Pai S Balakrishna, Bozdayi A Mithat, Pai Rekha B, Beker Tolunay, Sarioglu Mustafa, Turkyilmaz Ahmet R, Grier Jason, Yurdaydin Cihan, Schinazi Raymond F
Veterans Affairs Medical Center, Medical Research 151 H, 1670 Clairmont Road, Decatur, Georgia 30033, USA.
Antimicrob Agents Chemother. 2005 Jul;49(7):2618-24. doi: 10.1128/AAC.49.7.2618-2624.2005.
The emergence of resistance to lamivudine has been one of the major stumbling blocks to successful treatment and control of hepatitis B virus (HBV) infections. The major mechanism of resistance has been attributed to the alteration in the YMDD motif of the HBV polymerase due to an amino acid change of rtM204 to V/I and an accompanying rtL180M conversion. A novel mutation pattern in a patient having clinical breakthrough under lamivudine therapy was discovered. The mutant had a rtL180C/M204I genotype and was detected after 2 years of therapy with lamivudine. To characterize this novel variant, site-directed mutagenesis was performed using a vector construct containing the HBV genome. Transient transfection studies in human hepatoma cells with HBV carrying the new mutant demonstrated that the rtL180C/M204I mutant was resistant to lamivudine up to 10 microM. The resistance profile was comparable to that of the previously reported rtL180 M/M204I-containing virus. These observations were further confirmed by generation of stable cultures transfected with the mutant virus.
对拉米夫定产生耐药性一直是成功治疗和控制乙型肝炎病毒（HBV）感染的主要障碍之一。耐药的主要机制归因于HBV聚合酶YMDD基序的改变，这是由于rtM204氨基酸变为V/I以及伴随的rtL180M转换。在接受拉米夫定治疗出现临床突破的患者中发现了一种新的突变模式。该突变体具有rtL180C/M204I基因型，在接受拉米夫定治疗2年后被检测到。为了表征这种新变体，使用包含HBV基因组的载体构建体进行了定点诱变。用携带新突变体的HBV在人肝癌细胞中进行的瞬时转染研究表明，rtL180C/M204I突变体对高达10 microM的拉米夫定具有耐药性。其耐药谱与先前报道的含rtL180 M/M204I的病毒相当。用突变病毒转染产生稳定培养物进一步证实了这些观察结果。
