A substitution in the pre-S1 promoter region is associated with the viral regulation of hepatitis B virus

C2729T mutation associated with HBV mother-to-child transmission reduces HBV production via suppressing LHBs expression

Mother-to-child transmission (MTCT) is still the main route of hepatitis B virus (HBV) infection. However, the virological factors affecting HBV MTCT have not been fully elucidated. In this study, based on a prospective cohort of mother-infant pairs with positive maternal hepatitis B surface antigen (HBsAg), we found that the average nucleotide mutation rate of HBV preS1 promoter (SPI) region in the immunoprophylaxis success group was significantly higher than that in the immunoprophylaxis failure group. Among the nucleotide mutations of the HBV SPI region, the C2729T mutation had the highest frequency. Next, we found that the C2729T mutation promoted HBsAg release but reduced HBV production by suppressing the expression of large hepatitis B surface antigen (LHBs), and overexpressing LHBs could rescue this phenomenon. Based on the fact that the C2729T mutation could alter the binding site of hepatocyte nuclear factor 1 (HNF1) in the HBV SPI region, we uncovered that such an alteration could downregulate the transcriptional activity of SPI by attenuating the binding ability of HNF1 and HBV SPI region. This study suggests that HBV C2729T mutation may contribute to the immunoprophylaxis success of HBV MTCT by reducing HBV production, which supplements the virological factors affecting HBV MTCT.

Pre-S1 Mutations as Indicated by Serum Pre-S1 Antigen Negative is Associated with an Increased Risk of Hepatocellular Carcinoma in Chronic Hepatitis B Patients

Objective

Pre-S1 antigen (pre-S1) is a component of hepatitis B virus large surface antigen (L-HBsAg). This study aimed to investigate the association between clinical pre-S1 antigen (pre-S1) status and adverse prognostic events in chronic hepatitis B (CHB) patients.

Methods

This study retrospectively enrolled 840 CHB patients with comprehensive clinical data, including 144 patients with multiple follow-up of pre-S1 status. All patients were tested for serum pre-S1 and divided into pre-S1 positive and negative groups. Single factor and logistic multiple regression analyses were performed to explore the association between pre-S1 and other HBV biomarkers with the risk of hepatocellular carcinoma (HCC) in CHB patients. The pre-S1 region sequences of HBV DNA were obtained from one pre-S1 positive and two pre-S1 negative treatment-naïve patients using polymerase chain reaction (PCR) amplification followed by Sanger sequencing.

Results

The quantitative HBsAg level was significantly higher in the pre-S1 positive group than that in the pre-S1 negative group (Z=-15.983, P<0.001). The positive rate of pre-S1 increased significantly with the increase in HBsAg level (χ 2=317.963, P<0.001) and HBV DNA load (χ 2=15.745, P<0.001). The pre-S1 negative group had a higher HCC risk than the pre-S1 positive group (Z=-2.00, P=0.045, OR=1.61). Moreover, patients in the sustained pre-S1 negative group had a higher HCC risk (Z=-2.56, P=0.011, OR=7.12) than those in the sustained pre-S1 positive group. The sequencing results revealed mutations in the pre-S1 region from samples of pre-S1 negative patients, including frameshift and deletion mutations.

Conclusion

Pre-S1 is a biomarker that indicates the presence and replication of HBV. Pre-S1 sustained negativity attributed to pre-S1 mutations in CHB patients may be associated with a higher risk of HCC, which has clinical significance and warrant further investigations.

In vitro characterization of six hepatitis B virus genotypes from clinical isolates using transfecting linear HBV genomes

