Detection of Mutations in Chronic Hepatitis B Virus under Lamivudine Treatment: Direct Sequencing and CLIP Sequencing

Park, Hyunwoong; Kwon, Hye Lin; Song, Sang Hoon; Park, Kyoung Un; Song, Junghan; Park, Sung Sup; Kim, Eui Chong

Abstract

BACKGROUND
Hepatitis B Virus (HBV) is a major risk factor for hepatocellular carcinoma, and about five to six percents of people are infected with HBV in Korea. Lamivudine is a first-line drug having good control against HBV replication, but long-term treatment by lamivudine induces drug resistance. We analyzed the rate of HBV resistance mutation for lamivudine by direct sequencing and CLIP sequencing.
METHODS
HBV DNA was isolated from 371 patients who were in treatment, or were planning to be treated with lamivudine. The direct sequencing for lamivudine resistance mutation was performed in 371 patients and CLIP sequencing in 138 patients. We analyzed the mutation rate and the type of mutations for lamivudine resistance.
RESULTS
The mutation was detected in 203 patients (54.7%) and (CTG) L180M (ATG) was most common (36.1%) followed by (ATG) M204I (ATT) (29.9%) and (ATG) M204V (GTG) (18.6%). According to the duration of treatment, mutation rates were as follows: 45.3% for less than one year, 71.7% for one to two years, 66.7% for two to three years, and 87.9% for more than three years. The results of the direct sequencing and CLIP sequencing agreed in 134 out of 138 patients, in whom both tests were performed.
CONCLUSIONS
We confirmed that HBV mutation rates for lamivudine resistance increased as the lamivudine treatment period increased. The lamivudine resistance mutations detected were similar to the previous studies. CLIP sequencing showed good correlation with the direct sequencing and gave additional mutation information. CLIP sequencing is a promising tool for the detection of lamivudine resistance mutation in HBV that can assist treatment plans.