摘要
目的 对比研究同一慢性乙型肝炎患者拉米夫定治疗前及病情急性恶化后乙型肝炎病毒 (HBV)株的结构基因组。方法 对治疗前及出现病情急性恶化后的慢性乙型肝炎患者的两株HBV全基因进行克隆、测序 ,分析各读码框架核苷酸和氨基酸的变化。结果 出现病情急性恶化后的HBV株与治疗前毒株比较 ,共有 30个氨基酸发生替代 (包括YMDD基序的M 5 5 0V变异和上游的L5 2 6M变异 ) ,P、X、S和PreC/Core 4个开放读码框架的替代氨基酸数 (变异率 )分别为 10 (1.2 % )、4(2 .6 % )、8(2 .0 % )和 8(3.8% ) ,氨基酸总变异率为 1.9%。其中 ,HBVPreC区的第 1898位核苷酸发生G→A变异 ,产生一个终止密码子 ,导致HBeAg缺失 ;PreS2的起始密码子出现ATG→ATA变异 ,可致PreS2表达缺陷 ;另有变异位点分布于已知CTL、B和T细胞的细胞表位。结论 对拉米夫定耐药并致病情急性恶化的HBV株在YMDD基序之处共有 2 9个氨基酸变异。
Objective To compare the structural genome variations of lamivudine resistant HBV strain from a patient with acute exacerbation after lamivudine therapy with pretretment HBV strain. Methods Full length genomes of two HBV strains before lamivudine treatment and after occurring severe acute exacerbation during lamivudine treatment were cloned and sequenced in a patient with chronic hepatitis B. Nucleotide sequence and predicted amino acid sequences of 4 open reading frames in two HBV strains were analyzed. Results Compared with pretreatment full length HBV genome, there were 30 amino acid substitutions in four ORFs of lamivudine resistant HBV strain, including substitution of valine for methionine at residue 550(M550V)accompanied by substitution of methionine for leucine at residue 526(L526M). The numbers of amino acid substitutions in ORF P, X, S, Precore/Core were 10(1.19%), 4(2.60%), 8( 2.00%) and 8 (3.77%) respectively. The total variation rate along the whole HBV genome was 1.86%. A G→A change at nucleotide position 1898 resulted in a precore stop codon and led to lack of HBeAg expression; At the preS2 initiation codon ATG was changed to ATA which caused the loss of preS2 protein expression. Some amino acid changes occurred within the known CTL, B or T cells epitopes.Conclusions In a patient with severe acute exacerbation during lamivudine therapy, together with 29 additional amino acid substitutions were detected outside the YMDD motif in the lamivudine resistant HBV strain.
出处
《中华传染病杂志》
CAS
CSCD
北大核心
2003年第4期260-264,共5页
Chinese Journal of Infectious Diseases