Hepatitis B virus (HBV) infection is a global public health problem with about 257 million chronically infected people and over 887000 deaths annually. In this study, 32 whole HBV genomes of various genotypes were amplified from clinical isolates to create transfection clones. The clones were sequenced, and their biological properties characterized by transfecting linear HBV clones into HepG2 cells. We analysed the SPI and SPII promotor regions, X-gene, BCP/PC sequences, core, preS/S and HBV polymerase sequences. HBV clones analysed in this study revealed differential replication kinetics of viral nucleic acids and expression of proteins. Sequence analysis of HBV clones revealed mutations in preS1, preS2 and S genes; deletion and insertion and point mutations in BCP/PC region; including novel and previously reported mutations. Among the patient samples tested, HBV genotype B clones were more likely to have higher frequencies of mutations, while sub-genotype A1 and A2 clones tended to have fewer mutations. No polymerase drug resistant mutations were seen. HBeAg mutations were primarily in the BCP/PC region in genotype B, but core truncations were found in genotype E. S gene mutations affecting HBsAg expression and detection were seen in all genotypes except A2. Using an HBV clone with repetitive terminal sequences and a SapI restriction site allowed us to analyse HBV analyte production in cell culture and characterize the genetics of viral phenotypes using complete HBV genomes isolated from serum/plasma samples of infected patients.

Meta-analysis: Association between hepatitis B virus preS mutation and hepatocellular carcinoma risk

Previous observational studies suggested that hepatitis B virus (HBV) preS mutation plays an important role in the existence of HBV-related hepatocellular carcinoma (HCC). However, the results are still debatable. With an increasing number of studies about this topic, this study employed a meta-analysis to identify the association between HBV preS mutation and HCC risk. We searched for eligible studies from PubMed, ProQuest, CINAHL, ScienceDirect and Springer databases to assess the association between HBV mutation and HCC risk. This meta-analysis was conducted using RevMan 5.3 to provide pooled estimate for odds ratio (ORs) with 95% confidence intervals (95% CIs). Twenty-one clinical studies were included in this meta-analysis study which consisted of 1738 participants with HBV-related HCC and 3740 HBsAg-positive patients without HCC. All studies used samples of Asian population. PreS deletion was the most common mutation found in all studies. We found that ORs of HBV overall preS deletion was associated with HCC (OR = 3.28; 95% CI = 2.32-4.65; P < .00001; random-effects model). Each preS1 and preS2 deletion was associated with increased risk of HCC, with OR 2.42 (95% CI = 1.25-4.68, P = .008) and 3.36 (95% CI = 2.04-5.55, P < .00001), respectively. PreS2 start codon mutation was also significantly associated with HCC risk (OR = 2.47; 95% CI: 1.15-5.27; P = .02; random-effect model). The result of this meta-analysis suggested that HBV preS deletion (all, preS1 and preS2) and preS2 start codon mutation might contribute to the increased risk of HBV-related HCC.

In silico functional and structural characterization of hepatitis B virus PreS/S-gene in Iranian patients infected with chronic hepatitis B virus genotype D

Objective

Chronic hepatitis B (CHB) virus infection is the most prevalent chronic liver disease and has become a serious threat to human health. In this study, we attempted to specify and predict several properties including physicochemical, mutation sites, B-cell epitopes, phosphorylation sites, N-link, O-link glycosylation sites, and protein structures of S protein isolated from Ahvaz.

Materials and methods

Initially, hepatitis B virus DNA (HBV DNA) was extracted from five sera samples of untreated chronic hepatitis B patients. The full-length HBV genomes were amplified and then cloned in pTZ57 R/T vector. The full sequences of HBV were registered in the GenBank with accessions numbers (MK355500), (MK355501) and (MK693107-9). PROTSCALE, Expasy's ProtParam, immuneepitope, ABCpred, BcePred, Bepipred, Algpred, VaxiJen, SCRATCH, DiANNA, plus a number of online analytical processing tools were used to analyse and predict the preS/S gene of genotype D sequences. The present study is the first analytical research on samples obtained from Ahvaz.

Results

We found major hydrophilic region (MHR) mutations at "a" determining region that included K122R, N131T, F134Y, P142L, and T126N mutations. Moreover, Ahvaz sequences revealed four sites (4, 112, 166, and 309) in the preS/S gene for N-glycosylation that could possibly be a potential target for anti-HBV therapy.

Conclusion

In the present study, mutations were identified at positions T113S and N131T within the MHR region of S protein; these mutations can potentially decrease the effect of hepatitis B vaccination in vaccine recipients.