receptors, including tetraspanin CD81 and the high density
lipoprotein receptor scavenger receptor class B type I (SRBI).
39 It was reported that these two receptors are not sufficient
for HCV entry and that more host proteins are involved.40
CLDN1 is a transmembrane protein and belongs to a family of
tight junction proteins that act as a barrier in cellular
permeability.41 It has been proposed that during the course
of HCV entry, CLDN1 interacts with CD81 and influences the
cell entry process, including endocytosis.42 Although direct
binding between HCV particles and CLDN1 has not been
conclusively demonstrated, it has been shown that monoclonal
anti-CLDN1 antibodies prevent HCV infection.43 The peptide
sequence VFDSLL, which is likely to interact with MA026, is
conserved in the first extracellular loop (EL1) of CLDN1, and
this loop is required for HCV entry.37 The SPR analysis showed
an interaction between MA026 and CLDN1-GST, and this
result supports our hypothesis that MA026 might interact with
CLDN1 and thereby prevent CLDN1 from interacting with
CD81 and the HCV particle.