论文部分内容阅读
AIM:Quasispecies of hepatitis C virus (HCV) are thefoundation for rapid sequence evolution of HCV to evadeimmune surveillance of hosts.The consensus sequenceevolution of a segment of HCV NS3 region,which encompassesputative cytotoxic T cell epitopes,was evaluated.METHODS:Three male patients,infected with HCV throughmultiple transfusions,were identified from clinical symptomsand monitored by aminotransferase for 60 months.Bloodsamples taken at months 0,32,and 60 were used for viralRNA extraction.A segment of HCV NS3 region was amplifiedfrom the RNA extraction by RT-PCR and subjected tosubcloning and sequencing.HLA types of these threepatients were determined using complement-dependentmicrolymphocytotoxic assay.CTL epitopes were predictedusing MHC binding motifs.RESULTS:No patient had clinical symptoms or elevation ofaspartate/alanine aminotransferase.Two patients showedpositive HCV PCR results at all 3 time points.The otherone showed a positive HCV PCR result only at month 0.Areported HLA-A2-restricted CTL epitope had no alteration inthe HLA-A2-negative carrier over 60 months.In the HLA-A2-positive individuals,all the sequences from 0 month 0showed an amber mutation on the initial codon of theepitope.Most changes of consensus sequences in the samepatient occurred on predicted cytotoxic T cell epitopes.CONCLUSION:Amber mutation and changes of consensussequence in HCV NS3 region may be related to viral immuneescape.
AIM: Quasispecies of hepatitis C virus (HCV) are the foundation for rapid sequence evolution of HCV to evadeimmune surveillance of hosts.. The consensus sequence evolution of a segment of HCV NS3 region, which includes sequences of cytotoxic T cell epitopes, was was. METHODS: Three male patients , infected with HCV through multiple transfusions, were identified from clinical symptoms and monitored by aminotransferase for 60 months. Bloodsamples taken at months 0, 32, and 60 were used for viral RNA extraction. A segment of HCV NS3 region was amplified from the RNA extraction by RT-PCR and subjected tosubcloning and sequencing. HLA types of these three individuals were determined using complement-dependentmicrolymphocytotoxic assay. CTL epitopes were predicted using MHC binding motifs.RESULTS: No patient had clinical symptoms or elevation of aspartate / alanine aminotransferase. Two patients showed positive HCV PCR results at all 3 time points. the otherone showed a positive HCV PCR result only at month 0.Areported H LA-A2-restricted CTL epitope had no alteration inthe HLA-A2-negative carrier over 60 months. In the HLA-A2-positive individuals, all the sequences from 0 month 0 ago an amber mutation on the initial codon of the episode. Most changes of consensus sequences in the samepatient occurred on predicted cytotoxic T cell epitopes.CONCLUSION: Amber mutation and changes of consensus sequence in HCV NS3 region may be related to viral immuneescape.