Could resistant and escape variants of hepatitis B virus be a problem in the future?

Phylogenetic Analysis and Emerging Drug Resistance against Different Nucleoside Analogues in Hepatitis B Virus Positive Patients

Several nucleotide analogues have been approved for use in treating hepatitis B virus (HBV) infection. Long-term exposure to therapy leads to the emergence of mutations within the HBV DNA polymerase gene, resulting in drug resistance, a major factor contributing to therapy failure. Chronic HBV patients from the Khyber Pakhtunkhwa province, Pakistan, who had completed 6 months of therapy participated in this study. Samples were collected from 60 patients. In this study, the entire reverse transcriptase domain of the HBV polymerase gene was amplified using nested polymerase chain reaction and sequenced. Drug-resistant mutations were detected in nine (22.5%) patients. All of these patients had lamivudine-resistant mutations (rtM204V + L180M), while seven individuals (17.5%) had both lamivudine- plus entecavir-resistant mutations (L180M + M204V + S202G). N236T, a mutation that gives rise to tenofovir and adefovir resistance, was observed in two (5%) patients. T184A, a partial drug-resistant mutation to entecavir, was found in five (12.5%) patients. Furthermore, other genotypic variants (100%) and vaccine escape mutations (5%) were additionally observed. Moreover, pN459Y (35%), pN131D (20%), pL231S (20%), pP130Q (17.5%), pS189Q (12.5%), pP161S (5%), pH160P (2.5%), pT322S (2.5%), and pA223S (2.5%) mutations in the polymerase gene, as well as sA166V (17.5%), sQ181K (12.5%), sV184R (7.5%), sA17E (5%), sP153S/K (5%), sW156C (5%), sC76Y (2.5%), and S132F (2.5%) mutations in the small surface gene, were identified for the first time in this study. Phylogenetic analysis showed that genotype D was predominant amongst the HBV carriers. Subtype D1 was found in most patients, while two patients were subtype D9. These novel findings may contribute to the body of knowledge and have clinical significance for treating and curing HBV infections in Pakistan.

A chronic hepatitis B patient infected with HBsAg diagnostic-escape strain in the presence of anti-HBs positivity

Hepatitis B virus (HBV) is an important pathogen responsible for serious diseases like chronic hepatitis, cirrhosis and liver cancer. Turkey is located in the intermediate endemic region based on the average HBV surface antigen positivity. The high replication capacity of HBV and the lack of proofreading activity of the reverse transcriptase (RT) enzyme makes the virus prone to mutations. In this study, S gene mutation which is detected in a chronic HBV case without any follow-up and treatment is presented. Although patient was HBsAg negative and anti-HBs positive in the examinations, the mutation analysis was performed upon the high level of HBV DNA load and sG145R (vaccine escape) mutation in S gene region and rtI169F, rtV173L, rtA181G and rtT184R mutations in pol gene region were detected. S gene region mutations may cause false negatives in diagnostic assays that detect HBsAg. At the same time, it is a public health problem because these HBV variants can also be transmitted by vertical and horizontal routes. Therefore, when atypical serological profiles are encountered, it is of utmost importance to remember S gene mutations and perform necessary analyses.

Molecular Epidemiology of Hepatitis B Virus in Turkish Cypriot

There is an increased demand for molecular and epidemiological information regarding Hepatitis B Virus (HBV) infection as the disease severity depends on these specifications. We have aimed to analyze nucleos(t)ide analogues (NA) resistance and typical HBsAg escape mutations with the dispersion of HBV genotype/subgenotype/HBsAg serotypes on overlapping pol/S gene regions in the Turkish population. Samples were collected in Northern Cyprus. Reverse transcriptase (rt) region between 80–250 amino acids were amplified. Typical HBsAg escape mutations were determined as HBIg escape (6.48%), vaccine escape (8.34%), HBsAg misdiagnosis (9.25%), and immune escape mutations (8.34%). NAs resistances were determined as primary (2.78%), partial (2.78%), and compensatory mutations (26.85%) in overlapping pol/S gene region. The study patients were predominantly infected with HBV genotype D/D1 (98%). However, the predominant HBsAg serotype was ayw2 (99%). The most common NA resistance mutation was rtQ215H/P/S (16.67%), however, for S gene the misdiagnosis mutations were observed most frequently (9.25%). We can conclude that HBV D/D1 is the dominant strain and ayw2 is the dominant serotype in the Turkish Cypriot. Cyprus is an island located in the Eastern Mediterranean region, and it is, therefore, a key location for human trafficking and immigration; as a result of this reputation, it is necessary to analyze HBV phylogenetically for local dynamics, and our results indicate that treatment naïve population is prone to these pol/S gene mutations. However, if HBV strains were also analyzed among Greek Cypriots too, this would enable a complete island survey. With this work, we believe that we have enlightened this subject for further research.

Evaluation of the pol/S Gene Overlapping Mutations in Chronic Hepatitis B Patients in Northern Cyprus

Mutations associated with the pol and the S gene can emerge as a consequence of the high replication capacity and proofreading deficiencies of hepatitis B virus during replication. The current study was constructed to evaluate primary, partial, compensatory and the escape mutations in chronic hepatitis B patients in Northern Cyprus. The samples of HBsAg positive treatment naïve 100 patients were involved in this study. HBV pol gene region was sequenced, amplified and HBV pol/S gene mutations were determined. The samples of thirty-two patients were excluded because of their low viral load (HBV < 1000 ıu/ml). Among the sequenced 68 samples, there was a partial mutation (1.5%) and 36.7% displayed a resistance profile to lamivudine, adevofir, and telbivudine. Immune response escape, vaccine escape, HBIg and diagnosis escape mutations were determined in 24%, 10%, 6%, and 4% samples of the patients, respectively. Additionally, there were six different combined mutations. These data underscored that there is no concern for primary mutations in Northern Cyprus, however, we have identified a compensatory mutation (rtV173M) that may have primary mutation characteristics by combining with other mutation patterns. Additionally, HBsAg escape mutants demonstrated that detection of the S gene together with the pol gene mutations might be beneficial and important to monitor the surveillance of S variants.