不良结局家族聚集性乙型肝炎病毒感染者HBV基因型/亚型及前C/C启动子区变异特征分析

Characteristics of HBV genotype/subgenotype and mutations in precore/core promoter region in patients suffering from family clustering HBV infection with unfavorable prognosis

目的:分析不良结局家族聚集性乙型肝炎病毒(Hepatitis B virus,HBV)感染者HBV基因亚型和前C/C启动子(Corepromoter,CP)区变异特征。方法:选择101名不良结局家族聚集性HBV感染者为实验组,92名无明显家族聚集性的慢性HBV感染者作对照,用巢氏PCR及直接测序法检测基因亚型及前C/CP区变异位点,比较实验组和对照组的不同基因亚型构成比率及前C/CP区核苷酸变异频率,分析实验组HBV基因亚型及热点变异与临床疾病谱的关系。结果:在实验组和对照组中,Ba均为优势基因亚型,其次为C2、C1亚型,仅在实验组检测出1例Bj亚型。C基因型在实验组中构成比率显著高于对照组(P<0.01);实验组83.3%(5/6)感染C1基因亚型的患者发生肝硬化和(或)肝癌(Liver cirrhosis/hepatocellular carcinoma,LC/HCC),明显高于Ba(29.9%,P<0.01)和C2亚型(11.8%,P<0.01);各位点变异频率在2组中无明显差异(P>0.05);实验组17个位点发生变异,其中A1752、A1775、G1899位点变异在无症状HBV携带者(Asymptomatic carriers,ASC)、慢性乙型肝炎(Chronic hepatitisB,CHB)、慢性重型乙型肝炎(Chronic severe hepatitis B,CSHB)及LC/HCC组间分布差异均无统计学意义(P>0.05);随着病情加重,T1753、A1762、G1764、A1846、G1896位点变异率在ASC、CHB、CSHB和LC/HCC组中呈逐渐增加的趋势。LC/HCC组A1762T/G1764A双突变率及A1762T/G1764A/1896A三联变异率显著高于ASC组(P<0.01)。结论:本地区,不良结局家族聚集性HBV感染者C基因型患者构成比率增加,C1基因亚型及前C/CP区多个位点变异可能与慢性HBV感染者不良结局相关。

Objective：To study the characteristics of HBV genotype/subgenotype and mutations in precore/core promoter（CP）region in chronic HBV-infected patients suffering from HBV clustering infection families with unfavorable prognosis and to analyze its cor relation with the outcome of HBV infection.Methods：A total of 101 family clustering chronic HBV infected patients with unfavorable prognosis were enrolled in this study,including 31 cases of asymptomatic carriers（ASC）,27 cases of chronic hepatitis B（CHB）,13 cases of chronic severe hepatitis B（CSHB）,30 cases of liver cirrhosis and/or hepatocellular carcinoma（LC/HCC）and 92 CHB patients without family assemble features were taken as control group.HBV genotype/subgenotypes and mutations in precore/CP region of all samples were determined by nested-PCR combined with direct nucleotide sequence analysis.Results：Subgenotype Ba was predominant in both experimental group and control group,followed by C2 and C1,only 1 subgenotype Bj was detected in experimental group.The prevalence of genotype C was dramatically higher and Ba was significant lower in experimental group than in control group（P〈0.001）.In addition,patients infected with subgenotype C1 had higher prevalence of（LC/HCC）than patients infected with subgenotype Ba or C2（83.3% vs.29.9%,11.8%,P〈0.001）.There was no significant difference in the frequency of mutations in precore/CP region between the two groups.In experimental group,substitution mutations were detected at 17 sites,the variation rate in A1752,A1775,G1899 was not statistically different among ASC,CHB,CSHB and LC/HCC groups,while the prevalence of mutations in T1753,A1762,G1764,A1846,G1896 showed a trend of gradual increase along with diseases progression.In LC/HCC group,the frequencies of A1762T/G1764A double mutants and A1762T/G1764A/G1896A triple mutants were 73.3% and 36.7% respectively,obviously higher than those in ASC（22.6%,9.7%,P〈0.01）and CHB group（29.6%,P〈0.05）.Conclusions：The patients in experimental group show dramatically increased prevalence of genotype C infection.Subgenotype C1 and multiple-site mutations in precore/CP region may be associated with the poor prognosis after HBV infection.