In 1989, we noted 90% of anti-HCV positivity among plasma donors of a commercial blood product-manufacturing unit. A common source of HCV infection was suspected. In the present study, molecular approach was used to confirm thecommon source of HCV infection in plasmapheresis unit. Of the 111 anti HCV positive samples collected in 1989 and stored at –20°C, 38 were scored HCV RNA positive. These were used for amplifying the hyper-variable region of HCV genome. All amplified products were sequenced. Based on phylogenetic analysis, of the 38 HCV RNA positive samples, 24 were classified as genotype 3 and remaining 14 belonged to genotype 1. The sub-genotype distribution was 3a (13), 3i (11) and 1b (14). High anti-HCV positivity in the plasmapheresis unit was not related to a single source of infection as suggested by us on the basis of serology but represented circulation of different distinct genotypes probably acquired through different transmission modes.
