Gretch D R, Polyak S J, Wilson J J, Carithers R L, Perkins J D, Corey L
Department of Laboratory Medicine, University of Washington Medical Center, Seattle 98195, USA.
J Virol. 1996 Nov;70(11):7622-31. doi: 10.1128/JVI.70.11.7622-7631.1996.
To evaluate the possibility that distinct viral quasispecies play a role in the pathogenesis of progressive hepatitis C virus (HCV) infection, we performed a detailed evaluation of HCV quasispecies before and after liver transplantation in five patients infected with HCV genotype 1, three of whom developed severe recurrent hepatitis C and two of whom developed asymptomatic posttransplant infections with high-titered viremia. HCV quasispecies were characterized by using a combination of nucleotide sequencing plus heteroduplex tracking assay of the second envelope gene hypervariable region (HVR). An average of 30 HVR clones were analyzed per specimen; an average of five specimens were analyzed per patient over a 6- to 24-month study period. The complexity of HCV quasispecies in pretransplant serum varied, ranging from one to nine genetically distinct variants for the five patients. However, in all five cases, relatively homogenous quasispecies variants emerged after liver transplantation. In the three patients who developed recurrent hepatitis, quasispecies major variants present in pretransplant serum were efficiently propagated immediately after liver transplantation and were propagated throughout the course of acute and chronic hepatitis. In contrast, in the two asymptomatic cases, we observed rapid depletion of pretransplant quasispecies major variants from posttransplant serum, followed by emergence of new quasispecies variants by posttransplant day 30. Genetic analysis suggested that in these cases, the new quasispecies variants were derived from minor variants present at relatively low clonal frequency (less than 5% of HVR clones) within the pretransplant quasispecies populations. These data demonstrate that quasispecies tracking patterns are associated with the rapidity and severity of HCV-associated liver disease after liver transplantation. Further characterization of HCV quasispecies in animal model systems is warranted.
为评估不同的病毒准种是否在丙型肝炎病毒（HCV）进行性感染的发病机制中起作用，我们对5例感染HCV 1型的患者在肝移植前后的HCV准种进行了详细评估，其中3例发生了严重的复发性丙型肝炎，2例发生了无症状的移植后高滴度病毒血症感染。通过结合核苷酸测序和第二包膜基因高变区（HVR）的异源双链追踪分析来鉴定HCV准种。每个标本平均分析30个HVR克隆；在6至24个月的研究期间，每位患者平均分析5个标本。移植前血清中HCV准种的复杂性各不相同，5例患者中基因上不同的变体从1种到9种不等。然而，在所有5例病例中，肝移植后出现了相对均一的准种变体。在发生复发性肝炎的3例患者中，移植前血清中存在的准种主要变体在肝移植后立即有效地增殖，并在急性和慢性肝炎过程中持续增殖。相比之下，在2例无症状病例中，我们观察到移植后血清中移植前准种主要变体迅速消失，随后在移植后第30天出现新的准种变体。基因分析表明，在这些病例中，新的准种变体源自移植前准种群体中克隆频率相对较低（低于HVR克隆的5%）的次要变体。这些数据表明，准种追踪模式与肝移植后HCV相关肝病的快速性和严重性相关。有必要在动物模型系统中进一步鉴定HCV准种。
