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

16
HCV targets and enters hepatocytes via at least 3 receptors; CD81,
scavenger receptor B-I (SR-BI) and claudin-1 (CLDN1) (91, 120, 179), this
process will be covered in section 1.4. After entry to the cytoplasm the HCV
genome acts as an mRNA for the production of a single 3000 amino acid
polyprotein. Unlike some Flaviviruses such as dengue, HCV lacks a 5’ cap
and as such initiates translation via an internal ribosomal entry site (IRES).
The IRES is found in the 5’ UTR and contains a series of RNA stem loop
structures which initiate translation by bringing the 40s ribosomal subunit into
contact with the viral start codon (18, 251, 318)
The polyprotein comprises 10 proteins, the structural proteins, Core, E1 and
E2 are found at the amino terminus and the non-structural proteins p7-NS5B
comprise the remainder. Upon its translation a series of trans-membrane
domains anchor the polyprotein to the endoplasmic reticulum (Figure 1-2)
(181, 241). There is an alternate reading frame within the HCV genome
whereby a ribosomal frameshift within the core region yields a series of
protein products of unknown function (46, 255).