Detection by in situ hybridization of hepatitis C virus positive and negative RNA strands using digoxigenin-labeled cRNA probes in human liver cells

In situ hybridization was performed using cRNA probes on human liver biopsies to localize both positive and negative RNA strands of hepatitis C virus. From the 5′ non-coding region of the viral genome, 210 bp, were amplified by reverse transcriptase-polymerase chain reaction and cloned in a plasmid. Probes were produced by in vitro transcription, and labeled using digoxigenin-11-UTP. Positive HCV-RNA strands were detected in all 20 of the patients analyzed, whereas negative strands were detected in only nine patients, as confirmed using computerized image analysis. Both probes labeled the cytoplasm of hepatocytes with a perinuclear intensification. Few of the mononuclear cells infiltrating the portal connective space contained positive HCV-RNA strands only. Stacks of dilated endoplasmic reticulum cisternae were observed by electron microscopy and their relationship with the infection was discussed. This study confirmed that non-radioactive in situ hybridization represents a useful tool to analyze the localization and replication of hepatitis C virus in liver tissue.