Interspousal transmission of hepatitis C virus: Application of comparing the variability of HVR1 nucleotide region

Background/Aims: The interspousal transmission of hepatitis C virus (HCV) has been a controversial issue in previous studies. We thus aim to investigate the possibility of HCV transmission between spouses by comparing the variability of HCV hypervariable region 1 (HVR1) between spouses and non-spouses. Methodology: Four spouses both positive for anti-HCV antibody and HCV RNA were enrolled in our study. Reverse transcriptional polymerase chain reaction (PCR) of HVR1 region was done from each patient for blood samples. The amplified PCR products were molecularly cloned, and eight to ten clones from each patient were analyzed. In addition to the phylogenetic analysis, comparing the variability of nucleotide and deduced amino acid sequences of HVR1 and outside HVR1 from these clones by a computer software program PHYLIP version 3.57 was performed in each patient, between spouse and among non-family patients. Results: All eight patients were infected with genotype Ib HCV. The sequences of eight to ten clones of HCV HVR1 in each patient showed quasispecies nature of HCV. Moreover, the variabilities of nucleotide sequence and deduced amino acid sequence of HVR1 were much higher than those outside of HVR1. Between spouses, the variabilities of HVR1 were significantly lower (p<0.001) than those of non-family members in 3 of 4 families. Clones of the same patient displayed the closest relationship in the phylogenetic tree. In addition, spouses of three families showed a closer relationship than other non-family patients. Conclusions: This study strongly suggests that sexual transmission does exist, which can be confirmed by comparing the variability of HVR1 nucleotide region of HCV.