Hepatitis C virus intracellular host interactions

Abstract

Hepatitis C virus (HCV) infects about 170 million people worldwide causing a major healthcare problem. The virus lifecycle is greatly dependent on the host-cell for effective replication. In this thesis, the intracellular interactions of the non-structural HCV proteins with the host-cell were investigated. NS4b, the non-structural protein responsible for the induction of intracellular membrane alterations, was demonstrated to associate to membranes via its C-terminal tail. This attachment to the membrane is similar to the bacterial protein d-LDH, i.e. through positive residues (amino acid side chains) with the negative headgroups of lipids. The NS3 protein was examined for post-translational modifications and we observed phosphorylation of this viral protein. Furthermore, NS3 interacting host-cell proteins were isolated. GLT25D1, which galactosylates collagenous proteins, was shown to be an NS3 associated protein. Additionally, GLT25D1 was shown to be a soluble luminal ER-protein, suggesting galactosylation of collagenous proteins takes place in the ER. Together this thesis exemplifies that the virus interacts in many ways with the host-cell (protein-protein and protein-membrane) and that regulatory mechanisms could be present (phosphorylation).