Hepatitis B Virus Carrying Drug-resistance Compensatory Mutations in Chronically Infected Treatment-naive Patients

Objective: The prevalence of hepatitis B virus (HBV) is highly variable throughout the world. Geographical regions are classified according to the prevalence of hepatitis B surface antigen in the general population as high (>8%), moderate (2-7%), and low endemicity (<2%). Turkey has a moderate endemicity level of HBV infection which is a serious health problem. Currently, there are various nucleos(t)ide analogues with anti-HBV activity and they are mostly used in the treatment of chronic hepatitis B (CHB) and cirrhosis. The risk of drug resistance increases because these drugs are still being used as monotherapy. It has been reported that HBV drug resistance-related mutations can occur also in patients who are classified as treatment-naive and who have not received any oral anti-HBV treatment. Materials and Methods: This prospective and descriptive epidemiological study aimed to determine the genotype/subgenotypes of HBV and to investigate the drug resistance mutations in treatment-naive CHB patients. The study included 149 CHB patients who had no chronic co-infections, and have not received treatment for CHB infection. In 53 of the samples collected from the patients, the amount of viral DNA was enough for sequence analysis to search for drug resistance. BigDyeTM Terminator Cycle Sequencing Kit (Applied Biosystems, Foster City, Calif., USA) was used for sequencing of the serum samples from these patients and drug resistance mutations were determined and genotype/subgenotype detection was performed. Results: The mean viral load value was calculated as 9.84x10(6), and there was no primary drug resistance in any of these 53 samples which were sequenced. There were compensatory resistance-related amino acid changes in 19 samples. Genotype D was determined as HBV in all cases. Conclusion: The early detection of drug resistance-related mutations can be important in determination of treatment protocol, and prevention of unnecessary drug use, complications, and economic loses.