Lee Chang Hong, Kim Soo-Ok, Byun Kwan Soo, Moon Myung Soon, Kim Eun-Ok, Yeon Jong Eun, Yoo Wangdon, Hong Sun Pyo
Department of Internal Medicine, Konkuk University Medical College, Seoul, Korea.
Gastroenterology. 2006 Apr;130(4):1144-52. doi: 10.1053/j.gastro.2006.01.005.
BACKGROUND & AIMS: Hepatitis B virus (HBV) tyrosine, methionine, aspartate, aspartate (YMDD) mutants with or without additional compensatory mutations occur in chronically infected patients during lamivudine therapy and may be associated with accompanying viral breakthrough. The aim of this study was to determine whether a predominance of YMDD mutants could be a prognostic marker for occurrence of viral DNA breakthrough.
YMDD genotypes in 740 consecutive samples collected from 116 patients throughout lamivudine treatment were retrospectively analyzed using a matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS)-based genotyping assay, termed restriction fragment mass polymorphism (RFMP). RFMP exploits differences in molecular masses between wild-type and variant bases of rtM204V/I following PCR amplification of HBV DNA with a lower limit of detection being 100 copies/mL.
The study demonstrated that YMDD mutants occur throughout the course of lamivudine therapy irrespective of occurrence of viral DNA breakthrough, indicating that a mere detection of YMDD mutants could not sufficiently predict the viral DNA breakthrough, although presence of YMDD mutants is associated with high incidence of viral DNA breakthrough (odds ratio, 7.8; P = .0012; relative risk = 8.7%), and a 5-fold predominance of YMDD mutant to wild-type virus was significantly associated with viral DNA breakthrough (odds ratio, 604.5; P < .0001; relative risk = 93.8%).
Close and periodical testing by RFMP assay should be useful to detect the predominance of YMDD mutants for monitoring drug resistance, enabling early intervention and prevention.
慢性感染患者在拉米夫定治疗期间会出现带有或不带有额外补偿性突变的乙肝病毒（HBV）酪氨酸、甲硫氨酸、天冬氨酸、天冬氨酸（YMDD）突变体，这些突变体可能与随后的病毒突破有关。本研究的目的是确定YMDD突变体占优势是否可作为病毒DNA突破发生的预后标志物。
使用基于基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF MS）的基因分型检测方法，即限制性片段质量多态性（RFMP），对116例患者在整个拉米夫定治疗期间连续收集的740份样本中的YMDD基因型进行回顾性分析。RFMP利用在对HBV DNA进行PCR扩增后，rtM204V/I野生型和变异型碱基之间分子量的差异，检测下限为100拷贝/毫升。
该研究表明，无论病毒DNA是否突破，YMDD突变体在拉米夫定治疗过程中均会出现，这表明仅检测到YMDD突变体并不能充分预测病毒DNA突破，尽管YMDD突变体的存在与病毒DNA突破的高发生率相关（优势比，7.8；P = 0.0012；相对风险 = 8.7%），并且YMDD突变体与野生型病毒的比例达到5倍时与病毒DNA突破显著相关（优势比，604.5；P < 0.0001；相对风险 = 93.8%）。
通过RFMP检测进行密切和定期检测，对于检测YMDD突变体占优势以监测耐药性、实现早期干预和预防应该是有用的。
