Useful Markers for Predicting in Vivo Infectivity of Hepatitis C Virus

Aiming to find useful markers for predicting the in vivo infectivity of hepatitis C virus (HCV), we investigated differences between inocula with high and low in vivo infectivity. Measurement of the genomic RNA titer by reverse transcriptase-polymerase chain reaction (RT-PCR) alone was not sufficient. However, combining RT-PCR with differential flotation in 1.063 g/ml solution, immunoprecipitation with anti-human immunoglobulin, as well as adsorption to HPB Ma cells (recently shown to support replication of HCV), appeared to have a high predictive value for estimating whether a sample will be highly infectious in vivo. Furthermore, rough estimation of the in vivo infectivity titer of a sample can be obtained from its in vitro infectivity titer measured in HPB Ma culture.