The role of scavenger receptor BI in hepatitis - eTheses Repository ...

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4 Results: Scavenger Receptor BI and BII Expression Levels Modulate
HCV Infectivity.
We aimed to use the tools developed during the previous chapter to
investigate the importance of SR-BI/II in HCV infection. To address this it was
necessary to carry out work using the recently developed HCVcc system.
4.1 Over expression of SR-BI/II in Huh-7.5 cells.
Huh-7.5 cells are a human hepatoma cell line isolated by Keril Blight and co-
workers that are highly permissive to HCV replication (37). They contain a
mutation in the retinoic acid-inducible gene I, which encodes a protein
responsible for detection of intracellular viral RNA, an important component in
the Interferon induction pathway (299, 345). As a result HCVcc can establish
a robust and prolonged infection of these cells.
Koutsoudakis et. al. established that HCV infection of Huh-7.5 cells is
dependent on a critical level of CD81 expression and that susceptibility to
HCV increased at higher CD81 density (159). We aimed to investigate
whether this was the case for SR-BI. However, at the present time there are
no human hepatoma cell lines that do not express SR-BI. Moreover, our
attempts to silence SR-BI using siRNA targeting have been unsuccessful
(data not shown) and previous studies suggest that it is an inappropriate tool
for investigating HCV entry (171, 326). Therefore to study HCVcc dependence
on SR-BI/II expression levels we employed the TRIP lentivirus system,
validated earlier (page 105), to over express SR-BI and II in Huh-7.5 cells.