Dynamics of defective hepatitis C virus clones in reinfected liver grafts 1 in liver transplant recipients ; ultra - deep sequencing analysis

22 23 Hepatitis C virus (HCV) reinfects liver allografts in transplant recipients, replicating 24 immediately after transplantation, followed by a rapid increase in serum HCV RNA 25 levels. We evaluated dynamic changes in the viral genetic complexity after HCV 26 reinfection of the graft liver and identified the characteristics of replicating HCV clones 27 using a massive-parallel ultra-deep sequencing technique to determine full-genome 28 HCV sequences in the liver and serum of five transplant recipients with genotype 1b 29 HCV infection before and after liver transplantation. Recipients showed extremely high 30 genetic heterogeneity before transplantation, and the HCV population was not 31 significantly different between the liver and serum of each individual. Viral quasispecies 32 complexity in the serum was significantly lower after liver transplantation than before, 33 suggesting that specific HCV clones selectively proliferated after transplantation. 34 Defective HCV clones lacking the structural region of the HCV genome did not increase 35 and full-genome HCV clones selectively increased immediately after liver 36 transplantation. Re-increase of the same defective clone existing before transplantation 37 was detected 22 months after transplantation in one patient. Ultra-deep sequencing 38 technology revealed reduced genetic heterogeneity of HCV after liver transplantation. 39 Dynamic changes in defective HCV clones after liver transplantation indicate that these 40 clones have important roles in the HCV life cycle. 41 42