Abstract

Background:
Chronic hepatitis B (CHB) remains widely encountered in Turkey. We profiled mutations in the overlapping polymerase (pol) and surface (S) genes among adults with chronic hepatitis B virus (HBV) receiving or eligible for nucleos(t)ide analogs (NAs).

Aim:
To characterize pol/S overlap mutations in patients with chronic HBV receiving or eligible for NA therapy.

Methods:
In 2018, 93 hepatitis B surface antigen positive patients were enrolled at Kocaeli University Hospital in 2018. The pol/S overlap was amplified by nested polymerase chain reaction (PCR) and sequenced using Sanger methods. Genotypes and resistance/escape variants were inferred from the sequences. Comparisons were performed using Pearson’s chi-square or Mann–Whitney U tests (α = 0.05).

Results:
Genotyping was successful in 73/93 (78.5%). Genotype D predominated (n = 72); subgenotype were D1 (88.9%), D2 (6.9%), D3 (1.3%), and A2 (2.7%); one case belonged to genotype A. Pol variants were detected in 25/93 (26.9%), notably Q149K, L91I, V173L, L180M, M204I/V, S202G, and N236D. Sgene substitutions occurred in 20/93 (21.5%), most often W196L/S, E164D, G130R, Y134N, Q129H/R, and N131D. Mutation patterns were not associated with sex, age, or HBeAg status (all p > 0.05).

Conclusion:
In this Turkish cohort, genotype Debye was dominant, and pol and S substitutions were frequent. Routine regional genotyping with sustained molecular surveillance and, where possible, next-generation sequencings should inform antiviral selection and resistance monitoring.

Key words: Antiviral agents; Drug resistance; Gene mutations; Genotype D; Hepatitis B.