the less dominant by region. Historical and recent continental and intercontinental migrations can provide a plausible explanation for the HBV genotype distribution pattern on the African continent.

Acute and chronic HBV infection in central Argentina: High frequency of sub-genotype F1b, low detection of clinically relevant mutations and first evidence of HDV

Introduction

Genomic analysis of hepatitis B virus (HBV) identifies phylogenetic variants, which may lead to distinct biological and clinical behaviors. The satellite hepatitis D virus (HDV) may also influence clinical outcomes in patients with hepatitis B. The aim of this study was to investigate HBV genetic variants, including clinically relevant mutations, and HDV infection in acute and chronic hepatitis B patients in central Argentina.

Methods

A total of 217 adult HBV infected patients [acute (AHB): n = 79; chronic (CHB): n = 138] were studied; 67 were HBV/human immunodeficiency virus (HIV) coinfected. Clinical and demographic data were obtained from medical records. Serological markers were determined. Molecular detection of HBV and HDV was carried out by RT-Nested PCR, followed by sequencing and phylogenetic analysis.

Results

Overall, genotype (gt) F [sub-genotype (sgt) F1b] was the most frequently found. In AHB patients, the gts/sgts found were: F1b (74.7%) > A2 (13.9%) > F4 (7.6%) > C (2.5%) > A1 (1.3%). Among CHB patients: F1b (39.1%) > A2 (23.9%) > F4 (18.2%) > D (9.4%) > C and F6 (3.6% each) > A1, A3 and B2 (0.7% each). The distribution of sgt A2 and gt D was significantly different between HBV mono and HBV/HIV coinfected patients [A2: 15.9% vs. 35.7% (p < 0.05), respectively and D: 14.6% vs. 1.8% (p < 0.05), respectively]. Mutation frequency in basal core promoter/pre-Core (BCP/pC) region was 35.5% (77/217) [AHB: 20.3% (16/79), CHB: 44.2% (61/138)]. In the open reading frame (ORF) S, mutations associated with vaccine escape and diagnostic failure were detected in 7.8% of the sequences (17/217) [AHB: 3.8% (3/79), CHB: 10.1% (14/138)]. ORF-P amino acid substitutions associated with antiviral resistance were detected in 3.2% of the samples (7/217) [AHB: 1.3% (1/79), CHB 4.3%, (6/138)]. The anti-HDV seropositivity was 5.2% (4/77); one sample could be sequenced, belonging to gt HDV-1 associated with sgt HBV-D3.

Discussion

We detected an increase in the circulation of genotype F in Central Argentina, particularly among AHB patients, suggesting transmission advantages over the other genotypes. A low rate of mutations was detected, especially those with antiviral resistance implications, which is an encouraging result. The evidence of HDV circulation in our region, reported for the first time, alerts the health system for its search and diagnosis.

Hepatitis B virus genotypes in Brazil: Introduction and dissemination

Hepatitis B is a viral infectious disease highly spread worldwide with a long evolutionary history associated with human migrations through the continents and countries. Hepatitis B virus (HBV) was disseminated probably from Africa and diverged into ten genotypes (HBV-A to HBV-J) distributed around the world. In Brazil, almost all HBV genotypes were already reported, with a predominance of three ones: A (52.1%), D (36.8%), and F (7.7%). This review aimed to evaluate the introduction and dissemination of the main HBV genotypes and subgenotypes in Brazil over the last centuries to explain the current epidemic scenario. The highest frequency of HBV-A is a consequence of the introduction and spreading of HBV-A1 in the 16th to 19th centuries due to the African slave trade, but the more recent introduction of HBV-A2 from Europe also contributed to the current situation. HBV-D is the second most frequent genotype because it was consecutively introduced by migrations from Europe (mainly subgenotype D3, but also D2) and the Middle East (D1) in the 19th to 20th centuries. On contrary, HBV-F (F1a, F1b, F2a, F2b, F3, and F4) was disseminated by the Amerindians in all South American countries, including Brazil, by migrations inside the continent for more than three centuries ago. Other HBV genotypes are rare and eventually frequent in some human groups because of the dissemination by very specific epidemiological routes. In conclusion, the current scenario of the HBV epidemics is a consequence of the introduction and dissemination of some subgenotypes from the three main genotypes A, D, and F over the last five centuries.

Genetic diversity of hepatitis B virus in Yunnan, China: identification of novel subgenotype C17, an intergenotypic B/I recombinant, and B/C recombinants

Yunnan is considered to be a geographical hotspot for the introduction, mutation and recombination of several viruses in China. However, there are limited data regarding the genotypic profiles of hepatitis B virus (HBV) in this region. In this study, we characterized 206 HBV strains isolated from chronic hepatitis B patients in Yunnan, China. Initial genotyping based on 1.5 kb sequences revealed that genotype C was the most prevalent at 52.4 % (108/206), followed by genotype B at 30.6 % (63/206) and unclassified genotypes at 17.0 % (35/206). To characterize the 35 unclassified strains, 32 complete HBV genomes were amplified and analysed; 17 isolates were classified within a known subgenotype, 8 were classified as B/C recombinants, 1 was classified as a B/I recombinant and 6 constituted a potentially novel C subgenotype that we designated as C17, based on the characteristics of a monophyletic cluster, >4 % genetic distances, no significant evidence of recombination and no epidemiological link among individuals. Thus, multiple subgenotypes - namely B1, B2, B4, C1, C2, C3, C4, C8 and C17 - and two distinct intergenotypic recombinants exist in Yunnan, China, highlighting the complex and diverse distribution pattern of HBV genotypic profiles.

Long-term evolution of hepatitis B virus genotype F: Strong association between viral diversification and the prehistoric settlement of Central and South America

The genotype F (HBV-F) is an autochthonous Native American strain of the hepatitis B virus. In this study, we reconstruct the HBV-F long-term evolution under a hypothesis of co-divergence with humans in Central and South America, since their entry into the region 14.5-16 thousand years ago. The Bayesian phylogeographic reconstruction supported a virus-host co-expansion; however, two evolutionary scenarios would have been present. Whereas subgenotype F1 spreads along a Pacific coastal route and would have evolved associated with Central American and Andean cultures from the west of the continent, subgenotypes F2-F6 spread along the Atlantic coastline and inner pathways associated with communities inhabiting the tropical forest lowlands. Then, we propose a model for HBV-F evolution in which the selection of differential biological characteristics in these two main groups would be related to their evolution in host populations with different genetic backgrounds and dissimilar demographic conditions.