Distribution of hepatitis B virus genotypes in Europe and clinical implications: a review

Immune Escape and Drug Resistance Mutations in Patients with Hepatitis B Virus Infection: Clinical and Epidemiological Implications

Hepatitis B virus (HBV) genetic variability, shaped by high mutation rates and selective pressures, complicates its management and increases the emergence of drug-resistant and immune-escape variants. This study aims to analyze immune escape mutations (IEMs) and drug resistance mutations (DRMs) in patients with HBV infection exposed to antiviral therapies and exhibiting detectable plasma HBV viremia. This monocentric retrospective real-life study was carried out at the ASST Spedali Civili di Brescia, Italy, from 2015 to 2023. A total of 102 consecutive patients with detectable serum HBV-DNA exposed to at least one NA and for whom a drug resistance assay was available were included in our study. HBV sequences were amplified, sequenced, and analyzed for mutations using Geno2pheno and Stanford University tools. Phylogenetic analysis and statistical regression were performed to confirm genotypes and identify mutation patterns and associated risk factors. Our study shows a 38.2% prevalence of DRMs, with M204I/V (95%) and L180M (64%) being the most common, and a 43% prevalence of IEMs, primarily in the major hydrophilic region. Genotype D3 exhibited a higher mutation burden than other genotypes. Significant associations were found between HBsAb presence and increased IEM burden, while HBeAg was protective against DRMs. Atypical serological profiles were observed in 18.6% of patients, including cases of HBV reactivation under immunosuppressive therapy. This study highlights the high prevalence of IEMs and DRMs in a real-world setting, particularly among HBV genotype D3 carriers. These findings underscore the importance of mutation surveillance to guide therapeutic strategies, vaccine design, and public health policies to address the challenges posed by HBV genetic variability.

[The prevalence clinically significant virus mutations among patients with chronic viral hepatitis B.]

The prevalence of clinically significant virus mutations in patients with chronic viral hepatitis B from the Kyrgyz Republic was analyzed. Blood plasma samples of 64 patients with verified chronic viral hepatitis B obtained from Kyrgyzstan indigenous people were used in the work. Asymmetric PCR was carried out with extended oligonucleotides and the first reaction amplification product was further used in a new PCR with one of the nested pairs overlapping primers that flanked the entire HBV genome together, followed by sequencing. Based on the phylogenetic analysis of 64 HBV isolates obtained from patients from the Kyrgyz Republic, it was shown that only the genotype D virus was present in the examined group, the HBV subgenotype D1 (68.75%) prevailed compared with the HBV subgenotype D2 (18.75%) and subgenotype D3 (12.5%). For all subgenotypes, several independent infection sources are obvious, subclusters that include isolates from Kyrgyzstan, Kazakhstan and Uzbekistan are distinguished, as well as subclusters that include isolates only from Kyrgyzstan, which are less similar to isolates previously deposited in the international database, which probably indicates an independent HBV homologous evolution in the region. Clinically significant mutations were identified in 26.5% of patients. Including 12.5% with escape mutations that prevent the virus detection and / or allow the virus to replicate despite the vaccine (122K, 128V, 133I, 134N). Another 12.5% of the isolates are characterized by mutations that are independently associated with the liver cirrhosis and hepatocellular carcinoma development, including 21, 24, 27 nucleotides deletions in the Pre-S2 region and the S11F mutation in the PreCore region. In one case, unusual 236S and 250P mutations were found in the positions described as drug resistance sites of the P region associated with the resistance development to adefovir, tenofovir, and entecavir. The hepatitis B virus genetic structure analysis, early virus mutations detection in patients with chronic hepatitis B virus can help to choose the right vaccination strategy, antiviral and immunosuppressive therapy, as well as predict the clinical course and disease progression.

HBV genotypes circulation in pregnant women in Romania: a pilot study

Background: The risk of mother to child transmission of hepatitis B virus (HBV) is recognized worldwide, a reason for which the World Health Organization aims to reduce this public health issue of major concern in the next ten years. The aim of our study was to detect circulating HBV genotypes in a selected population of pregnant women, as scientific evidence to recommend personalized antiviral therapy and to obtain updated epidemiological information.

Methods: HBsAg positive pregnant women were selected by the National Institute of Public Health Romania. Blood samples were collected after signing the informed consent. The HBV genotypes were tested by INNO LiPA HBV genotyping method.

Results. The D genotype was detected in 9/18 (50%) patients, genotype A in 3/18 (16.7%), and genotype F in 3/18 (16.7%) patients. Three patients had double infection, 11 had unique infection, and 4 had no detectable genotype.

Conclusion. This study confirmed the results of previous studies regarding HBV genotype circulation in our country, with the mention that F genotype was a new one for our area. These data are useful from an epidemiological point of view and also for therapeutical reasons, as it is known that therapy should be genotype guided.