丙型肝炎病毒1b亚型E2区序列与干扰素治疗应答的关系

Sequence analysis of E2 genes from Shanghai hepatitis C virus 1b isolates and its relation to response of interferon treatment

目的探讨上海地区丙型肝炎病毒(HCV)1b亚型感染者E2区的高变区1(HVR1)和高变区2(HVR2)、双链RNA激活的蛋白激酶真核翻译启动因子磷酸化同源区域(PePHD)及其邻近区域的基因序列与干扰素应答的相关性。方法收集上海地区24例HCV1b慢性感染者在α干扰素治疗前后及随访过程中的血清标本,用逆转录聚合酶链反应扩增E2区的HVR1、HVR2、PePHD及其邻近区域的基因并进行测序和氨基酸同源性分析。结果治疗前的HVR1区氨基酸序列高度变异,基于HVR1序列的种系发生树提示序列变化与干扰素应答类型无关。持续应答组(SR)、无应答组(NR)和复发组(TR)治疗前的HVR2区平均氨基酸变异数分别为2.0、1.0和1.5,统计学分析显示SR组与NR组差异有显著性(t=3.098,P<0.05)。治疗前的PePHD序列高度保守,无1例存在氨基酸变异。观察4例NR患者治疗过程中的PePHD序列,也未发现有任何氨基酸的突变。进一步比较PePHD邻近区域的氨基酸序列发现存在个别位点的变异(平均氨基酸变异SR组6.67,NR组5.75,TR组7.43),但变异的多少与疗效无关(SR组∶NR组t=1.413,P=0.195;SR组∶TR组t=1.706,P=1.107;TR组∶NR组t=0.682,P=0.504)。结论与HCVE2基因的HVR1区、PePHD区及其邻近区域序列与患者对干扰素的应答无相关性比较。

Objective To elucidate the relationship between the sequences of HCV E2 gene (including HVR1, HVR2, PePDH and flanking region) from Shanghai hepatitis C virus 1b isolates and the response of HCV patients to interferon (IFN α)therapy. Methods Sera from 24 patients with HCV 1b infection were collected before, during and after IFN α therapy. The dominant sequences of HCV E2 HVR1,E2 HVR2,PePHD and its flanking region(a.a.603 a.a.752) were determined. Phylogenetic tree analysis based on pretreatment HVR1 sequences was undertaken. Results The E2 HVR1 sequences from pre treatment sera were highly diverse among different isolates. Phylogenetic tree based on HVR1 sequences showed no correlation of the sequence variations with treatment response. The average amino acid mutations in sustained responders (SRs), non responders (NRs) and transient responders (TRs) within HVR2 region were 2.0 , 1.0 and 1.5 respectively. The frequency of mutations in SRs was significantly higher than that in NRs( t = 3.098 , P < 0.05 ). Mutation within PePHD sequences was not observed in any patient before treatment and the sequences did not change under interferon pressure in non responders. Several mutations occurred in PePHD flanking region, but there was no correlation between the mutations and therapeutic respouse(SRs∶NRs, t = 1.413 , P = 0.195 , >0.05 ; SRs∶TRs t = 1.706 , P = 1.107 ,> 0.05 ; TRs∶NRs t = 0.682 , P = 0.504 , >0.05 ). Conclusions While there is no correlation between the sequences of HVR1, PePDH and flanking region and the outcome of IFN treatment, mutation frequency with HVR2 region seemed to be related to treatment response and maybe be helpful in predicting the efficacy of IFN therapy.