Genetic evolution of structural region of hepatitis C virus in primary infection

AIM：To investigate the dynamics of hepatitis Cirus(HCV)variability through putative envelope genes during primary infection and the mechanism of viral genetic evolution in infected hosts.METHODS:Serial serum samples prospectively collected for12to34months from a cohort of acutely HCV-infected individuals were obtained,and a 1-kb fragment spanning E1and the5′half of e2,including Thirty-three cloned cDNAs representing each specimen were assessed by a method that combined a single-stranded conformational polymorphism(SSCP)and heteroduplex analysis(HDA)method to determine the number of clonotypes hypervariable region,was amplified by reverse transcriptase PCRand cloned.Nonsynonymous mutations per nonsynonymous site(dn),synonymous mutations per synonymous site(ds),dn/ds ratio and genetic distances within each sample were evaluated for intrahost evolutionary analysis.RESULTS:Quasispecies complexity and sequence diversity were lowen in early samples and a further increase after serocon version,although ds value in the envelope genes was higher than dn value during primary infection.The trend,pronounced in most of samples,toward lower ds values in the E1 than in the 5′portion of E2.Quasispecies complexity was higher and E2dn/ds ratio was a trend toward higher value in later asmples during persistent viremia,We also found individual features of HCV genetic evolution in different subjects who were infected with different HCV genotypes.CONCLUSION:Mutations of actively replicating virus arise stochastically with certain functional constaints.Aconplexity quasispecies exerted by a combination of either neutral evolution or selective forces shouws clear differences in individuals,and associated with HCV persistence.

AIM:To investigate the dynamics of hepatitis C virus (HCV)variability through putative envelope genes during primary infection and the mechanism of viral genetic evolution in infected hosts. METHODS:Serial serum samples prospectively collected for 12 to 34 months from a cohort of acutely HCV- infected individuals were obtained,and a 1-kb fragment spanning E1 and the 5' half of E2,including Thirty-three cloned cDNAs representing each specimen were assessed by a method that combined a single-stranded conformational polymorphism(SSCP)and heteroduplex analysis(HDA)method to determine the number of clonotypes hypervariable region,was amplified by reverse transcriptase PCR and cloned.Nonsynonymous mutations per nonsynonymous site(dn),synonymous mutations per synonymous site(ds),dn/ds ratio and genetic distances within each sample were evaluated for intrahost evolutionary analysis. RESULTS:Quasispecies complexity and sequence diversity were lower in early samples and a further increase after seroconversion,although ds value in the envelope genes was higher than dn value during primary infection.The trend,pronounced in most of samples,toward lower ds values in the E1 than in the 5' portion of E2.Quasispecies complexity was higher and E2 dn/ds ratio was a trend toward higher value in later samples during persistent viremia.We also found individual features of HCV genetic evolution in different subjects who were infected with different HCV genotypes. CONCLUSION:Mutations of actively replicating virus arise stochastically with certain functional constaints. A complexity quasispecies exerted by a combination of either neutral evolution or selective forces shows clear differences in individuals,and associated with HCV persistence.