Naturally occurring polymerase and surface gene variants of hepatitis B virus in Turkish hemodialysis patients with chronic hepatitis B.

The aim of this study was to assess the frequencies and patterns of naturally occurring genotypic resistance to nucleos(t)ide analogues (NUCs) and typical hepatitis B surface antigen (HBsAg) amino acid substitutions in naive hemodialysis (HD) patients with chronic hepatitis B. In order to achieve this, the genotypic resistance to NUCs and HBsAg amino acid substitutions were classified into primary/compensatory resistance mutation and antiviral drug-associated potential vaccine-escape mutation (ADAPVEM)/typical HBsAg amino acid substitution, respectively. Direct sequencing of polymerase (pol) gene of hepatitis B virus (HBV) was performed on DNA samples obtained from 248 HBsAg-positive Turkish patients. Overall, 38% (n = 94) of HBsAg-positive HD patients had detectable HBV DNA in their serum. Naturally occurring primary and compensatory resistance mutations to NUCs were detected in 30% (n = 28) and 52% (n = 49) of HD patients, respectively. However, 6 types of ADAPVEMs and 48 types of typical HBsAg amino acid substitutions were found in 10.6% (n = 10) and 46% (n = 43) of the HD patients, respectively. Our study suggests that every HD patient diagnosed with chronic hepatitis B, who is a potential candidate for NUCs treatment, should also be monitored for the baseline pol gene sequence changes before the initial treatment, for a more effective management of future treatment options. Further, a relatively higher frequency of ADAPVEMs variants needs to be addressed as a public health problem.