Temporal evolution and global spread of hepatitis B virus genotype G

Hepatitis B virus (HBV) infection is considered a major health problem in the world. HBV is classified into genotypes A to J disseminated worldwide. Genotypes A, D and F are the most frequent in the Western World, B and C are predominant in the East, and E, F, H and J are infrequent and restricted to specific regions. HBV-G is a rare genotype, but it has been detected in different continents. This study aimed to report the temporal evolution and global spread of HBV-G comparing whole-genome sequences of this genotype from different regions in the world. Bayesian coalescent analysis was performed to estimate the time to the most recent common ancestor (tMRCA) and the population dynamics in the last decades. The results demonstrated that tMRCA of all HBV-Gs dated back to 1855 (95% highest posterior density interval [HPD 95%]: 1778 - 1931). This genotype has a possible origin in North America and it was disseminated to other continents (South and Central America, Europe, Asia and Africa) more than one century later (around the 1970s). The viral population demonstrated constant spreading from 1855 to the 1980s, followed by an increase in the 1990s and reached a plateau after the 2000s. Wide spreading at the beginning of the 1990s was probably associated with the dissemination by highly sexual active groups and injecting drug users. In conclusion, the present study demonstrated that HBV-G was originated in the 19th century with main events of spread at the end of the 20th century.

Whole-gene analysis of two groups of hepatitis B virus C/D inter-genotype recombinant strains isolated in Tibet, China

Tibet is a highly hepatitis B virus (HBV) endemic area. Two types of C/D recombinant HBV are commonly isolated in Tibet and have been previously described. In an effort to better understand the molecular characteristic of these C/D recombinant strains from Tibet, we undertook a multistage random sampling project to collect HBsAg positive samples. Molecular epidemiological and bio-informational technologies were used to analyze the characteristics of the sequences found in this study. There were 60 samples enrolled in the survey, and we obtained 19 whole-genome sequences. 19 samples were all C/D recombinant, and could be divided into two sub-types named C/D1 and C/D2 according to the differences in the location of the recombinant breakpoint. The recombination breakpoint of the 10 strains belonging to the C/D1 sub-type was located at nt750, while the 9 stains belonging to C/D2 had their recombination break point at nt1530. According to whole-genome sequence analysis, the 19 identified strains belong to genotype C, but the nucleotide distance was more than 5% between the 19 strains and sub-genotypes C1 to C15. The distance between C/D1with C2 was 5.8±2.1%, while the distance between C/D2 with C2 was 6.4±2.1%. The parental strain was most likely sub-genotype C2. C/D1 strains were all collected in the middle and northern areas of Tibet including Lhasa, Linzhi and Ali, while C/D2 was predominant in Shannan in southern Tibet. This indicates that the two recombinant genotypes are regionally distributed in Tibet. These results provide important information for the study of special HBV recombination events, gene features, virus evolution, and the control and prevention policy of HBV in Tibet.

Widespread hepatitis B virus genotype G (HBV-G) infection during the early years of the HIV epidemic in the Netherlands among men who have sex with men

Background

Hepatitis B virus (HBV) variants belong to different genotypes, A-J, whose worldwide distribution is linked with geography, probably because viral spread was associated with ancient human migrations. HBV genotype G (HBV-G) is an aberrant genotype with little sequence divergence, suggesting a recent origin. HBV-G is strongly associated with certain risk groups such as intravenous drug users (IDUs) and men who have sex with men (MSM), but hardly with geography. The origin and epidemiology of HBV-G remain unresolved, as is the disease association.

Methods

To estimate the prevalence and possible time of introduction of HBV-G into the MSM community in Amsterdam, the Netherlands, we have retrospectively analysed 226 blood serum samples from HBsAg positive MSM enrolled in the Amsterdam Cohort Studies (ACS) on HIV infection and AIDS dating from 1984 to 1999 using genotype-specific PCR assays.

Results

Of the 226 HBsAg-positive samples, 149 were HBV DNA positive. Of those, 104 were positive for HBV genotype A (HBV-A) and five for HBV-G, and 40 showed a dual infection with both HBV-A and HBV-G. Being HIV-infected was significantly associated with a reduced HBV DNA viral load in blood, but not with the prevalence of HBV-G. Early virus already contained stop codons in the precore region and a 36 bp insertion in the core gene which are the characteristics of HBV-G.

Conclusions

HBV-G was introduced before 1985 into the Amsterdam MSM community. Early isolates show very limited sequence variation, confirming a low evolutionary rate. HBV-G acquisition was independent of HIV infection, but being HIV-infected was significantly associated with a reduced HBV viral load in blood, indicating a beneficial effect of early HIV infection in controlling HBV replication.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1599-7) contains supplementary material, which is available to authorized users.

High prevalence of occult hepatitis B virus genotype H infection among children with clinical hepatitis in west Mexico

Studies on the prevalence of infection with hepatitis B virus (HBV) among children are scarce in Latin American countries, especially in Mexico. This study was aimed to investigate the prevalence of HBV infection, occult hepatitis B infection (OBI) and HBV genotypes among children with clinical hepatitis. In total, 215 children with clinical hepatitis were evaluated for HBV infection. HBV serological markers and HBV DNA were analysed. OBI diagnosis and HBV genotyping was performed. HBV infection was found in 11.2% of children with clinical hepatitis. Among these HBV DNA positive-infected children, OBI was identified in 87.5% (n = 21/24) of the cases and 12.5% (n = 3/24) were positive for both HBV DNA and hepatitis B surface antigen. OBI was more frequent among children who had not been vaccinated against hepatitis B (p < 0.05) than in those who had been vaccinated. HBV genotype H was prevalent in 71% of the children followed by genotype G (8%) and genotype A (4%). In conclusion, OBI is common among Mexican children with clinical hepatitis and is associated with HBV genotype H. The results show the importance of the molecular diagnosis of HBV infection in Mexican paediatric patients with clinical hepatitis and emphasise the necessity of reinforcing hepatitis B vaccination in children.

High prevalence of hepatitis B virus dual infection with genotypes A and G in HIV-1 infected men in Amsterdam, the Netherlands, during 2000-2011

Background

Hepatitis B virus (HBV) is divided into 8 definite (A-H) and 2 putative (I, J) genotypes that show a geographical distribution. HBV genotype G, however, is an aberrant genotype of unknown origin that demonstrates severe replication deficiencies and very little genetic variation. It is often found in co-infections with another HBV genotype and infection has been associated with certain risk groups such as intravenous drug users and men having sex with men (MSM). We aimed to estimate the prevalence of HBV-G in the Netherlands by analysing samples from HBV-positive patients visiting the Academic Medical Center in Amsterdam.

Methods

Ninety-six HBV-infected patients, genotyped as HBV-A or HBV-G infected, were retrieved from the clinical database. Blood plasma samples were analysed with a newly-developed real-time PCR assay that detects HBV-A and HBV-G. For three patients, the HBV plasma viral load (pVL) of both genotypes was followed longitudinally. In addition, three complete genomes of HBV-G were sequenced to determine their relationship to global HBV-G strains.

Results

Ten HBV-G infections were found in the selected Dutch patients. All concerned HIV-1 infected males with HBV-A co-infection. Dutch HBV-G strains were phylogenetically closely related to reference HBV-G strains.

Conclusions

In this study, HBV-G infection in the Netherlands is found exclusively in HIV-1 infected men as co-infection with HBV-A. A considerable percentage (37%) of men infected with HBV and HIV-1 are actually co- infected with two HBV genotypes.