Detection of hepatitis C virus positive and negative strand RNA in hematopoietic cells: correlation with viral load and genotype

As with other members of the hepatitis virus group, infection by hepatitis C virus (HCV) unambiguously targets cells of hepatic origin. The demonstrat ion of actual active replication targeting extra-hepatic cells such as hema topoietic cells has been more ambiguous. Published reports suggest that per ipheral blood mononuclear cells (PBMC) as well as possibly bone marrow cell s (BMC) could be the site of active replication [1-3], Two recent studies h ave explored factors that can be associated with artefactual (PCR) detectio n of genomic RNA in biological samples, in particular of the putative repli cation intermediate or negative strand RNA [3,4], Such factors predominantl y include the use of primers located in the highly structured 5' non-coding region (5'NCR) as well as the concentration of positive strand RNA in the biological sample studied that can result in self-priming and/or false-prim ing of templates. The definitive demonstration of the existence of extra-hepatic reservoirs s usceptible to viral replication and identification of factors (viral or cel lular) influencing such existence are obviously of primary interest. Conseq uences of extra-hepatic replication of HCV could be for example associated with a particular pattern of immune response, a particular infecting viral load or genotype, a particular pattern of response to antiviral treatment. We have started to address these issues using specific analytical tools dir ected at the detection of positive and negative strand viral RNA, the deter mination of viral load and viral genotype.