丙型肝炎病毒非结构基因5b变异与干扰素治疗的相互影响

Interaction between variability of nonstructural gene5b of hepatitis C virus and interferon therapy

目的研究ＨＣＶ基因组的变异与干扰素治疗应答的关系以及干扰素治疗后患者体内病毒株的改变和变异。方法８例慢性丙型肝炎患者给予干扰素治疗，于治疗前及治疗后采集患者血清，扩增其血清中ＨＣＶ非结构基因５ｂ（ＮＳ５ｂ）区ｃＤＮＡ，克隆后，每例患者挑取６个克隆，测定重组子中ＮＳ５ｂｃＤＮＡ序列。结果４例患者在治疗后血清中ＨＣＶ阴性，为干扰素反应组，另４例于治疗中、治疗后血清中ＨＣＶＲＮＡ持续阳性，为非反应组。治疗前，反应组４例患者血清中分别含有１、１、１及３株ＨＣＶ，而非反应组４例患者血清中分别含有４、５、６及６株ＨＣＶ。与ＨＣ－Ｃ２或ＨＣ－Ｊ６相比，患者血清中ＨＣＶ的误义突变与无义突变之比在反应组为（１７．６１～３０．９５）％间，在非反应组为（３３．１１～７６．４７）％。治疗后，非反应组４例患者中，分别有２、３、４及４株ＨＣＶ被清除，各有２株ＨＣＶ存留于血清中。平均氨基酸变异数在消失病毒株与存留的病毒株中分别为４．３～５．５与５．５～９．０。有２株存留的病毒株在治疗后发生了突变，１株于２７２４位由甘氨酸突变为精氨酸，２７４２位由缬氨酸突变为丙氨酸。结论ＨＣＶ在准种及核苷酸水平上的变异均影响干扰素治疗的效果。干扰素治疗中?

Objective To investigate the relation between variability of hepatitis C virus (HCV) isolates and interferon therapy response, and analyze the change and mutation of HCV isolates after interferon therapy. Methods Eight patients with chronic hepatitis C were treated with interferon. Nonstructural gene 5b of HCV was amplified and cloned. Six HCV clones from each patient were sequenced before and after treatment. The patients were classified into two groups according to response or nonresponse to IFN. Results Before treatment , one to three isolates were found respectively from 4 responders, on the other hand, four , five, six, and six isolates respectively in 4 nonresponsers. By comparison with HC C2 or HC J6, the ratio of nonsynonymous to synonymous substitution ranges from 17.61% to 30.95% in responder group, but 33.11% to 76.47% in nonresponser group. The sequence of pre and post treatment were composed. And the comparison showed that average numbers of varying amino acid ranged from 5.5 to 9.0 among remaining isolates, and 4.3 to 5.5 among disappeared isolates. Moreover, two changed amino acids(G R and V I) were found in post treatment clones of patient B010 compared with it's pretreatment clones, and one (V A) in patient B024. Conclusions NS5b quasispecies as well as genetic heterogeneity correlate with IFN effectiveness. The heterogeneity of HCV in different hierarchical strata has common impact on IFN treatment in the same individuals. HCV elimination and mutation may occur alternatively during IFN therapy.